摘要:

AbstractThe calcitonin (SCT) from salmon ultimobranchial bodies which (like mammalian calcitonins) lowers the plasma calcium concentration in mammals can also affect cyclic AMP (cyclic adenosine 3′,5′‐monophosphate) metabolism and proliferation of lymphoblasts in normal and prostaglandin E1(PGE1)‐treated rat thymocyte populations in three different ways. In the first case, low concentrations (0.5–5.0 ng per milliliter) of SCT lower (by a calcium‐mediated process) the ability of PGE1to transiently increase cyclic AMP synthesis, but the reduced surge of cyclic AMP production is still ample to stimulate lymphoblasts in the cell population to initiate deoxyribonucleic acid (DNA) synthesis. Secondly, these low SCT concentrations affect the eventual progression of the PGE1‐stimulated, DNA‐synthesizing lymphoblasts into mitosis by a calcium‐mediated process. Depending on the extracellular calcium concentration and the magnitude of the initial increment in the intracellular cyclic AMP content, SCT can either promote or inhibit the progression of the stimulated cells into mitosis. SCT's third action is a rapid (within 5 minutes), calcium‐independentelevationof the cellular cyclic AMP content in otherwise untreated thymic lymphocyte populations exposed to a very high concentration (100 ng per milliliter) of the hormone. This early, transient rise in the cyclic AMP level is followed by a calcium‐dependent increase in lymphoblast proliferation. An attempt is made to interrelate and explain the different actions of SCT on cyclic AMP metab

ISSN:0021-9541    

DOI:10.1002/jcp.1040800302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractMedium calcium ions were essential to the development of the lymphocyte transformation response induced by PHA. Magnesium ions could not substitute for calcium ions. Calcium exerted its influence during the induction phase of the process before DNA synthesis began since its removal after the response had fully developed did not alter subsequent levels of nucleic acid synthesis. The early development of RNA synthesis was prevented by low calcium levels indicating that calcium either directly influenced the initiation of this process or some prior event(s).

ISSN:0021-9541    

DOI:10.1002/jcp.1040800303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractAlthough it is well known that thymus function changes with age, it is not known whether these changes are associated with specific thymocyte populations. Since one criterion of specificity is cell size, we studied the size distribution of thymocytes from mice 0.5 days to 30.5 months of age. Body weight, thymus weight, and thymocyte yield were also measured. The mean cell volume of thymocytes from 8.5 to 13 week old mice was 326 μ3, with two detectable subpopulations. Mean thymocyte size was found to change with age. During the first postnatal week, the mean cell volume of the whole thymocyte population increased from 200 to 350 μ3, and the percentage of large cells increased greatly and constituted 90% of the whole population at four days of age. A rather slow decline in mean cell volume with some fluctuation occurred throughout the remaining life span, and at 30.5 months the mean had dropped to about 190 μ3. We suggest on the basis of these data that large thymocytes are involved in the contribution of the thymus to early postnatal development of the immune system and that the age‐related functional capacity of the thymus is related to the size of the thymocyte popula

ISSN:0021-9541    

DOI:10.1002/jcp.1040800304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractThe transmembrane potential of cells from a continuous cell line (BHK‐21) has been investigated by a combination of electrophysiological and flame photometric techniques. The ratio of sodium permeability to potassium permeability (PNa/PK) determined from membrane potentials recorded at varying external potassium concentrations was 0.082; from membrane potential measurements and the intracellular sodium and potassium concentrations of cells in 6.8 mM K+media the value was 0.075. The PNa/PKratio was not temperature dependent. Dinitrophenol (1 mM) did not significantly alter the membrane potential of cells incubated for one hour with the inhibitor. However, iodoacetate (1 mM) and sodium fluoride (30 mM) caused a significant depolarization during a one‐hour incubation. Measurements of sodium and potassium concentrations during incubation at 4°C showed a decrease in internal potassium and an increase in internal sodium accompanied by a decreased membrane potential. Ion concentrations and membrane potentials were measured in cells recovering at 37°C following 24 hours at 4°C. Membrane potentials in excess of EKduring the first ten minutes of recovery may indicate electrogenic p

