Showing papers by "University of Groningen published in 1970"
TL;DR: In suicide victims the cerebral concentration of indoleamines proved to differ from that in a control group and, according to Shaw et al.12, the 5-HT concentrations were diminished, and Bourne etAl.13 were unable to corroborate this but did find a diminished concentration of 5-HIAA.
Abstract: ACCORDING to the serotonin (5-hydroxytryptamine, 5-HT) hypothesis there is a causal relationship between mental depression and 5-HT deficiency in the brain1–3. Some depressive patients—mainly those suffering from an endogenous depression—display the following clinical signs. (1) The concentration of 5-hydroxyindoleacetic acid (5-HIAA) in the cerebrospinal fluid (CSF) (refs. 4 and 5) and the urinary concentrations of 5-HT (ref. 6) and 5-HIAA (refs. 7 and 8) are unusually low. (2) The transformation of 5-hydroxytryptophan into 5-HT seems to be defective9 (although in a later publication Coppen1 reported his inability to reproduce these findings). (3) Precursors of 5-HT which readily enter the brain—5-hydroxytryptophan10 and tryptophan11—can have a therapeutic effect. Finally, in suicide victims the cerebral concentration of indoleamines proved to differ from that in a control group and, according to Shaw et al.12, the 5-HT concentrations were diminished. Bourne et al.13 were unable to corroborate this but did find a diminished concentration of 5-HIAA.
243 citations
TL;DR: It is concluded that the intact mitochondrial DNA of S. carlsbergensis and S. cerevisiae consists of a circular molecule with a contour length of approx.
200 citations
TL;DR: Results of simulation studies with population models that were set up to illustrate the ideas about stabilization of population fluctuations and spreading of the risk of extinction expounded by den Boer (1968) turn out that increasing the number of age classes may increase stability and that models where there is exchange of individuals between subpopulations by \ldmigration\rd are more stable than populations consisting of isolatedSubpopulations.
Abstract: 1. This paper discusses results of simulation studies with population models that were set up to illustrate the ideas about stabilization of population fluctuations and spreading of the risk of extinction expounded by den Boer (1968). In particular, the number of factors influencing net reproduction, the heterogeneity of the habitat and the possibility of a population's containing animals of different age classes were considered as possibly contributing to stabilization and to spreading of risk. 2. The model defined by equation (3.1.2), where r(t) denotes the net reproduction from t to t+1, f i (t) denotes the value of the i-th environmental factor in year t, and where the other symbols denote positive constants, was simulated by choosing for the f i(t) sequences of meteorological data from published tables. Such sequences may be serially correlated as well as correlated among themselves and using such real data was considered to be more realistic than working with sequences of independent random numbers, for example. Increasing the number k of factors turned out to stabilize fluctuations in the density. This fact could also be mathematically proved under not very restrictive assumptions. In a model where the logarithm of the net reproduction on the average is some-what greater than zero, and where "crashes" may occur at high densities, the population may persist for a very long time, even if the "size" of the crashes does not depend on density, and the times at which the crashes occur are chosen at random. 3. A model formulated in terms of matrices and vectors, in which a population was supposed to consist of 9 subpopulations and of several age classes was simulated. It was assumed that after a reproduction period the animals migrate between the subpopulations or emigrate from the whole population. It turned out that increasing the number of age classes may increase stability and that models where there is exchange of individuals between subpopulations by \ldmigration\rd are more stable than populations consisting of isolated subpopulations. Letting the exchange between subpopulations be \lddensity-dependent\rd had some stabilizing effect too, but not very conspicuously so.
156 citations
TL;DR: The ontogeny of behavioral state cycles in white rats has been studied from their 2nd to their 30th day of life and state 2 and state 4 epochs increase only slightly whereas state 3 and state 5 epochs do not show a particular trend.
Abstract: The ontogeny of behavioral state cycles in white rats has been studied from their 2nd to their 30th day of life. A scale of 5 behavioral states, based on operationally defined categories was employed: state 1: quiet sleep; state 2: active sleep; state 3: quiet wakefulness; state 4: active wakefulness and state 5: locomotion. The percentage of time which young rats spend awake is 2% on the 2nd day, increases then and remains at about 40–60% after the 11th day. Until the 10th day the total sleep time is equally distributed between active sleep and quiet sleep state. After that day a decrement in the relative amount of active sleep occurs. The mean duration of single epochs spent in state 1 increases from less than 1 min on the first days to 6–8 min at about the 25th day. State 2 and state 4 epochs increase only slightly whereas state 3 and state 5 epochs do not show a particular trend.
