Facilitation in Sea Anemones

1952 ◽  
Vol 29 (2) ◽  
pp. 235-254
Author(s):  
D. M. ROSS
Keyword(s):  
Bile Salt ◽  
Standardized Tests ◽  
Single Stimulus ◽  
Living Animal ◽  
Sea Anemones ◽  
Nerve Net ◽  
Reported Effect ◽  
High Doses ◽  
Electrical Stimuli ◽  
Very High

1. The previously reported effect of anemone extracts, the occurrence of quick closing responses to single electrical stimuli in Metridium, has been re-investigated. In standardized tests it was found that whereas hundreds of stimuli are required for each response to a single stimulus in untreated animals, after anemone extract the incidence of such responses is one per nine stimuli. 2. The incidence of these responses falls off with decreasing doses of extract and the effect disappears when less than 1/500th of the material from a single large Metridium is administered. There is no evidence that extracts from ‘stimulated’ and ‘unstimulated’ (i.e. anaesthetized or quick-frozen) anemones differ in potency. Extracts from divided animals show greater activity in the ‘sphincter-disk’ fraction. 3. The incidence of the responses also falls off in time and is highest from 15 to 30 sec. after beginning the treatment. The effect is sporadic and short-lived and responses to two or more successive stimuli are exceptional. 4. A number of treatments, such as drastic changes in pH, KCl(K+ x 8), tetramethylammonium hydroxide (1 : 100), NH4C1 (1 : 340) and especially bile salt and saponin, have similar effects. Drugs with neuro-muscular effects elsewhere (acetylcholine, adrenaline, tyramine, histamine, etc.) were generally ineffective except at very high doses. Food stimulants too were ineffective. 5. From the time relations and other aspects of the responses to single stimuli it is concluded that the effect should not be attributed to a substance with the function of a ‘facilitator’ in the living animal. 6. While the effects are consistent with the passage of occasional adventitious impulses in the nerve net, there is a singular absence of spontaneous or post-stimulus contractions. Certain implications of this feature of the results are discussed.

Daunorubicin and Platelet Function

1981 ◽  
Vol 45 (01) ◽  
pp. 038-042 ◽  
Author(s):  
M E Pogliani ◽  
R Fantasia ◽  
G Lambertenghi-Deliliers ◽  
E Cofrancesco
Keyword(s):  
Electron Microscope ◽  
Cellular Membrane ◽  
Hemorrhagic Diathesis ◽  
Clot Retraction ◽  
Freezing And Thawing ◽  
Platelet Factor ◽  
High Doses ◽  
Very High ◽  
Platelet Functions

SummaryThe influence of Daunorubicin on some platelet functions in vitro was investigated, using different concentrations of the drug (0.01-0.02-0.04 μg/ml). Daunorubicin was shown to inhibit Collagen and Thrombin induced platelet aggregation and the intensity of inhibition depended on both drug concentration and the time of preincubation.Daunorubicin was also shown to inhibit the release reaction, the platelet prostaglandin pathway and the availability platelet factor 3; the drug at concentrations for clinical use does not damage the platelet membrane, as is the case with the freezing and thawing test, in platelet uptake of 14C-serotonin and as confirmed by the electron microscope. When very high doses (0.16 mg) of Daunorubicin are used, lysis of the platelets can be observed and this is confirmed under the electron microscope by the presence of empty platelets with fractures at the level of the cytoplasmic membrane.Finally, Daunorubicin causes irreversible inhibition of reptilase clot-retraction, even if this is less severe than with Vincristine. Working with gel-filtered platelets, it would appear that the inhibition exercised by the drug on platelet reactions is not caused through modifications in Ca++ metabolism.The authors suggest that Daunorubicin, at the dosages used clinically, induces in vitro thrombocytopathy without damaging the cellular membrane as confirmed by the electron microscope.This impairment of platelet functions could play a part in hemorrhagic diathesis observed during Daunorubicin therapy.

scholarly journals Quantifying prescribed high dose opioids in the community and risk of overdose

