Showing papers by "Radboud University Nijmegen published in 1971"
TL;DR: A strain of Streptococcus mutans was treated with a mutagenic agent, which resulted in isolation of a mutant which, compared to the original strain, had lost the ability to form sticky deposits on hard surfaces in sucrose medium.
160 citations
TL;DR: Data from the literature on the equilibrium between urea and cyanate which were difficult to combine, have been correlated by computer calculation and accumulation of cyanate in urea solutions was quantitatively studied.
149 citations
TL;DR: In this article, the long time behavior of the velocity auto-correlation function in a d-dimensional Lorentz gas is discussed on the basis of kinetic theory, and it is found that this function has, for long times, a negative tail of the form t - ( 1 2 d+1 )
102 citations
TL;DR: In this paper, the main fatty acids of nine strains of Bifidobacterium var. pennsylvanicus were found to be normal C14, C16, and C18 saturated acids and monoenoic acids.
Abstract: Normal C14, C16, and C18 saturated acids and C16 and C18 monoenoic acids are the main fatty acids of nine strains of Bifidobacterium. Their lactobacillic acid content was less than 5%. Lactobacillus strains contained the same fatty acids as main compounds except for octadecanoic acid, which was present only in very low amounts. Eight of nine Lactobacillus strains contained in the stationary phase more than 15% lactobacillic acid. No correlation was observed between the fatty acid composition and other physiological characteristics used in the literature for classification of strains of one genus. Aging of the culture, which involved a decrease of the pH, caused a lengthening of the chain length of the fatty acids of B. bifidum var. pennsylvanicus but only a conversion of octadecenoic to lactobacillic acid in the lactobacilli. Lowering of the temperature of cultivation decreased the chain length of the fatty acids of B. bifidum var. pennsylvanicus. L. lactis did not show any influence of the temperature on the chain length of the fatty acids. The percentage of unsaturated acids was temperature independent in both organisms.
75 citations
TL;DR: The differences in phospholipid composition between bifidobacteria and lactobacilli may be another argument to differentiate these two genera.
Abstract: Phospholipid composition of 10 Bifidobacterium strains of human intestinal origin and of 9 Lactobacillus strains was determined by quantitative two-dimensional thin-layer chromatography. Phospholipids of three Bifidobacterium strains from honey bees and of two strains from bovine rumen liquor were qualitatively investigated. Diphosphatidylglycerol and phosphatidylglycerol were present in strains of both genera. All Bifidobacterium strains contained as specific phospholipids a new polyglycerolphospholipid, compound 15, and its lyso derivatives, earlier detected in B. bifidum var. pennsylvanicus. Also, lyso compounds of diphosphatidylglycerol and alanyl phosphatidylglycerol were only present in this genus in variable amounts. Lysyl phosphatidylglycerol was the only ninhydrin-positive phospholipid in seven Lactobacillus strains. In L. delbruckii and L. helveticus it was absent and partially replaced by an unidentified ninhydrin-negative phospholipid. The differences in phospholipid composition between bifidobacteria and lactobacilli may be another argument to differentiate these two genera.
60 citations
TL;DR: It has been demonstrated by comparative electrophoresis on polyacryalmide gels, that long contact of α-crystallin with urea eventually gives rise to a high degree of carbamylation which may lead to erroneous conclusions about the number of real subunits.
57 citations
TL;DR: By means of experimental induction of puff formation of certain groups of loci in Drosophila hydei, it was demonstrated that a local change in protein-dye binding capacity is one of the first events in puff formation.
