In situ biomechanics of the syrinx and sound generation in pigeons.

1997 ◽  
Vol 200 (16) ◽  
pp. 2165-2176 ◽  
Author(s):  
F Goller ◽  
O N Larsen
Keyword(s):  
Tissue Adhesive ◽  
Sound Generation ◽  
Sound Stimulation ◽  
Direct Observations ◽  
Vibratory Motion ◽  
Strong Stimulation ◽  
Weak Stimulation ◽  
Stimulation Of

The in situ biomechanics of the vocal organ, the syrinx, was studied in anesthetized pigeons using fiberoptic instruments. The role of syringeal muscles was determined by electrical stimulation, and phonation was induced by injecting gas into the subsyringeal air sacs. This study presents the first direct observations of the biomechanical processes that occur in an intact syrinx. Contraction of one of the syringeal muscles, the m. tracheolateralis (TL), withdraws the lateral tympaniform membranes (LTM) from the syringeal lumen, causing opening of the syringeal airways. Shortening of a second muscle, the sternotrachealis (ST), draws the syringeal cartilages closer to each other, causing the LTM to fold into the syringeal lumen. Maximal ST contraction does not lead to complete closure of the syrinx. As air-sac pressure is increased by the injection of gas, the LTM are drawn into the syringeal lumen and balloon in a rostral direction until they touch, thus forming a fold-like valve. Air-induced phonation is always associated with vibrations of the membrane folds, suggesting that pulsatile release of air into the trachea by vibratory motion of the LTM generates sound. During air-induced phonation, strong stimulation of the TL terminates sound generation by abducting the LTM, whereas weak stimulation changes the geometry of the membrane folds, which is accompanied by changes in the acoustic structure of the sound. Stimulation of the ST has little effect on air-induced sounds. The LTM appear to be the main sound generators, since disabling the medial tympaniform membranes (MTM) with tissue adhesive does not prevent phonation or change the frequency and amplitude structure of display coos in spontaneously vocalizing pigeons. Moreover, the activity of the syringeal muscles appears to have a mainly modulatory function, suggesting that the basic sound-generating mechanism is similar in both air-induced and natural phonation.

scholarly journals STUDIES ON THE EFFECT OF CERTAIN TOXIC SUBSTANCES IN BACTERIAL CULTURES ON THE MOVEMENT OF THE INTESTINES

1926 ◽  
Vol 43 (6) ◽  
pp. 785-795 ◽  
Author(s):  
E. E. Ecker ◽  
A. Rademaekers
Keyword(s):  
Intravenous Injection ◽  
Toxic Substances ◽  
Propulsive Efficiency ◽  
Spasmodic Contraction ◽  
Strong Stimulation ◽  
Small Intestines ◽  
Slight Rise ◽  
Longitudinal Muscles ◽  
Stimulation Of

Following intravenous injection, filtrates of young cultures of B. paratyphosus B often produce marked diarrhea in rabbits. A study was made of the effect of these toxic filtrates on the motility of the small intestines of the rabbit. The observations were made on a segment of the small intestines in situ, and in the living animal. It was found that an immediate slight rise of tone of the longitudinal muscles occurred following intravenous injection of sterile broth. The same rise was noted after the injection of the toxic filtrate; but with these it was followed later (10 minutes elapsing at least) by a very strong but gradual rise of the diastolic and systolic tone, i.e., by spasmodic contraction of the intestinal muscle, which persisted at times for as long as 2 hours. In order to record simultaneously the effect on the longitudinal and circular muscles, and the propulsive efficiency of the segment the Sollmann and Rademaekers modification of Baur's technique was employed. This arrangement showed that the stimulation of the longitudinal muscles is accompanied by a similarly strong stimulation of the circular muscles, by peristalsis, and therefore by a greatly increased propulsion of intestinal contents which was sufficient to overcome the inhibition that usually occurs after preparation of the animal. With this arrangement an instance of peristaltic spasm was also noted. Broth alone failed to produce the phenomenon. Isotonic magnesium chloride or sulfate added to the bath relaxed the muscles again. Animals under deep urethane anesthesia did not show the diarrhea occurring in the intact controls, but sometimes exhibited it after the effect of the anesthetic had disappeared. So far no effects have been observed on the isolated strip (Magnus method), and further studies are being made to localize the effect, to neutralize it with a specific antiserum, and to observe the effect of filtrates of other members of the bacterial group including the dysentery bacilli.

scholarly journals miR-210 promotes IPF fibroblast proliferation in response to hypoxia

