Further Evidence for 'Active' Reflex Vasodilatation

1971 ◽  
Vol 49 (2) ◽  
pp. 147-159 ◽  
Author(s):  
D. G. Wyse ◽  
L. Beck ◽  
T. F. Burks ◽  
C. T. Spalding
Keyword(s):  
Experimental Evidence ◽  
Vascular Tone ◽  
Perfusion Pressure ◽  
Blocking Agent ◽  
The Other ◽  
Other Hand ◽  
Adrenergic Activity ◽  
Total Magnitude ◽  
Ganglionic Blocking

Further experimental evidence has been presented which strengthens the hypothesis of active reflex dilatation. The administration of a ganglionic blocking agent in a dose sufficient to block completely adrenergic tone failed to lower the perfusion pressure in the isolated extremity to the same level as was reached during the nadir of reflex dilatation. Thus, it is reaffirmed that simple withdrawal of adrenergic vascular tone (passive reflex dilatation) cannot entirely account for the total magnitude of reflex dilatation. Although chronic reserpine pretreatment eliminated both reflex constriction and dilatation, acute reserpine administration reduced reflex dilatation at a time when reflex constriction and perfusion pressure were little affected. On the other hand, the administration of the substituted phenothiazine, methotrimeprazine, eliminated adrenergic tone but had little effect on reflex dilatation. The latter two types of experiment provide further important dissociations between reflex dilatation and inhibition of existing adrenergic activity. Administration of cocaine by several different routes reduced reflex dilatation, but the reduction in reflex dilatation does not appear to be due to inhibition of reuptake of adrenergic amine. Neither does blockade of active reflex dilatation by the antihistamine, tripelennamine, appear to be related to its possible ability to block reuptake of adrenergic amine. Classic autoregulatory stimuli fail to elicit a response analogous to active reflex vasodilatation, and antihistamines fail to alter autoregulatory readjustments while reducing very effectively active reflex vasodilatation.

scholarly journals Blood Perfusion of the Kidney of Lophius Piscatorius L.

1953 ◽  
Vol 32 (2) ◽  
pp. 329-336 ◽  
Author(s):  
L. Brull ◽  
E. Nizet ◽  
E. B. Verney
Keyword(s):  
Blood Flow ◽  
Critical Level ◽  
Perfusion Pressure ◽  
Blood Perfusion ◽  
Urine Flow ◽  
The Other ◽  
Protein Nitrogen ◽  
Other Hand ◽  
Flow Through

Lophius kidneys perfused with the heparinized blood (venous) of the fish secrete urine in which total non-protein nitrogen is concentrated, magnesium highly concentrated, and chloride only slightly so or not at all. Oxygenation of the blood, or lowering the temperature of the perfusate from c. 20° to c. 5° C. does not appear to influence secretion. The blood flow through the kidneys increases with the perfusion pressure, the increase often becoming disproportionately large. The urine flow, on the other hand, above a certain critical level is largely independent of changes in perfusion pressure.

scholarly journals The influence of porphyrins on iron-catalysed generation of hydroxyl radicals

1988 ◽  
Vol 250 (1) ◽  
pp. 197-201 ◽  
Author(s):  
J Van Steveninck ◽  
J P J Boegheim ◽  
T M A R Dubbelman ◽  
J Van der Zee
Keyword(s):  
Cytochrome C ◽  
Horseradish Peroxidase ◽  
Experimental Evidence ◽  
Xanthine Oxidase ◽  
Hydroxyl Radicals ◽  
Anion Radical ◽  
The Other ◽  
Haematoporphyrin Derivative ◽  
Other Hand

Uroporphyrin I, haematoporphyrin and haematoporphyrin derivative had no effect on O2-. generation during oxidation of hypoxanthine by xanthine oxidase and on the formation of hydroxyl radicals (OH.) in the hypoxanthine/xanthine oxidase/Fe3+-EDTA/deoxyribose system. On the other hand, these porphyrins strongly inhibited O2-. formation in a horseradish peroxidase/H2O2/NADPH mixture, whereas they augmented OH. generation in this system after addition of Fe3+-EDTA. Experimental evidence suggests that these observations should be ascribed to the formation of a porphyrin anion radical in the horseradish peroxidase/NADPH system. The formation of this anion radical was confirmed by e.s.r. spectroscopy. This radical is apparently unable to reduce cytochrome c, but it can replace O2-. in the OH.-generating Haber-Weiss reaction.

Musical Analysis: Hearing Is Believing?

1984 ◽  
Vol 2 (2) ◽  
pp. 237-244 ◽  
Author(s):  
Stephen Walsh
Keyword(s):  
Experimental Evidence ◽  
Psychological Testing ◽  
The Other ◽  
Musical Analysis ◽  
Other Hand ◽  
Perceptual Psychology ◽  
The Mind ◽  
The Way

Written by a musician untrained in psychology, this article draws attention to problems arising from the separation of the disciplines of perceptual psychology and musical analysis. Psychologists are apt to make prescriptions about the nature of music based on a narrow and often primitive understanding of the medium. Musicians, on the other hand, are in the habit of basing analysis on sweeping assumptions about the nature of perception for which there is little experimental evidence. The author argues, however, that although it would be useful for such assumptions to be subjected to rigorous psychological testing, the assumptions themselves are not to be dismissed as evidence of the way the mind understands music.

scholarly journals A comparison of virulence of two strains ofLegionella pneumophilabased on experimental aerosol infection of guinea-pigs

1985 ◽  
Vol 95 (1) ◽  
pp. 29-38 ◽  
Author(s):  
R. I. Jepras ◽  
R. B. Fitzgeorge ◽  
A. Baskerville
Keyword(s):  
Experimental Evidence ◽  
Legionella Pneumophila ◽  
Guinea Pigs ◽  
The Other ◽  
Avirulent Strain ◽  
Lung Macrophage ◽  
Other Hand ◽  
Strain Nctc ◽  
Aerosol Infection ◽  
Extracellular Location

SUMMARYTwo strains ofLegionella pneumophila(LP) serogroup I, of differing virulence, were examined in terms of numbers of viable organisms in tissues, pyrexia and mortality following aerosol infection. The Corby strain was the more virulent, with Pyrexia and deaths of guinea-pigs 3 to 6 days after infection. This strain multiplied very rapidly in the lungs to reach a peak of 5 × 1011viable organisms/lung. Organisms were present in the blood, liver, spleen and kidney. The Philadelphia-1 strain (NCTC 11192) was unable to replicate in the lung and was cleared between 14 and 21 days after infection. Pyrexia was not observed. No guinea-pigs died and viable LP was not found in any organ other than the lung.Lung lavages on aerosol infected animals were performed and the virulent Corby strain was found to be mainly intracellular. The avirulent Philadelphia-1 strain was found predominantly in the extracellular location. There were approximately 10 times the number of viable virulent LP in the lung macrophage fraction than in the lung PMNL fraction. In comparison, there were approximately equal numbers of the viable avirulent strain in the macrophages and the PMNL. Experimental evidence suggests that the macrophage preferentially supports the growth of the virulent Corby strain compared with the PMNL. The avirulent strain on the other hand appears to be destroyed by both the macrophages and the PMNL.

scholarly journals Kaluza theory with zero-length extra dimensions

2016 ◽  
Vol 25 (11) ◽  
pp. 1640004 ◽  
Author(s):  
O. C. Stoica
Keyword(s):  
Gauge Theory ◽  
Experimental Evidence ◽  
Extra Dimensions ◽  
The Other ◽  
New Approach ◽  
Degenerate Metric ◽  
Other Hand ◽  
Abelian Case ◽  
Spacetime Metric ◽  
As If

A new approach to the Kaluza theory and its relation to the gauge theory is presented. Two degenerate metrics on the [Formula: see text]-dimensional total manifold are used, one corresponding to the spacetime metric and giving the fiber of the gauge bundle, and the other one to the metric of the fiber and giving the horizontal bundle of the connection. When combined, the two metrics give the Kaluza metric and its generalization to the non-Abelian case, justifying thus his choice. Considering the two metrics as fundamental rather than the Kaluza metric explains why Kaluza’s theory should not be regarded as five-dimensional (5D) vacuum gravity. This approach suggests that the only evidence of extra dimensions is given by the existence of the gauge forces, explaining thus why other kinds of evidence are not available. In addition, because the degenerate metric corresponding to the spacetime metric vanishes along the extra dimensions, the lengths in the extra dimensions is zero, preventing us to directly probe them. Therefore, this approach suggests that it is not justified to search for experimental evidence of the extra dimensions as if they are merely extra spacetime dimensions. On the other hand, the new approach uses a very general formalism, which can be applied to known and new generalizations of the Kaluza theory aiming to achieve more and make different experimental predictions.

The Inhibition of Renin Secretion by Alpha-Adrenergic Stimulation in the Isolated Rat Kidney

1974 ◽  
Vol 47 (5) ◽  
pp. 471-479 ◽  
Author(s):  
R. Vandongen ◽  
W. S. Peart
Keyword(s):  
Adrenergic Receptors ◽  
Perfusion Pressure ◽  
Rat Kidney ◽  
Blocking Agent ◽  
Renal Perfusion ◽  
Renin Secretion ◽  
Adrenergic Stimulation ◽  
Beta Adrenergic ◽  
Renal Perfusion Pressure ◽  
Adrenergic Activity

1. The respective role of alpha-adrenergic and beta-adrenergic receptors in mediating the effect of catecholamines on renin secretion was examined in the isolated perfused rat kidney. 2. Noradrenaline, which has combined alpha- and beta-adrenergic activity, stimulated renin secretion only in the presence of the alpha-receptor blocking agent phenoxybenzamine. This stimulatory effect was largely prevented by the addition of the beta-blocking agent, propranolol. The vasoconstrictor action of noradrenaline, and thus the rise in mean renal perfusion pressure, was abolished by phenoxybenzamine. Our previous finding that noradrenaline alone stimulated renin release was inconclusive (Vandongen, Peart & Boyd, 1973). 3. Noradrenaline stimulated renin secretion when calcium was excluded from the perfusion fluid, to which disodium EDTA (25 mmol/l) was added. The vasoconstrictor action of noradrenaline was considerably attenuated under these conditions. 4. Methoxamine, which has only alpha-adrenergic activity, did not increase renin secretion when infused alone or with phenoxybenzamine. The increase in renin secretion after beta-adrenergic stimulation with isoproterenol was significantly suppressed by methoxamine, although this was associated with an increase in mean renal perfusion pressure. 5. These findings indicate the importance of intrarenal beta-adrenergic receptors in the stimulation of renin secretion and suggest that an opposite inhibitory effect on renin secretion follows alpha-adrenergic activity. 6. Although the results do not exclude a direct effect of vascular tone and renal perfusion pressure, it is suggested that the stimulation and inhibition of renin secretion is related to smooth muscle activity by the involvement of a calcium-dependent process similar to that involved in contraction and relaxation. This would accord with the common derivation of the renin-producing and vascular smooth muscle cells

301. The effect of over-ripening upon the activity of Cheddar cheese starters

1943 ◽  
Vol 13 (2) ◽  
pp. 127-135 ◽  
Author(s):  
C. K. Johns ◽  
H. L. Bérard
Keyword(s):  
New Zealand ◽  
Experimental Evidence ◽  
Cheddar Cheese ◽  
The Other ◽  
Extreme Conditions ◽  
Single Strain ◽  
Permanent Damage ◽  
Cheese Making ◽  
Other Hand

The belief that over-ripening of starters is responsible for their weakening and for slow acid development during Cheddar cheese-making has been widely held by cheese-makers for many years. Statements that over-ripening is harmful have been made by investigators in several countries(1,2,3,4), but experimental evidence in support of this view is scanty. On the other hand, Whitehead(5) in New Zealand has shown that prolonged over-ripening of single-strain starters under rather extreme conditions merely resulted in a temporary checking of their activity; between wide limits of size of inoculum and period of incubation no permanent damage was done.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

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