Reactivation of cytoplasmic actomyosin in Physarum plasmodia extracted with glycerol and dimethylsulphoxide

1987 ◽  
Vol 87 (2) ◽  
pp. 231-239
Author(s):  
R. Bell ◽  
F. Achenbach
Keyword(s):  
Calcium Sensitivity ◽  
Inhibitory Effect ◽  
Prolonged Treatment ◽  
Short Term ◽  
Extraction Procedures ◽  
Term Extraction ◽  
Cytoplasmic Actomyosin ◽  
Structural Preservation ◽  
Physarum Plasmodia

Thin-spread plasmodia of Physarum were subjected to extraction procedures using 50% glycerol or DMSO (dimethylsulphoxide) followed by labelling of actin with fluorescent phallotoxins. During the reactivation of the actomyosin system by 2 mM-MgATP fluorescent actin fibres contract isotonically, which results in numerous fluorescent ‘contraction beads’. After short-term extraction 1 mM-Ca2+ has an inhibitory effect on the reactivation. This calcium sensitivity is abolished after long-term extraction with glycerol. Calcium at 10 mM irreversibly inhibits reactivation, irrespective of the duration of extraction. The inhibitory effect of 10 mM-calcium is prevented by phallotoxin labelling prior to incubation in Ca2+. The DMSO model shows an improvement in structural preservation when compared with the glycerol models. However, reactivation is inhibited by prolonged treatment with DMSO.

scholarly journals The Inhibitory Effect of Protamine on Platelets is Attenuated by Heparin without Inducing Thrombocytopenia in Rodents

Marine Drugs ◽  
2019 ◽  
Vol 17 (9) ◽  
pp. 539
Author(s):  
Joanna Miklosz ◽  
Bartlomiej Kalaska ◽  
Kamil Kaminski ◽  
Malgorzata Rusak ◽  
Krzysztof Szczubialka ◽  
...  
Keyword(s):  
Factor Xa ◽  
Bleeding Risk ◽  
Inhibitory Effect ◽  
Antiplatelet Activity ◽  
Short Term ◽  
Platelet Factor ◽  
Antithrombotic Activity ◽  
Formation Number ◽  
Induced Aggregation

Protamine sulfate (PS) is a polycationic protein drug obtained from the sperm of fish, and is used to reverse the anticoagulant effect of unfractionated heparin (UFH). However, the interactions between PS, UFH, and platelets are still not clear. We measured the platelet numbers and collagen-induced aggregation, P-selectin, platelet factor 4, β-thromboglobulin, prostacyclin metabolite, D-dimers, activated partial thromboplastin time, prothrombin time, anti-factor Xa, fibrinogen, thrombus weight and megakaryocytopoiesis in blood collected from mice and rats in different time points.. All of the groups were treated intravenously with vehicle, UFH, PS, or UFH with PS. We found a short-term antiplatelet activity of PS in mice and rats, and long-term platelet-independent antithrombotic activity in rats with electrically-induced thrombosis. The antiplatelet and antithrombotic potential of PS may contribute to bleeding risk in PS-overdosed patients. The inhibitory effect of PS on the platelets was attenuated by UFH without inducing thrombocytopenia. Treatment with UFH and PS did not affect the formation, number, or activation of platelets, or the thrombosis development in rodents.

scholarly journals Non-steroidal factors in bovine follicular fluid inhibit or facilitate the action of pulsatile administration of GnRH on LH release in the female rat

1999 ◽  
Vol 161 (2) ◽  
pp. 237-243 ◽  
Author(s):  
JA van Dieten ◽  
MN Helder ◽  
C van den Oever ◽  
J de Koning
Keyword(s):  
Follicular Fluid ◽  
Inhibitory Effect ◽  
Female Rats ◽  
Minor Effect ◽  
Female Rat ◽  
Short Term ◽  
Ovx Rats ◽  
Lh Release ◽  
Intact Rats

Using steroid-free bovine follicular fluid (bFF), we studied the action of gonadotrophin surge-inhibiting factor/attenuating factor (GnSIF/AF) on GnRH-induced self-priming in phenobarbital-blocked female rats. For the experiments we used intact rats, short-term (4 h) ovariectomized (OVX) rats and long-term (14 days) OVX rats. In the latter case the rats were injected with 17beta-oestradiol benzoate (OB, 40 micrograms) or vehicle only, 2 or 48 h before the experiment. GnRH (10-50 pmol/kg body weight) was injected intra-arterially in 5 or 15 pulses, respectively 60 or 20 min apart, starting 1 or 4 h after injection of bFF (0.5 or 1.0 ml). In response to 25 pmol/kg GnRH pulses (1/h), we observed no effect in the long-term OVX rats, a minor effect in the intact rats and an enhanced self-priming effect in the short-term OVX rats. Administration of bFF attenuated or even completely inhibited the self-priming process. However, in the case of long-term OVX rats LH release was inhibited only after long-term OB priming. Furthermore, 4 h after administration of bFF, LH release in response to 25 pmol/kg GnRH pulses (3/h) was inhibited transiently in intact rats and long-term OVX rats. The results support the hypothesis of a functional antagonistic action between GnRH and GnSIF/AF. However, when injected 1 h before, bFF facilitated the initial release of the surge-like LH pattern in intact rats in response to 3 pulses/h of GnRH. These results are consistent with an important role of GnSIF/AF and other non-steroidal ovarian factors in the control of both low LH concentrations and the generation of the LH surge. Some genomic action of oestradiol might be a prerequisite for the inhibitory effect of GnSIF/AF on GnRH-induced LH release.

