362 results
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2. Note on certain recent papers on the so-called Golgi apparatus
- Author
-
John R. Baker
- Subjects
symbols.namesake ,Cells ,symbols ,Golgi Apparatus ,Humans ,General Medicine ,Golgi apparatus ,Biology ,Neuroscience - Published
- 1951
3. Control of Free Methionine Production in Wild Type and Ethionine-Resistant Mutants of Chlorella sorokiniana
- Author
-
Owens, Lowell D.
- Published
- 1974
4. In vitro experiments on gingival exudate measurements.
- Author
-
Leirskar, Jakob
- Subjects
EXUDATES & transudates ,PLEURA ,CELLS ,GINGIVAL fluid ,GAMMA globulins ,ALBUMINS ,INTERNAL migration - Abstract
A laboratory technique for measuring the mobility of solutions on filter paper has been presented. Various exudates exhibited different mobilities on filter paper; this also applied to exudates of the same origin (pleura punctates). When diluted, the exudates exhibited increased mobility, indicating that the concentrations of various exudate components were of importance. The addition of cells (5 × 10
6 and 25 × 106 P 388 D cells/ml exudate) did not significantly change the mobility, whereas the mobility of protein fractions (human albumin and gamma globulin) was inversely related to the concentration of the solutions. These findings may he of significance to the reliability of present methods used for the quantitation of gingival exudation. [ABSTRACT FROM AUTHOR]- Published
- 1971
- Full Text
- View/download PDF
5. The Magic Capsules.
- Subjects
COPYING ,CARBON copy ,COLORING matter ,CRAYONS ,EQUIPMENT & supplies - Abstract
The article focuses on the project by National Cash Register Co. in order to improve carbon copying. It states that research chief of the company Robert G. Chollar created capsules that can turn a white paper into blue. It also mentions that the company is building the capsules in various experimental products like the colorless crayon that marks on paper which can be magnetized and polarized.
- Published
- 1957
6. On the Potassium Management of the Yeast Cell in the Presence of Weak Acids.
- Author
-
Malm, Mignon
- Subjects
POTASSIUM ,CELLS ,ACIDS ,CHEMISTRY ,PERMEABILITY ,OSMOSIS - Abstract
Earlier investigations have shown that potassium emerges from the yeast cell when the latter is shaken in a NaF solution. The potassium emergence seems to be caused by changed electrostatic conditions in the cell. Fluoride penetrates into the cell in the form of undissociated hydrogen fluoride. In the cell HF dissociates to a large extent into fluoride and hydrogen ions. The more acid the solution surrounding the cells is the more hydrogen ions can be carried into the cells in this way. In an earlier paper, calculations showed that the pH in the cell can hereby be decreased considerably. The changed pH in the cell will surely influence the activity of the enzymes. As a result, non diffusible anions could be transformed to diffusible ones. In this way potassium, originally electrostatically attracted to non-diffusible anions, is set free and can leave the cell. If the hydrogen ions were responsible for the potassium emergence, one would expect that other weak acids would also cause a potassium loss from the cell, that is, acids which are able to penetrate into the cell and which are not attacked by the enzymes of the cell. The aim of the present work was to examine the influence of a number of weak acids on the potassium management of the cell. The following weak acids were examined: formic, acetic, propionic. butyric. isobutyric, lactic, β-hydroxy-butyric, succinic, tartaric and citric acid. The experiments showed that the permeation ability alone of the weak acids is not decisive for a potassium emergence. It was considered if the dissociation constant of the weak acids was decisive for the potassium emergence. It appeared that only those acids, whose dissociation constant are about 10
-4 cause a distinct potassium emergence. Acids with a dissociation constant about 10-5 seem already to be too weak. An increase in the concentration of these can, nevertheless, promote a potassium emergence. Independent of each other dr. H. Ussing and later professor E. J. Conway drew the author's attention to the possibility that potassium could perhaps leave the cell together with fluoride or formate ions as an ion pair. The size of the anions of the other acids, on the contrary, does not permit a permeation, and therefore causes no potassium emergence. Investigations on this subject will be presented in a coming paper. [ABSTRACT FROM AUTHOR]- Published
- 1950
- Full Text
- View/download PDF
7. Uptake and metabolism of 3′,5′-cyclic adenosine monophosphate and N6,O2′-dibutyryl 3′,5′-cyclic adenosine monophosphate in isolated bovine thyroid cells
- Author
-
Gerald Burke and M. Szabo
- Subjects
Chromatography, Paper ,Cells ,Cell ,Thyroid Gland ,Biophysics ,Tritium ,Biochemistry ,Phosphates ,chemistry.chemical_compound ,Cyclic AMP ,Extracellular ,medicine ,Animals ,Cyclic adenosine monophosphate ,Nucleotide ,Molecular Biology ,Incubation ,chemistry.chemical_classification ,Adenine Nucleotides ,Imidazoles ,Temperature ,Phosphorus Isotopes ,Biological Transport ,Metabolism ,Aminophylline ,Inosine ,In vitro ,Butyrates ,Kinetics ,medicine.anatomical_structure ,chemistry ,Hypoxanthines ,Cattle ,Mathematics ,Intracellular - Abstract
1. 1. Accumulation of intracellular radioactivity was measured during incubation of isolated bovine thyroid cells with cyclic [ 32 P]AMP, cyclic [8- 3 H]AMP and dibutyryl cyclic [8- 3 H]AMP. With cyclic [ 32 P]AMP, 32 P cell/medium ratios ranged from 0 to to 0.04 compared to a maximum 3 H cell/medium ratio of 0.29 with cyclic [ 3 H]AMP and 0.16 with dibutyryl cyclic [ 3 H]AMP. The excess of intracellular cyclic [ 3 H] over cyclic [ 32 P]AMP radioactivity was due to extracellular formation of more penetrable dephosphorylated cyclic AMP metabolites which probably served as precursor of intra-cellular cyclic AMP. 2. 2. Less than 10% of intracellular cyclic [ 32 P] of cyclic [ 3 H]AMP survived enzymatic degradation whereas only one-half of intracellular dibutyryl cyclic [ 3 H]AMP was degraded during a 60-min incubation. Nonetheless, these data indicate that incubation of cells with 3 mM cyclic AMP would result in intracellular cyclic AMP levels considerably higher than those measured in thyrotrophin-stimulated cells. 3. 3. Conclusions: (a) the ability of dibutyryl cyclic AMP to simulate TSH effects on thyroid in vitro , and the inability of cyclic AMP to do so do not appear to be due to the greater accumulation of the substituted nucleotide inside the cell, (b) although susceptibility of cyclic AMP to intracellular enzymic hydrolysis may account for its biological ineffectiveness, intracellular cyclic AMP levels achieved in the presence of exogenous cyclic AMP are of sufficient magnitude to warrant other considerations, and, (c) effects of dibutyryl cyclic AMP on thyroid in vitro may be due predominantly to the substituted nucleotide itself or to N 6 -monobutyryl cyclic AMP rather than to cyclic AMP formed by deacylation.
- Published
- 1972
8. The Enzymatic Activity of Aspirates of Preovulatory Human Follicles
- Author
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P. C. Steptoe, R. G. Edwards, and E. V. YoungLai
- Subjects
endocrine system ,medicine.medical_specialty ,Chromatography, Paper ,medicine.drug_class ,Cells ,media_common.quotation_subject ,Biology ,Tritium ,Chorionic Gonadotropin ,Mixed Function Oxygenases ,Human chorionic gonadotropin ,Follicle ,Ovarian Follicle ,Internal medicine ,Follicular phase ,medicine ,Humans ,Ovulation ,Progesterone ,media_common ,chemistry.chemical_classification ,Carbon Isotopes ,Hydroxysteroid Dehydrogenases ,General Medicine ,Enzyme ,Endocrinology ,chemistry ,Pregnenolone ,Female ,Follicle Stimulating Hormone ,Menopause ,Gonadotropin ,Gonadotropins ,medicine.drug - Abstract
Follicular contents were aspirated during laparoscopy just before ovulation from eight follicles from patients pretreated with human menopausal gonadotropin and human chorionic gonadotropin. The aspirates from each follicle were incubated for 1 h in a modified Tyrode B medium containing radioactive pregnenolone and progesterone in order to determine the relative efficiency of the 3β-hydroxysteroid dehydrogenase and 17α-hydroxylase systems. Labelled 17α-hydroxyprogesterone was not isolated but the conversion of pregnenolone to progesterone ranged from 9.9% to 45.4% of the recovered radioactivity.
- Published
- 1972
9. Free amino acids and nucleic acid content of cell nuclei isolated by a modification of Behrens' technique
- Author
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Garson H. Tishkoff, Alexander L. Dounce, Richard M. Freer, and Shirley R. Barnett
- Subjects
Alanine ,chemistry.chemical_classification ,Cell Nucleus ,Autolysis (biology) ,Cytoplasm ,Chromatography ,Physiology ,Chemistry ,Liver cell ,Cells ,Proteins ,Glutamic acid ,Hydrolysate ,Article ,Amino acid ,Rats ,Paper chromatography ,Biochemistry ,Nucleic Acids ,Nucleic acid ,Animals ,Amino Acids - Abstract
1. Nuclei were prepared from frozen rat liver by a modification of the technique of Behrens, and were studied with regard to the content of free amino acids and nucleic acid. 2. Under rigorously controlled conditions, preparations of nuclei are obtained by the Behrens' method which form a gel in the presence of 5 or 10 per cent NaCl or of water plus a small amount of dilute alkali; whereas when conditions are less rigorously controlled, nuclei are obtained which form no such gel. The property of forming gels with alkali is probably characteristic of all cell nuclei which have not undergone autolysis. 3. Nuclei prepared by the Behrens' technique contain the enzymes arginase, catalase, and esterase in very appreciable concentrations. 4. The free amino acids of the isolated cell nuclei, as well as of other liver cell fractions, have been investigated using the technique of paper chromatography. 5. The chromatographic patterns of the free amino acids of whole cells, ground cytoplasm, and isolated cell nuclei were very similar or identical. A feature of interest in these chromatograms was the faintness or absence of the spots due to a number of the essential amino acids, as compared to the intensities of the spots due to glycine, alanine, and glutamic acid. Glutathione was present in the isolated nuclei as well as in the whole cells. 6. Chromatograms made from hydrolysates of nuclei showed high concentrations of the essential amino acids and were similar to chromatograms of hydrolysates of typical proteins.
- Published
- 1950
10. Heterotrophic growth of the nitrogen fixing blue-green alga Nostoc muscorum
- Author
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A. H. El-Refai, M. A. Nashat, and H. M. Salem
- Subjects
Time Factors ,Chromatography, Paper ,Nitrogen ,Cells ,Carboxylic Acids ,General Medicine ,Cyanobacteria ,Applied Microbiology and Biotechnology ,Culture Media ,Glucose ,Plant Growth Regulators ,Nitrogen Fixation ,Genetics ,Carbohydrate Metabolism ,Citrates ,Amino Acids - Published
- 1974
11. N6-(delta2-isopentenyl)adenosine 5'-monophosphate: formation and effect on purine metabolism in cellular and enzymatic systems
- Author
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A Y, Divekar, H K, Slocum, and M T, Hakala
- Subjects
Time Factors ,Adenine Nucleotides ,Chromatography, Paper ,Cells ,Phosphotransferases ,Glycine ,Lyases ,Ketone Oxidoreductases ,Alkenes ,Adenosine Monophosphate ,Ligases ,Methotrexate ,Purines ,Hypoxanthines ,Animals ,Carbon Radioisotopes ,Pentosyltransferases ,Sarcoma 180 ,Inosine Nucleotides ,Cells, Cultured - Published
- 1974
12. Isolated adrenal cells: steroidogenesis and cyclic AMP accumulation in response to ACTH
- Author
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Robert J. Beall and George Sayers
- Subjects
endocrine system ,medicine.medical_specialty ,Chromatography, Paper ,Cells ,Biophysics ,Adrenocorticotropic hormone ,In Vitro Techniques ,Tritium ,Biochemistry ,chemistry.chemical_compound ,Adrenocorticotropic Hormone ,Corticosterone ,Internal medicine ,Adrenal Glands ,medicine ,Cyclic AMP ,Animals ,Molecular Biology ,Carbon Isotopes ,Adrenal cortex ,Adenine ,Low dose ,Chromatography, Ion Exchange ,Rats ,Kinetics ,medicine.anatomical_structure ,Endocrinology ,chemistry ,Second messenger system ,Barium Sulfate ,hormones, hormone substitutes, and hormone antagonists ,Protein Binding - Abstract
After the addition of 1000 μU of ACTH to isolated adrenal cells, accumulation of cyclic AMP preceded corticosterone production. This observation supports the thesis that cyclic AMP mediates the steroidogenic action of ACTH on the adrenal cortex. Alterations in the concentration of cyclic AMP and of corticosterone in cell suspensions exposed to various doses of ACTH may be described as follows: (1) low doses of ACTH (5–25 μU) stimulated steroidogenesis without causing detectable changes in the concentration of cyclic AMP; (2) intermediate doses of ACTH (50–250 μU) induced parallel increases in cyclic AMP and corticosterone accumulation; and (3) large doses of ACTH (250 – 10,000 μU) caused additional increases in the concentration of cyclic AMP without causing further increases in corticosterone accumulation. The bearing of these results on the second messenger theory is discussed.
- Published
- 1972
13. Micro-electrophoresis for RNA and DNA base analysis
- Author
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J E, Edström and V, Neuhoff
- Subjects
Brain Chemistry ,Electrophoresis ,Microscopy ,Staining and Labeling ,Chromatography, Paper ,Cells ,Microchemistry ,Histological Techniques ,DNA ,Micromanipulation ,Pyrimidines ,Evaluation Studies as Topic ,Purines ,Methods ,RNA ,Microscopy, Phase-Contrast ,Spectrophotometry, Ultraviolet ,Nerve Tissue ,Mathematics ,Subcellular Fractions - Published
- 1973
14. The dispersal of dermal cells with sodium dodecyl sulfate
- Author
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R. H. Pearce and B.J. Grimmer
- Subjects
Male ,Pathology ,medicine.medical_specialty ,Isotonic saline ,Chromatography, Paper ,Nitrogen ,Ultraviolet Rays ,Cells ,Sodium Chloride ,General Biochemistry, Genetics and Molecular Biology ,Surgical pathology ,chemistry.chemical_compound ,Surface-Active Agents ,medicine ,Animals ,Humans ,Trypsin ,General hospital ,Sodium dodecyl sulfate ,Glycosaminoglycans ,Skin ,business.industry ,Ground substance ,Sodium Dodecyl Sulfate ,Hexosamines ,Rats, Inbred Strains ,Rats ,Hydroxyproline ,Uronic Acids ,chemistry ,Spectrophotometry ,Fatty Alcohols ,business - Abstract
SummarySDS (5 mM) removes histologically detectable cells from skin previously freed of ground substance with isotonic saline. Such extracts correspond in composition to those produced by trypsin.The staff of the Surgical Pathology Service, Vancouver General Hospital, assisted in the collection of specimens. Mrs. B. Barkocsy prepared the histological sections.
