Showing papers by "Utrecht University published in 1974"
425 citations
TL;DR: It is interesting to note that the current membrane model accentuates the fluidity of the membrane, which phospholipids undergo a rapid lateral diffusion within the two monolayers of the bilayer.
296 citations
TL;DR: Two proteins have been isolated from homogenates of bovine brain cortical tissue which specifically stimulate the above phospholipid exchange and exhibit a marked preference for phosphatidylinositol transfer, and the effects of membrane concentration (microsomal protein or liposomal phospholIPid) on relative rates of phosphatids transfer have been determined.
243 citations
235 citations
TL;DR: Amnesia for a one-trial step-through passive avoidance response was induced in rats by application of CO2 until respiratory arrest occurred and the vasopressin-analogue desglycinamide lysine vasoppressin (DG-LVP) antagonized the amnesia when administered 1 hr prior to the acquisition trial or 1 hr before the test trial.
210 citations
TL;DR: There was a highly significant difference between sexes in hedonic scores, women finding the odor more unpleasant, but not in threshold values, and females to be more sensitive than males.
Abstract: Some eighty years ago, Toulouse and Vaschidel reported conflicting results of various research workers studying sex differences in olfactory sensitivity. These French authors found a distinct difference in sensitivity to the odor of camphor in favor of females, whereas some years previously Bailey and his coworkersz.3 had concluded that males were more sensitive. Since then many studies have been carried out to settle this issue, but even today the evidence is conflicting. Sex differences in sensitivity were not found, among others, by Mesolella,4 Kloek,B Matzker,a Amoore and Venstrom,T Venstrom and Amoore,* and Griffiths and Patterson.9 Kloek examined several hundred subjects of both sexes and used, besides “neutral” odors like coffee, cloves, nutmeg, and cinnamon, odors that probably have a biological (sexual) significance, steroid sex hormynes and their metabolites, and also pentadecanolide (Exaltolide). He did not, however, obtain quantitative data on sensitivity but merely asked his subjects to state whether they perceived the compounds, and if so, how strongly; he also asked them to verbalize their impressions. Amoore and Venstrom used a number of neutral odors and a substance related to Exaltolide, namely Thibetolide. Griffiths and Patterson used androstenone and found that 7.6y0 of the women were unable to detect the odor, in contrast to 44.3% of the men. From those who could smell the odor a number of subjects was selected and their thresholds were determined. There was a highly significant difference between sexes in hedonic scores, women finding the odor more unpleasant, but not in threshold values. Among the authors who found females to be more sensitive, in addition to Toulouse and Vaschide, were Le Magnen,lo Schneider and Wolf,ll and Koelega.12 Le Magnen used mainly the odor of pentadecanolide, Schneider and Wolf used a neutral odor, citral, and Koelega found differences for both biological odors, pentadecanolide and oxahexadecanolide (Musk R-I) and a neutral odor (amylacetate). According to Le Magnen,lo adult women are very sensitive to pentadecanolide and many women experience the odor as very intense, whereas young children and adult men can hardly smell it; about 50% of the adult males show an anosmia for this substance. Le Magnen formulated the hypothesis that the sensitivity to pentadecanolide and urinoid odors (including pyridine) is determined by sex hormones: estrogens would improve sensitivity, whereas androgens would lead to a low sensitivity to these biological odors and to a higher sensitivity for neutral odors (safrol, for example).+
204 citations
TL;DR: There was a pronounced effect of body weight and height on breast cancer risk; the significance of this in explaining international differences in incidence is stressed.
Abstract: A prospective study of breast-cancer risk in postmenopausal women has been carried out with the cooperation of 50 general practitioners. A total of 7,259 women have been followed up for an average period of 5.4 years (maximum 8.1 years); 70 cases of breast cancer occurred. The main finding was a pronounced effect of body weight and height on breast cancer risk; the significance of this in explaining international differences in incidence is stressed. High parity counteracted the risk of high weight regarding breastcancer. Single women did not show a high risk because of their relatively low body weight. The relative risk in women with a previous mastectomy was five-fold.
202 citations
TL;DR: The concept of lateral compressibility of lipids at the transition temperature is firmly substantiated by these observations.
192 citations
TL;DR: The endoplasmic reticulum appears to be the principal site in the cell for the synthesis of sphingomyelin, CDPdiglycerides, phosphatidylinositol, phosph atidylserine and the formation of lecithin, and Interestingly, the biosynthesis of phosphatidsserine appears toBe four times more active in rough than in smooth microsomes, which might suggest a ribosomal localization of this process.
