bluuebunny/crossref_metadata_2025_split huggingface dataset:
SV40‐induced transformation of human diploid cells: Crisis and recovery
Authors: Girardi A. J. , Jensen F. C. , Koprowski H. 
Published: February 2005

AbstractNineteen cultures of human embryonic or adult‐tissue cells were exposed to SV40 as primary cultures or developed cell strains in Phase II of cultural life; 12 cultures were exposed to virus in Phase III, at the end of in vitro life. 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 proliferation in 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 SV40 and enhancement of production of SV40‐induced complement‐fixing antigen.
Separation of rabbit red cells by density methods and characteristics of separated layers
Authors: Prentice Theodore C. , Bishop Charles 
Published: February 2005

AbstractRed cells from rabbits (reticulocyte count 1–2%) injected 4–6 days previously with Fe59 were centrifuged in isotonic hypodense media (plasma, buffer, saline) for 30 minutes at 1,600 G and layers were removed to achieve density fractionation. An important criterion of separation was the fractionation ratio (specific activity of hemoglobin in any layer/specific activity of hemoglobin in unfractionated blood) which indicated whether a layer contained mainly “new” or “old” red cells. The most important factor in enhancing the fractionation ratio was the centrifugal force, but time also had an effect. All isotonic media were essentially equivalent, but hypertonic media (sucrose) were quite poor. Dextran and PVP were also not good in promoting density separation. The exact degree of separation achieved by various combinations of conditions is documented, but no system achieves a true equilibrium, as shown by the fact that refractionation can split any fraction into subfractions of higher and lower hemoglobin specific activity. Upper layers were characterized by greater cell size, more reticulocytes, more free cholesterol, phospholipid, and ATP, and a faster rate of glycolysis. The distribution of Fe59 in the fractionated blood was followed serially for up to ten weeks, the most homogeneous distribution being seen only in the first week or two. After that the Fe59 was not sharply restricted to any density fraction. This suggested that the most significant density change takes place as the reticulocyte matures.
Puff development and DNA synthesis in Sciara salivary gland chromosomes in tissue culture
Authors: Cannon Grace B. 
Published: February 2005

AbstractA method for the tissue culture of salivary glands of Sciara coprophila in a chemically defined medium is presented. When the chromosomes of the posterior lobe of the gland have puffs and the chromosomes of the anterior lobe do not have puffs prior to culture, puffs will develop in the anterior lobe chromosomes within a 24 hour culture period. When these chromosome II puffs are at their largest, fully extended state and a bulb on chromosome III is in a larva nearing pupation, the puffs and bulb become condensed in culture more rapidly than in normal development. This condensed state of the chromatin is thought to be heterochromatin. The uptake of tritiated thymidine was compared in homologous glands of 20 larvae in six different stages of development and all glands were labeled before and after culture, indicating that the culture method does not interfere with DNA synthesis.
Discontinuous decay of the action potential of the rat gastrocnemius as recorded from an intracellular location
Authors: Locke Simeon , Brown Paul B. 
Published: February 2005

AbstractFractionation of intracellular action potential has been observed, with (1) an initial graded decline of amplitude and appearance of a notch; (2) a progressive delay and eventual disappearance of a component, with a stepwise decrease in area, and (3) the occasional sequential disappearance of as many as three components of the same order of magnitude in area and amplitude.The possibilities of block, movement, or extracellularly recorded responses as cause for these physiological “quanta” have been reviewed. One possible hypothesis is the existence of “patches” of membrane with independent characteristics of excitability and responsivity, which become manifest as a result of damage inflected by the electrode.
A study of rose bengal and sulfhydryl reagents on stromal fragments of rabbit and human erythrocytes
Authors: Dastoli Frank R. , Green James W. 
Published: February 2005