- Published
- 1972
15. A Device for Preparing Cell Spreads.
- Author
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Doré, C. F. and Balfour, Brigid M.
- Subjects
CELLS ,BIOLOGY ,OVUM ,PHYSIOLOGY ,CYTOLOGY ,IMMUNOLOGY - Abstract
Describes a device for preparing cell spreads. Steps involved in preparing a suitable cell suspension; Features of the apparatus used in the process; Instrument's use of centrifugal force to speed up the sedimentation of the cells.
- Published
- 1965
16. THE RELATIONSHIP OF COMPARTMENTATION OF ORGANIC ACID METABOLISM TO BICARBONATE-ION SENSITIVITY OF ROOT GROWTH IN CALCICOLES AND CALCIFUGES.
- Author
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Lee, J. A. and Woolhouse, H. W.
- Subjects
GRASSES ,SPECIES ,AMINO acids ,CELLS ,METABOLISM ,SCIENTIFIC experimentation - Abstract
It was shown previously that cell elongation in the roots of certain calcifuge grasses was inhibited by concentrations of bicarbonate and malate which promoted cell elongation in relate calcicole species. The present paper reports experiments in which [2-[sup14]C]-acetate was supplied to excised roots of a calcifuge Deschampsia flexuosa and a calcicole species Arrhenatherum elatius. Time course studies of the pattern of [sup14]C incorporation into the organic and amino acids of th roots indicates an active tricarboxylic acid cycle in both species but differing in that in Deschampsia the respiratory malate pool was more completely compartmented from other malate pool in the cells, whereas in Arrhenatherum a progressive mixing of the malate pools occurred Treatment of roots with a pulse of [2-[sup14]C]-acetate followed by exposure to 10 m-equiv./I HCO[sup-,sub3] for 3 hours resulted in a substantial modification in the pattern of [sup14[C incorporation from acetate in Deschampsia but not in Arrhenatherum. The results are discussed in relation to the differential effects of bicarbonate on root growth in the two species. [ABSTRACT FROM AUTHOR]
- Published
- 1971
- Full Text
- View/download PDF
17. The Young Turks.
- Subjects
CONFERENCES & conventions ,MEDICAL societies ,PHAGOCYTOSIS ,HISTORY - Abstract
The article discusses the highlights of the meeting of the American Society for Clinical Investigation, held in October 1952 in Atlantic City, New Jersey. Doctor William Barry Wood Jr., professor of medicine at Washington University, discussed developments in medical research, practice and teaching. The history of the Society for Clinical Investigation since it was founded in 1908 is mentioned. Research on phagocytosis was also highlighted at the meeting.
- Published
- 1952
18. Method for Obtaining Wool Roots for Histochemical Examination
- Author
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William Ellis
- Subjects
Multidisciplinary ,genetic structures ,Plant roots ,Cells ,Wool ,chemical and pharmacologic phenomena ,Biology ,Pulp and paper industry ,Plant Roots ,eye diseases ,Animals ,Humans ,Wool fibre - Abstract
A USEFUL technique has been developed for obtaining moderately large samples of wool roots for histochemical examination. It is hoped that this technique will assist in elucidating the mode of formation of the wool fibre and also facilitate investigations already in progress in this laboratory, which are concerned with developing methods for removal of wool from sheepskins.
- Published
- 1948
19. Two Forms of the DNA Ligase of Human Cells.
- Author
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Pedrali Noy, Guido C. F., Spadari, Silvio, Ciarrocchi, Giovanni, Pedrini, Antonia M., and Falaschi, Arturo
- Subjects
NUCLEIC acids ,LIGASES ,ENZYMES ,BACILLUS subtilis ,BACILLUS (Bacteria) ,DNA ligases ,CELLS ,PROTEINS ,BIOCHEMISTRY - Abstract
We have further characterized the polynucleotide ligase purified from cultures of the human heteroploid line EUE [Spadari, Ciarrocchi and Falaschi, Eur. J. Biochem. 22, 75 (1971)]. The 350-fold purified enzyme gives positive response with four different assays; the rates with the different substrates are different, but the variations are identical to those observed with the purified ligase induced by T4-phage. The enzyme can reconstitute the transforming activity of Bacillus subtilis DNA inactivated by pancreatic DNAase. The human cell enzyme is unable to use a hybrid substrate where an interrupted polydeoxynucleotide is annealed to a polyribonucleotide, whereas in the same conditions the T4 enzyme gives appreciable activity. The partial dependence of the purified enzyme on proteins present in a boiled crude extract, reported in the previous paper, seems due to an aspecific protective effect of the soluble proteins of cell extracts. The enzyme does not show any appreciable sequence specificity in the phosphodiester bond it can form. The purified enzyme can be fractionated into two molecular forms, one having a molecular weight of 190000, the other 95000; fresh extracts of EUE cells contain almost exclusively the high molecular-weight form; ageing of the extract or purification lead to the appearance of the second peak, without variations in the total activity. This could correspond to the conversion of a dimer structure into a monomer. The “dimer” has a pH optimum close to 8.1, whereas the “monomer” has its optimum at 7.5; this explains the bimodal pH curve previously described in the purified enzyme. [ABSTRACT FROM AUTHOR]
- Published
- 1973
- Full Text
- View/download PDF
20. Nucleoside-Diphosphate Derivatives of 2-Deoxy-D-glucose in Animal Cells.
- Author
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Schmidt, Michael F. G., Schwarz, Ralph T., and Scholtissek, Christoph
- Subjects
NUCLEOSIDES ,PYROPHOSPHATES ,GLUCOSE ,CELLS ,ANIMALS - Abstract
After administration of
14 C-labelled 2-deoxy-D-glucose or ³H-labelled nucleosides to cells in tissue culture the following activated intermediates of the deoxysugar have been isolated and characterized: the 6-phosphate derivative, the 1-phosphate derivative, the 1,6-bisphosphate derivative. UDP-2-deoxy-D-glucose, GDP-2-deoxy-D-glucose and 2-deoxy-D-gluconic acid 6-phosphate. After extraction with acid and organic solvents. 2-deoxy-D-glucose could be recovered by acid hydrolysis from the cells. Labelled 2-deoxy-D-galactose was not found either bound to UDP or to the cells, indicating that no significant epimerisation of 2-deoxy-D-glucose at the UDP level occurred in these cells. [ABSTRACT FROM AUTHOR]- Published
- 1974
- Full Text
- View/download PDF
21. Relations between Structure and Function in Cytoplasmic Membrane Vesicles Isolated from an Escherichia coli Fatty-Acid Auxotroph.
- Author
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Shechter, Emanuel, Letellier, Lucienne, and Gulik-Krzywicki, Tadeusz
- Subjects
CELL membranes ,FATTY acids ,ESCHERICHIA coli ,CELLS ,BIOCHEMISTRY - Abstract
The results presented in this paper establish relationships between structural morphological and functional properties of cytoplasmic membrane vesicles isolated from an Escherichia coli unsaturated fatty acid auxotroph. The membranes were isolated from cells grown in the presence of either oleic, linoleic, linolenic or elaidic acids. High-angle X-ray diffraction studies show that the order-disorder transitions induced by temperature variations and associated with the paraffin chains of the lipids are a function of the fatty acid composition of the membranes. In some cases "cocrystallization" of various lipid species takes place within a single type of ordered domains. In other cases there is segregation of various lipid species into more than one distinct type of ordered domain. The various order-disorder transitions observed induce morphological changes in the hydrophobic core of the membranes which can be detected by freeze-etch electron microscopy. A random distribution of particles on the fracture faces is observed when the paraffin chains of the lipids are disordered. Upon ordering of the paraffin chains, particles are excluded from the ordered domains and as a consequence, smooth areas and areas with densely packed particles are observed. The ratio of the smooth surface to particulated surface is proportional to the amount of ordered paraffin chains present. Moreover, the size of the smooth domains is a function of the fatty acid composition of the membranes. Discontinuities in the rate of D-lactate-dependent proline uptake as a function of temperature correlate with the order-disorder transitions observed. The high energies of activation at low temperatures are attributed to decreased mobility of the carrier proteins upon aggregation. In contrast, phosphoenolpyruvate-dependent vectorial phosphorylation does not respond to the ordering of the paraffin chains. [ABSTRACT FROM AUTHOR]
- Published
- 1974
- Full Text
- View/download PDF
22. THE MACROPHAGE ELECTROPHORETIC MOBILITY (MEM) TEST FOR MALIGNANT DISEASE.
- Author
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Preece, A. W. and Ann Light, P.