ISSN:0021-9541    

DOI:10.1002/jcp.1040800305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractChinese hamster cell lines have a strong tendency to maintain as modal chromosome number the euploid one characteristic of the species. By following the evolution of karyotypes in cloned subpopulation it has been possible to show that these pseudodiploid constitutions are not simply established due to a selective advantage but they are actually generated in populations where pseudodiploid classes had been absent. The possible role of the mitotic apparatus in keeping and restoring the euploid number is discussed.

ISSN:0021-9541    

DOI:10.1002/jcp.1040800306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractThe sedimentation behaviour of single human red blood cells fixed with glutaraldehyde at pH 7.4 and 6.4 was studied and compared to resiflts previously reported for normal fresh cells. The cells fixed at pH 7.4 were observed to have normal shapes while those fixed at pH 6.4 were more spherical and less disc‐like. Fixation of glutaraldehyde removed “membrane flicker,” resulting in increased stability as indicated by a decrease in the number of orientation changes per minute from 2.93 ± 0.16 (SEM) to 1.74 ± 0.10 (SEM). An orientation change was defined as a change of 45° in any direction. Fixation also increased the edge‐to‐flat time preference ratio from 2.5 to 4.7, and increased the sedimentation velocities in all three orientations, despite a measured 2.5% decrease in mean cell density.Fixation of cells at pH 6.4 showed that the decrease in stability and preference for the on‐edge orientation was associated with an increase in the spherici

ISSN:0021-9541    

DOI:10.1002/jcp.1040800307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

Abstract3T3 and SV‐40 transformed 3T3 mouse fibroblasts were cultured in media with serum and antibiotics plus ammonia (NH3z NH4+) added as NH4C1. Both cell lines cultured without added ammonia showed normal morphology and multiplication even though ammonia in the medium at the end of the culture period ranged from 35 to 48 μg/ml. Ammonia concentrations being significantly higher in media removed from cells at the end of the culture period than in media incubated identically without cells, verified that cells released substantial quantities of ammonia in addition to components of the medium which underwent spontaneous breakdown. Both cell lines showed changes in morphology and highly significant reductions in cell multiplication which increased progressively as the concentration of added ammonia on the initial day of culture was increased to 35μg/ml. Control 3T3 cultures released significantly greater quantities of ammonia per cell than control cultures of transformed cells but their multiplication was more adversely affected by added ammonia. There were downward shifts in pH of the culturing medium for both cell lines as culture age increased at all concentrations of added ammonia, However, significant reductions in cell multiplication resulted from additions of ammonia that did not produce significant changes in extracellular pH. The data show that studies upon the effects of pH of the medium on cultured cells require control of ammonia concentrati

