摘要:

AbstractThis study was performed using radioactive isotopes of calcium and strontium as tracers in a perfused gill preparation. There were two levels in the uptake rates for strontium and calcium: a passive rate of 0.5 × 10−7cm/sec, and 1.8 × 10−7cm/sec, respectively, and a tenfold higher energy dependent rate of 5.1 × 10−7cm/sec for strontium and 17 × 10−7cm/sec for calcium. There was no evidence of discriminatory interaction between calcium and strontium at the passive levels of transport. Strontium was found to substitute for calcium at the active transport levels only if the calcium concentration of the environmental water was below approximately 0.1 mM Ca++/1.The rate of calcium and strontium loss from the gill was estimated as about 20 times faster than the influx rates. This caused the postulation that the net transfer of calcium ions across the gill could change, dependent upon the degree of saturation of the calcium‐binding sites wi

ISSN:0095-9898    

DOI:10.1002/jcp.1030650102

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractLethally irradiated LAF1mice were protected by various numbers of isogenic bone marrow cells. At intervals, cells from femoral bone marrow and spleen were assayed for their content of colony forming units (CFU) by retransplantation into other lethally irradiated mice and counting of spleen nodules at eight days. CFU numbers in femoral marrow were restored to preirradiation levels by about eight weeks. In the spleen, restoration was earlier and more rapid and for several weeks the CFU content exceeded the normal level. Prior splenectomy did not alter the pattern of CFU restoration in the femoral marrow postirradiation. However, splenectomy did appear to slightly improve survival of irradiated marrow‐protected mice. It is argued that the CFU may not be the essential protective cell, and the existence of a precursor “stem” cell in normal marrow is postu

ISSN:0095-9898    

DOI:10.1002/jcp.1030650103

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractDirect measurements have shown that the heat output from the frog sartorius muscle stimulated under isometric conditions is maximum when the muscle is at reference length and is decreased at stretched and shortened lengths. Experiments were conducted to determine if oxygen consumption following isometric stimulation varied with length in the same manner as did heat.A modified version of a differential volumeter was used consisting of two small sealed chambers each containing one of a pair of frog sartorius muscles. In the presence of a CO2absorbant extra oxygen consumption is indicated by movement of the index drop toward the chamber containing the stimulated muscle.It was found that at 12°C the oxygen consumption resulting from ten isometric twitches at reference length is 11.93 μ1/g and decreases to 5.10 μ1/g at 0.75 RL and 8.64 μ1/g at 1.25 RL. The absolute value of the oxygen consumption is in agreement with Hill's heat studies using appropriate heat‐oxygen conversion factors. No Feng “stretch response” of an increase in the rate of resting oxygen consumption was observed.Measurements of developed tension were found to parallel the oxygen consumption and heat curves, being 2.28 kg/cm2at 1.00 RL and decreasing to 1.45 kg/cm2at 1.25 RL and approaching zero at 0.75 RL.At the shortest lengths the oxygen consumption (5.0 μ1/g) is suggested to represent the equivalent of activation heat since no elastic elements were stretched. Such a suggestion is in agreement with heat studies showing that the energy of activation is approximately half of the maximum initial energy liberated in an isometric c

ISSN:0095-9898    

DOI:10.1002/jcp.1030650104

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractThe effect of ATP on the binding of Na, K, Mg and Ca ions by rat liver microsomes was investigated. Addition of increasing amounts of ATP to a suspension of microsomes in an ionic medium containing these cations caused a marked decrease in divalent cation binding and a concomitant increase in monovalent cation binding by the microsomes. The strong nonbiological complexing agent EDTA produced qualitatively similar but quantitatively greater changes in binding. Although ATP‐dependent binding of monovalent cations has been interpreted by other investigators in terms of an ATPase system and the formation of a hypothetical monovalent cation binding intermediate, the present data demonstrate that the role of ATP may also be reasonably explained in terms of mass law interactions of the various known solute species and fixed membrane binding sites involve

ISSN:0095-9898    

DOI:10.1002/jcp.1030650105

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractAn attempt is described to demonstrate a phosphorylated intermediate correlated with the membrane ATPase reaction in human red cell ghosts. It was found that ghosts incubated with γ‐labeled ATP32incorporate 400 to 1600 μM P/kg dry weight and that this incorporation required Mg, could be enhanced by the addition of Na and perhaps of strophanthidin but was inhibited by Ca, cooling or heat denaturation. If the total P32content of ghosts washed with Tris is taken as the Tris‐insoluble fraction, this fraction can be divided, operationally, into the PCA‐insoluble fraction, and the PCA‐soluble fraction‐B. It was found that the PCA‐soluble fraction‐B was composed primarily of unsplit, intact ATP32(as shown in parallel experiments with C14‐labeled ATP) and some Pi32. The PCA‐insoluble fraction contained only Pi32. If the Pi32contained in the PCA‐insoluble fraction represents an intermediate in the membrane ATPase, this Pi32should be exchangeable upon restitution of the ATPase activity. However, this Pi32was found to be stable and nonexchangeable upon reincubation of prelabeled ghosts under conditions which reactivate the ATPase reaction. Two alternative interpretations were considered: (1) that the P32that is incorporated into an intermediate product of the ATPase reaction is masked by nonspecific binding of P32and, (2) that the phosphorylated product is resident in the PCA‐soluble fraction‐B. Further experiments are needed to eva