scholarly journals Cytosolic translational responses differ under conditions of severe short-term and long-term mitochondrial stress

2019 ◽  
Vol 30 (15) ◽  
pp. 1864-1877 ◽  
Author(s):  
Lukasz Samluk ◽  
Malgorzata Urbanska ◽  
Katarzyna Kisielewska ◽  
Karthik Mohanraj ◽  
Min-Ji Kim ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Genetic Alterations ◽  
Prolonged Treatment ◽  
Compensatory Mechanism ◽  
Antimycin A ◽  
Short Term ◽  
Mitochondrial Stress ◽  
Mtor Kinase ◽  
Inhibition Of Protein Synthesis

Previous studies demonstrated that cells inhibit protein synthesis as a compensatory mechanism for mitochondrial dysfunction. Protein synthesis can be attenuated by 1) the inhibition of mTOR kinase, which results in a decrease in the phosphorylation of S6K1 and 4E-BP1 proteins, and 2) an increase in the phosphorylation of eIF2α protein. The present study investigated both of these pathways under conditions of short-term acute and long-term mitochondrial stress. Short-term responses were triggered in mammalian cells by treatment with menadione, antimycin A, or CCCP. Long-term mitochondrial stress was induced by prolonged treatment with menadione or rotenone and expression of genetic alterations, such as knocking down the MIA40 oxidoreductase or knocking out NDUFA11 protein. Short-term menadione, antimycin A, or CCCP cell treatment led to the inhibition of protein synthesis, accompanied by a decrease in mTOR kinase activity, an increase in the phosphorylation of eIF2α (Ser51), and an increase in the level of ATF4 transcription factor. Conversely, long-term stress led to a decrease in eIF2α (Ser51) phosphorylation and ATF4 expression and to an increase in S6K1 (Thr389) phosphorylation. Thus, under long-term mitochondrial stress, cells trigger long-lasting adaptive responses for protection against excessive inhibition of protein synthesis.

Immunocytochemistry of the acellular slime mould Physarum polycephalum. I. Preparation, morphology, and reliability of results concerning cytoplasmic actomyosin patterns in sandwiched plasmodia

1983 ◽  
Vol 60 (1) ◽  
pp. 13-28
Author(s):  
W. Naib-Majani ◽  
M. Osborn ◽  
K. Weber ◽  
K.E. Wohlfarth-Bottermann ◽  
H. Hinssen ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Physarum Polycephalum ◽  
Natural Habitat ◽  
Cytoskeletal Proteins ◽  
Reliability Of Results ◽  
Positive Identification ◽  
Term Extraction ◽  
Slime Moulds ◽  
Cytoplasmic Actomyosin

Small phaneroplasmodia of Physarum polycephalum migrate, under sandwich conditions between two agar sheets and a membrane of cellophane, as thin protoplasmic sheets. This method suitably simulates the situation in the natural habitat of acellular slime moulds; i.e. the narrow clefts of the forest soil. The highly differentiated system of cytoplasmic fibrils displayed under these conditions survives both long-term extraction with glycerol and fixation with methanol, procedures that remove the strong inherent autofluorescence, thus allowing the use of immunocytochemical studies. The complicated fibrillar system of sandwiched plasmodia consists of: (1) a membrane-associated cortical filament layer in the anterior region; (2) a more or less regular polygonal fibrillar network in the intermediate region; and (3) a helically twisted fibrillar system encircling endoplasmic pathways as well as isolated strands in the posterior region. So far, three different cytoskeletal proteins have been identified immunocytochemically as constituents of the fibrillar structures: actin, myosin and AM-protein (fragmin). No positive identification of alpha-actinin, filamin and tropomyosin was obtained using antibodies against vertebrate proteins. Electron microscopy of glycerol-extracted specimens treated with antibodies against actin and myosin revealed that the 6 nm filaments consist of actin, whereas the electron-dense material between single actin filaments appears to be myosin. The AM-protein modulating the polymer status of actin is located in all fibrillar structures.

