Role of peripheral chemoreceptors in response to smoke-induced apnea vs tracheal occlusion

Reflex autonomic changes which occur after cigarette smoke enters the upper airways are partially due to peripheral chemoreceptor stimulation. Chemoreceptor denervation attenuates but does not abolish smoke induced bradycardia. Denervation nearly abolishes bradycardia induced by tracheal occlusion. Hypertension accompanies smoke induced apnea but does not occur during tracheal occlusion.     

Male production induced by antibiotic treatment inEncarsia formosa (Hymenoptera: Aphelinidae), an asexual species

The production of large numbers of males in the thelytokous speciesEncarsia formosa was induced by feeding antibiotics to their mothers. The males induced by antibiotic treatment produce sperm and sometimes mate with females, but insemination does not occur.     

The assessment of tobacco smoke toxicity in organ culture. II. Ultrastructural studies on the immediate response of foetal rabbit tracheal epithelium to short-term exposures of whole smoke.

Foetal rabbit tracheal organ cultures were exposed under defined conditions to whole cigarette smoke and fixed immediately for electron microscopy. After an exposure to 4 or 8 puffs, epithelial intercellular spaces were enlarged, the apical portion of many cells bulged out into the lumen and many cilia were swollen. An exposure to 12 puffs produced a breakdown of the epithelium.     

Skeletal muscle capillary densities during reactive hyperemia

Reactive hyperemia was induced in hindlimbs of rats by occlusion of the femoral artery. Using fluorescein dye as a peripheral vascular marker, we observed that there was an increase in the number of flowing capillaries supplying the muscle fibres following release of the occlusion. The results indicate that the number of flowing capillaries is not dependent on the duration of occlusion (2-10 min).     

Skeletal muscle capillary densities during reactive hyperemia

Summary Reactive hyperemia was induced in hindlimbs of rats by occlusion of the femoral artery. Using fluorescein dye as a peripheral vascular marker, we observed that there was an increase in the number of flowing capillaries supplying the muscle fibres following release of the occlusion. The results indicate that the number of flowing capillaries is not dependent on the duration of occlusion (2–10 min).     

Central influence of vasopressin on baroreceptor reflex in normotensive rats and its lack in spontaneously hypertensive rats (SHR)

Summary In normotensive Wistar rats intracerebroventricular (i.c.v.) injection of 30 mU of lysine⁸-vasopressin enhances significantly the cardiovagal reflex bradycardia induced by a blood pressure rise. This effect is absent in spontaneously hypertensive rats (SHR) of the Okamoto strain.     

Beitrag zur Wirkung des Hygroton®

Summary When Hygroton® and spironolactone are given together to rats, the urinary excretion of sodium and chlorides induced by Hygroton increases with increasing doses of spironolactone, but that of potassium does not.     

Action of N-butylnorsympathone on the effects of cardioaccelerator nerve stimulation in the dog]

In Dogs anaesthetized with pentobarbital (30 mg . kg-1), N-butylnorsympathone (20 mg . kg-1 i.v.) reduced the bradycardia induced by stimulating the cardiac nerve (1, 2, 5, 10 Hz). Phentolamine (1 mg . kg-1 i.v.) or yohimbine (0.3 mg . kg-1 i.v.), two potent alpha-adrenoceptor blocking agents known to block presynaptic alpha-adrenoceptor induced a recovery of the effect of cardiac nerve stimulation. Prazosine (0.050 mg . kg-1 i.v.) an alpha-adrenoceptor blocking agent known to be ineffective on presynaptic alpha-adrenoceptors did not induce a recovery. However neither phentolamine or yohimbine were able to prevent the effects of N-butylnorsympathone. Neither haloperidol (0.050 to 2 mg . kg-1 i.v.) or pimozide (0.20 to 1 mg . kg-1 i.v.) induced a recovery or prevented the effects of N-butylnorsympathone. These results suggest that N-butylnorsympathone may stimulate presynaptic receptors which do not resemble classical presynaptic alpha-adrenoceptors or dopamine receptors.     

Sex determining mechanisms: an evolutionary perspective

Theories on the evolution of sex determining mechanisms are reviewed for male and female heterogamety, environmental sex determination, and briefly, haplo-diploidy and hermaphroditism. Because of their discrete and well-defined nature, sex determining mechanisms lend themselves to three types of evolutionary questions: what variety occurs and might be expected but does not occur, how do changes occur from one mechanism to another, and why do certain changes occur? All three approaches were illustrated for these different sex determining mechanisms. A generality emerging from these studies is that, at the level of selection of the sex ratio, there are no intrinsic problems in evolving from one sex determining mechanism to another: straightforward transitions between different mechanisms exist under various conditions.     

Hydrogen bonding by the sulphydryl group of glutathione.

The occurrence of hydrogen bond in the sulphydryl group of glutathione was investigated by means of Raman Spectroscopy. Evidence is obtained that SH group is free and H-bonding does not occur.     