AbstractStromal fragments of human and rabbit erythrocytes, prepared by osmotic hemolysis, were used as sources of ATPase in a study of the action of the fluorescein dye, rose bengal, and of sulfhydryl reagents on this membrane component. Only the Na‐K independent ATPase was systematically studied but the dye was observed, at concentrations of 10−3 M, to completely inhibit the Na‐K dependent activity. Over a concentration range of 1.6 × 10−7 to 10−3 M the dye had a graded inhibitory effect on the Na‐K independent ATPase in Tris buffer with little difference in the sensitivity of the enzyme from the stroma of the two species. The activity of the cation independent enzyme was not changed by darkness or anaerobic conditions in the presence of the dye and its action could not be attributed to photosensitization. Repeated washing to remove the dye failed to reduce its effect on rabbit stroma and only partially succeeded with human stromal fragments. The dye was shown not to be a competitive inhibitor of ATP for the stromal ATPase of either species. Attempts to reduce the rose bengal effect by use of the sulfhydryl agents, glutathione or cysteine were unsuccessful although glutathione did protect ATPase against the common sulfhydryl inhibitors. It is concluded that the dye is affecting an essential group on or near the enzyme either by direct bonding or irreversibly changing essential bonds.
The effects of hibernation on the in vitro synthesis of DNA by hamster lymphoid tissue
Authors: Manasek F. J. , Adelstein S. J. , Lyman C. P. 
Published: February 2005

AbstractDNA synthesis was studied in vitro in lymphoid tissue taken from hibernating, cold adapted and active golden hamsters in an attempt to elucidate the mechanism of suppressed DNA synthesis during hibernation. The rates of DNA synthesis at temperatures varying from 4 to 37°C were greatest in cells from active animals, less from cold adapted and least from hibernating animals. The depression in cells from cold adapted animals was 70% reversible by returning the animals to a warm environment 40 minutes before they were sacrificed but the hibernating animals had to be aroused for more than 12 hours before their rates recovered, suggesting a different mechanism responsible for depression in these two instances.Radioautographic and biochemical measurements of DNA synthesis in cells taken from hibernating animals indicated that the depressed synthesis seen during hibernation is the result of a reduction in the percentage of cells engaged in DNA synthesis. This implies that the low body temperatures of hibernation produce a block in the cell cycle of lymphoid cells not unlike that observed when other mammalian cells are exposed to cold in vitro.
Circus reexcitation as a cause of repetitive activity in crayfish lateral giant axons
Authors: Kusano Kiyoshi , Grundfest Harry 
Published: February 2005

AbstractUnpolarized electrotonic connections between the two lateral giant axons of crayfish nerve cord have been demonstrated. Presumably they are also the sites of the tightly coupled unpolarized ephaptic junctions by which activity from one axon may be transmitted to the other. Commissures between the segmental branches of the two axons are probably the sites of the junctions. If septal transmission is blocked in one axon, the inactive segment can be excited by the activity of the other axon. The segmentally arrayed ladder of ephaptic junctions forms a series of delay lines and circus activity can occur in the loops between the two axons. Two segments form a loop with a delay line of 4 msec. The frequency of repetition is about 250/second. Each additional segment introduces another delay of about 4 msec. For a three‐segment loop the repetition rate is about 125/second. The delays at ephaptic junctions between neurons in vertebrate nervous systems are probably too brief to cause repetitive activity.
Renal transport of glucose by the aglomerular fish Lophius americanus
Authors: Malvin Richard L. , Cafruni Edward J. , Kutchai Howard 
Published: February 2005

AbstractThe renal excretion of glucose by the aglomerular fish Lophius americanus was studied. It was found that glucose is a normal constituent of Lophius urine. U/P ratios were approximately 0.02. However, after elevation of plasma glucose level or injection of phlorizin the U/P ratio for glucose was increased as much as ten fold. This increase in U/P ratio was observed even if urine was collected directly from the ureter rather than from the bladder. These results are consistent with the hypothesis that glucose is able to diffuse across the renal tubular epithelium, which also has the ability to reabsorb glucose which diffuses into the urine.
Oxygen consumption, thermal conductance, and torpor in the California pocket mouse Perognathus californicus
Authors: Tucker Vance A. 
Published: February 2005