139 citations
TL;DR: In the food deprived VMH hyperphagic animal the glucose level is comparable to that in the deprived intact animal, but the insulin response is also in this case very exaggerated.
135 citations
TL;DR: The palynological investigation of a 12 m long core from the Ghab valley, north-western Syria covers the greater part of the last glacial period and the Postglacial and reflects an alternation of periods in which steppe vegetations expanded and those in which forests increased.
Abstract: SUMMARY
This paper deals with the palynological investigation of a 12 m long core from the Ghab valley, north-western Syria. The core covers the greater part of the last glacial period and the Postglacial. The pollen diagram reflects an alternation of periods in which steppe vegetations expanded and those in which forests increased. Tree growth was determined by humidity rather than by temperature. On the whole, the second part of the last glacial was drier than the first part. The period preceding the Late-glacial was especially unfavourable for tree growth.
114 citations
TL;DR: In this paper, the preparation, crystal structures and some properties of the compounds Aitp,mx2 are reported, where A = Li, Na, K; M = Nb, Ta; X = S, Se.
Abstract: The preparation, crystal structures and some properties of the compounds Aitp,mx2 are reported, where A = Li, Na, K; M = Nb, Ta; X = S, Se. The compounds were prepared by heating mixtures of the elements or by heating mixtures of the alkali metals with the dichalcogenides, MX2. The selenides prepared were homogeneous only for p ≈ 2 3 , for some of the sulfides a homogeneity range from about p = 0.4 to 0.7 was found. The compounds ApMX2 are thermally stable; in moist air they are slowly hydrolized with formation of hydrogen sulfide or selenide. The compounds ApMX2 are hexagonal; the alkali metals are situated between MX2 slabs. The coordination of M( = Nb, Ta) is trigonal-prismatic in all the compounds. The coordination of Na and K is also trigonal-prismatic in the selenides and in most of the sulfides, but in some polymorphs of the sulfides the coordination of the alkali metals may be octahedral. The occurrence of trigonal-prismatic coordination is discussed.
111 citations
TL;DR: In this paper, electrical resistivity measurements at high temperatures were carried out in a closed vessel, with the sample in equilibrium with its own vapour pressure, and the properties of α and β-MoTe 2 were discussed in terms of a schematic energy level diagram.
106 citations
01 Jan 1970
TL;DR: The conversion of glutamate to glutamine is thought to be important for the detoxification of ammonia in the brain and the incorporation of carbon or nitrogen from a variety of precursors in these amino acids is fast and extensive, indicating a rapid turnover of these compounds.
Abstract: Glutamate and glutamine are present in nervous tissue in large amounts. Both amino acids play a role in a large number of reactions in brain. The incorporation of carbon or nitrogen from a variety of precursors in these amino acids is fast and extensive, indicating a rapid turnover of these compounds. The conversion of glutamate to glutamine is thought to be important for the detoxification of ammonia in the brain.
95 citations
TL;DR: The advantages are discussed of the use of artificial baits over live baits in hook and line fishing for pike in a drainable pond, using either a spinner or a small live fish as bait.
Abstract: Tagged pike Esox lucius L. in a drainable pond were fished by hook and line, using either a spinner or a small live fish as bait. Catch per unit effort could be used as a measure for catchability because all captured pike were immediately returned to the pond and mortality was low.
Catchability to spinner fishing decreased to very low levels after about half of the population had been caught in this way. Catchability to live bait fishing remained unaffected both by intensive spinner and live bait fishing.
It was difficult to capture pike more than once by spinning. In live bait fishing, on the other hand, the number of recaptures closely matched the number expected if catchability remains unaffected by earlier capture.
The advantages are discussed of the use of artificial baits over live baits in hook and line fishing for pike.
92 citations
TL;DR: The latency of the enzyme in vitro, as shown by the effect of the detergent Triton X-100, is discussed in relation to the proposed heterogeneity of UDP glucuronyltransferase.
Abstract: 1. The detergent Triton X-100 activates UDP glucuronyltransferase from rat liver in vitro six- to seven-fold with p-nitrophenol as substrate. The enzyme activity when measured in the presence of Triton X-100 is increased significantly by pretreatment of male rats with phenobarbital for 4 days (90mg/kg each day intraperitoneally). If no Triton X-100 is applied in vitro such an increase could not be shown. In all further experiments the enzyme activity was measured after activation by Triton X-100. 2. The Km of the enzyme for the substrate p-nitrophenol does not change on phenobarbital pretreatment. 3. When the microsomal fraction from the liver of untreated rats is subfractionated on a sucrose density gradient, 47% of the enzyme activity is recovered in the rough-surfaced microsomal fraction, which also has a higher specific activity than the smooth-surfaced fraction. 4. Of the increase in activity after the phenobarbital pretreatment 50% occurs in the smooth-surfaced fraction, 19% in the rough-surfaced fraction and 31% in the fraction located between the smooth- and rough-surfaced microsomal fractions on the sucrose density gradient. 5. The latency of the enzyme in vitro, as shown by the effect of the detergent Triton X-100, is discussed in relation to the proposed heterogeneity of UDP glucuronyltransferase.