- Subjects
MACROPHAGES ,ANTIGEN presenting cells ,PATIENTS ,CELLS ,CONNECTIVE tissue cells ,PHAGOCYTES ,RETICULO-endothelial system - Abstract
This paper describes further confirmation of the successful application of the macrophage electrophoretic mobility (MEM) test to the detection of malignant disease. Results from fifty-one patients and eighteen controls are presented. The apparatus and technique used for the measurement of macrophage elctrophoretic mobility differed from those previously used in other investigations. Further information is presented on the nature and behaviour of macrophage slowing factor(s), and experiments concerning the possible use of cells other than guinea-pig macrophages as indicators of slowing factor production are also described. [ABSTRACT FROM AUTHOR]
- Published
- 1974
23. Stratum corneum in psoriasis vulgaris. A transmission and scanning electron microscopic study.
- Author
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Brody, Isser, Mishima, Yutaka, and Matsunaka, Masahiro
- Subjects
SCANNING electron microscopy ,TRANSMISSION electron microscopy ,CYTOPLASM ,ELECTRONS ,CELLS ,SKIN - Abstract
This is a transmission and scanning electron microscopic study of stratum corneum in psoriasis vulgaris. In transmission electron microscopy numerous granules and vacuoles are observed. They display the same variations in size and shape and the same arrangement and distribution in the cytoplasm. They are also observed in the intercellular space. Both single and confluent granules and vacuoles occur. The granules contain either a rather opaque homogeneous or heterogeneous substance. Usually the vacuoles appear to be electron-optically empty, but many vacuoles containing substances similar to those in the granules are also found. The cell surfaces may be smooth, or they may show areas with numerous single excavations and excavations in rows, areas with distinct cytoplasmic protrusions and areas with a more regularly wavy shape. In scanning electron microscopy the cell surfaces may be predominantly smooth; they may display pores and areas with villi. Well-developed and low villi occur. In this paper it is suggested that the excavations along the cell surfaces are the result of an excretion of single and confluent granules and vacuoles into the intercellular space, and that the excavations may correspond to the poles and the distinct cytoplasmic protrusions to the well-developed villi. [ABSTRACT FROM AUTHOR]
- Published
- 1974
- Full Text
- View/download PDF
24. POLICE SCIENCE TECHNICAL ABSTRACTS AND NOTES.
- Author
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Williams, John F., Kirwan, William E., Schorr, C. A., O. H., E. W., and Nicol, Joseph D.
- Subjects
POLICE ,CHEMICALS ,SPECTROPHOTOMETRY ,CELLS - Abstract
This section presents technical abstracts on police science. In the article, Multiple Thickness Cell Assemblies--Application to Ultraviolet Spectrophotometry, D. D. Tunnicliff has devised multiple cell assemblies with cells of varying thicknesses to take advantage of varying cell length rather than concentrations in ultraviolet absorption spectrophotometry. The article, Plastic Vessel for pH Measurements of Small Samples, by Kenneth M. Richter, furnished dimensions and sketches of an adapter shaped to the Beckman standard electrodes for samples as small as 0.25 ml. A shoulder in one well of the adapter serves to prevent damage to the calomel electrode. The paper, Control of Fine Chemicals and Pharmaceuticals--Report for Analysts by W. B. Fortune, was presented at the Symposium on Analysis of Fine Chemicals and Pharmaceuticals at the American Chemical Society meeting in Atlantic City, New Jersey in September, 1956. The paper points out the increasingly difficult problems of identification and analysis of the many new drugs and chemicals being produced. Classical methods are inadequate, and new methods are hardly keeping pace with development and production of new products. Of particular interest to the Forensic Chemist or Criminalist are the comments about the need of applying confirmatory tests and not relying on single or inadequate identification tests.
- Published
- 1957
25. Eiweiss-Abbau durch Acridinorange bei Hefezellen.
- Author
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Bogen, Hans J. and Keser, Margarete
- Subjects
CHROMATOGRAPHIC analysis ,AMINO acids ,CELLS ,METHIONINE ,LEAVENING agents ,YEAST - Abstract
A quantitative estimation of nitrogen in baker's yeast (suspensions of 1 g. yeast in 50 and 500 ml. distilled water) by the Kjeldahl method shows that 80 per cent of the total N are incorporated in the insoluble protein fraction and 20 per cent are found in the fraction of free amino acids. &frac910; of the latter are remaining within the cells, and &frac110; appears in the surrounding medium. After killing the cells the major part of free amino acids is released into the fluid, while the protein, however, remains unaltered. After a 12 hour's treatment of the cell suspensions with the fluorescing dye acridine-orange (10
-1 g./l.), the protein fraction contains only 69 per cent (suspension 1: 50) and 30 per cent (suspension 1 : 500) of the total N. The fraction of free amino acids has increased to 31 and 70 per cent, respectively. The distribution of the amino acid N between the cells and the surrounding medium ist 28 % : 3 % (suspension 1 : 50) and 37 % : 33% (suspension 1 : 500). This indicates that the acridine-dye causes a breakdown of more than 60 per cent of the total protein and in increase of permeability, especially in the suspension I : 500 where each cell may accumulate greater amounts of the dye, in consequence of which the stained cells are killed. Protein breakdown is complete already after 1/2 hour, while exosmosis of the newly formed amino acids into the medium continues for many hours. Methyl green (10-4 g./l.) shows similar but weaker effects concerning the breakdown of proteins but does not increase the permeability. Combination of the two dyes shows additive effects concerning the break- down of proteins, while, on the other hand, methyl green protects the semi- permeability against the alteration by acridine. A qualitative study by means of paper chromatography on the amino acid content of living, killed, and stained cells shows no significant differences in the composition of the three fractions. Only the methionine content is altered: the protein of living and heat-killed yeast cells contains methionine, while the fraction of free amino acids is free of methionine. In acridine- treated cells; however, methionine disappears from the protein and is found in the fraction of free amino acids, thus indicating that there may exist several protein fractions in the cells which are differently affected by the dyes. It seems probable that, since acridine does not directly hydrolyze the proteins, it may act by blocking the protein turnover on the side of synthesis, while the normal breakdown continues, resulting in an accumulation of free amino acids. The first step of its action may consist in an adsorption on RNS-templates, as it is known for methyl green. Furthermore, acridine-orange, on account of `its toxicity, seems inadequate as an indicator for the discrimination between living and dead cells, as Strugger formerly has proposed. [ABSTRACT FROM AUTHOR]- Published
- 1954
- Full Text
- View/download PDF
26. STUDIES ON BOTTOM-LIVING ALGAE IN SOME LAKES OF THE ENGLISH LAKE DISTRICT.
- Author
-
Round, F. E.