Abstract: In Diptera, the polytene chromosome puffs, regarded to be morphological manifestations of active genes (1, 2, 9), contain an increased quantity of protein if compared with their inactive state . By means of experimental induction of puff formation of certain groups of loci in Drosophila hydei, it was demonstrated that a local change in protein-dye binding capacity is one of the first events in puff formation (3) . This change in dye binding capacity due to a local increase in protein concentration (10) occurs in the virtual absence of de novo protein synthesis (7) . Radioautographic analyses of chromosomal amino acid incorporation during induced puff formation failed to provide evidence for enhanced incorporation in puff-forming loci (10) . Because the same puff in active and inactive state displays an identical histone content (8), the local increase in protein concentration should result from an accumulation of preexisting nonhistone protein(s) . In an attempt to characterize the changes occurring at the genome level upon experimental gene activation, in the first instance nonhistone protein patterns of salivary gland nuclei in which specific puffs were induced in vivo or in vitro by a temperature treatment or a hormone (ecdysone) treatment were compared with those of nuclei of untreated glands .
53 citations
52 citations
TL;DR: Results indicate that the (Na+−K+)-ATPase system plays the primary role in transcellular isotonic fluid transport in gallbladder despite the absence of a secretory potential.
48 citations
TL;DR: It is suggested that the lower level of oxidative N -demethylation in the new-born rat is related to the presence of hemopoietic cells and to the rate of growth of the liver, rather than to a postnatal interference by maternal substances during the nursing period.
48 citations
TL;DR: The Rb+ uptake mechanism of yeast is activated by small amounts of Rb- or K+, giving rise to a deviation from normal Michaelis-Menten kinetics at concentrations below 0.6 mM Rb+.
TL;DR: The dominance of the Pyroglyphidae in house dust has been influenced by a number of factors, including the humidity in houses dropped recently to such an extent that only Pyrogelphidae can survive.
Abstract: The dominance of the Pyroglyphidae in house dust has been influenced by a number of factors. The humidity in houses dropped recently to such an extent that only Pyroglyphidae can survive. When temperature and relative humidity are favorable forAcarus siro andGlycyphagus destructor as well asDermatophagoides pteronyssinus, Dermatophagoides diminished in numbers by competition. Introduction of the predatorCheyletus eruditus into this mixed breeds causes the extermination ofDermatophagoides. The vacuum cleaner trapped mites, butDermatophagoides was protected by its habit to hide in cracks and crevices. The use of insecticides has a more killing effect onAcarus andGlycyphagus than onDermatophagoides.
TL;DR: It was concluded that neither the polar moiety nor the diglyceride part of 95% of the phospholipids in the rod outer segments are essential for the spectral integrity of rhodopsin, ruling out the possibility that the retinaldehyde group in r Rhodopsin is linked to phosphatidyl ethanolamine.
TL;DR: The changes observed in the early third instar salivary gland cells indicate that the onset of mucopolysaccharide synthesis is inhibited by the steroid treatment, and it may be suggested that the steroid ecdysterone is an effective trigger of mechanisms active in cytodifferentiation.
TL;DR: The specific water permeability of the nail plate appeared to be independent of nail thickness in the finger nails of a healthy volunteer, and the effective area of the described capsule has been determined applying an electric analog.
TL;DR: Swiss mice infected with Plasmodium berghei are unable to produce antibodies against rabbit erythrocytes or to develop transplantation immunity against skin heterografts to the same degree as uninfected controls.
TL;DR: A new method was developed by means of the combined gas chromatograph-mass spectrometer to identify the propyl analogues of cannabidiol, tetrahydrocannabinol and cannabinol in hashish.
TL;DR: The results indicate that both the acid and the alkaline Bohr effect are equally affected, and that the DPG binding to deoxyhemoglobin (Hb) is much stronger than to carboxyhemoglobin(HbCO) and that Hb binds effectively one DPG molecule.
TL;DR: It appeared to be probable, that in the deamination and N-dealkylation process the tertiary hydrogen atom is of importance.
TL;DR: The influence is described of various diets on growth, food consumption, and digestion in locusts during the fifth larval instar and adult somatic growth period and some indices as growth rate and efficiency of conversion of food to body substance are discussed.
TL;DR: An electron transfer series of complexes of the [M-S′ 2 S″ 2 ] Z -type has been investigated, using maleonitrile dithiolate and N,N-di-n-butyldithiocarbamate as the ligands as mentioned in this paper.