TL;DR: In this article, a numerical solution for the Reynolds number of the boundary layer is presented, which is valid for any Reynolds number, and the asymptotic value of the integrated skin friction agrees very well with the exact value.
Abstract: A numerical solution joining Carrier and Lin's solution near the leading edge to the boundary layer solution at large distance of the leading edge is presented. The solution is valid for any Reynolds number. Results are given for the skin friction, the integrated skin friction, the displacement thickness, the pressure along the plate and the velocity ahead of the plate. The asymptotic value of the integrated skin friction agrees very well with the exact value. The displacement thickness is already different from zero for small distances ahead of the plate.
TL;DR: The antibiotics chloramphenicol and oxytetracycline completely blocked the formation of cytochrome c oxidase in regenerating rat liver if the serum concentration was continuously kept above 7 μg/ml serum for chlorampshenicol or 6 μg/ML for oxytettetracy Cline, and the activity of this enzyme was lower than in mitochondria from control animals.
TL;DR: The anatomy and histology of the gonads, the functional anatomy of the accessory organs, the occurrence of cyclical changes in the gonad, the mutual behaviour of male and female under different conditions, the temporal pattern of spawning, and periodic changes in responsiveness of reproductive behaviour patterns to adequate external stimulation are given.
Abstract: In this paper on the cichlid fish Aequidensp ortalegrensis,in formation is given on 1) the anatomy and histology of the gonads, 2) the functional anatomy of the accessory organs, 3) the occurrence of cyclical changes in the gonads, 4) the mutual behaviour of male and female under different conditions, 5) the temporal pattern of spawning, and 6) periodic changes in responsiveness of reproductive behaviour patterns to adequate external stimulation, in an attempt to contribute to a picture of the mechanism of reproduction in this species. Zie: Summary
TL;DR: The differential diagnosis, together with a brief explanation, was given for each type of sclerosing inflammation.
TL;DR: In this article, the structure of Mo2.06S3 has been determined and refined from X-ray powder data, and the metal atoms lie in octahedral holes of a chh close packing of sulfur, but they are displaced from the octahedron centers in such a way that zigzag MoMo chains are formed.
TL;DR: Evidence is yielded that the nonketotic form of hyperglycinemia is due to absence or nonfunction of the enzymic system responsible for the conversion of glycine to CO2, NH3, and hydroxymethyltetrahydrofolic acid.
Abstract: Extract: Liver biopsies were performed on three patients suffering from the nonketotic form of hyperglycinemia. Direct assay of the enzymes involved in glycine-serine conversion revealed that the enzymic defect underlying this disease was due to nonfunction or absence of a glycine cleavage system. This enzyme system catalyzes the conversion of glycine to hydroxymethyltetrahydrofolic acid, carbon dioxide, and ammonia. In patients with hyperglycinemia, serine to glycine conversion is normal and patients depend on this metabolic conversion for their supply of C1 units. As glycine formed in this reaction cannot participate as a C1-unit donor, it cannot be metabolized further and consequently will accumulate. A therapeutic approach was devised to supply the organism with sufficient C1 units and was achieved by addition of methionine to a diet devoid of serine and glycine. As a consequence, the patient with hyperglycinemia does not rely so heavily on the glycine-serine conversion to fulfill his requirements for C1 units and glycine will not accumulate. Levels of glycine in plasma fell to normal values after feeding a diet with 0.3 g methionine/kg/24 h for a period of 10 days. It was demonstrated that the decrease in plasma glycine by administration of methionine was not due to increased excretion of glycine in the urine. Speculation: These studies have yielded evidence that the nonketotic form of hyperglycinemia is due to absence or nonfunction of the enzymic system responsible for the conversion of glycine to CO2, NH3, and hydroxymethyltetrahydrofolic acid. To meet the requirements of the organism for C1 units the conversion of serine to glycine proceeds at an accelerated rate. This can be compensated by addition of methionine to the diet, which serves as an alternate C1-unit donor. Patients with hyperglycinemia that do not respond to serine- and glycine-free diets may respond to diets rich in methionine.