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Joe Schofield ◽  
Deborah Steven ◽  
Rebecca Foster ◽  
Catriona Matheson ◽  
Alexander Baldacchino ◽  
...  
Keyword(s):  
Risk Factors ◽  
Service Improvement ◽  
High Dose ◽  
Opioid Overdose ◽  
Opioid Prescribing ◽  
Patient Level ◽  
Strong Opioid ◽  
High Doses ◽  
Strong Opioids ◽  
Very High

Abstract Background Opioid prescribing for a range of health issues is increasing globally. The risk of fatal and non-fatal overdose is increased among people prescribed strong opioids: in high doses in the context of polypharmacy (the use of multiple medications at the same time), especially with other sedatives; and among people with multiple morbidities including cardiorespiratory, hepatic and renal conditions. This study described and quantified the prescribing of strong opioids, comorbidities and other overdose risk factors among those prescribed strong opioids, and factors associated with high/very high opioid dosage in a regional health authority in Scotland as part of a wider service improvement exercise. Methods Participating practices ran searches to identify patients prescribed strong opioids and their characteristics, polypharmacy, and other overdose risk factors. Data were anonymised before being analysed at practice and patient-level. Morphine Equivalent Doses were calculated for patients based on drug/dose information and classed as Low/Medium/High/Very High. Descriptive statistics were generated on the strong opioid patient population and overdose risk factors. The relationship between the prescribing of strong opioids and practice/patient-level factors was investigated using linear and logistic regression models. Results Eighty-five percent (46/54) of GP practices participated. 12.4% (42,382/341,240) of individuals in participating practices were prescribed opioids and, of these, one third (14,079/42,382) were prescribed strong opioids. The most common comorbidities and overdose risk factors among strong opioid recipients were pain (67.2%), cardiovascular disease (43.2%), and mental health problems (39.3%). There was a positive significant relationship between level of social deprivation among practice caseload and level of strong opioid prescribing (p < 0.001). People prescribed strong opioids tended to be older (mean 59.7 years) and female (8638, 61.4%) and, among a subset of patients, age, gender and opioid drug class were significantly associated with prescribing of High/Very High doses. Conclusions Our findings have identified a large population at potential risk of prescription opioid overdose. There is a need to explore pragmatic models of tailored interventions which may reduce the risk of overdose within this group and clinical practice may need to be tightened to minimise overdose risk for individuals prescribed high dose opioids.

EFFECTS OF ECDYSONES, JUVENILE HORMONE ANALOGS, AND 6-OXOOCTANOIC ACID ON THE DEVELOPMENT OF THE MOSQUITO, CULEX TARSALIS (DIPTERA: CULICIDAE)

1974 ◽  
Vol 106 (1) ◽  
pp. 79-85 ◽  
Author(s):  
P. I. Ittycheriah ◽  
M. S. Quraishi ◽  
E. P. Marks
Keyword(s):  
Juvenile Hormone ◽  
Topical Treatment ◽  
Adult Emergence ◽  
Fourth Instar ◽  
Culex Tarsalis ◽  
Juvenile Hormone Analog ◽  
Hormone Analog ◽  
High Doses ◽  
Hormone Analogs ◽  
Very High

AbstractEggs, larvae, and pupae of Culex tarsalis Coquillett were treated with ecdysones, juvenile hormone analogs, and 6-oxooctanoic acid. Effects of these agents on mortality, induction of supernumerary stages, and adult emergence were determined. Topical treatment of eggs with CRD9499 (a juvenile hormone analog), β-ecdysone, and 22-isoecdysone caused a reduction in adult emergence. Treatment of fourth-instar larvae with these chemicals not only induced mortality but also caused the formation of supernumerary intermediate stages. Larvae of C. tarsalis were very susceptible to CRD9499, but pupae were resistant. The ecdysones caused some mortality but only at very high doses and would thus be of little use as larvicides. 6-Oxooctanoic acid caused high rates of mortality at 0.001 M concentrations.

