摘要:

Abstract—(1) Mouse cerebrum slices swell in tris‐buffered Krebs‐Ringer medium. Swelling is rapid at first, then slows to a more or less constant rate. Even after 3 hr incubation, water content/g of tissue dry wt. shows no sign of an asymptotic limit. Swelling is the same at 37° and at 0°.(2) Tissue water measured by incubation with tritiated water is equal to total tissue water measured by drying slices. Equilibration between tritiated water and tissue water is complete within 2 min.(3) Tissue liquid can be divided into three phenomenologically distinguishable compartments:first inulin space, which is the compartment permeable to inulin at both 0° and 37°;second inulin space, which is the compartment permeable to inulin at 37° but not at 0°; and 37°non‐inulin space, which is the compartment impermeable to inulin at both 0° and 37°. The evidence for this is:(a) Penetration of inulin into tissue is greater at 37° than at 0°. After the first 20 min the rate of penetration at 0° is approximately equal to the rate of penetration at 37°, and only slightly less than the rate of increase of total tissue water. Therefore the smaller inulin space observed at 0° cannot be due to slower entry of inulin.(b) The inulin content of slices incubated in inulin‐containing medium at 37° and cooled to 0° in the same medium is the same as the inulin content of tissue incubated at 37° without subsequent cooling. In contrast, the inulin content of tissues preincubated in inulin‐free medium at 37° and then incubated in inulin‐containing medium at 0° is the same as the inulin content of tissues incubated in inulin‐containing medium at 0° without preincubation at 37°. Therefore the smaller inulin space at 0° than at 37°can be due neither to a reversible temperature‐dependent change in the size of one single inulin space nor to an irreversible, greater swelling of a single inulin space at the higher temperature, but is due to some portion of the 37° inulin space becoming impermeable to inulin at 0°.(c) Some inulin is retained by tissue incubated with inulin at 37°, then transferred to inulin‐free medium at 0°; the amount of retained inulin is equal to the difference between inulin content of tissue incubated with inulin at 37° and tissue incubated with inulin at 0°. This confirms 3b above and in addition shows that inulin which has entered the second inulin space at 37° is trapped there when this space becomes impermeable to inulin at 0°.(4) The penetration of the amino acids, L‐lysine and D‐glutamate at 0° is equal to the penetration of inulin at 37°. This confirms the real existence of the 37° inulin space at 0°, and shows that the barrier at 0° between the first and second inulin spaces does not exist for these substances.(5) The amino acids L‐leucine and glycine penetrate total tissue water at 0°. L‐leucine is actively transported at this temperature.(6) The amino acids α‐aminoisobutyric acid, L‐leucine, and L‐lysine at 2 mmhave no effect at 37° on either the inulin space or the non‐inulin space.(7) The inulin space is insensitive at 37° to physiologically significant changes in the medium. In contrast, the non‐inulin space is quite sensitive to these changes. Addition of D‐glutamate greatly increases the non‐inulin space; addition of ouabain or cyanide, or omission of glucose, increases the non‐inulin space slightly; and replacement of Na+ion by choline+i

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10315.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—(1) Nerve‐ending particles isolated from crude mitochondrial preparations from rat brain by discontinuous Ficoll density gradient ultracentrifugation were shown to possess a Mg2+and energy‐dependent transport system for Na+.(2) Ouabain or iodoacetate plus cyanide exerted an inhibitory effect on the outfiux but not the influx of Na+.(3) When K+was added to a medium containing particles loaded with Na+(22Na), an immediate release of Na+from these particles was observed; this suggests the existence of a Na+–K+exchange transport system.(4) The K+effect was inhibited by 10‐4M‐ouabain only at low (about 3·3 mm), but not at high (20 mm), K+concentrations.(5) The uptake and release of Na+by the nerve‐ending particles were found to be temperature‐dependent.(6) Only nerve‐ending particles with intact synaptosomal membranes were found to tra

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10316.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—–Radioactively labelled leucine and orotic acid were injected into the ventral horn of the lumbar region of the spinal cord. The outflow of labelled products into the sciatic nerve was studied.Leucine is rapidly incorporated into protein and to a lesser extent into lipid. The labelled protein is transported down the nerve, apparently by axoplasmic flow. This labelled protein was present in all sub‐cellular fractions of nerve although the soluble fraction had the highest specific activity.Orotic acid is converted to a number of nucleotide derivatives and RNA. Both the nucleotides and RNA move down the sciatic nerve, but the pattern of movement is diffuse whereas protein appears to move as a discrete band.The results suggest that two systems may be operating, one in which part of the RNA is transported by axoplasmic flow along the nerve and the other involving a synthesis of RNA in the nerve from precursors which flow down the nerve. This labelled RNA was membrane bound and on sedimentation analysis, proved to be predominantly of ribosomal

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10317.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Bath chicken spinal cord and the posterior chamber of the rat eye have been injected with either [3H]leucine or [3H]orotic acid. The movement of newly synthesized protein and RNA down the sciatic and optic nerves was followed by means of autoradiography. Protein moved down both nerves by axoplasmic flow, the protein being confined to intra‐axonal spaces. RNA appeared to move at about the same rate as protein, but much of the newly formed RNA appeared in structures outside the axons, particularly in Schwann and glial cells. There was, however a considerable proportion of the RNA inside the axons. This RNA may be involved in the direction of protein synthesis at sites along the axonal proces