TL;DR: The obtained subunits of hemocyanin are highly heterogeneous, in accordance with the results of dissociation experiments, and the cause of this phenomenon is still unknown.
TL;DR: The model of the overcritically damped oscillator for the semicircular canal remains valid during growth if a quadratic bending of the cupula is assumed.
Abstract: 1. The dimensions of the semicircular canals of pike can be expressed as allometric functions of the body length L .
2. The equal sensitivity of pike of different sizes to rotatory stimulation can be explained as a quadratic bending of the cupula.
3. In the pike the sensitivity is of the same order of magnitude for the vertical and horizontal semicircular canals.
4. In the pike the growth rate of the volumes of duct and ampulla is the same for the horizontal semicircular canal and for the posterior semicircular canal.
5. The special growth rate of the dimensions of the horizontal semicircular canal of the ray can be explained by a quadratic bending of the cupula.
6. For equally large cupulae the sensitivity of the horizontal semicircular canal is of the same order of magnitude for twenty-three mammals, fourteen birds and one reptile as it is for the pike.
7. Within the limits of error the ‘growth rate’ of the diameter of the narrow duct is the same in mammals as in the pike.
8. At the same body mass the absolute value of the diameter of the narrow duct is smaller in mammals than in the pike by a factor of 1.69.
9. For a body mass of 1 kg the value of the enclosed area of the horizontal semicircular canal is 6 times smaller in mammals than in pike.
10. The model of the overcritically damped oscillator for the semicircular canal remains valid during growth if a quadratic bending of the cupula is assumed.
TL;DR: The synthesis and properties of the Niobium complexes (π-C 5 H 5 ) 2 NbCl 2, (π -C 5H 5 ), (π C 6 H 5 ), and (π −C 3 H 5, ) are described in this paper.
TL;DR: In this article, the crystal structures of rhombohedral Ti 3 S 4 and hexagonal Ti 4 S 5 were determined by X-ray powder diffraction methods based on close packings of sulfur atoms of the types (chchchh ) 3 and (chhh ) 2, respectively.
TL;DR: In this paper, the normal mode expansion technique is employed to obtain numerical results for the solution of the slab albedo problem in one-speed transport theory with anisotropic scattering.
12 Feb 1970
TL;DR: Papain (EC 3.4.10) is a proteolytic enzyme which is isolated from the Papaya, a common tropical tree, and its SH group is required for enzymic activity.
Abstract: Papain (EC 3.4.4.10) is a proteolytic enzyme which is isolated from the Papaya, a common tropical tree. It is a sulphydryl enzyme and its SH group is required for enzymic activity. Papain as usually prepared (Kimmel & Smith 1954) contains only a small portion of active molecules. The majority of the molecules are inactive because their sulphydryl group is blocked. Part of the blocking is caused by disulphide formation with cysteine (Sluyterman 1967). This disulphide can be reduced by an excess of cysteine resulting in an active enzyme preparation. The free SH content never reaches 100% and is often not more than about 50% , so that we must distinguish between papain molecules with a reversibly and an irreversibly blocked SH group. The chemical nature of the irreversible blocking is not yet known. It might well be due to a higher oxidation state of the sulphur which cannot be reduced by an excess of cysteine (Glazer & Smith 1965).
TL;DR: The results demonstrate that the preparation procedure developed yields cells in higher amounts in apparently better morphological condition and with biochemical functions comparable to those of the intact tissue.
TL;DR: The structure of UTe2 has been determined by X-ray powder methods as discussed by the authors, and the compound is orthorhombic, space group Immm; a = 4.1617; b = 6.1276; c = 13.965 A.
Abstract: The structure of stoichiometric uranium ditelluride, UTe2, has been determined by X-ray powder methods. The compound is orthorhombic, space group Immm; a = 4.1617; b = 6.1276; c = 13.965 A . Uranium is coordinated by eight tellurium atoms (average distance UTe = 3.17 A ) forming a trigonal prism with two capped, square faces. Half of the tellurium atoms form infinite straight chains with TeTe distances of 3.06 A. β-ErSe2 is probably isostructural with UTe2.
TL;DR: Only hexafluorenium and d-tubocurarine could be extracted into the organic solvent to a significant degree, suggesting that lipid solubility is an important factor in the transport of bis-quaternary ammonium compounds from plasma to bile.
TL;DR: In the absence of activators, a low concentration of the substrate Ala-Phe-amide enhances the rate of hydrolysis of Gly- Phe-pnitroanilide, and the enzyme activity as a function of the activator concentration shows Michaelis-Menten kinetics.