The Behaviour and Neuromuscular System of Gonactinia Prolifera, A Swimming Sea-Anemone

1971 ◽  
Vol 55 (3) ◽  
pp. 611-640
Author(s):  
ELAINE A. ROBSON
Keyword(s):  
Electrical Stimulation ◽  
Mechanical Stimulation ◽  
Motor Units ◽  
Nerve Cells ◽  
Sea Anemone ◽  
Neuromuscular System ◽  
Sea Anemones ◽  
Nerve Net ◽  
Local Contraction ◽  
Electric Shocks

1. In Gonactinia well-developed ectodermal muscle and nerve-net extend over the column and crown and play an important part in the anemone's behaviour. 2. Common sequences of behaviour are described. Feeding is a series of reflex contractions of different muscles by means of which plankton is caught and swallowed. Walking, in the form of brief looping steps, differs markedly in that it continues after interruptions. Anemones also swim with rapid tentacle strokes after contact with certain nudibranch molluscs, strong mechanical disturbance or electrical stimulation. 3. Swimming is attributed to temporary excitation of a diffuse ectodermal pacemaker possibly situated in the upper column. 4. From the results of electrical and mechanical stimulation it is concluded that the endodermal neuromuscular system resembles that of other anemones but that the properties of the ectodermal neuromuscular system require a new explanation. The size and spread of responses to electric shocks vary with intensity, latency is variable and there is a tendency to after-discharge. There is precise radial localization, for example touching a tentacle or the column causes it to bend towards or away from the stimulus. 5. A model to explain these and other features includes multipolar nerve cells closely linked to the nerve-net which would act as intermediate motor units, causing local contraction of the ectodermal muscle. This scheme can be applied to other swimming anemones but there is no evidence that it holds for sea anemones generally.

scholarly journals Vitamin B12 transport in blood. I. Congenital deficiency of transcobalamin II

Blood ◽  
1975 ◽  
Vol 45 (1) ◽  
pp. 71-82 ◽  
Author(s):  
E Gimpert ◽  
M Jakob ◽  
WH Hitzig
Keyword(s):  
Vitamin B12 ◽  
Binding Capacity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Congenital Deficiency ◽  
Complete Clinical Remission ◽  
High Concentrations ◽  
High Doses ◽  
Vitamin B12 Binder ◽  
Very High ◽  
Transcobalamin Ii

Abstract Some characteristics of vitamin B12 binding and transport in the serum of an infant with congenital hereditary transcobalamin II (TC II) deficiency were studied using the following parameters and methods: vitamin B12 level and binding capacity; electrophoretic mobility in polyacrylamide gel electrophoresis; various immunodiffusion and absorption experiments, using a specific anti-TC II antiserum and the patient's serum as antigen. The results of these studies point to a deficient synthesis of TC II. Parenteral administration of high doses of vitamin B12 was followed by rapid and complete clinical remission and the appearance of vitamin B12 binder in the alpha 2 region which is similar to “fetal binder.” Thus, very high concentrations of vitamin B12, either carrier free or bound to this alpha 2 binder, were able to correct the disturbed physiology of TC II deficiency, presumably by normalization of DNA-thymine synthesis.

scholarly journals GDF3 is a BMP inhibitor that can activate Nodal signaling only at very high doses

2009 ◽  
Vol 325 (1) ◽  
pp. 43-48 ◽  
Author(s):  
Ariel J. Levine ◽  
Zachary J. Levine ◽  
Ali H. Brivanlou
Keyword(s):  
Nodal Signaling ◽  
High Doses ◽  
Very High

scholarly journals Corticosterone Upregulates Gene and Protein Expression of Catecholamine Markers in Organotypic Brainstem Cultures

2019 ◽  
Vol 20 (12) ◽  
pp. 2901 ◽  
Author(s):  
Carla L. Busceti ◽  
Rosangela Ferese ◽  
Domenico Bucci ◽  
Larisa Ryskalin ◽  
Stefano Gambardella ◽  
...  
Keyword(s):  
Adrenal Cortex ◽  
Cell Metabolism ◽  
Internal Organs ◽  
Dopamine Beta Hydroxylase ◽  
Expression Of Genes ◽  
Gene And Protein Expression ◽  
Specific Receptors ◽  
Catecholamine Neurons ◽  
High Doses ◽  
Very High

