Showing papers by "Charles University in Prague published in 1976"
01 Jan 1976
TL;DR: Critical evaluation of this knowledge reveals that most progress has been achieved during the past fifteen years after electron microscopic application, which requires better resolution than that obtained with the light microscope.
Abstract: Considerable knowledge of microsporidian structure has been accumulated during 150 years of research. Critical evaluation of this knowledge reveals, however, that most progress has been achieved during the past fifteen years after electron microscopic application. Although some light microscope observations have contributed amazingly accurate data on microsporidian structure, the extreme smallness of microsporidia (the spores of which are probably the smallest eukaryotic cells) as well as the compactness and complexity of their structural organization requires better resolution than that obtained with the light microscope.
231 citations
177 citations
TL;DR: In this paper, it was shown that for any integer r ≥ 1, there is a finite graph H with cl(H ) = m, such that if the edges of H are r -colored in any way, then H contains an induced subgraph G isomorphic to G with all its edges the same color.
153 citations
TL;DR: Using liquid ion-exchanger semimicroelectrodes with a side pore, changes of extracellular potassium concentration (Ke+) were measured in adult rabbit and cat gastrocnemius muscles and in venous effluent blood flowing from the cat GastrocNemius muscle during various bouts of activity induced by sciatic nerve stimulation.
Abstract: Using liquid ion-exchanger semimicroelectrodes with a side pore, we measured changes of extracellular potassium concentration (Ke+) in adult rabbit and cat gastrocnemius muscles and in venous effluent blood flowing from the cat gastrocnemius muscle during various bouts of activity induced by sciatic nerve stimulation. 1. Isometric tetanic contractions (at 50 Hz) of various durations caused transient accumulation of Ke+ which was non-linearly related to the duration of muscle activity. The peak values of Ke+ in response to muscle stimulation were analogous in rabbits and cats, attaining values, e.g. after a 20-sisometric tetanus, between 8-9 mEq/1K+ in both species. 2. Potassium concentration in venous effleunt blood (K+ven) was transiently increased after isometric tetani. Since blood flow was measured at the same time, it was possible to calculate the amount of K+ lost by the muscle after tetani of various durations. A 32 g gastrocnemius muscle of the cat, for example, loses 9.36 +/- 1.52 muEqK+ after a 20-s isometric tetanus, which corresponds roughly to 0.5% of the total muscle potassium content. The loss of K+ in this muscle was 29.3 pEq K+ /impulse/100 g fresh muscle tissue. 3. There was no evident difference between the amount of K+ released during isometric tetani, or tetanic contractions performed under isotonic conditions. Single twitches evoked by indirect stimulation at 1 HZ for several minutes also induced a small rise in K+ven. 4. If the loss of K+ from the muscle into the blood stream is transiently prevented by arterio-venous occlusion installed immediately before a 10-s isometric tetanus, most K+ is released subsequently when blood flow is renewed, if the occlusion lasts for 20-25 s. It is not until blood flow is occuded for 40-60 s that most K+ is apparently resorbed and only a minor portion is released and is to be found in the venous blood. 5. The transient accumulation of muscle extra-cellular potassium may locally affect nerve endings, skeletal and smooth muscle cells.
123 citations
TL;DR: The interaction between humus and 18 elements in lake water has been studied using centrifugation, ultrafiltration and filtration through ion exchange membranes as discussed by the authors, and it has been found that the association is probably very low for halogenes and alkali ions.
122 citations
TL;DR: In this paper, an authoregressive model is introduced and investigated, the parameters of which are random variables, and necessary and sufficient conditions for stationarity are derived, where the covariance function of a stationary autoregressive series with random parameters satisifies the same Yule-Walker equations as in the usual autoregression model with fixed parameters.
Abstract: In the paper an authoregressive model is introduced and investigated, the parameters of which are random variables. The necessary and sufficient conditions for stationarity are derived. It is shown that the covariance function of a stationary autorgressive series with random parameters satisifies the same Yule-Walker equations as in the usual autoregressive model with fixed parameters. The inverse variance matrix in stationary case is also given.
94 citations
TL;DR: It is concluded that the increase of cytosol thymidine-kinase activity in CMV-infected cells was due to an enhancement of cellularThymidine kinase.
Abstract: In human diploid fibroblast LEP cells infected with AD169 strain of human cytomegalovirus (CMV) a sharp increase of cytosol thymidine kinase activity was observed. The properties of the cytosol enzymes from infected and non-infected cells were compared. No significant differences between the enzymes from infected and control cells were observed in substrate specificity, pH dependence, thermostability and relative electrophoretic mobility. Human sera containing high titres of CMV complement-fixing antibodies did not neutralize the enzyme from infected cells. It is concluded from these results that the increase of cytosol thymidinekinase activity in CMV-infected cells was due to an enhancement of cellular thymidine kinase.
65 citations
TL;DR: In this paper, the authors summarize current knowledge on chemically bonded stationary phases and their preparation and effect on chromatographic processes in GC and HPLC are described and the complex separation mechanism on these phases is discussed.
Abstract: This review is intended to summarize current knowledge on chemically bonded stationary phases. Their preparation and effect on chromatographic processes in GC and HPLC are described and the complex separation mechanism on these phases is discussed.
62 citations
TL;DR: In this article, the electromagnetic field of a general stationary source, occurring in the vicinity of a rotating (Kerr) black hole, is obtained by solving the Maxwell and Teukolsky equations.