AbstractNon‐torpid P. californicus have body temperatures which increase slightly as ambient temperature increases from 5° to 35°C. Their minimum oxygen consumption fits Newton's law of cooling, since minimum thermal conductance below thermal neutrality is virtually constant at 0.19 ml O2 (gm hr °C)−1. There is a thermal neutral point at 32.5° rather than a thermal neutral zone. Oxygen consumption at the thermal neutral point is 0.97 ml O2 (gm hr)−1. Maximum thermal conductance, measured at 35°, is 0.37 ml O2 (gm hr °C)−1. Evaporative water loss accounts for 5 and 15% of the value of minimum and maximum thermal conductance, respectively.Minimum oxygen consumption of mice in torpor is continuously dependent on body temperature from thermal neutrality to deep torpor. Q10 values are between 1.6 and 3.2. The thermal conductance of torpid mice at ambient temperature below 30° is 0.19 ml O2 (gm hr °C)−1 which is identical to the minimum thermal conductance of non‐torpid mice. Torpid mice at an ambient temperature of 30° have thermal conductance values between 0.23 and 0.40 ml O2 (gm hr °C)−1 depending on their posture.Maximum oxygen consumption is linearly related to body temperature. At a normal body temperature of 38°, it is 11.6 ml O2 (gm hr)−1 which is no greater than that of similar sized mammals which do not enter torpor.Although P. californicus consistently enters into and arouses from torpor at ambient temperatures of 15° to 30°, the torpor cycle is severely disturbed at temperatures between 10° and 12°. At these temperatures mice show irregular temporal patterns of torpor, do not enter torpor completely, and cannot arouse from torpor if body temperature falls below 15°.Observations on the behavior of torpid and non‐torpid P. californicus at various ambient temperatures are included in this report.
Comparative carbohydrate catabolism and methemoglobin reduction in pig and human erythrocytes
Authors: Rivkin Saul E. , Simon Ernest R. 
Published: February 2005

AbstractPig red cells were characterized structurally and chemically, the rates of certain of their carbohydrate metabolic pathways were determined, the capacity to utilize these pathways for methemoglobin reduction was measured, and the results were compared with similar studies in human erythrocytes. Pig cells are smaller, contain less hemoglobin but are similar to human cells in mean cellular hemoglobin concentration. Unlike most other mammalian red cells, including human erythrocytes, pig cells are glucose “free” or nearly so; plasma concentrations of glucose are similar in both species. On a per cell basis, the content of adenosine triphosphate and reduced glutathione is similar in both species. Pig red cells catabolize glucose at about one‐tenth the human rate; for each mole of glucose consumed, two moles of lactate are formed. In both species, a similar proportion (5 to 10%) of the total glucose catabolized passes via the phosphogluconate oxidative pathway. Both species form lactate from inosine at similar rates; the pathways involved appear similar. Pig hemolysates prepared in water form lactate from glucose, glucose‐6‐phosphate, or inosine; freeze‐thawing destroys this potential. Methemoglobin reduction rates of red cells suspended in plasma are similar in both species. With human cells the plasma glucose concentration accounts for the rate; with pig cells, the lactate level appears responsible. Cells of both species apparently link methemoglobin reduction to reduced diphosphopyridine nucleotide generated via Embden‐Meyerhof glycolysis but can couple reduced triphosphopyridine nucleotide, generated via the phosphogluconate oxidative pathway, to methemoglobin reduction as well.
Oxidation of cholesterol by rat liver mitochondria: Effect of thyroidectomy
Authors: Kritchevsky David , Tepper Shirley A. 
Published: February 2005