2014 ◽  
Vol 307 (4) ◽  
pp. L283-L294 ◽  
Author(s):  
Vidya Bodempudi ◽  
Polla Hergert ◽  
Karen Smith ◽  
Hong Xia ◽  
Jeremy Herrera ◽  
...  
Keyword(s):  
Idiopathic Pulmonary Fibrosis ◽  
Hypoxia Inducible Factor ◽  
Clinical Feature ◽  
Similar Distribution ◽  
Fibroblast Proliferation ◽  
Downstream Target ◽  
Progressive Hypoxia ◽  
Stimulation Of

Idiopathic pulmonary fibrosis (IPF) is characterized by the relentless spread of fibroblasts from scarred alveoli into adjacent alveolar units, resulting in progressive hypoxia and death by asphyxiation. Although hypoxia is a prominent clinical feature of IPF, the role of hypoxia as a driver of the progressive fibrotic nature of the disease has not been explored. Here, we demonstrate that hypoxia robustly stimulates the proliferation of IPF fibroblasts. We found that miR-210 expression markedly increases in IPF fibroblasts in response to hypoxia and that knockdown of miR-210 decreases hypoxia-induced IPF fibroblast proliferation. Silencing hypoxia-inducible factor (HIF)-2α inhibits the hypoxia-mediated increase in miR-210 expression and blocks IPF fibroblast proliferation, indicating that HIF-2α is upstream of miR-210. We demonstrate that the miR-210 downstream target MNT is repressed in hypoxic IPF fibroblasts and that knockdown of miR-210 increases MNT expression. Overexpression of MNT inhibits hypoxia-induced IPF fibroblast proliferation. Together, these data indicate that hypoxia potently stimulates miR-210 expression via HIF-2α, and high miR-210 expression drives fibroblast proliferation by repressing the c-myc inhibitor, MNT. In situ analysis of IPF lung tissue demonstrates miR-210 expression in a similar distribution with HIF-2α and the hypoxic marker carbonic anhydrase-IX in cells within the IPF fibrotic reticulum. Our results raise the possibility that a pathological feed-forward loop exists in the IPF lung, in which hypoxia promotes IPF fibroblast proliferation via stimulation of miR-210 expression, which in turn worsens hypoxia.

Regulation of diaphragmatic oxygen uptake by endothelium-derived relaxing factor

1993 ◽  
Vol 265 (1) ◽  
pp. H123-H130 ◽  
Author(s):  
H. Y. Chang ◽  
M. E. Ward ◽  
S. N. Hussain
Keyword(s):  
Blood Flow ◽  
Saline Group ◽  
Mechanically Ventilated ◽  
O2 Extraction ◽  
Endogenous Nitric Oxide ◽  
Phrenic Artery ◽  
Endothelium Derived Relaxing Factor ◽  
Stimulation Of

The role of endogenous nitric oxide (NO) in the regulation of phrenic blood flow (Qphr) and O2 consumption (VO2) of the in situ isolated left hemidiaphragms was assessed in two groups of anesthetized, mechanically ventilated dogs. Saline was infused into the phrenic artery for 20 min in one group, whereas N omega-nitro-L-arginine (L-NNA, 6 x 10(-4) M) was infused in the other (L-NNA) group. Qphr and diaphragmatic VO2 were measured at rest and during 2 min of continuous 3-Hz stimulation of the left phrenic nerve. The animals were progressively hemorrhaged, and the measurements were repeated at various arterial pressures (Pa). For the resting diaphragm, Qphr at a mean Pa of 145 mmHg was lower in the L-NNA group than in the saline group; however, diaphragmatic VO2 values were similar in both groups. Qphr decreased with the decline in Pa in both groups, but O2 extraction ratios obtained at mean Pa of 25–45 mmHg were similar in both groups (71 vs. 73%). For the contracting diaphragm, Qphr and diaphragmatic VO2 values at a given Pa were lower in the L-NNA group than in the saline group (except at mean Pa < 75 mmHg). O2 extraction ratios obtained at a given Pa were similar in both groups. We concluded that 1) EDRF inhibition limits diaphragmatic blood flow both at rest and during 3-Hz stimulation; 2) diaphragmatic O2 extraction is unaffected by EDRF inhibition; and 3) the effect of EDRF release on diaphragmatic VO2 is dependent on the level of metabolic demands.

scholarly journals Role of CD1A and HSP60 in the antitumoral response of oesophageal cancer

2011 ◽  
pp. 225-232
Author(s):  
Simona Corrao ◽  
Giampiero La Rocca ◽  
Rita Anzalone ◽  
Lorenzo Marasà ◽  
Felicia Farina ◽  
...  
Keyword(s):  
Oesophageal Cancer ◽  
Molecular Mechanisms ◽  
Tumor Antigens ◽  
Normal Epithelium ◽  
Improve Treatment ◽  
Molecular Events ◽  
New Strategies ◽  
Stimulation Of

Oesophageal cancer (OC) is one of the most common and severe forms of tumor. A wider knowledge of molecular mechanisms which lead to a normal epithelium becoming a neoplasm may reveal new strategies to improve treatment and outcome of this disease. In this review, we report recent findings concerning molecular events which take place during carcinogenesis of the oesophagus. In particular, we focus on the role of two molecules, CD1a and Hsp60, which are overexpressed in oesophageal and many other types of tumor. Both molecules may present tumor antigens and promote in situ the stimulation of an antitumoral immune activity. We suggest there is a synergistic action between these molecules. Further knowledge about their intracellular pathways and extracellular roles may help develop new antitumoral tools for OC.

The Role of Peripheral Nervous System in Colour Changes of Bufo Arenarum Hensel

1954 ◽  
Vol 31 (4) ◽  
pp. 631-638
Author(s):  
A. O. M. STOPPANI ◽  
P. F. PIERONI ◽  
A. J. MURRAY
Keyword(s):  
Nervous System ◽  
Peripheral Nervous System ◽  
Peripheral Nerves ◽  
Secondary Role ◽  
Bufo Arenarum ◽  
Colour Changes ◽  
Stimulation Of

1. Stimulation of the peripheral nerves of Bufo arenarum Hensel produces a partial paling of the skin due to concentration of pigment in the intracutaneous melanophores, and dispersion of guanin-granules in the guanophores. This effect is attributed to the liberation in situ of an adrenergic-like substance. Noradrenalin and the cutaneous secretion (which contains adrenalin and active bases) play no part in the blanching of the skin. 2. The nervous system plays a secondary role in the paling of the skin which follows hypophysectomy. 3. There is no evidence that stimulation of the peripherai nervous system is essential for the colour changes of B. arenarum.

Mechanical stimulation in the sea-anemone Calliactis parasitica

1955 ◽  
Vol 143 (911) ◽  
pp. 226-238 ◽  
Keyword(s):  
Mechanical Stimulus ◽  
Mechanical Stimuli ◽  
Nervous Impulse ◽  
Excitable System ◽  
Passive Deformation ◽  
Calliactis Parasitica ◽  
Strong Stimulation ◽  
Sufficient Intensity ◽  
Weak Stimulation ◽  
Stimulation Of

1. A method of administering measured local mechanical stimuli is described. Experiments were done upon the anemone Calliactis parasitica . 2. Mechanical stimuli show rapid apparent adaptation—partly due to simple mechanical causes such as contracture and passive deformation of the tissues. 3. When conditions are standardized a mechanical stimulus of sufficient intensity on the column gives a nervous impulse. These mechanical stimuli can be used in the same way as electric shocks to give facilitated responses. 4. Increasing the mechanical intensity of the stimulus shows a threshold below which no impulse is generated; and with further increase of strength, trains of increasing numbers of impulses. There exists a system capable of graded mechanical excitation. Gradation is also to be observed below the threshold since there can be summation of subliminal stimuli. 5. The excitable system appears to be orientated tangentially and responds to stretch rather than to pressure. 6. The excitable system is purely endodermal. The ectoderm and mesogloea act only as an integument. 7. On histological grounds there are grave difficulties in supposing that impulses set arise simply and directly in the numerous simple sense organs. The possibility is noted that the graded excitation of the mechanically sensitive system causes the nerve-net to fire off impulses. 8. The sensitivity of different parts of the animal varies greatly. In Calliactis the oral disk is as least 4000 times as sensitive as the column. 9. The combination of a simple mechanically excitable system with the gross morphological features of the bodily organization permits purposive and varied responses. Thus strong stimulation of the column leads to the closure reflex, whilst weak stimulation of the disk by contact or by water movements leads to appropriate responses connected with feeding or rejection.

The role of the anteriolateral bed nucleus of the stria terminalis in stress-induced nociception

2012 ◽  
Vol 302 (11) ◽  
pp. G1301-G1309 ◽  
Author(s):  
Lee Tran ◽  
Brandt Wiskur ◽  
Beverley Greenwood-Van Meerveld
Keyword(s):  
Stria Terminalis ◽  
Mrna Levels ◽  
Bed Nucleus ◽  
Corticotrophin Releasing Factor ◽  
Visceromotor Response ◽  
Dependent Mechanism ◽  
Von Frey Filaments ◽  
Stimulation Of