TL;DR: The correlation between the dose of anticonvulsant drug and the level of folate in the serum was studied in 52 epileptic children and adolescents and the effect on fit frequency and I.Q. was measured.
Abstract: SUMMARY
The correlation between the dose of anticonvulsant drug and the level of folate in the serum was studied in 52 epileptic children and adolescents The effect on fit frequency and IQ of addition of 15 mg folic acid per day to the anticonvulsant therapy was measured in a double blind study during 12 months in 37 children
A close inverse relation was found between total dose of anticonvulsant drug and the serum level of folate Phenytoin was effective in this respect at a daily dose of 150 mg No effect of 90 mg phenobarbital or 75 mg phenytoin was demonstrated
No effect on fit frequency of 15 mg folic acid per day added to the anticonvulsant medication was found Addition of 15 mg folic acid prevented an increase in IQ scores in 32 children, indicating a negative effect of folic acid on mental functions in epileptic children
RESUME
On a etudie les correlations entre les drogues anti-convulsivantes et le niveau d'acide folique chez 52 sujets, enfants et adolescents epileptiques Dans une etude double aveugle pendant 12 mois chez 37 enfants on a evolue l'effet de l'addition au traitement anti-epileptique de 15 mg d'acide folique par jour sur la frequence des crises et du QI
On a trouve une etroite correlation negative entre la dose totale des drogues anti-epileptiques et le taux du folate serique Dans cette optique le diphenylhydantoine etait efficace a des doses de 150 mg par jour
II n'y avait pas d'effet pour 90 mg de phenobarbital ou pour 75 mg de diphenylhydantoine On n'a pas trouve d'effet sur la frequence des crises en ajoutant au traitement anti-convulsivant 15 mg d'acide folique par jour L'addition de 15 mg d'acide folique empechait l'amelioration des resultats aux tests chez 32 enfants, suggerant ainsi un effet negatif de l'acide folique sur l'activite mentale des enfants epileptiques
TL;DR: In this article, the dry mass in Drosophila hydei salivary gland chromosomes was established with a Leitz double beam interference microscope, where optical path differences per unit area of the induced puffs 2-48C and 4-81B (temperature induced) were recorded.
Abstract: Relative values for the dry mass in puff-forming regions of Drosophila hydei salivary gland chromosomes were established with a Leitz double beam interference microscope. All measurements were made after RNA digestion. Optical path differences per unit area of the induced puffs 2-48C and 4-81B (temperature induced) and a cytoplasm-free background were recorded. In each of the nuclei used for these measurements, the same procedure was applied to two reference regions in the vicinity of the puff, region 2, 47A-48B and region 4, 81C-82C respectively. For comparison of the dry mass values of a puff region at various time intervals after the onset of puff induction, ratios of the optical path differences of the puff region over that of the reference region were calculated. These ratios were established at 5, 10, 30, 60 and 120 min after the onset of a temperature treatment and compared with the ratio in non-treated animals. From the data it can be concluded that the dry mass in the induced puffs increases gradually up to 30 min. At this time the dry mass ratio for puff 2-48C has reached a value of 150% and that of puff 4-81B, 210%. It is concluded that this increase in dry mass is due almost entirely to a local accumulation of non-histone protein.
TL;DR: Observations support the hypothesis of a genetically controlled cholinergic mechanism which is located in the brain and which facilitates exploratory behaviour in mice.
Abstract: Peripheral administration of scopolamine tended to reduce the frequencies of three exploratory acts in mouse strain C57BL/6 and to increase them in strain DBA/2, whereas methylscopolamine was ineffective. Physostigmine diminished these exploratory scores in both genotypes, whereas neostigmine had no such effects. These observations support the hypothesis of a genetically controlled cholinergic mechanism which is located in the brain and which facilitates exploratory behaviour in mice.
TL;DR: A high resolution zonal centrifugation technique is described which allows the isolation of two species of lens messengers differing by a number of criteria from the bulk of ribosomal RNA and tRNA.