Glucocorticoids are produced by the adrenal cortex and regulate cell metabolism in a variety of organs. This occurs either directly, by acting on specific receptors in a variety of cells, or by stimulating catecholamine expression within neighbor cells of the adrenal medulla. In this way, the whole adrenal gland may support specific metabolic requirements to cope with stressful conditions from external environment or internal organs. In addition, glucocorticoid levels may increase significantly in the presence of inappropriate secretion from adrenal cortex or may be administered at high doses to treat inflammatory disorders. In these conditions, metabolic alterations and increased blood pressure may occur, although altered sleep-waking cycle, anxiety, and mood disorders are frequent. These latter symptoms remain unexplained at the molecular level, although they overlap remarkably with disorders affecting catecholamine nuclei of the brainstem reticular formation. In fact, the present study indicates that various doses of glucocorticoids alter the expression of genes and proteins, which are specific for reticular catecholamine neurons. In detail, corticosterone administration to organotypic mouse brainstem cultures significantly increases Tyrosine hydroxylase (TH) and Dopamine transporter (DAT), while Phenylethanolamine N-methyltransferase (PNMT) is not affected. On the other hand, Dopamine Beta-Hydroxylase (DBH) increases only after very high doses of corticosterone.

Tools for risk assessment in radiation therapy

2012 ◽  
Vol 41 (3-4) ◽  
pp. 197-207 ◽  
Author(s):  
P. Ortiz López
Keyword(s):  
Radiation Therapy ◽  
Radiological Protection ◽  
Quality And Safety ◽  
Energy Agency ◽  
Safety Issues ◽  
Safety Programme ◽  
Specific Safety ◽  
High Doses ◽  
Very High ◽  
Icrp Publication

Radiotherapy has unquestionable benefits, but it is also associated with unique and specific safety issues. It is the only application of radiation in which humans are intentionally delivered very high doses. Safety in radiotherapy remains heavily dependent on human actions. A step-by-step approach is suggested for the prevention of accidental exposures in radiation therapy: (1) allocation of responsibilities to qualified professionals, and design of a quality and safety programme - no radiotherapy practice should be operated without these key elements; (2) use of the lessons from accidental exposures to test whether the quality and safety programme is sufficiently robust against these types of events –publications by the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency provide a collection of lessons to facilitate this step; and (3) find other latent risks by posing the questions ‘What else could go wrong?’ or ‘What other potential hazards might be present?’ in a systematic, anticipative manner - methods to do so are described briefly in ICRP Publication 112.

Croonian Lecture - The elementary nervous system

1952 ◽  
Vol 140 (899) ◽  
pp. 147-168 ◽  
Keyword(s):  
Spontaneous Activity ◽  
Complete Analysis ◽  
Muscle Fibres ◽  
Sea Anemones ◽  
Structural Units ◽  
Normal Behaviour ◽  
Histological Studies ◽  
Nerve Net ◽  
Physiological Properties ◽  
Elementary Form

Nervous organization is found in a most elementary form in the sea-anemones. Their behaviour is brought about partly by specific muscles, partly by the mechanically complex operation of fields of muscle fibres. Stimulation causes conduction of all-or-nothing impulses to the muscles. Histological studies confirm and extend the early work of Sharpey-Schäfer on the organization of the coelenterate nerve-net. Much of the later histological work is vitiated by confusion of other fibrous structures with nerve cells. Both physiological and critical histological studies show" that the net is synaptic. Simple reflexes play only a limited part in actinian behaviour. There is evidence that several distinct kinds of spontaneous activity are built into the normal behaviour mechanisms. A response often consists of a prolonged change in pattern of spontaneous activity, rather than a reflex. The complexity and variety of physiological properties utilized in the behaviour of these animals is surprising and often recalls central nervous phenomena. Nevertheless, we are perhaps nearer a complete analysis of the structural units on which behaviour is based in these than in any other animals.

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