- Subjects
DIATOMS ,ALGAE ,PHYTOPLANKTON ,CELLS ,FRESHWATER phytoplankton ,CRYPTOGAMS ,PLANTS ,AQUATIC resources ,LAKES - Abstract
The article discusses the study regarding the distribution of the Bacillariophyceae algae living on the sediments of some lakes of the English Lake District. The author mentions that the study measures the seasonal change in total diatom population and in certain genera by obtaining the summation of the counts of cell numbers of all species and other individual genera. The study confirms the reports of earlier papers that the benthic epipelic diatom community goes through distinct seasonal changes including low winter growth, high spring growth, and moderate autumn growth.
- Published
- 1960
- Full Text
- View/download PDF
27. The Ototoxic Antibiotics.
- Author
-
Meuwissen, Hilaire J. and Robinson, Geoffrey C.
- Subjects
OTOTOXIC agents ,ANTIBIOTICS ,INNER ear diseases ,PHARMACOLOGY ,CELLS ,GLUCOSE ,THERAPEUTICS - Abstract
The paper briefly discusses the action of the ototoxic antibiotics on the human labyrinth, reviews their pharmacologic properties and summarizes their clinical indications. The ototoxic antibiotics are a group of drugs with remarkable pharmacological similarities. Most ototoxic antibiotics cause severe damage and destruction, primarily of the sensory cells of the inner ear. The available data indicate that these cells depend mainly on glucose for energy, and that ototoxic antibiotics damage the apparatus for glucose breakdown. A good understanding of the absorption, distribution and excretion of the drugs is essential for safe therapeutic application. Unfortunately, administration to patients with renal insufficiency is at present the main cause of iatrogenic deafness. The necessary precautions and the changing indications for the drugs are outlined.
- Published
- 1967
- Full Text
- View/download PDF
28. The Separation of Different Cell Glasses from Lymphoid Organs VI. THE EFFECT OF OSMOLARITY OF GRADIENT MEDIA ON THE DENSITY DISTRIBUTION OF CELLS.
- Author
-
Williams, N., Kraft, N., and Shortman, K.
- Subjects
CELLS ,SUCROSE ,ALBUMINS ,SERUM ,IMMUNOGLOBULINS ,OSMOSIS - Abstract
Ficoll, a polymer of sucrose, and bovine serum albumin have been compared as media for preparation of density gradients for separation of lymphoid cells. Direct vapour pressure osmometer measurements demonstrated that Ficoll at high concentrations has a marked effect on the osmolarity of the medium in which it is dissolved. Albumin, prepared in the manner we have described in earlier papers of this series, has no effect, and density gradients prepared with this albumin do not contain gradients of osmolarity. Antibody forming calls give basically similar density distributions after separation in both media, apart from a slight overall shift to the dense end due to shrinkage in Ficoll. Heterogeneous, multiple peak distribution profiles, or relatively simple, homogeneous profiles may be obtained in both media, depending on the source of antibody-forming cells, the stage of differentiation of the population, and the degree of resolution of the gradient. Antibody-forming cell density heterogeneity is a property of the cell population, rather than an artifact of the separation system. Different animal species have a wide variation in the osmolarity of their sera. Albumin-gradients of osmolarity which were not iso-osmotic for the mouse caused a general shift in the density of mouse cell populations but no marked change in the relative distribution of cells. However, a change from iso-osmotic conditions did affect the ability of cells to reband on a second gradient. The use of gradients iso-osmotic for the particular species under study is recommended as a general procedure. [ABSTRACT FROM AUTHOR]
- Published
- 1972
29. The Formation of Immunoglobulins by Human Tissues <em>in vitro</em> II. QUANTITATIVE STUDIES.
- Author
-
van Furth, R.
- Subjects
IMMUNOGLOBULINS ,TISSUES ,CELLS ,SPLEEN ,LYMPHATICS ,AUTORADIOGRAPHY - Abstract
The present paper deals with some of the quantitative aspects of immunoglobulin formation in vitro. The results of this study show that isolated spleen cells synthesize about 1.25 μg IgG per 10
8 lymphoid cells during the first 6 hours of incubation. The initial rate of synthesis was not maintained throughout the 48 hours of incubation, but decreased markedly after 6 hours. Comparison of the intensity of the autoradiographic line with the amount of radioactive immunoglobulin in the precipitation line revealed that a very distinct line (gradation + + +) corresponds to about 0.0125 μg IgG. The limit of visibility (+) is reached at approximately 0.0002/μg radioactive IgG. [ABSTRACT FROM AUTHOR]- Published
- 1966
30. PATHWAYS OF PENETRATION" OF ELECTROLYTES THROUGH STRATUM CORNEUM.
- Author
-
Middleton, J. D.
- Subjects
ELECTROLYTES ,ABSORPTION (Physiology) ,PHASE partition ,CELLS ,SOLVENTS ,SOLUTION (Chemistry) - Abstract
There is considerable evidence that electrolytes can penetrate the stratum corneum but there is no evidence on whether this penetration occurs through or between the corneum cells. In this paper evidence is presented which shows that the equilibrium water content of intact corneum immersed in electrolyte solutions depends upon the electrolyte concentration and obeys the laws of osmosis. Removal of lipid by solvent extraction destroys the osmotic properties. This evidence indicates that the osmotic properties of corneum depend upon the presence of a lipid-containing semipermeable membrane system. Other evidence indicates that this membrane system is the cell walls of the corneum cells themselves. If electrolytes cannot enter the corneum cells in these osmotic experiments it follows that they cannot enter the corneum cells during penetration through the stratum corneum and that they must therefore pass between the cells. [ABSTRACT FROM AUTHOR]
- Published
- 1969
- Full Text
- View/download PDF
31. A. A. A. S.
- Subjects
SCIENCE news briefs ,ENERGY conservation ,TWENTIETH century - Published
- 1931
32. PYODERMA GANGRENOSUM WITH CLUMPING OF BLOOD CELLS AND ABNORMAL PLASMA PROTEIN.
- Author
-
Bolton, F. G., Hewitt, M., Yeoman, W. B., and Warin, R. P.
- Subjects
PYODERMA ,SKIN infections ,CELLS ,LEUCOCYTES ,CRYOGLOBULINS ,BLOOD plasma - Abstract
In a case of pyoderma gangrenosum without associated disease, clumping of cells was noted during routine leucocyte counts. It was probably due to a cryoglobulin in the patient's plasma. [ABSTRACT FROM AUTHOR]
- Published
- 1959
- Full Text
- View/download PDF
33. Progress.
- Subjects
SCIENTIFIC bureaus ,ULTRAVIOLET radiation - Published
- 1929
34. Light scattering at various angles. Theoretical predictions of the effects of particle volume changes.
- Author
-
Latimer P and Pyle BE
- Subjects
- Chloroplasts radiation effects, Computers, Erythrocytes radiation effects, Escherichia coli radiation effects, Latex radiation effects, Leukocytes radiation effects, Microspheres, Mitochondria radiation effects, Models, Biological, Scattering, Radiation, Yeasts radiation effects, Cells radiation effects, Colloids, Light, Radiation Effects, Subcellular Fractions radiation effects
- Abstract
The Mie theory of scattering is used to provide new information on how changes in particle volume, with no change in dry weight, should influence light scattering for various scattering angles and particle sizes. Many biological cells (e.g., algal cells, erythrocytes) and large subcellular structures (e.g., chloroplasts, mitochondria) in suspension undergo this type of reversible volume change, a change which is related to changes in the rates of cellular processes. A previous study examined the effects of such volume changes on total scattering. In this paper scattering at 10 degrees is found to follow total scattering closely, but scattering at 45 degrees , 90 degrees , 135 degrees , and 170 degrees behaves differently. Small volume changes can cause very large observable changes in large angle scattering if the sample particles are uniform in size; however, the natural particle size heterogeneity of most samples would mask this effect. For heterogeneous samples of most particle size ranges, particle shrink-age is found to increase large angle scattering.