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10318.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—This paper deals with the synthesis of 3‐pyrazolidone and the biochemical action of hydrazinopropionic acid. The latter compound is formed upon alkaline hydrolysis of 3‐pyrazolidone.Hydrazinopropionic acid was foundin vitroto be a very potent inhibitor of bacterial aminobutyrate transaminase as well as of aminobutyrate transaminase and glutamate decarboxylase from mouse brain. This inhibition was shown to occur despite the presence of high concentrations of pyridoxal phosphate in the incubation media.Injections of 20 mg hydrazinopropionic acid/kg into mice resulted in complete inhibition of aminobutyrate transaminase in brain and approximately 20 per cent inactivation of glutamate decarboxylase. This inhibition could not be prevented or antagonized by administration of pyridoxine to the animals. Addition of pyridoxal phosphate to homogenates of brain from animals treated with hydrazinopropionic acid also failed to reactivate the enzymes.The tentative conclusion reached from these results is that hydrazinopropionic acid has inhibitory action because of its close similarity to GABA with respect to molecular size, structural configuration and molecular charge distribution. This can be demonstrated by comparing a Dreiding model of hydrazinopropionic acid with that representing

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10319.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The ChAc activity of spinal and sympathetic ganglia was measured throughout the embryonic life of the chick.In spinal ganglia, the ChAc activity reached a first peak when the maximal proliferation of neuroblasts occurred. Then, the relative ChAc activity decreased. After the 12th day of incubation, the enzyme activity increased again and reached a second peak on the 16th day.In sympathetic ganglia, the general course of the development of ChAc activity was similar to spinal ganglia. However, higher enzymic activity was found. Furthermore, the earlier peak of ChAc activity occurred 48 hr later than the corresponding peak in spinal ganglia.The behaviour of ChAc activity in these two areas of the developing nervous system is interpreted as a function of their histogenesi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10320.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The characteristics of DNA‐dependent RNA polymerase activity in intact rat cerebral cortex nuclei tested at low ionic strength are presented. The system was most dependent on the presence of spermidine and an ATP‐generating system and to a lesser extent on Mg2+and K+for maximal incorporation. Substitution of Mg2+by Mn2+or of K+by Na+resulted in substantially less activity than under the optimum conditions described. Maximal incorporation was about 10 per cent that of brain nuclear systems of high ionic strength.In addition, the labelling patterns of thein vitroRNA products were shown to be very similar to those foundin vivo.The stability of isolated nuclei toward degradation of RNA synthetic capacity and products formed was much greater than that of a similar liver s

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10321.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Immunoelectrophoretis, gel filtration‐electrophoresis and immuno‐gel filtration of cerebral fluid samples obtained from five patients with subacute sclerosing leucoencephalitis and known to contain an abnormal γ‐globulin fraction (γe) produced strong evidence that the γc‐globulin is made up of several components of small molecular size. This fraction is obviously not homogeneous, since some of the cases show more than one precipitate on immuno‐gel filtration with immune serum against γ‐globulin. The γcappears to be closely related to the Fab‐fragment

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10322.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Choline acetyltransferase (acetyl‐CoA: choline 0‐acetyltransferase, I.U.B. 2.3.1.6) activity and total protein content in visual and extra‐visual areas were compared in normal Long‐Evans rats and in rats subjected to complete light‐deprivation for 21 days from birth. The enzyme activity and the protein content in the superior colliculi, lateral geniculate bodies and visual cortex, as well as in the sensory‐motor cortex, hypothalamus, brain stem and cerebellum, were measured in both mothers and progeny. By means of a radiochemical technique modified in this laboratory, a significant decline of ChAc activity was observed in the lateral geniculate bodies and superior colliculi, with no significant decline in the visual cortex of the experimental progeny. Total protein content, measured colorimetrically, was significantly decreased in the superior colliculi of the progeny. The biochemical data obtained from all other brain areas in the experimental animals (progeny and mothers) and controls demonstrated no marked differences. The enzymic alterations observed in the cholinergic system of progeny after complete light‐deprivation during this critical period of CNS development can be specifically correlated with decreased functional maturation of the visual system. If it is accepted that ACh is a neuro‐transmitter in some parts of the visual pathway, the data presented here suggest that complete light‐deprivation from birth to 21 days of age in the rat has an effect on a biochemical system involved in sy

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10323.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—‐The hydrolysis of 2‐ [14C]acyl‐labelled and [Me‐3H]choline‐labelled lecithins by rat brain homogenates has been studied. The acyl‐labelled substrate was hydrolysed with the production of both radioactive lysolecithin and radioactive free fatty acid in the proportions of 60 per cent and 40 per cent; traces of labelled mono‐ and diglyceride were also formed.In addition to radioactive lysolecithin the [3H]choline‐labelled lecithin also gave rise to much smaller amounts of radioactive water soluble derivatives, consisting almost entirely of free choline and phosphorylcholine with only traces of glycerylphosphorylcholine.The results provide evidence for the production of a mixture of 1‐ and 2‐acyl isomers of lysolecithin by phospholipase action in brain homogenates at pH 7·4, the latter

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb10324.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY