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At least 811 records · Page 45Linked to original sources
PubMed2002

Organization of work via a natural substance: regulation of nest construction in social wasps.

In social insects, colony-level complexity emerges from simple individual-level behaviors and interactions. In the evolution of insect societies, selection has acted to promote efficiency through division of labor. Nest construction of social wasps is an excellent model system to study division of labor and the performance of a decentralized behavioral regulation. After re-examination of Jeanne's (1996) demand-driven "non-taskmates feedback" hypothesis, an alternative mechanism is suggested whereby the regulation of behavior is based on a natural substance (water) which is itself also a building material. By experimenting with a simple model system, we show that the model's predictions agree with observational data and cover a wide range of evolutionary transitions. According to the internal and external parameters, the colony builds up storage of water that is used both as regulator and building material. Through individual interactions, pulp foragers and water foragers emerge from general laborers and their ratio becomes balanced. The emergent foragers ensure both the stabilization of the quantity of stored water and the steady construction of the nest according to the given conditions. Perturbations of the system alter colony-level dynamics in a similar way as was observed in nature: water and pulp addition increase pulp arrivals and building rate; removal of pulp foragers decreases pulp input and construction rate, but not the water influx; removal of water foragers causes overcompensation of water input after a delay. After comparing the predictions of the model to natural data, assumptions found in the literature on organization of work and regulation of behavior are re-examined. A new, more parsimonious model of organization of work is proposed that may cover wide variety of cases where hormones and learning cannot be accounted for the regulation of behavior.

Animals↗
PubMedDate not supplied

Atrial flutter following a wasp sting.

Wasp stings have been associated with a wide variety of local and systemic reactions including, rarely, tachyarrhythmias. We discuss a case of atrial flutter occurring in a 64-year-old man following a single sting in the absence of anaphylaxis. The pathogenesis is discussed and the literature reviewed.

Animals↗
PubMed2003

Silent acute myocardial infarction following a wasp sting.

Hymenoptera sting can lead to an acute myocardial infarction by different pathogenetic mechanisms depending on the presence of preexistent coronary atherosclerosis, the development of shock or the therapeutic use of epinephrine. The case of a 67-year-old man with acute myocardial infarction with ST-segment elevation after a wasp sting treated with fibrinolysis and without significant coronary atherosclerosis is reported. Of particular interest in the present case report is the silent presentation and the absence of any pharmacological interference. It follows that in any case of hymenoptera envenomation a standard ECG is advisable even when a clearly defined allergic reaction is not present.

Aged↗
PubMed2003

Polyembryony in parasitic wasps: evolution of a novel mode of development.

Major developmental innovations have been associated with adaptive radiations that have allowed particular groups of organisms to occupy empty ecospace. Well-known developmental novelties associated with the conquest of new habitats include the evolution of the tetrapode limb, allowing the radiation of vertebrates into a terrestrial habitat, and formation of insect wings that permitted their dispersal into the air. However, an understanding of the evolutionary forces and molecular mechanisms behind developmental novelties still remains tenuous. A little-studied adaptive radiation in insects from the developmental perspective is the evolution of parasitism. The parasitic lifestyle has allowed parasitic insects to occupy a novel ecological niche where they have evolved a plethora of life history strategies and modes of embryogenesis, developing on or within the body of the host. One of the most striking adaptations to development within the body of the host includes polyembryonic development, where certain wasps form clonally up to 2000 embryos from a single egg. Taking advantage of well-established insect phylogeny, techniques developed in a model insect, the fruit fly, and a wealth of knowledge in comparative insect embryology, we are starting to tease apart the evolutionary events that have led to this novel mode of development in insects.

Animals↗
PubMed2005

[Acute myocardial infarction after wasp sting without anaphylactic reaction].

Bites of hymenopterans (bees, wasps and hornets) are very frequent phenomena that can stir up allergical reactions in venom-susceptible patients but that seldom provoke acute myocardial infarction. In the literature we can find case reports of myocardial infarction after bites of hymenopterans, and preceded by an allergic reaction (sometimes with angiographic evidence of undamaged coronary arteries). The pathophysiological determinant seems to be related to the chemical composition of hymenopterans venom, basically made up by vasoactive and thrombogenic substances able to create vasospasm and coronary thrombosis. Our report refers to a 65-year-old male patient without prior cardiological and allergic events who, bitten by a sharm of three bees, complains of an acute large anterior myocardial infarction with angiographic evidence of thrombotic lesion of the proximal left anterior descending artery treated with direct stenting with procedural success, without showing allergical symptoms. The pathophysiological determinant seems to be related to the release of vasoactive amines and thrombogenic substances contained into the hymenopterans venom, the former able to produce vasospasm, the latter able to create diffuse thrombosis. The use of adrenaline itself to counteract the possible systemic allergic reaction appears to advise against the treatment of patients with cardiological symptoms or coronary artery disease and because of its strong vasoactive activity (it leads, in fact, to vasoconstriction) and thrombogenic effects.

Aged↗
PubMed1992

Wasp sting-induced linear keratitis.

A 52-year-old man was stung by a wasp on his left conjunctiva. On the day of the injury, severe chemosis and perilimbal cell infiltration were observed. On the next day, a peculiar linear keratitis was seen. Systemic and topical corticosteroids were applied successfully.

Animals↗
PubMed1977

[Comparison of structural and functional organization of adrenocorticotropic hormone and wasp kinin].

A comparative study of structural and functional organization of the polypeptides -- ACTH and wasp kinin was made. The effects of fragments Lys 17, 18-ACTH11(-18)-NH2--(I) and WK4(-12)--(II), possessing "common" fragments and a cluster of basic amino-acids, on the lipolytic and steroidogenic effects of ACTH and myotropic effects of bradykinin were studied. Both fragments I and II potentiate ACTH-induced lipolysis and steroidogenesis in isolated rat fat and adrenal cells but suppress the myotropic effect of bradykinin on guinea pig ileum. The similarity of biological effects of ACTH and WK fragments support our supposition on the similarity in structurally functional organization of these peptides.

Adipose Tissue↗
PubMed1990

[The Pharmacia CAP system as a new measure of specific IgE. Application in the diagnosis of hypersensitivity to the venom of the Vespula wasp].

Every improvement can make the measurement of specific IgE more effective. This is the case with the CAP system, a new solid phase technique which uses an Immunocap made from hydrophilic polymer, encased in a capsule, for the fixation of anti-IgE or allergen. The Immunocap fixes 3 times more protein than paper discs. Another improvement is that of calibration of the CAP System by the WHO standard for IgE, with the results expressed in KUI/I: 0.35 to 100 KUI/I for specific IgE and 2 to 2,000 KUI/I for total IgE. The study was of patients who had an anaphylactic or systemic reaction after wasp stings. The subjects were divided into two groups A and B and compared with a reference Groupe C. The study also included subjects who were sensitive to mites, grass pollens and egg. Finally, the technique itself was submitted to a reproducibility test. The results confirm that the sensitivity and specificity of the test were both equal to unity. The CAP System therefore offers the possibility of detecting the lowest amounts of IgE.

Anaphylaxis↗
PubMed1990

Isolation, partial purification and pharmacodynamics of a slow contractile substance in the venom sac extract of the wasp Vespa cincta Fabr.

The venom of V. cincta contains acetylcholine (ACh), histamine and 5-hydroxytryptamine (5-HT). Blockers of these agonists did not block completely the hypotensive and smooth muscle contractile activity of venom. On smooth muscle, there was a residual slow contraction. The active substance which produced this slow contraction was separated by solvent extraction, gel filtration and TLC. The purified material (which has been provisionally designated "Vecikinin") lowered cat, rat and guinea pig blood pressure, increased amplitude of cardiac contraction, and increased capillary permeability. Vecikinin contracted several smooth muscle preparations (rat uterus, rat ascending colon, guinea pig ileum, guinea pig colon and rat ileum), while relaxing rat duodenum. Its contractile activity was not lost on boiling, but acid or alkali-boiling reduced its contractile activity. It was inactivated on incubation with chymotrypsin and carboxypeptidase but not with trypsin, pepsin or leucine aminopeptidase. It is a peptide, appears to be of low molecular weight, and could be distinguished from substance P, angiotensin, bradykinin and hornet or wasp kinin.

Animals↗
PubMed1989

Mastoparan, a wasp venom peptide, identifies two discrete mechanisms for elevating cytosolic calcium and inositol trisphosphates in human polymorphonuclear leukocytes.