AbstractNormal and thyroidectomized rats were maintained on normal diets and on diets containing 0.3% N‐propylthiouracil. The normal rats on normal diets had significantly lower serum cholesterol levels than did any of the other groups. Liver cholesterol levels were elevated only in the thyroidectomized rats fed normal diet. The hypercholesteremic effect of N‐propylthiouracil observed in the thyroidectomized rats appears to be due to release of liver cholesterol.Liver mitochondrial preparations from all four groups of rats oxidized cholesterol‐26‐14C and sodium octanoate‐1‐14C to 14CO2 to the same extent. The data further support the hypothesis that the effect of thyroid on cholesterol degradation is mediated at the level of nuclear hydroxylation.
The exchange of C14 glucose across the membrane of the human erythrocyte
Authors: Mawe R. C. , Hempling H. G. 
Published: February 2005

AbstractWe have measured the equilibrium efflux of C14 labeled glucose across the cell membrane of the human erythrocyte under conditions when glucose was present in equal concentrations on both sides of the cell membrane, and also the net efflux of C14 labeled glucose from glucose‐loaded cells into a large extracellular environment that contained no glucose. A method of ultrafiltration through millipore filter discs was developed to obtain samples of medium during the loss of cell isotope to a medium free of isotope. Fluxes with half times as low as five seconds could be determined accurately and reproducibly. With this method we have extended the observations of other workers down to glucose concentrations of 0.03 M and found as others had previously that the half time for tracer exchange would decrease with a decrease in the equilibrium glucose concentrations. Further, by measuring equilibrium fluxes and maximal net fluxes of cells from the same blood sample, we have obtained evidence that the carrier laden with glucose is transported more rapidly than the free carrier.
The effect of peritoneal fluid on glucose‐U‐C14 oxidation by rat peritoneal leukocytes
Authors: Hrachovec Josef P. 
Published: February 2005

AbstractThe rate of C14O2 evolution from uniformly labeled glucose by washed white cells from peritoneal exudates increased several times after prolonged soaking of the cells in protein‐free medium and was repressed again upon incubation of the cells in peritoneal fluid of higher concentrations, whereas incubation in lower concentrations had a stimulatory effect, as compared to this rate by the cells incubated in protein‐free medium alone. Similarity of this effect of peritoneal fluid to the protective action of blood serum on the cells in tissue culture and the possible mechanism of action of both were discussed.It is suggested that the metabolism of the cells in multicellular organism is repressed by humoral macromolecular substances, and that the increase of glucose‐U‐C14 oxidation by the cells after prolonged soaking in protein‐free medium is related to the first step in the processes by which the cells move from a dormant state in vivo into that of active growth and cell divisions in vitro.
Transformation of hamster embryo cells in vitro by polyoma virus: Morphological, karyological, immunological and transplantation characteristics
Authors: Defendi V. , Lehman J. M. 
Published: February 2005

AbstractThe transformation process induced by polyoma virus in mass cultures of hamster embryo cells has been analyzed chronologically for several parameters: morphology, karyology, antigenicity and transplantability. Morphological changes, as manifested by the altered growth pattern of the culture, were the first indication of transformation. The expression of morphological transformation differed among colonies from a single culture and among the various cell lines; its pattern could change with prolonged growth of the cultures. Established lines originating from each transformed culture eventually produced tumors in syngeneic and allogeneic animals. Tumorigenicity was low (MTD ± 106) soon after morphological transformation, but increased progressively as the cells were carried in vitro (MTD < 103). Polyoma virus disappeared in eight lines, but persisted in one. The non‐virus releaser lines were resistant to superinfection with polyoma virus. The polyoma‐induced transplantation antigen (PV‐ITA) was found in four of six lines; it was not demonstrable in later passages of some lines that were initially positive and was not detected in the virus carrier culture. The polyoma‐induced CF antigen (PV‐ICFA), however, was present in all the cultures exposed to polyoma virus even at passage levels where the PV‐ITA was not demonstrable. Some chromosomal changes in type and in ploidy were present at, or shortly after, the time of morphological transformation. Although very low at first, frequency of chromosome changes increased with time in a random pattern. Three of four lines remained near‐diploid, the fourth line became subtetraploid soon after morphological transformation. The incidence of chromosomal damage (chromatid breaks, dicentrics and fragments) was low in all four lines analyzed, even in the virus carrier culture. There was a parallel increase in frequency of abnormal metaphases and of transplantability.It is concluded that after an initial and yet obscure polyoma virus cell interaction, cells evolve toward malignancy in a pattern that does not show specificity for the inducing virus. The viral genome, if present in the transformed cells, does not appear to direct or regulate the evolution of the cells in vitro.
On the homology of the cranial muscles of the cypriniform fishes
Authors: Takahasi Nisuke 
Published: February 2005