- Published
- 1972
- Full Text
- View/download PDF
35. Free amino acids and nucleic acid content of cell nuclei isolated by a modification of Behrens' technique.
- Author
-
DOUNCE AL, TISHKOFF GH, BARNETT SR, and FREER RM
- Subjects
- Animals, Rats, Amino Acids, Cell Nucleus, Cells, Cytoplasm, Nucleic Acids, Proteins
- Abstract
1. Nuclei were prepared from frozen rat liver by a modification of the technique of Behrens, and were studied with regard to the content of free amino acids and nucleic acid. 2. Under rigorously controlled conditions, preparations of nuclei are obtained by the Behrens' method which form a gel in the presence of 5 or 10 per cent NaCl or of water plus a small amount of dilute alkali; whereas when conditions are less rigorously controlled, nuclei are obtained which form no such gel. The property of forming gels with alkali is probably characteristic of all cell nuclei which have not undergone autolysis. 3. Nuclei prepared by the Behrens' technique contain the enzymes arginase, catalase, and esterase in very appreciable concentrations. 4. The free amino acids of the isolated cell nuclei, as well as of other liver cell fractions, have been investigated using the technique of paper chromatography. 5. The chromatographic patterns of the free amino acids of whole cells, ground cytoplasm, and isolated cell nuclei were very similar or identical. A feature of interest in these chromatograms was the faintness or absence of the spots due to a number of the essential amino acids, as compared to the intensities of the spots due to glycine, alanine, and glutamic acid. Glutathione was present in the isolated nuclei as well as in the whole cells. 6. Chromatograms made from hydrolysates of nuclei showed high concentrations of the essential amino acids and were similar to chromatograms of hydrolysates of typical proteins.
- Published
- 1950
- Full Text
- View/download PDF
36. RNA Ligase Activity in Phage-Infected Bacteria and Animal Cells.
- Author
-
Linné, Tommy, Öberg, Bo, and Philipson, Lennart
- Subjects
RNA ,LIGASES ,CELLS ,ESCHERICHIA coli ,PHOSPHODIESTERS ,ORGANOPHOSPHORUS compounds - Abstract
An RNA ligase which is dependent on ATP and Mg
2+ for maximal activity with 5'-32 P-labeled poly(I) · poly(C) as substrate has been purified from Escherichia coli infected with phage T4. Ligase activity was demonstrated by the transfer of alkaline phosphatase sensitive 5'-32 P termini into an alkaline phosphatase resistant form. The formation of phosphodiester bond was verified by hydrolysis of the reaction product and determining the transfer of32 p from the 5' position to the 2'(3') position by electrophoresis. An increase in sedimentation rate of poly(I) · poly(C) was also observed after reaction with RNA ligase. The enzyme also showed an ATP-PP1 exchange activity. The activity on the synthetic polyribonueleotides poly(A), poly(U), poly(A) · poly(U) and poly(I) · poly(C) was examined and an increased efficiency of the substrate was obtained when [5'-32 P]poly(U) formed a complex with poly(A). [5'-32 P]Poly(A) was a good substrate both with and without the complementary strand. With 5'-32 P-labeled poly(I) · poly(C) as substrate RNA-ligase activity was detected in mammalian cells such as KB, HeLa and L-cells. The activity seems to increase after infection with encephalomyelocarditis (EMC) virus or poliovirus, but not aider infection with adenovirus type 2. The RNA ligase activity was confined to the cytoplasmic fraction of the cells. [ABSTRACT FROM AUTHOR]- Published
- 1974
- Full Text
- View/download PDF
37. Source of Amino Acids Used for Protein Synthesis in HeLa Cells.
- Author
-
van Venrooij, Walter J., Moonen, Hans, and van Loon-Klaassen, Lucy
- Subjects
AMINO acids ,PROTEIN synthesis ,LEUCINE ,TRANSFER RNA ,PROTEOLYSIS ,CELLS - Abstract
HeLa cells, prelabeled with [³H[leucine for several generations, were pulse-labeled with [
14 c]-leucine. The14 C/³H ratio of the leucine in the medium, in the total amino acid pool and bound to transfer RNA was determined.It was found that the14 C/³H ratio of the leucyl-tRNA was identical with that of the extracellular medium while that of the amino acid pool was much lower. These results confirm previous reports that selection of amino acids for protein synthesis takes place before the amino acids are released intracellularly.Further, it is concluded that amino acids resulting from intracellular proteolysis are not reutilized directly under the conditions of our experiments.A possible model of intracellular amino acid pathways is discussed. [ABSTRACT FROM AUTHOR]- Published
- 1974
- Full Text
- View/download PDF
38. Serum Factors Affecting the Incorporation of [3]Thymidine by Lymphocytes Stimulated by Antigen. I. SERUM CONCENTRATION.
- Author
-
Forsdyke, D. R.
- Subjects
SERUM ,THYMIDINE ,LYMPHOCYTES ,ANTIGENS ,LYMPH nodes ,CELLS ,LABORATORY rats ,IMMUNITY - Abstract
Lymph node cells from immunized rabbits were cultured with varying concentrations of antigen in preheated (56°, 30 minutes) autologous serum which had been collected before immunization. [
3 H]Thymidine was present for the last 6 hours of the 24-hour culture period and the radioactive labelling of acid-precipitable material was then determined. Changes in labelling due to variations of culture conditions were interpreted according to whether they were specific for control or antigen-treated cultures or non-specific. Cell concentration and serum concentration were predominantly non-specific variables influencing the labelling in control and antigen-treated cultures to a proportionate extent. However, at serum concentrations below 5 per cent labelling was disproportionately inhibited in antigen-treated cultures; there were further minor disproportionate inhibitions at higher serum concentrations. Labelling was inhibited by increasing the concentration of serum from 25 to 50 per cent, mainly due to a non-diffusible competitive inhibitory activity. Isotope-dilution analysis of the effects of serum on labelling over a wide range of serum concentrations indicated that the relationship was a complex one with at least three step-wise stimulations of the maximum labelling rate being produced by increasing the serum concentrations from 0 to 25 per cent. Labelling in antigentreated cultures containing post-immunization serum was less than labelling in cultures containing an equal volume of preimmunization serum, but labelling in control cultures was enhanced by post-immunization serum. These results are shown to be compatible with the proposals (i) that labelling in control cultures reflects the response of cells to low concentrations of endogenous antigens, and (ii) that preimmunization serum and post-immunization serum contain ‘natural’ and ‘acquired’ antibodies respectively, which normally buffer cell-borne receptor sites against reaction with endogenous and exogenous antigens. [ABSTRACT FROM AUTHOR]- Published
- 1973
39. SOME OBSERVATIONS ON THE POST-PLUCKING DEPRESSION IN TRITIATED THYMIDINE UTILIZATION IN MOUSE SKIN AND SOME TENTATIVE CELL KINETIC DETERMINATIONS.
- Author
-
Potten, Christopher S.
- Subjects
- *
CELLS , *DNA synthesis , *SKIN , *GROWTH factors , *THYMIDINE , *ANESTHESIA - Abstract
Immediately after plucking the hairs from a mouse, with its skin in the resting phase of the hair growth cycle, both the labeling index and incorporation levels of ³HTdR are lowered. This depression persists until stimulated cells enter S, usually about 10 hours after plucking. These observations are confirmed using a combination of liquid scintillation and autoradiographic procedures. The dpm per punch of fixed skin, the labeling index of the basal layer, the grains per labeled basal layer cell and the proportion of labeled DNA are all reduced following plucking. The dpm per punch of fresh skin is concomitantly enlarged by plucking through an increase in the fixative-soluble pool, which may be due to the induction of vascular changes. Anesthesia apparently reduces slightly the incorporation levels into fixed unplucked skin. The vascular changes and anesthesia depression of incorporation cannot account for the depression in incorporation into fixed tissue which must be due to a more direct effect on DNA synthesis. The data could be explained on the basis of a reduction in the rate of synthesis combined with a block to entry into S or to progression through S. Using the autoradiographic and liquid scintillation techniques presented in this paper and published previously, a number of calculations were made regarding the proliferative population size in the epidermis and hair follicle. The cycle time for basal layer cells in unplucked skin is estimated to be 141 hours with an upper limit on the growth fraction of 0.92. [ABSTRACT FROM AUTHOR]
- Published
- 1972
- Full Text
- View/download PDF
40. A Mutant of <em>Escherichia coli</em> Defective in Ribonucleosidediphosphate Reductase 1. Isolation of the Mutant as a Deoxyuridine Auxotroph.
- Author
-
Fuchs, James A. and Neuhard, Jan
- Subjects
- *
ESCHERICHIA coli , *NUCLEOTIDES , *CELLS , *THYMIDINE , *NUCLEIC acids , *GENETICS - Abstract
A procedure to isolate Escherichia coli mutants defective in ribonucleotide reduction is described. Using a parental strain defective in dCTP deaminase (paxA) and thus unable to synthesize dUMP from deoxycytidine nucleotides, we selected for cells unable to reduce UDP at a rate sufficient to satisfy the cell's need for thymidine nucleotides. This was accomplished by selecting for cells resistant to 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine (trimethoprim) in the presence of thymidine and screening these cells for a thymidine requirement that could be satisfied by deoxyuridine. Genetic analysis as well as enzyme assays of four such mutants chosen for study indicated that three had a defective thymidylate synthetase. One, LD195, which had normal thymidylate synthetase activity, was found to have a conditional deoxyuridine requirement that is only expressed under favourable growth conditions. Since restoration of a functional dCTP deaminase to derivatives of LD195 eliminated the deoxyuridine requirement, it was concluded that a combination of two mutations is responsible for the expression of this phenotype. Analysis of nucleotide pools of LD195 grown exponentially under permissive conditions revealed that both the dTMP and dTTP pools were 6-fold lower than in the parent indicating a deficiency in the production of a thymidine nucleotide precursor. Enzyme assays of crude extracts of LD195 indicated that this deficiency was due to a defective ribonucleosidediphosphate reductase. This conclusion is proven by an extensive enzymatic analysis presented in an accompanying paper. [ABSTRACT FROM AUTHOR]
- Published
- 1973
- Full Text
- View/download PDF
41. Biosynthesis of UDP N-Acetylhexosamine in Bovine Retina.
- Author
-
Tesoriere, Giovanni, Vento, Renza, Magistro, Domenico, and Dones, Filippo
- Subjects
- *
RETINA , *BIOSYNTHESIS , *EPITHELIAL cells , *GLUCOSAMINE , *CELLS , *SUGARS , *AMINES - Abstract
In this paper the metabolism of amino sugars in the retina and in the pigment epithelial cells has Been studied. Extracts obtained from the retina and from the pigment epithelial cells are capable, in the presence of suitable cofactors, of converting [1.14C]glucosamine into UDP-N-acetylhexosamines. Chromatographic investigations with the use of Dowex resin column have permitted the identitication of the principal intermediaries of amino sugar metabolism: GlcNAc, GIcN-6-P, Glc-NAc-6-P, UDP-GlcNAc, UDP-GalNAc. Both the retina and the pigment epithelial cells are, further, capable of synthesizing those amounts of acetyl coenzyme A necessary for the formation of acetylated amino sugars. The metabolism of amino sugars in the retina would appear to be much more active than in the pigment epithelial cells; this would indicate that the greater part of the synthesis of mucopolysaccharides of the interstitial matrix takes place in the retina. In the course of this research, furthermore, the presence of three compounds has been ascertained, the identification of which is still in progress. [ABSTRACT FROM AUTHOR]
- Published
- 1971
- Full Text
- View/download PDF
42. Kinetics of the Auxin Catabolism.
- Author
-
Pilet, Paul-Emile
- Subjects
AUXIN ,METABOLISM ,PLANT hormones ,BIOCHEMISTRY ,ENZYMES ,CELLS - Abstract
1. IAA destruction by root cells extracts following three distinct phases: a lag period, an activation phase and an equilibrium state. 2. The induction phase and the natural tangent, which is measured on the curve giving the IAA inactivation at the middle of the steady phase, permit a characterisation of the kinetics of the auxin catabolism. 3. Results of the experiments were then analysed in terms of enzyme biokinetics. 4. Relations between enzyme activity and enzyme concentration and substrate level are examined. As an oxidating agent H
2 O2 was used and the action of 2,4-dichlorophenol and gibberellic acid on the IAA inactivation was studied. 5. Analyses of pH and temperature effects were then made. 6. Finally, the importance of the various oxidation products resulting from the IAA destruction by the root tip extracts is discussed. [ABSTRACT FROM AUTHOR]- Published
- 1961
- Full Text
- View/download PDF
43. Uptake and Distribution of Radioactive Carbon from Labelled Substrates by Various Cellular Components of Spinach Leaves.
- Author
-
Holm-Hansen, O., Pon, N.G., Nishida, K., Moses, V., and Calvin, Melvin
- Subjects
SPINACH ,LEAVES ,CARBON ,RADIOACTIVITY ,CARBON dioxide ,CELLS - Abstract
Cellular constituents(chloroplasts,sap and mitochondrial), separated from spinach leaves, were allowed to photosynthesize in the presence of radio active bicarbonate. The radiocarbon fixed by the chloroplasts was distributed mainly in the phosphate ester while the radiocarbon fixed by the sap was located mostly in the amino acids. the mitochondrial fraction fixed very little radioactive carbon dioxide. the rate of carbon dioxide fixation by the recombined mixture of sap and chloroplasts was greater than the sum of the separate components. the distribution pattern of the fixed radiocarbon of the recombined mixture, however, was qualitatively similar to a combination of the radiocarbon distribution of the separated chloroplasts and sap. The results of experiments carried out with these cellular constituents in the dark and in the presence of other substrates, labelled and unlabelled, are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 1959
- Full Text
- View/download PDF
44. The Assimilation of Ammonia and Nitrate by Nitrogen-Starved Cells of Chlorella vulgaris. I. The Assimilation of Small Quantities of Nitrogen.
- Author
-
Syrett, P. J.