ISSN:0021-9541    

DOI:10.1002/jcp.1040800308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractMechanisms which determine sodium and potassium content and volume of rat thymic and human chronic lymphocytic leukemia (CLL) lymphocytes have been studied. The deleterious effect of cell isolation on monovalent cation content was proven by comparing thymus sodium and potassium concentration to that of thymocytes prepared from autologous hemithymus.In vivodistribution ratios of sodium‐24 and potassium‐42 between thymus water and plasma water were very similar to the distribution ratios of non‐radioactive isotopes (sodium‐23 and potassium‐39). The similar lymphocyte: thymocyte ratio of (a) cell volume (1.48), (b) cell sodium plus potassium (1.47) and (c) cell water (1.50) demonstrated the close correlation of lymphocyte volume with monovalent cation content and water content. Steady‐state CLL lymphocyte sodium (32 ± 1.9 mM) and potassium (131 ± 5.1 mM) and thymocyte sodium (31 ± 1.2 mM) and potassium (136 ± 3.9 mM) were similar; however, these steady‐state levels were maintained by quantitatively different membrane functions. Radiopotassium and radiosodium uptake by thymocytes was more rapid than by CLL lymphocytes. Ouabain‐sensitive potassium influx was 2.4 times greater in thymic (8.70 ± 2.28 mmoles/cm2/min × 10−8) than in CLL (3.24 ± 0.45 mmoles/cm2/min × 10−8) lymphocytes. Potassium exodus was also slower in CLL lymphocytes as compared to thymocytes. Ouabain‐sensitive sodium accumulation and ouabain‐insensitive sodium accumulation were also slower in CLL lymphocytes than in rat thymocytes. Half‐maximal ouabain inhibition of sodium entry was 7.5 × 10−3Min thymic and CLL lymphocytes. The inhibitory effect of ouabain on sodium and potassium transport was easily reversible. Oligomycin inhibited ouabain‐sensitive potassium accumulation in both lymphocyte types. Four lines of evidence indicate the presence in the lymphocyte of a system of leaks and pumps, the latter subserved by a ouabain and oligomycin‐sensitive (sodium‐potassium) ATPase: (a) steady‐state monovalent cation gradient (K ∼ 20:1, Na ∼ 5:1), (b) the inability to maintain normal sodium and potassium gradients at cold temperature and in the presence of ouabain, (c) the effect of ouabain and oligomycin on active potassium influx and (d) the restitution of steady‐state sodium and potassium concentration after cell isolation, ouabain treatment and cold exposure. CLL lymphocytes as compared to rat thymocytes have a decreased rate of ouabain‐insensitive sodium uptake and potassium exodus requiring a reduced rate of active sodium extrusion and potassium accumulation to maintain steady‐state cation content. Ouabain‐sensitive ATPase is difficult to locate in lymphocytesin vitropossibly because it comprises a very small proportion of membrane ATPase since magnesium activated ecto‐ATPase in intact lymphocytes is 1500 to 2500 times that of the intact erythrocyte. The inhibition by ouabain of blast transformation, mitosis, amino acid accumulation and nucleic acid synthesisin vitro, may reflect the importance of ouabain‐sensitive ATPase and m

ISSN:0021-9541    

DOI:10.1002/jcp.1040800309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractIn both photosynthetic (Pyrodinium bahamense, Gonyaulax polyedra, Pyrocystis Iunula, P. noctiluca, P. fusiformis) and nonphotosynthetic (Noctiluca miliaris) bioluminescent dinoflagellates chemical stimulation can by‐pass mechanical stimulation. The effective ions are Ca++, K+, NH4+and H+. Other chemicals found effective are those implicated in Ca++transport or binding. There are interspecies differences in degrees of mechanical and chemical stimulability. Photoinhibition of mechanical stimulability is the result of two effects, the first a reduction in total bioluminescence potential and the second a decrease in mechanical stimulability resulting experimentally in a decreased rate of light emission. This latter effect can be reversed with Ca++ions. Chemicals which bind Ca++or displace Ca++can mimic the effects of photoinhibition. The chemical inhibition of mechanical stimulability is also reversed by Ca++ions. A scheme is proposed which is consistent for all species examine

ISSN:0021-9541    

DOI:10.1002/jcp.1040800310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY

摘要:

AbstractColonies of elongated fibroblast‐like cells (stellate colonies) developed in agar cultures of mouse pleural cavity cells mixed with whole blood. Cultures of pleural cells alone developed only abortive clusters of round cells. The frequency of colony‐forming cells in the pleural cavity was highest in neonatal mice (200/105cells) and fell progressively with aging. Stellate colony‐forming cells were not in cell cycle but were radiosensitive. In adult mice, only occasional colony‐forming cells were detected in peritoneal cavity, thymic, spleen, lymph node or bone marrow cell populations. Stellate colony formation was not stimulated by the granulopoietic regulator, colony stimulating factor. The active component in whole blood required for stellate colony formation was present in plasma but not serum or washed red or whit

ISSN:0021-9541    

DOI:10.1002/jcp.1040800311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1972

数据来源: WILEY