ISSN:0095-9898    

DOI:10.1002/jcp.1030650106

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractHarvey and Nedergaard ('64 Proc. Nat. Acad. Sci.,51: 757–765) have shown that midguts isolated from mature larvae of the Cecropia silkworm, when perfused in aerated, agitated physiological solution, exhibit a large electrical potential with the lumen‐side positive to the blood‐side. Isotope studies show that potassium carries 83% of the current generated by the midgut when the potential is shortcircuited. These and other data demonstrate that potassium is actively transported from blood‐side to lumen‐side of the midgut epithelium. Neither the potential nor the current requires sodium.The effects of various chemicals on this sodium‐independent active transport of potassium were examined. The short‐circuit current was rapidly and reversibly inhibited by anoxia and 2,4‐dinitrophenol. An irreversible inhibition was effected by iodoacetate. No observable change was produced by cholinesterase inhibitors, adrenalin, pituitary hormones or small changes in pH. Ouabain, a cardiac glycoside which is thought to be a specific inhibitor of sodium transport, was without effect at concentrations as high as 10−4M.Barely affected by 5% CO2,the current was strongly and reversibly depressed by 25% CO2. The carbonic anhydrase inhibitor hygroton at 10−3M was without effect, but the related sulfonamide cardrase caused 36% inhibition at this concentration. The sulfonamides are barely soluble in water and perhaps penetrate the midgut cells with difficulty. Another type of carbonic anhydrase inhibitor, sodium sulfide, caused reversible inhibitions of 31% at 10−4M and 87% at 10−3M respectively. Clearly the potassium transporting system ofHyalophora cecropiahas important differences from sodium systems, and possibly employs a potassium, h

ISSN:0095-9898    

DOI:10.1002/jcp.1030650107

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractBy means of an amperometric titration method, the acid soluble sulfhydryl, protein sulfhydryl, and disulfide content of Ehrlich ascites tumor cells were determined before and after exposure to edathamil. No statistically significant differences were found between exposed and control groups. The addition of edathamil did not alter oxygen utilization. Changes in the viscosity of cell cytoplasm were determined by observation of the movement of lipoid granules with a phase contrast microscope following high speed centrifugation. The decrease in viscosity observed with edathamil could be prevented by the addition of glutathione simultaneously or 30 minutes later. A shift from intermolecular SS to intramolecular SS during sol‐gel transformation is suggested by the increased viscosity following the addition of glutathion

ISSN:0095-9898    

DOI:10.1002/jcp.1030650108

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractTotal cellular‐N, acid soluble‐N, lipid plus chlorophyll‐N, and the levels of the individual amino acids were measured during synchronous growth of a high temperature strain, 7‐11‐05, ofChlorella pyrenoidosa. Total cellular‐N increased exponentially except for a small but reproducible deviation from log‐linearity which occurred at approximately the middle of the 14 hour synchronous growth cycle. Although the level of acid soluble‐N (as % of total cellular‐N) exhibited definite periodism during synchronous growth, the amount of nitrogen in this pool was small (approximately 4–8%). Lipid‐ plus chlorophyll‐N showed only slight fluctuations during cellular development; however, the trend followed that previously observed for phospholipid‐P. The levels of the protein amino acids were expressed on a mole‐percentage basis of the total protein amino acids. The level of most of the protein amino acids remained essentially constant during the course of synchronous growth. The levels of the basic and acidic amino acids as well as alanine exhibited more significant periodism than the other protein amino acids. The total protein amino acid‐N level comprised approximately 63% of the total cellular‐N

ISSN:0095-9898    

DOI:10.1002/jcp.1030650109

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractNineteen cultures of human embryonic or adult‐tissue cells were exposed to SV40as primary cultures or developed cell strains in Phase II of cultural life; 12 cultures were exposed to virus in Phase III, at the end ofin vitrolife. After the expected proliferative response, infected cultures exhibited morphological change, accelerated growth, and prolongation of propagability. After an average of 22.6 weeks for cultures infected as primary explants or in Phase II, the proliferative stage of transformation ended in a stage of “crisis.” Crisis was characterized by progressive decline in vigor of culture proliferation, increasingly abnormal cell division, and limitation in propagability of cells eventually resulting in diminution in cell number. Cytological features of crisis included detachment of cells and appearance of multinucleated and giant cells. Temporally and cytologically, crisis was similar for transformed cells whether of adult or embryonic origin, whether derived from skin, buccal mucosa or lung, whether in Phase II or III of culture life at the time of infection (the “older” cultures entering crisis sooner than the “younger”), and whether propagated continuously or with intervening periods of growth arrest or proliferationin vivo. After a variable time “recovery” of cultures from crisis occurred by repopulation from small groups of surviving but seemingly dormant cells. The new populations, always obtained with care of cultures in crisis, formed continuously propagable cell lines. Control uninfected cultures have always exhibited the finite life terminating in Phase III which is characteristic of human diploid cell strains. Passage of transformed cultures through crisis and recovery was accompanied by loss of capacity to release infectious SV40and enhancement of production of SV40‐induced comple

ISSN:0095-9898    

DOI:10.1002/jcp.1030650110

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractThe karyology of a permanent human cell line, which retains a viral induced complement‐fixing antigen as a result of its original transformation with simian virus 40, is described. This line, W‐18VA2, is primarily subdiploid after more than two and one‐half years of cultivationin vitroand exhibits high variability of chromosome number and form in the parental line as well as in various clones and sub

ISSN:0095-9898    

DOI:10.1002/jcp.1030650111

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY