摘要:

Zusammenfassung.Einleitend wird besprochen, dass Anlass zu dem Verdacht besteht, Mandelsäure hemme die Desaminierung gewisser Aminosäuren und damit auch deren Oxydation. Dies könnte eine Erklärung dafür bilden, dass in gewissen Fällen bei intensiver Mandelsäuretherapie eine nur geringe Ammoniakbildung beobachtet wird.In vor allem Nieren‐ und Lebergewebe von weissen Ratten wird mit Warburg‐Technik die Oxydation mit und ohne Mandelsäure in verschiedener Konzentration sowie mit und ohne die Aminosäuren Alanin und Prolin untersucht. Weiterhin wird die Desaminierung mit Hilfe von Bestimmung des während der Ver‐suche gebildeten Ammoniaks studiert.Die Untersuchungen haben gezeigt l.) dass Mandelsäure sowohl von Nieren‐ als auch von Lebergewebe verbrannt wird, jedoch stärker vom Nierengewebe; 2.) dass Mandelsäure die spontane Oxydation sowohl im Nieren‐ als auch im Lebergewebe und ebenso die Oxydation von zugesetztem Alanin und Prolin hemmt; sowie 3.) dass Mandelsäure als ein starkes D

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01445.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY

摘要:

Summary.Ultra‐violet absorption‐spectra have been measured of individual isotropic and anisotropic segments in striated muscle‐fibres from insects. By means of comparisons with ultra‐violet micro‐photographs it is shown to be probable that the results obtained in this way are applicable to striated musculature in general. The absorption‐curves show that the main part of the adenine derivatives (adenylic acid and adenyl‐pyrophosphoric acid) in the resting muscle are localized in I. These segments seem to have their main function as the seat of chemical energetic processes while A is the seat of the contractile elements. From observations on fatigued muscle‐fibres one deduces that energy is transferred from I to A by adenyl‐pyrophosphate whose energy is released by the phosphatase that is bound to the myosin.The background to the striation of the muscle‐fibres thus seems to be a differentiation of contractile parts and chemically‐working parts respectively. The transport of energy from the latter to the former is performed by adenyl‐pyrophosphoric acid.The work has been supported by funds from the Rockefeller Foundation and the foundation “Thérèse o

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01446.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY

摘要:

Summary.The precise form of the photopic spectrum of the pigeon has been measured with the electrophysiological technique used with other animals in previous contributions to this problem.The filtering effect of the coloured oil globules has been discussed in relation to the photopic spectrum.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01447.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY

摘要:

Summary.Experiments have been carried out on decerebrate cats with a view to studying the effect of frequency of stimulation upon reflex activity.With frequencies between 50–100 per sec. stimulation of the sciatic nerve activated a late secondary extensor reflex after a latent period of 3–5 sec. This reflex was transient in the sense that it lasted only about 15–30 sec. The optimal frequency, for which this transient reflex was maximal, was 90—100 per sec.The transient extensor contraction was found to be part of a complex general defensor pattern involving extension of all limbs, ventroflexion of the trunk and the tail, wihdrawal of the head, and a number of vegetative components such as micturition, raise of blood pressure (cf. Aschkenaz1939), and pupil dilatation. The vegetative effects were also observed in animals which had received dial and therefore did not show the motor reactions. The whole defensor reflex pattern was optimally evoked by the frequency optimal for the extensor contraction.The transient extensor reflex turned up bilaterally. When evoked by an ipsilateral stimulus in the midst of a crossed extensor it showed itself as a transitory contraction in the trough of the ipsilateral inhibitory effect. However, it turned up equally well without a background of crossed extension. When elicited by crossed stimulation the transient effect had the shape of a hump on the ordinary crossed extensor reflex, provided that the frequency of the stimulus was sufficiently high.No proprioceptive background was necessary for the transient extensor contraction, as shown by deafferentation.Section of the spinal cord in the lower thoracic region did not abolish the reflex.The transient reflex could be elicited from n.popliteusbut not from nn.peroneus, saphenusandgl

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01448.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY

摘要:

Summary.Direct application of different substances to the motor end plate of lizard muscle led to the following results:Acetylcholine(threshold 5 × 10‐6μg) initiates a short twitch‐like contraction. After the first application, the end plate is refractory to further doses and to electric stimulation of the nerve.Direct electric stimulation of the end plate and application ofpotassium(threshold 10‐4μg) orrubidiumare still effective. Potassium or rubidium do not show any blocking action, as does acetylcholine.Acetylcholine and potassium applied to thefibre substancehave no effect even in a tenfold concentration.Acetylcholine, potassium, and other stimulating substances cause a decrease in the end plate — fibre potential.The threshold of the motor end plate is not altered by poisoning withveratrine.Just as total muscle, the veratrinized fibre reacts to stimulation with protracted contractions.In the first stage,curarineblocks the end plate for nerve impulses and for acetylcholine, while direct electric stimulation of the end plate and application of potassium are still effective. In a later stage, the excitability in response to these stimuli is abolished, only the direct excitability of the fibre substance is retained.The present material supports the assumption of two boundary aces in the motor end plate.The present work has been supported by grants from theCarlsberg Foundationand theMichaelsen

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01449.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY

摘要:

Summary.In the present paper we have submitted to closer investigation, the methods given by Burtonfor the measurement of the skin's blood flow by means of finger plethysmography and the results are compared with skin‐temperature determinations.Our experiments show that the cuff pressure necessary to arrest the venous return, varies greatly from one subject to another and also in the same subject under different conditions. The reasons for this have been submitted to closer analysis and as the essential reason for this variation is put forward a varied compressibility of the finger arteries corresponding to a varied degree of contraction.It could be shown that the refill curves recorded photographically allow a far more accurate determination of the rate of flow if during measurements the hand is placed 20–30 cm above heart level; whereby the blood volume, that can flow into the veins in the course of the registration period without pressure increase, rises very considerably.If the hand is raised above heart level a reduction of the blood flow occurs as the reduced hydrostatic blood pressure in the finger artery is not entirely compensated by means of vasodilatation. With a rise of 20–30 cm, which is here recommended as the normal measuring position, this reduction is only slight however.Where considerable changes occur in the blood pressure as in the transition from rest to work or vice versa we find it impossible to utilize the finger's pulse volume as an expression of its blood

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01450.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY

摘要:

Summary.At the beginning of heavy work an instantaneous and considerable reduction of the skin's circulation always occurs which subsequently remains low for several minutes. With light work the decrease in the flow is less pronounced and is usually absent after repeated starts. From our experimental results we conclude that the vasoconstriction in the skin is of regulatory significance for the adjustment of the circulation at the transition from rest to heavy work.As the decrease in the blood flow occurs practically instantaneously at the start of work it is assumed that it is of nervous origin — caused either by cortical impulses or by reflex influences from the working muscles. It is shown that the expectation of work plays no part in evoking the vasoconstriction.On the basis of experiments with registration of the finder's volume, we believe that the skin has no significance as an active blood depot at transition from rest to wor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01451.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY

摘要:

Summary.A series of determinations of the blood flow of the skin of the finder was undertaken at rest and during work at varied external temperature. The results show that even comparatively slight variations in the external temperature are accompanied by very considerable differences in the finger's blood flow. No relation was found between the subjective temperature sensations and the absolute values of the blood flow, but an incipient increase in the flow is attended by sensations of warmth and conversely, an incipient decrease is accompanied by sensations of cold. A programme for a more thorough study of the cause of the sensations of warmth has been outlined.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01452.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY

摘要:

Zusammenfassung.Hypoxische Erregung des isoliert perfundierten Glomusgebietes beim Hund mit ausgeschalteten Barorezeptoren fülirte sowohl erne starke Atmungsteigerung als auch eine sehr ausgesprochene Blutdrucksteigerung herbei

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01453.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY

摘要:

Summary.The guinea‐pig method for standardization of digitalis preparations (Knaffl‐Lenz1926) has been tested with various concentrations, rates of injection and weights.1. The lethal dose (or log lethal dose) varies proportionately to the quantity of drug injected per min and 100 g. The variations may amount to max. 44%, on an average 20%, when following Knaffl‐Lenz' original directions. When keeping standard conditions, or adjusting the lethal doses to a constant rate of injection by means of the calculated regression equation, the standard average deviation is 10—12%.2. When determined atrepealedintervals under standard conditions theguinea‐pig unitshows an average variation of 5—10%.3. The potency of digitalis preparations should be expressed in international units or g of a standard preparation and be uniformly tested on the same stock of animals as the standard. Under these conditions the guinea‐pig unit has a stand, error of 3–5%, 5–6 animals being used for each test, and the guinea‐pig method seems to be a fairly good method

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1942.tb01454.x

出版商:Blackwell Publishing Ltd    

年代:1942

数据来源: WILEY