Mastoparan, a tetradecapeptide toxin from wasp venom stimulates secretion in mast cells and enhances GTPase activity of several purified guanine nucleotide regulatory proteins (G proteins). This suggests that this toxin may effect cellular functions through activation of G proteins. In this report, we probed the effects of mastoparan on cytosolic calcium concentration ([Ca2+]i) and inositol trisphosphate (IP3) formation in human polymorphonuclear leukocytes (PMN). At noncytotoxic concentrations up to 35 microM, mastoparan induced a dose-dependent elevation in [Ca2+]i in PMN, as determined by the fluoroprobe Fura 2. The increase in [Ca2+]i was attained through two discrete processes involving an initial rapid and transient calcium rise followed by a slower sustained increase. The initial but not the second [Ca2+]i increase was absent in PMN pretreated with pertussis toxin. The second but not the first [Ca2+]i rise required external calcium. The kinetics of [Ca2+]i changes and dependency on extracellular calcium induced by mastoparan correlated with the production of IP3. Pertussis toxin inhibited only the initial phase of IP3 production. The ability of pertussis toxin to ADP-ribosylate Gi-like proteins in PMN membrane was potentiated in the presence of mastoparan. Thus, mastoparan activates phospholipase C in PMN through two independent mechanisms. The first pathway is similar to that induced by chemoattractant receptors in that the rapid and transient activation of phospholipase C is dependent on a pertussis toxin-sensitive Gi protein. The second pathway is delayed, sustained, insensitive to pertussis toxin, and requires extracellular calcium.

Amino Acid Sequence↗
PubMed1988

Mastoparan, a peptide toxin from wasp venom, mimics receptors by activating GTP-binding regulatory proteins (G proteins).

Mastoparan, a peptide toxin from wasp venom, is a nonspecific secretagogue. We show here that mastoparan increases the GTPase activity and the rate of nucleotide binding of several purified GTP-binding regulatory proteins (G proteins) whose function is to couple cell-surface receptors to intracellular mediators. Mastoparan accelerated guanosine-5'-(3-O-thiotriphosphate binding and consequent G protein activation in part by promoting the dissociation of bound GDP, the mechanism by which receptors regulate G proteins. ADP-ribosylation by pertussis toxin, which uncouples receptors from G proteins, selectively inhibited mastoparan-stimulated activation. Like receptors, mastoparan was more potent if the G protein was reconstituted in phospholipid vesicles and was active at micromolar concentrations of Mg2+. The structure of mastoparan in a lipid bilayer is similar to that predicted for a cationic intracellular loop of G protein-coupled receptors. Mastoparan thus displays a novel mode of toxicity by acting directly on G proteins to mimic the role normally played by agonist-liganded receptors.

Adenosine Diphosphate Ribose↗
PubMed1978

[Allergic encephalomyelopolyradiculoneuritis from a wasp sting (clinico-pathologic report)].

The authors discuss clinico-pathomorphological observations of allergic encephalomyelopolyradiculoneuritis, due to wasp stings. A lethal outcome followed the 14th day of the disease. The clinical picture and morphological symptoms were characterized by allergic reactions of immediate and retarded types leading to severe lesions of the vital organs and the nervous system. Special attention is drawn to a selective lesion of the pallidonigral system conditioning the clinical picture of acutely developing parkinsonism. The polyradiculoneuritis and myelitical syndrome were also expressed.

Blood Vessels↗
PubMed1981

[Obsessional-type compulsive behavior caused by bilateral circumscribed pallidostriatal necrosis. Encephalopathy caused by a wasp sting].

A previously healthy young man developed encephalopathy after a wasp sting in 1968. Neurological complications included chorea, currently of a minor degree, replaced by buccofacial dyskinesias and compulsive movements. The most disabling consequences were of psychic nature, the patient presenting an unusually marked compulsive activity of an obsessional type. The whole psychic picture however was quite different from that of the usual neurosis, since there was neither anxiety nor doubt, but a mental vacuum contrasting with almost normal intellectual and affective capacities. It was as though there was a loss of the auto-activation system of psychic life, postulated by dynamic psychologists. C.A.T. demonstrated bilateral pallidostriatal necrosis. This suggests that the striatum plays a motor and psychic role. In the field of motor control, its hypoactivity appears to determine not only chorea but dyskinesias similar to tics and compulsive movements. In the psychic field, the striatum appears to play the very general role of an auto-activation system of intellectual and affective life, its deficiency leading to mental activity of a compulsive nature. Improvement in knowledge of striatal biology should clarify not only the basic mechanisms of chorea, but those of tics and obsessions.

Brain Diseases↗
PubMed1993

Wasp sting-induced retinal damage.

A 36-year-old man was stung by a wasp OD. He became delirious and had dyspnea, ocular pain, and severely decreased visual acuity OD. A broken stinger was found in the central deep cornea. Additional ocular findings were keratitis, iritis, cataract, secondary glaucoma, and unrecordable electroretinographic responses.

Adult↗