- Subjects
AMMONIA ,CHLORELLA ,CARBON dioxide ,CELLS ,ORGANIC compounds ,VITAL signs - Abstract
The rapid assimilation of small quantities of ammonium, nitrite and nitrate-N by nitrogen-starved cells of Chlorella vulgaris is accompanied by high rates of gas exchange. When all the added nitrogen has been assimilated the rates of gas exchange return to the control values. The total volume of oxygen taken up during the period of nitrogen assimilation is about the same whichever nitrogen source is added but the rate is highest with ammonium-N and lowest with nitrate-N. On the other hand, the rate of carbon dioxide production is much the same whichever salt is added but the total volume of carbon dioxide produced is greatest when nitrate-N is added and least with ammonium-N. The quantities of oxygen absorbed and carbon dioxide produced agree with those expected if ammonium, nitrite and nitrate-N are all assimilated to the same final products and if carbohydrate is the carbon source in the cells. A high respiration rate also follows the addition of hydroxylamine but the gas exchange differs markedly from that expected if hydroxylamine were assimilated to the same products as the other nitrogen sources. [ABSTRACT FROM AUTHOR]
- Published
- 1955
- Full Text
- View/download PDF
45. Studies on Growth and Metabolism of Roots. X. Investigations of the Calcium Effect.
- Author
-
Burström, Hans
- Subjects
PLANT growth ,PLANT metabolism ,PLANT roots ,CALCIUM ,CELLS ,PROTEIN synthesis ,PLANT hormones - Abstract
The influence of calcium on the properties of growing roots has been investigated. Calcium exerts two actions not found with potassium, iron, or boron. It increases the elasticity of the cells walls but is dispensable for the plasticity, which appears during the first phase of the cell elongation. Furthermore, it is necessary for the absorption of nitrate from external medium. The relation between calcium, protein synthesis, and auxin conditions have been cursorily discussed. The concept of plasticity of the wall versus elasticity has been examined, and it is suggested that these cannot always be applied in their strict sense to growing cells walls. The results corroborate the assumption that growth starts with an of the cells walls, which is independent of calcium, and is followed by a calcium-induced increase in the tensibility formation of the elastic components of the final wall by intussusception. [ABSTRACT FROM AUTHOR]
- Published
- 1954
- Full Text
- View/download PDF
46. The Assimilation of Ammonia by Nitrogen-Starved Cells of Chlorella vulgaris. III. The Effect of the Addition of Glucose on the Products of Assimilation.
- Author
-
Syrett, P. J. and Fowden, L.
- Subjects
NITROGEN ,AMMONIA ,CELLS ,GLUCOSE ,SUCROSE ,ORGANIC compounds - Abstract
(1) The uptake of ammonia by 'nitrogen-starved' cells of Chlorella vulgaris was studied. Rapid assimilation of NH
3 -N into soluble organic nitrogenous compounds, principally amide and free amino-acid nitrogen, occurred. (2) In the presence of glucose, the soluble organic nitrogen finally returned to the original nitrogen-starved level, the assimilated NH3 -N being incorporated into insoluble (protein) nitrogen. When no glucose was added, a large proportion of the assimilated nitrogen remained in the form of soluble organic compounds. (3) In both cases basic amino-acids represented a high percentage of the free amino-acids formed during ammonia assimilation, and even after 24 hrs, this percentage remained at a higher level than that found initially or in 'normal' cells. [ABSTRACT FROM AUTHOR]- Published
- 1952
- Full Text
- View/download PDF
47. Tryptophan Hydroxylase in Nucleated Thrombocytes of the Domestic Fowl.
- Author
-
Sorimachi, Masaru, Kataoka, Kiyoshi, Hori, Seiki, Hori, Shinichiro, and Fujisawa, Hitoshi
- Subjects
TRYPTOPHAN ,BLOOD platelets ,HYDROXYTRYPTOPHAN ,CHLOROPHENYLALANINE ,SOLUBILIZATION ,CELLS - Abstract
Using the labeled CO
2 trapping method, tryptophan hydroxylase activity was detected in the nucleated thrombocytes of the domestic fowl, but not in the mammalian platelets. This enzyme activity was around a 5-hydroxytryptophan production of 60 pmol×mg protein-1 ××h-1 . Certain properties such as optimal pH (7.0), Km value (12 μM), requirement for cofactor (2-amino-4-hydroxy-6,7-dimethyl-5,6,7,8-tetrahydroptetidine) and inhibition by p-chlorophenylalanine indicated a close resemblance to tryptophan hydroxylase from brain tissue. Solubilization of this enzyme was to some extent successful by digitonin treatment of the cells. [ABSTRACT FROM AUTHOR]- Published
- 1973
- Full Text
- View/download PDF
48. Existence and Functions of Two Enzymes with β-Ketoadipate: Succinyl-CoA Transferase Activity in <em>Pseudomonas fluorescens</em>.
- Author
-
Hoet, P.P. and Stanier, R.Y.
- Subjects
PSEUDOMONAS fluorescens ,TRANSFERASES ,ENZYMES ,BIOSYNTHESIS ,CELLS ,CARBOXYLIC acids - Abstract
This work shows that Pseudomonas fluorescens can synthesize two different inducible enzymes which possess β-ketoadipate: succinyl-CoA transferase activity. Transferase I is operative in the activation of free β-ketoadipic acid and is specifically induced in cells grown either with this acid, or with an aromatic precursor (benzoate) oxidized through the β-ketoadipate pathway. Transferase II is specifically induced m cells grown with saturated dicarboxylic adds of chain length C
6 through C10 , and its physiological function is that of an adipate :succinyl-CoA transferase; its ability to activate β-ketoadipic acid reflects non-specificity with regard to the CoA acceptor. [ABSTRACT FROM AUTHOR]- Published
- 1970
- Full Text
- View/download PDF
49. THE BIPHASIC OR SOIL-WATER CULTURE METHOD FOR GROWING ALGAE AND FLAGELLATA.
- Author
-
Pringsheim, E. G.
- Subjects
ALGAE ,CULTURES (Biology) ,FLAGELLATA ,MICROORGANISMS ,SCIENTIFIC apparatus & instruments ,PUTREFACTION ,NITROGEN ,CARBON compounds ,CELLS - Abstract
This article describes a technique for growing algae and flagellata cultures. There are five biological groups of microorganisms that may be grown in soil-water cultures. Equipment needed include hard glass, tubes, and larger containers such as glass cylinders or milk bottles. Organic substances supplying food materials are placed at the bottom of the vessel and covered with soil in a bid to prevent excessive putrefaction. An appropriate source of nitrogen and carbon compounds are casein, gelatine and similar substances. An advantage of this technique is that the organisms to be cultivated are chosen and separated from other forms at the outset. The cells to be used for inoculation should be passed through a sterile fluid to avoid contamination of the cultures with small algae.
- Published
- 1946
- Full Text
- View/download PDF
50. The Role of Immunoglobulins in Lymphocyte-Mediated Cell Damage, <em>in vitro</em> II. THE MECHANISM OF TARGET CELL DAMAGE BY LYMPHOID CELLS FROM IMMUNIZED RATS.
- Author
-
MacLennan, I. C. M. and Harding, B.
- Subjects
LYMPH nodes ,IMMUNOGLOBULINS ,IMMUNOLOGY ,CELLS ,RATS ,IMMUNIZATION - Abstract
Lymph node cells from Black Hooded (BH) rats immunized with Freund's complete adjuvant (CFA) are only poorly cytotoxic to target cells treated with target cell specific antibody. Normal spleen cells are highly cytotoxic to antibody coated target cells. When 10
6 lymph node cells, from rats immunized with Chang cells in CFA, are mixed with 107 spleen cells from unimmunized rats, the mixture is 8.6 times more cytotoxic than the sum of the cytotoxicities of the two lymphoid cell populations alone. Immune lymph node cells were no more cytotoxic in the presence of 5 per cent fresh guinea-pig serum than in the presence of heat inactivated guinea-pig serum. Immune spleen cells are prevented from damaging target cells by antagonists of protein synthesis such as Puromycin. Puromycin, however, does not alter the cytotoxic effect of either immune or nonimmune spleen cells on antibody coated target cells. From these experiments it is tentatively suggested that lymphoid cells from immunized animals mediate target cell damage by a reaction involving firstly immunologically specific responder cells which synthesise antibody and secondly non-specific effector cells which damage the antibody coated target cells. Evidence is presented which suggests that stable soluble factors may not be responsible for mediating target cell damage in this system. [ABSTRACT FROM AUTHOR]- Published
- 1970
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