Do any morphological pictures of separated excretion of histamine and heparine in tissue mast cells exist?

Zusammenfassung An Modellpräparaten wurde festgestellt, dass die Färbbarkeit der konjugierten Heparin-Histamin-Moleküle gleich ist wie die des Heparins selbst. Der fermentative Abbau des Heparins führt nicht zur vermehrten Freisetzung von Histamin.     

Epigenetic tinkering and evolution: is there any continuity in the role of cytosine methylation from invertebrates to vertebrates?

The function of DNA methylation has been investigated in depth in vertebrate and plant genomes, establishing that it is involved in gene silencing and transposon control. Data regarding insect methylation, even if still scanty, apparently argue against evolutionary conservation of DNA methylation functions. Cytosine methylation, therefore, proves to be an epigenetic tool repeatedly used to accomplish different functions in different taxa according to a sort of epigenetic tinkering occurring during evolution.     

Is lysine the source of the pyridine ring in nicotine?

Zusammenfassung Gibt man L(+)-Lysin--¹⁵N oder in allen Stellungen mit¹⁴C markiertes L(+)-Lysin zu keimfreien Kulturen von abgeschnittenen Wurzeln vonNicotiana tabacum, so erzeugen die Wurzeln Nikotin, welches kleine Mengen¹⁵N oder¹⁴C enthält. Ferner enthält das Nikotin mehr¹⁵N oder¹⁴C im Pyrrolidinring als im Pyridinring. Lysin liegt daher nicht auf dem direkten biogenetischen Weg zum Nikotin.

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Research performed under the auspices of the United States Atomic Energy Commission.     

What constitutes a network in the acinar cells of amphibian and mammalian pancreas?

Résumé Il a été montré que l'appareil réticulaire classique de Golgi dans les cellules pancréatiques des amphibies et des mammifères est un produit artificiel. Un certain nombre de raisons sont proposées pour expliquer ce fait.     

Is attenuation of tRNA charging responsible for the inhibition of protein labelling accompanying depolarisation of the cerebral cortical cells?

Summary Topical application of concentrated solutions of KCl resulted in reduction of charging of tRNA 7 min after s.c. injection of L-(U-¹⁴C) leucine. Neither radioactivity nor pool size of the total amino acids changed during this period.     

Does an initial phasic response exist in the receptor potential of taste cells?

The depolarizing receptor potentials to 0.5 M NaCl recorded from frog taste cells did not exhibit any phasic response, even when the rectangular waveform of stimulus onset was employed. The quickest depolarizations recorded reached the peak in 50 msec. On the other hand, the gustatory neural response showed initial overshoot of the impulse discharge even when 0.5 M NaCl was delivered at the slower rate of 0.06 ml/sec. It is concluded that the initial neural response may be associated with the rate of rise of the receptor potential before its plateau level is reached.     

Dissection of the molecular mechanisms that control the nuclear accumulation of transport factors importin-α and CAS in stressed cells

The physiological state of eukaryotic cells controls nuclear trafficking of numerous cargos. For example, stress results in the inhibition of classical protein import, which is characterized by the redistribution of several transport factors. As such, importin-alpha and cellular apoptosis susceptibility protein (CAS) accumulate in nuclei of heat-shocked cells; however, the mechanisms underlying this relocation are not fully understood. We now show that heat upregulates the initial docking of importin-alpha at the nuclear envelope and stimulates the translocation of CAS into the nuclear interior. Moreover, heat exposure compromises the exit of importin-alpha from nuclei and drastically increases its retention in the nucleoplasm, whereas CAS nuclear exit and retention are less affected. Taken together, our results support the idea that heat shock regulates importin-alpha and CAS nuclear accumulation at several levels. The combination of different stress-induced changes leads to the nuclear concentration of both transport factors in heat-stressed cells.     

What constitutes ‘apparato reticolare interno’ of Golgi in the goblet cells of vertebrate intestine?

Résumé L'auteur montre que l'appareil réticulaire classique de Golgi dans les cellules caliciformes intestinales des Vertébrés est un produit artificiel. Diverses raisons sont alléguées pour expliquer ce fait.     

Is there a critical tissue oxygen tension for bioenergetic status and cellular pH regulation in solid tumors?

Bioenergetic and metabolic status have been correlated with tissue oxygenation in murine fibrosarcomas (FSaII) of varying sizes (44–600 mm³). Ratios of -nucleoside triphosphates to inorganic phosphate (NTP/P_i) and phosphocreatine to inorganic phosphate (PCr/P_i) ratios derived from³¹P nuclear magnetic resonance spectroscopy (NMR) were positively correlated to median tissue O₂ tension (pO₂) values using O₂-sensitive needle electrodes. pH declined during growth with intracellular acidosis being evident in tumors >350 mm³. Whereas lactic acid formation greatly contributed to this decline in small and medium-sized tumors, adenosine triphosphate (ATP) hydrolysis and slowing down of the activities of pumps involved in cellular pH regulation seem to be major factors responsible for intracellular acidification in bulky tumors. PCr levels decreased at an early growth stage, whilst ATP concentrations dropped in bulky malignancies only, coinciding with a decrease in adenylate energy charge and a substantial rise in the levels of total P_i On average, median pO₂ values of ca. 10 mmHg represent a critical threshold for energy metabolism. At higher median O₂ tensions, levels of ATP, phosphomonoester (PME) and total P_i were relatively constant. This coincided with intracellular alkalosis or neutrality and stable adenylate ratios. On average, median pO₂ values <10 mmHg coincided with intracellular acidosis, ATP depletion, a drop in energy charge and rising P_i levels.     