TL;DR: The influence of Chlamzjdomonas glohosa and Chlorococcum ellipsoideum on each other’s growth was studied with two diffcrcnt cxperimcntal techniques.
Abstract: ARSTRACT The influence of Chlamzjdomonas glohosa and Chlorococcum ellipsoideum on each other’s growth was studied with two diffcrcnt cxperimcntal techniques. The first is a newly developed filter culture method in which two separate cultures of different species are connected via a filtering system through which medium is exchanged while the cells themselves are kept separate. Under these circumstances Chlorococcum in’hibits the growth of Chlumydomonus but not vice versa. In the second technique, traditional luixcd cultures, Chlorococcum inhibits Chlumydomonus only in unbuffered mcdiurn. In mediunl buffcrcd at 17EI 8.1 there is a slight stimulation of one or both species. The role of 1711 in the relation between the species seems therefore to bc very important.
TL;DR: An attempt was made to estimate the stoichiometric relationship between Na + flux and ATP hydrolysis by the Na-K-ATPase activity obtained in this study and ATP production estimated from CO 2 and lactate production reported in the previous paper.
TL;DR: The injection of gibberellic acid (GA3) into larvae of Drosophila hydei can affect the pattern of gene activities in a specific manner, which became clear from a study on the patterns of puffs in the giant chromosomes of the larval salivary glands.
Abstract: The injection of gibberellic acid (GA3) into larvae of Drosophila hydei can affect the pattern of gene activities in a specific manner. This became clear from a study on the pattern of puffs in the giant chromosomes of the larval salivary glands.
Depending upon the age of the larvae injected, either of two new puffs, 72B or 21B, appeared. Not only was the activity of these chromosome regions stimulated but the activity of some normally occurring puffs specific for the period shortly before puparium formation was affected. If GA3 was injected during the period shortly before puparium formation further development became influenced as revealed by a significant reduction in the number of flies emerging from treated animals.
Zusammenfassung
DER EINFLUSS VON GIBBERELLINSAURE AUF DIE ENTWICKLUNGSPROZESSE BEI DROSOPHILA HYDEI
Es wurde die Wirkung verschiedener Konzentrationen von Gibberellinsaure (GA3) nach Injektion in Drosophila-Larven unterschiedlichen Alters untersucht. Konzentrationen von 3 μg/Larve und hoher fuhrten bei jungen und mittleren Larven des 3. Stadiums zur Ausbildung eines neuen Puffs (72B) in den polytanen Chromosomen der Speicheldruse. Diese Reaktion wurde in 15–20% der Larven beobachtet.
In spateren Stadien der Entwicklung kurz vor der Pupariumbildung wird nach Injektion von 1 μg/Larve ein weiterer Puff (21B) in 10% der Larven induziert. Der Prozentsatz der Larven die diesen Puff 3 Stunden nach der Injektion aufweisen, nimmt mit steigender GA3-Konzen-tration zu. Nach Injektion von 5–6 μg/Larve war der Puff 21B in 80% der Tiere enthalten.
Zur selben Zeit lies sich eine Beinflussing der Aktivitat von zwei Puffs nachweisen, die fur die Periode der Pupariumbildung spezifisch sind. Die Aktivitat dieser Puffs wird durch die Injektion von GA3 herabgesetzt.
GA3 bewirkt nicht nur die Induktion neuer Puffs, sondern auserdem eine Verzogerung der Entwicklung. Nach der Injektion von 2 μg/Larve verzogert sich die Zeit der Pupariumbildung um 2–10 Stunden. Die Zahl der Fliegen, die aus Larven schlupfte, die kurz vor der Pupariumbildung eine Injektion von mehr als 3 μ GA3 erhielten, war deutlich herabgesetzt. Es wird vermutet, das GA3 eine spezifische Wirkung auf die Aktivitat des Genoms ausubt und damit eine Beeinflussung der normalen Entwicklung bewirkt.
TL;DR: Six main types of vascular communications were found; these appeared in twelve different combinations and included vascular connection in shared cotyledons is by way of the villous capillaries and the paravascular capillary network.