165 citations
TL;DR: The effect of cholesterol upon the phase transition occurring in various mixtures of synthetic disaturated phosphatidylcholines with fatty acid constituents of 12, 14, 16, and 18 carbon atoms was measured by differential scanning calorimetry.
159 citations
TL;DR: An increase in response vigour on the first day of extinction, compared with acquisition asymptote, was observed in all placebo conditions; ACTH 1–24 and ACTH 4–10 reduced themagnitude of this effect;ACTH 4-10 (7-D-Phe) increased the magnitude of thiseffect.
TL;DR: It is found that capillary values are 2–3 times higher than those in venous blood, and the normal range for venous plasma NHs was 6.5–35.0 μmol/l.
TL;DR: Particle aggregation, induced by lipid phase transition, could also be observed in Streptococcus faecalis membranes, but no aggregation was seen in the fracture faces of some Bacillus species and Staphylococcus aureus, and the non-appearance of aggregation could be explained by the presence of branched-chain fatty acids in the membrane lipids of these bacteria.
TL;DR: The dexamethasone concentration in the hypothalamus appeared to be much higher than after iv injection, and was not associated with a proportionally greater suppression of the pituitary-adrenal activity.
Abstract: Administration of 3H-dexamethasone with carrier to rats either into the third brain ventricle (ic) in doses ranging from 0.01 to 10 Wg, or intravenously in a dose of 10 μg was used to explore the site of the suppressive action of this steroid on pituitary-adrenal activity. Almost all of the radioactivity in the brain was shown to be unmodified dexamethasone. Following iv injection the uptake and disappearance patterns of dexamethasone in the brain were clearly distinct from that of the other tissues. Regional differences in concentration and uptake o:f dexamethasone could however be observed within the brain. In limbic and mesencephalic structures a rise in concentration was found up to 4 hr, yielding a maximum of approximately 0.025% of the injected dose per gram tissue. Four hr following ic injection, the dexamethasone concentration in the hypothalamus appeared to be much higher than after iv injection. This higher concentration was not associated with a proportionally greater suppression of the pituita...
TL;DR: In this article, spectral ratios of short-period core phases with common source and receiver and with nearly the same ray paths in the mantle have been formed to derive a Q-structure for 1 Hz compressional waves in the inner core.
Abstract: Summary
Spectral ratios of short-period core phases with common source and receiver and with nearly the same ray paths in the mantle have been formed to derive a Q-structure for 1 Hz compressional waves in the inner core. Data from one large array (NORSAR) have been used to extract the relevant phases, including the pairs (PKIKP, PKiKP), (PKIKP, PKP(BC)), (PKIIKP, PKiKP), (PKIIKP, PKKP(BC)). An array is needed in particular to separate PKIKP and PKiKP and to identify PKIIKP. In forming the spectral ratios, techniques like spectraforming and instantaneous spectral analysis have been employed. The data have been inverted using a number of different velocity models. The essential features of the resulting Q-models are the same: Q rises from a value of about 200 near the inner core boundary to about 600 at 400 km depth penetration. Below 450 km depth the Q-structure is not well constrained, but probably is below a value of 2000. It is suggested that the temperature at the inner core boundary is close to the melting point of iron and that partial melting occurs in at least part of the inner core. The low Q-structure greatly affects the amplitudes of phases like PKIIKP and PKJKP. It is verified that PKIIKP is observable only in exceptional cases and arguments are presented that PKJKP is too small to be observed.
TL;DR: Lecithins isolated from the total erythrocyte membrane and from the inner monolayer of the membrane possess identical fatty acid patterns and identical positional distributions of their fatty acyl constituents.
TL;DR: In this paper, it was shown that the major contribution to the high uniaxial anisotropy of the compound SmCo5 arises from the action of crystalline and exchange fields on the Sm3+ ion.
TL;DR: In this article, a steady state solution for a model of a lithospheric plate which cools while moving was proposed, which is compatible with data on topographical height and is expressed in the existence and cross-sectional shape of mid ocean ridges, where there is a relationship between depth of the ocean and age of the crust.
Abstract: IF newly formed oceanic crust is moving away from a spreading axis, it can be expected to contract by cooling. Vertically, the cooling is expressed in the existence and cross-sectional shape of the mid ocean ridges, where there is a relationship between depth of the ocean and age of the crust1. A steady state solution for a model of a lithospheric plate which cools while moving2–4 is compatible with data on topographical height.
TL;DR: The results suggest an inhibitory role of an α-adrenoceptor in the area of the nucleus tractus solitarii in the central control of blood pressure in anesthetized rats.
TL;DR: Both lysophospholipases from beef liver exhibited general esterolytic properties in that compounds like tributyrin and p -nitrophenylacetate were also hydrolysed, evidence is provided indicating that the hydrolysis of these compounds is an intrinsic property of the beef liver lysophile phospholipase.
TL;DR: In this article, a recent review of the strengths of about 600 γ-ray transitions between bound states in the A = 21-44 region is extended by including E0 transitions, and magnetic transitions of which the mixing ratio can be assumed to be negligibly small.
14 Jan 1974
TL;DR: Constructions are shown for cellular developmental models with continuous parameters, such as concentration of nutrients or inhibitors, size and age of cells or compartments, and it is proposed that some of the L-system results can be made use for these continuous component models.
Abstract: Constructions are shown for cellular developmental models with continuous parameters, such as concentration of nutrients or inhibitors, size and age of cells or compartments. It is proposed that we can make use of some of the L-system results for these continuous component models.
TL;DR: In this paper, the strengths of about 600 γ-ray transitions between bound states according to character (electric or magnetic), multipolarity, and isospin forbiddenness are classified.
TL;DR: In this paper, the presence of meson exchange currents in the tri-nucleon system is shown to modify significantly the charge form factor of 3 He in the region of the dip and the secondary maximum.
TL;DR: Synthetic bovine parathyroid hormone, containing the first 34 amino acids was shown to have a similar effect as PTE, indicating that the hemodynamic action of PTE indeed was due to the same chemical entity that influences calcium metabolism.
Abstract: In anesthetized dogs the arterial hepatic flowproper was calculated by subtracting gastroduodenal artery flow from hepatic artery flow, using probes from a sine wave electromagnetic flowmeter. Additionally, renal blood flow was measured. Using this technique, earlier evidence that parathyroid extract (PTE) augmented arterial hepatic and renal flow was confirmed. This information was valuable because in the earlier study the effects had been assessed only on celiac flow after extirpation of stomach, pancreas and/or spleen. Synthetic bovine parathyroid hormone, containing the first 34 amino acids was shown to have a similar effect as PTE. Thus, the hemodynamic action of PTE indeed was due to the same chemical entity that influences calcium metabolism. The augmentation of arterial hepatic flow (4–5-fold) was large, the dosage needed small (ED50 appr. 200 ng/kg, i.e., 0.6 IU/kg), the effect (maximum within 1 min) as well as the disappearance rate quick (return to 50% of the maximum obtainable within 15 min). ...
TL;DR: The effect of increasing concentrations of lysolecithin (1,2-dipalmitoyl-sn-glycerol-3-phosphorylcholine) on the gel → liquid crystal thermal transition was studied by differential scanning calorimetry (DSC) as discussed by the authors.
TL;DR: By infusion of ferritin in the pancreatic duct system in vivo and application of cytochemical techniques, it could be established that after stimulated exocytotic secretion, redundant apical cell membrane is withdrawn by at least two routes.
Abstract: Stimulation of secretion by pilocarpine results in a 70% loss of zymogen granules from pancreatic acinar cell during the first hr after injection of the drug. In previous work (Geuze and Poort, 1973), we found that the amount of membrane stored in the surface of the microvilli and of the numerous infoldings present in highly stimulated cells, increases during the first 2 hr and then decreases again during the 3rd hr after stimulation, concurrently with maximal endocytosis of sorbitol-[su14C]. Further observations on the fine structure of stimulated cells at various time intervals after injection of pilocarpine showed that during the first hr numerous smooth vesicles and multivesicular bodies (mvb's) appear in the apical cytoplasm, while the number of coated vesicles and their relative total volume increase significantly 3 hr after stimulation. By infusion of ferritin in the pancreatic duct system in vivo and application of cytochemical techniques (osmium impregnation, electron microscope autoradiography and acid phosphatase cytochemistry) it could be established that after stimulated exocytotic secretion, redundant apical cell membrane is withdrawn by at least two routes: 1) During the initial rapid increase of the amount of apical cell membrane, withdrawal is accomplished by interiorization of luminal invaginations into smooth endocytotic vesicles, which in turn give rise to mvb's by infolding and subsequent fission of their limiting membrane. 2) Once the bulk of stored secretion granules has been discharged, endocytotic coated vesicles become gradually more prominent as carriers for redundant cell membrane. The contents of endocytotic structures ultimately become incorporated in residual bodies, suggesting lysosomal degradation of cell membrane prior to eventual reutilization. Coated vesicles also originate by pinching off from mature Golgi cisternae and condensing vacuoles. A possible function of the coated membranes in the concentration of exportable protein within forming secretory granules is discussed.