Is the EHT black hole experiment a new experiment in the guise of an old experiment?

This paper analyzes the experiment presented in 2019 by the Event Horizon Telescope (EHT) Collaboration that unveiled the first image of the supermassive black hole at the center of galaxy M87. The intended aim of the paper is to assess whether the EHT Collaboration has made an “inference to the best explanation” (IBE) to conclude that the data effectively confirm the hypothesis that the object at the center of M87 is in fact a supermassive Kerr rotating black hole. I demonstrate that the EHT Collaboration has applied an IBE. It is shown that the hypothesis that at the center of M87 there is a supermassive Kerr rotating black hole was already the best explanation at the time in which the 2017 EHT experiment was conducted. My analysis is intertwined with considerations on realist and empiricist interpretations of IBE, which are used to assess whether the conclusion that the object at the center of M87 is a Kerr rotating black hole implies holding a realist commitment with respect to such object.     

The effect of αB-crystallin and Hsp27 on the availability of translation initiation factors in heat-shocked cells

The mechanism of the translational thermotolerance provided by the small heat shock proteins (sHsps) αB-crystallin or Hsp27 is unknown. We show here that Hsp27, but not αB-crystallin, increased the pool of mobile stress granule-associated enhanced green fluorescent protein (EGFP)-eukaryotic translation initiation factor (eIF)4E in heat-shocked cells, as determined by fluorescence recovery after photobleaching. Hsp27 also partially prevented the sharp decrease in the pool of mobile cytoplasmic EGFP-eIF4G. sHsps did not prevent the phosphorylation of eIF2α by a heat shock, but promoted dephosphorylation during recovery. Expression of the C-terminal fragment of GADD34, which causes constitutive dephosphorylation of eIF2α, fully compensated for the stimulatory effect of αB-crystallin on protein synthesis in heat-shocked cells, but only partially for that of Hsp27. Our data show that sHsps do not prevent the inhibition of protein synthesis upon heat shock, but restore translation more rapidly by promoting the dephosphorylation of eIF2α and, in the case of Hsp27, the availability of eIF4E and eIF4G. Received 9 December 2005; received after revision 16 January 2006; accepted 23 January 2006     

Bovine microvascular endothelial cells of separate morphology differ in growth and response to the action of interferon-γ

Five cell types recently isolated from the bovine corpus luteum differed in their epithelioid morphology and their cytoskeleton, but shared common criteria of microvascular endothelial cells^1,2. To give strong evidence for the separate entity, the growth rate of the 5 phenotypically different cells was studied. They were seeded at low density on day 0. Most of these cells were treated with 200 to 1000 U recombinant bovine interferon- (IFN-) for 3 days. The untreated remainder served as controls. Cell counts were made for all cultures on days 4, 7, 10 and 13. morphology: 13 d after treatment with IFN- senescent cells as well as intact cells occurred in cultures of cell types 1 to 4. Cultures of cell type 5 were apparently unchanged and resembled their untreated counterparts. Desminpositive cells in cultures of cell type 2 developed cell processes. Growth rate: In the absence of IFN-, the growth rate was high for cell types 3 and 4, moderate for cell type 1, and low for cell types 2 and 5. The presence of IFN- caused anti-proliferative effects. These were higher for cell types 3 and 4 than for cell types 1 and 2. IFN- could be cytotoxic on cell type 3. In contrast, the cytokine tended to support the cell growth of cell type 5. These findings substantiate the postulate that endothelial cells exhibiting separate morphology in culture also function differently.     

Effect of an ecdysteroid on DNA synthesis,DNA polymerase α and thymidine kinase activities ofDrosophila melanogaster cells in vitro

Summary 10^–7 M 20-OH-ecdysone treatment of a diploidDrosophila clone results in an inhibition of 60% of the DNA synthesis from 18 h of treatment on. After 48 h of hormone treatment the thymidine kinase activity is 70% inhibited; concomitantly a 60–70% lowering of the acid-soluble specific activity is observed. In the meantime the DNA polymerase activity is reduced.     

Spectrin and calpain: a ‘target’ and a ‘sniper’ in the pathology of neuronal cells

It is well documented that activation of calpain, a calcium-sensitive cysteine protease, marks the pathology of naturally and experimentally occuring neurodegenerative conditions. Calpain-mediated proteolysis of major membrane-skeletal protein, αII-spectrin, results in the appearance of two unique and highly stable breakdown products, which is an early event in neural cell pathology. This review focuses on spectrin degradation by calpain within neurons induced by diverse conditions, emphasizing a current picture of multi-pattern neuronal death and a recent success in the development of spectrin-based biomarkers. The issue is presented in the context of the major structural and functional properties of the two proteins.Received 7 March 2005; received after revision 22 April 2005; accepted 13 May 2005     

Is forecasting with large models informative? Assessing the role of judgement in macroeconomic forecasts

We evaluate residual projection strategies in the context of a large‐scale macro model of the euro area and smaller benchmark time‐series models. The exercises attempt to measure the accuracy of model‐based forecasts simulated both out‐of‐sample and in‐sample. Both exercises incorporate alternative residual‐projection methods, to assess the importance of unaccounted‐for breaks in forecast accuracy and off‐model judgement. Conclusions reached are that simple mechanical residual adjustments have a significant impact on forecasting accuracy irrespective of the model in use, likely due to the presence of breaks in trends in the data. The testing procedure and conclusions are applicable to a wide class of models and of general interest. Copyright © 2010 John Wiley & Sons, Ltd.