AbstractMuch more information than is available at present must be obtained before the phylogeny of the muscular system in the Teleostei can be worked out satisfactorily. As a step toward the solution of this problem, the present study gives a detailed description of twenty cranial muscles in a number of species belonging to three groups of cypriniform fishes: the Cyprinoids, Cobitoids, and Siluroids.Particular attention is given to the morphological relations of the following muscles: adductor mandibulae, geniohyoideus, levator arcus branchialis, adductor arcus palatini, retractor branchialis dorsalis, interarcualis dorsalis and the trapezius.Comparison is made between corresponding muscles in different members of the three groups of fishes, and various homologies are pointed out between muscles in cypriniform and those in other fishes, especially Amia, Scomber, Perca and Esox.
Nervous system of the earthworm, lumbricus terrestris L.
Authors: Hess Walter N. 
Published: February 2005

AbstractA study of the peripheral nerves of the earthworm shows that one pair of nerve trunks arise from the lateral regions of the cerebral ganglion, one pair from near the lateral, and two pairs from the ventral region of the circumpharyngeal connectives. These supply, in the order given, the prostomium, segment 1 and segment 2. Segment 3 and each succeeding segment, except the last, are supplied with three pairs of nerve trunks which arise from the nerve cord in the segment concerned. None of the nerve trunks of the body was observed to send branches to more than one segment, which shows that they are segmental in origin and distribution.The anterior portion of the central nervous system has undergone caudal migration and modification of its ganglia. Some of the nerve trunks have disappeared through atrophy, while others have become fused at their bases.A subepidermal nerve plexus is found at the base of the epidermal cells from which nerve fibers pass to the internal nerve net and to the central nervous system. This plexus also sends intercellular and intracellular fibers into the epidermis.The so‐called sense cells of the epidermis appear to be the cell bodies of sensory neurones which send nerve fibers to the ganglia of the central nervous system, where they form synaptic connections with other neurones.There is an enteric nerve plexus in the wall of the alimentary canal which is directly connected to the circumpharyngeal connectives.
Karyosphere formation and synapsis in the beetle, phanaeus
Authors: Hayden Margaret A. 
Published: February 2005

AbstractThe parasynaptic union of chromosomes associated with the formation of a karyosphere is demonstrated in the spermatocytes of Phanaeus.The twelve V‐shaped leptotene threads are polarized with their apices embedded in one plasmosome‐like body, their distal ends in another (primary and secondary caps, respectively), and undergo a conjugation of the parasynaptic type. The distal ends of the chromosomes are freed from their attachment in the secondary cap. The six pachytene loops retain their polarized configuration.The basichromatin of the pachytene chromosomes appears ultimately to be withdrawn to form the karyosphere comprising six chromatic bodies within an oxychromatic «plasmosome,» the latter probably derived from the primary cap. The two caps are believed to arise from the chromosomes. The primary cap apparently becomes incorporated again in the chromosomes; the secondary cap, together with linin remnants of the pachytene chromosomes, disintegrates in the nucleus as residual chromatin.In the dissolution of the karyosphere six ring‐shaped tetrads emerge arranged in a temporarily connected chain, giving under certain conditions, the misleading impression of twelve components arranged end to end. The entire content of the karyosphere appears to be employed in the formation of the chromosomes; no visible plasmosome remains.