Hydrogen bonding by the sulphydryl group of glutathione

Summary The occurrence of hydrogen bond in the sulphydryl group of glutathione was investigated by means of Raman Spectroscopy. Evidence is obtained that SH group is free and H-bonding does not occur.     

Attenuation by carbocromen of cardiac metabolism alterations due to ischemia.

Carbocromen prevents to some extent, particularly in subendocardial layer, carbohydrate cardiac metabolism alterations induced by the ischemia obtained by intermittent occlusion of left coronary artery.     

Sex determining mechanisms: An evolutionary perspective

Summary Theories on the evolution of sex determining mechanisms are reviewed for male and female heterogamety, environmental sex determination, and briefly, haplo-diploidy and hermaphroditism. Because of their discrete and well-defined nature, sex determining mechanisms lend themselves to three types of evolutionary questions:what variety occurs and might be expected but does not occur,how do changes occur from one mechanism to another, andwhy do certain changes occur? All three approaches were illustrated for these different sex determining mechanisms. A generality emerging from these studies is that, at the level of selection on the sex ratio, there are no intrinsic problems in evolving from one sex determining mechanism to another: straightforward transitions between different mechanisms exist under various conditions.     

Glycoprotein IIb/IIIa blockade inhibits platelet aminophospholipid exposure by potentiating translocase and attenuating scramblase activity

The present study investigated the mechanisms underlying the inhibition of platelet phosphatidylserine (PS) exposure by GPIIb/IIIa blockade. Platelet PS exposure induced by thrombin stimulation was cell-cell contact dependent. GPIIb/IIIa blockade by c7E3 or SR121566 inhibited thrombin-induced platelet PS exposure. Thrombin stimulation induced mild, while A23187 induced extensive platelet-derived microparticle (PDMP) generation. Thrombin-induced PDMP generation was not inhibited by GPIIb/IIIa blockade. Aminophospholipid translocase activity was reduced upon platelet activation by thrombin. The reduction of non-PS-exposing platelets was attenuated by GPIIb/IIIa blockade, while little translocase activity was seen in PS-exposing platelets. Thrombin increased scramblase activity slightly in non-PS-exposing platelets, which was inhibited by GPIIb/IIIa blockade, and markedly enhanced scramblase activity in PS-exposing platelets. Activation of platelet calpain and caspase-3 or cytosolic calcium mobilization were not altered by GPIIb/IIIa inhibition. Thus, GPIIb/IIIa blockade inhibits platelet PS exposure by enhancing translocase activity and attenuating scramblase activity, but does not inhibit PDMP generation. Received 13 December 2006; received after revision 5 February 2007; accepted 9 March 2007     

Morphological integration in the cranium during anuran metamorphosis

We examined the role of thyroid hormone in mediating morphological integration between cranial cartilage and bone during anuran metamorphosis. Exogenous T3 applied to premetamorphic tadpoles (Bombina orientalis) via intracranial implants of plastic micropellets precociously induced typical metamorphic changes in both tissues, but also dissociated the relative timing of developmental events between them. Morphological integration between the two primary cranial tissues is achieved in part by each tissue responding independently to endocrine factors and does not reflect a tight developmental coupling between them.     

The effects of lesions in several zones of the brain on cell multiplication in the glandular epithelium of the rat small intestine]

Radio-frequency lesions of tubero-infundibular region of the hypothalamus are followed by a significant increase of the mitotic rate in the small intestine glandular epithelium in rats. This increase does not occur when radio-frequency lesions are located in the anterior and posterior hypothalamus, in the dorsomedial thalamus and in the cerebral hemispheres.     

Attenuation by carbocromen of cardiac metabolism alterations due to ischemia

Summary Carbocromen prevents to some extent, particularly in subendocardial layer, carbohydrate cardiac metabolism alterations induced by the ischemia obtained by intermittent occlusion of left coronary artery.Acknowledgments. Financial support from the U.E.R. of biologie Humaine is gratefully acknowledged.     

Increase in membrane conductance by adrenaline in parotid acinar cells.

It is shown that excitation of the alpha- or beta-adrenoceptors in mouse parotid acinar cells causes a marked reduction of surface cell membrane resistance. The alpha-adrenoceptor induced membrane effect is an increase in K conductance. The beta-adrenoceptor induced membrane effect does not seem to be mediated by cyclic AMP.     

A factor potentiating serotonin in the induction of germinal vesicle breakdown in surf clam oocytes

Simultaneous addition of an aliquot of body fluid obtained from the surf clam, Spisula solidissima, enhanced oocyte germinal vesicle breakdown induced with serotonin but not with KCl. When the body fluid and serotonin were added sequentially to the oocytes, potentiation did not occur. Body fluids of both males and females were effective at a 200-fold dilution. The factor is stable when treated with heat, acid, base, trypsin and pronase. It is hydrophobic and not dialyzable through tubing with a molecular weight cutoff of 1000 daltons. The factor is probably not a protein.