Activation of the central amygdala (CeA) by corticosterone (CORT) induces somatic and colonic hypersensitivity through corticotrophin-releasing factor (CRF)-dependent mechanisms. However, the importance of the bed nucleus of the stria terminalis (BNST), part of the extended amygdala, on nociception remains unexplored. In the present study, we test the hypothesis that stimulation of the CeA by CORT induces somatic and colonic hypersensitivity through activation of the anteriolateral BNST (BNSTAL). Animals were implanted with micropellets of CORT or cholesterol (CHOL) onto the CeA or the BNSTAL. Mechanical sensitivity was quantified using electronic von Frey filaments, and colonic nociception was measured by quantifying a visceromotor response to graded colorectal distension. In situ hybridization was used to determine mRNA levels for CRF, CRF1, and CRF2 receptors in the BNSTAL. In a second group, animals were implanted bilaterally with 1) CORT or CHOL micropellets onto the CeA; and 2) cannulas localized to the BNSTAL to administer a CRF1 receptor antagonist (CP376395). Animals implanted with CORT onto the CeA, but not the BNSTAL, exhibited increased expression of CRF mRNA and increased CRF1-to-CRF2 receptor ratio in the BNST, as well as somatic and colonic hypersensitivity compared with CHOL controls. Infusion of CP376395 into the BNSTAL inhibited somatic and colonic hypersensitivity in response to elevated amygdala CORT. Somatic and colonic hypersensitivity induced by elevated amygdala CORT is mediated via a CRF1 receptor-dependent mechanism in the BNSTAL. The CeA through a descending pathway involving the BNSTAL plays a pivotal role in somatic and colonic nociception.

scholarly journals Strong stimulation of N<sub>2</sub> fixation in oligotrophic Mediterranean Sea: results from dust addition in large in situ mesocosms

2013 ◽  
Vol 10 (6) ◽  
pp. 10581-10613 ◽  
Author(s):  
C. Ridame ◽  
C. Guieu ◽  
S. L'Helguen
Keyword(s):  
Mediterranean Sea ◽  
N2 Fixation ◽  
Saharan Dust ◽  
Dust Deposition ◽  
Strong Stimulation ◽  
Stimulation Of

Abstract. The response of N2 fixation to contrasted (wet and dry) Saharan dust deposition was studied in the framework of the DUNE project "a DUst experiment in a low-Nutrient, low-chlorophyll Ecosystem" during which realistic simulations of dust deposition (10 g m

Direct Observations of Grain Boundary Phenomena during Indentation of Al and Al-Mg Thin Films

2003 ◽  
Vol 795 ◽  
Author(s):  
W. A. Soer ◽  
J. Th. M. De Hosson ◽  
A. M. Minor ◽  
E. A. Stach ◽  
J. W. Morris
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Dislocation Dynamics ◽  
Direct Observations ◽  
Transmission Electron ◽  
The Matrix ◽  
Grain Boundary Motion

ABSTRACTThe deformation behavior of Al and Al-Mg thin films has been studied with the unique experimental approach of in-situ nanoindentation in a transmission electron microscope. This paper concentrates on the role of solute Mg additions in the transfer of plasticity across grain boundaries. The investigated Al alloys were deposited onto a Si substrate as thin films with a thickness of 200–300 nm and Mg concentrations of 0, 1.1, 1.8, 2.6 and 5.0 wt% Mg. The results show that in the Al-Mg alloys, the solutes effectively pin high-angle grain boundaries, while in pure Al considerable grain boundary motion is observed at room temperature. The mobility of low-angle grain boundaries is however not affected by the presence of Mg. In addition, Mg was observed to affect dislocation dynamics in the matrix.

Psychotropic Drug Effects on Self-Stimulation of the Brain: A Control for Motor Output

1966 ◽  
Vol 19 (1) ◽  
pp. 79-82 ◽  
Author(s):  
B. P. H. Poschel ◽  
F. W. Ninteman
Keyword(s):  
Brain Stimulation ◽  
Drug Effects ◽  
Motor Output ◽  
Reward Value ◽  
Strong Stimulation ◽  
Weak Stimulation ◽  
Rewarding Brain ◽  
Self Stimulation ◽  
The Brain ◽  
Stimulation Of

Rats with electrodes in the posterior lateral hypothalamus were trained in a chamber having two platforms. When standing on one platform, S received rewarding brain stimulation continuously. Switching to the other platform turned stimulation off. The proportion of time spent on the positive platform indicated the reward value of stimulation. Preliminary tests determined that the time measure was positively related to stimulation intensity. Drug tests determined that tranylcypromine and methamphetamine greatly increased the reward value of weak stimulation, while chlorpromazine greatly decreased the reward value of strong stimulation. Since Ss were not required to work for brain stimulation, these effects on reward value were shown not to be mere artifacts of the drugs' effects on motor output.

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