Effect of Long-Term Aspirin Treatment on Platelet Adhesion to Chronically Damaged Canine Pulmonary Arteries

1981 ◽  
Vol 46 (04) ◽  
pp. 680-683 ◽  
Author(s):  
Robert G Schaub ◽  
Clarence A Rawlings ◽  
James C Keith
Keyword(s):  
Platelet Adhesion ◽  
Pulmonary Arteries ◽  
Inhibitory Effect ◽  
Blue Staining ◽  
Term Therapy ◽  
Short Term ◽  
Chronic Injury ◽  
Membrane Changes

SummaryThe effect of aspirin on platelet adhesion to chronically damaged pulmonary arteries was studied in 18 dogs. Chronic injury was produced in all dogs by infection with the canine heartwonn Dirofilaria immitis(DI). Ten dogs were subjected to 4 days of chronic injury. Eight dogs were subjected to 30 days of chronic injury. Five of the 4 day injury and 4 of the 30 day injury dogs received aspirin daily (325 mg/day orally). Aspirin was started 3 days prior to infection with DI. Pulmonary arteries were perfusion fixed in situ at physiologic pressure. The damaged pulmonary arteries were located by Evan’s blue staining (2ml/kg of 1% dye glven one hr prior to perfusion) and prepared for scanning electron microscopy. Both groups of dogs with 4 day DI infection had monolayers of platelets adhered to exposed subendothelium. Aspirin treated dogs had enhanced platelet adhesion to damaged arteries. Aspirin treatment for 33 days reduced platelet adhesion. The damaged arteries of treated dogs infected with DI for 30 days had very few platelets adhering to the damaged surface. However, non-treated dogs subjected to 30 days of infection had platelet adhesion equivalent to the 4 day non-treated infection group. These results suggest that although aspirin is ineffective in preventing platelet adhesion in short term therapy it is effective when given for longer time periods. This inhibitory effect may occur due to platelet membrane changes rather than because of aspirin inhibition of cyclooxygenase.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

1990 ◽  
Vol 48 (3) ◽  
pp. 374-375
Author(s):  
D.E. Loudy ◽  
J. Sprinkle-Cavallo ◽  
J.T. Yarrington ◽  
F.Y. Thompson ◽  
J.P. Gibson
Keyword(s):  
Antidepressant Drug ◽  
Beagle Dogs ◽  
Long Term Effects ◽  
Short Term ◽  
Platelet Counts ◽  
Toxicological Studies ◽  
Induced Aggregation ◽  
Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

Comparison of Auditory, Language, Memory, and Attention Abilities in Children With and Without Listening Difficulties

2020 ◽  
Vol 29 (4) ◽  
pp. 710-727
Author(s):  
Beula M. Magimairaj ◽  
Naveen K. Nagaraj ◽  
Alexander V. Sergeev ◽  
Natalie J. Benafield
Keyword(s):  
Auditory Processing ◽  
Short Term Memory ◽  
Group Differences ◽  
Long Term Memory ◽  
Short Term ◽  
Significant Group ◽  
Term Memory ◽  
Memory And Attention ◽  
Speed And Accuracy

Objectives School-age children with and without parent-reported listening difficulties (LiD) were compared on auditory processing, language, memory, and attention abilities. The objective was to extend what is known so far in the literature about children with LiD by using multiple measures and selective novel measures across the above areas. Design Twenty-six children who were reported by their parents as having LiD and 26 age-matched typically developing children completed clinical tests of auditory processing and multiple measures of language, attention, and memory. All children had normal-range pure-tone hearing thresholds bilaterally. Group differences were examined. Results In addition to significantly poorer speech-perception-in-noise scores, children with LiD had reduced speed and accuracy of word retrieval from long-term memory, poorer short-term memory, sentence recall, and inferencing ability. Statistically significant group differences were of moderate effect size; however, standard test scores of children with LiD were not clinically poor. No statistically significant group differences were observed in attention, working memory capacity, vocabulary, and nonverbal IQ. Conclusions Mild signal-to-noise ratio loss, as reflected by the group mean of children with LiD, supported the children's functional listening problems. In addition, children's relative weakness in select areas of language performance, short-term memory, and long-term memory lexical retrieval speed and accuracy added to previous research on evidence-based areas that need to be evaluated in children with LiD who almost always have heterogenous profiles. Importantly, the functional difficulties faced by children with LiD in relation to their test results indicated, to some extent, that commonly used assessments may not be adequately capturing the children's listening challenges. Supplemental Material https://doi.org/10.23641/asha.12808607

Abstract #283 Diabetes Increases Short-Term but not Long-Term Risk of Fracture: A Community-Based Study

2019 ◽  
Vol 25 ◽  
pp. 114
Author(s):  
Alyssa Dufour ◽  
Setareh Williams ◽  
Richard Weiss ◽  
Elizabeth Samelson
Keyword(s):  
Short Term ◽  
Community Based ◽  
Risk Of Fracture
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