Abstract: The electromagnetic field of a general stationary source, occurring in the vicinity of a rotating (Kerr) black hole, is obtained by solving the Maxwell and Teukolsky equations. The field is expressed both outside and inside the radius at which the source is located. As examples the fields of point charges, charged rings, current loops, and magnetic dipoles not necessarily located in axisymmetric positions are calculated. The electromagnetic field occurring when a Kerr black hole is placed in an originally uniform magnetic field is derived without assuming the alignment of the direction of the magnetic field and the axis of symmetry of the black hole.
60 citations
52 citations
TL;DR: The circulatory and metabolic changes during prolonged exercise (60 min) were studied in a group of 10 healthy prepubertal boys and the increasing blood free glycerol concentration indicates similar fat share on energy release in children as in adults.
Abstract: The circulatory and metabolic changes during prolonged exercise (60 min) were studied in a group of 10 healthy prepubertal boys. The boys worked on the treadmill and on the bicycle ergometer at two levels of load, namely at oxygen uptakes of 36--39%, and 60% of the respective VO2 max for both types of exercise. The identical relative work loads represent higher metabolic rate at the treadmill exercise. The rectal temperature was higher after exercises on treadmill than on bicycle. The heart rate increase during prolonged exercise was lower in boys than in adults in both types of exercise. Better cardiovascular adjustment is suggested. The blood lactate increase was negligible in the initial phase of exercise with subsequent removal from the blood during extended exercise, which was more pronounced at the treadmill exercises. The increasing blood free glycerol concentration indicates similar fat share on energy release in children as in adults. No biological handicap could be found for prolonged exercise in children. The preference of short-time exercises in children lies probably in the psychological sphere.
TL;DR: It may be concluded that the absolute amount of lean body mass demonstrates the most constant trend of development during adolescence, next to height, which is more constant than trends in body weight.
Abstract: Extract: Beginning at age 10 years, height, weight, body density, and bone age of 40 normal boys were measured yearly over a period of 8 years. From body density, lean body mass and body content of fat were calculated. Values for all measurements are included in the Appendix and mean values, including those for lean body mass and percentage of body fat, are presented for each year in Table 1. Coefficients of correlation between measurements made during the first and eighth years of study were high for height (0.68), weight (0.50), and lean body mass (0.60), but relatively low for body fat (0.25). Correlation coefficients between the various parameters in a given year are presented in Table 2. The maximum yearly increment in height, weight, and lean body mass of individual subjects coincided in time. The respective mean values for the year of maximum growth were 9.4 cm, 8.1 kg, and 7.5 kg. Throughout the growth spurt, the contribution of fat to increase in body weight was small. It may be concluded that, next to height, the absolute amount of lean body mass demonstrates the most constant trend of development during adolescence. Speculation: Lean body mass, like weight and height, follows individual patterns that are consistent throughout adolescence. The trends in height and lean body mass are more constant than trends in body weight.
TL;DR: In this article, the basic theory of UV detector response is presented, and the use of UAV response as a quantitative measure for small amounts of UV absorbing compounds is demonstrated, using this technique complete analysis of mixtures containing components differing in relative amounts by up to four orders of magnitude.
TL;DR: A procedure using heat inactivation and L-phenylalanine inhibition to quantitate the activities of bone, liver and intestinal alkaline phosphatase isoenzymes in human serum was confirmed by alkaline phosphate isoenzyme analysis using an electrophoretic procedure.
TL;DR: In this article, a simple teflon flow-through voltammetric cell has been constructed, which contains two platinum tubular electrodes and a saturated calomel reference electrode and has a very small dead volume.
TL;DR: In this article, the known synthesis of diphenylphosphineacetic acid (HA) was simplified, and the formation of the following species was detected and their stability constants were determined: HA (log β = 6·05), H 2 A + (7·6) and NiA 2(7·08).
TL;DR: It was concluded that changes occur in somatotypes of adolescent boys, but the influence of physical activity on the changes is inconclusive.
Abstract: The purpose of this study is to examine the stability of somato-types of boys with different activity levels followed longitudinally for eight years. Thirty-nine boys aged 11 were somatotyped annually (until 18 years) using the Heath-Carter anthropometric rating method. Three sub-groups were formed according to their levels of systematic physical activity designated High, Moderate, and Low Activity.
There were no differences in somatochart distributions of the Total Group, but there were considerable individual changes which cancelled each other in group comparisons. All boys changed their somatotype ratings at least once and 67% changed in component dominance. The inter-age correlations for the components were generally of poor prediction value, and the somatotype migratory distances showed considerable variation. The Total Group means differed on three components and this was attributed to differences within the Moderate Activity Group, the only sub-group to differ. It was concluded that changes occur in somatotypes of adolescent boys, but the influence of physical activity on the changes is inconclusive.
TL;DR: In this article, two samples of cellulose (molecular weight 2.97 × 105 and 1.25 × 105) were transformed into carbanilates (CTC) which were then fractionated by the elution method at a constant composition of the acetone-water elution mixture with the column temperature gradually increasing from −30°C to 30°C, and by the GPC method in acetone and tetrahydrofuran.
Abstract: Two samples of cellulose (molecular weight 2.97 × 105 and 1.25 × 105) were transformed into carbanilates (CTC) which were then fractionated by the elution method at a constant composition of the acetone-water elution mixture with the column temperature gradually increasing from −30°C to 30°C, and by the GPC method in acetone and tetrahydrofuran. Tetrahydrofuran appeared to be a more suitable solvent. The molecular weights of fractions obtained by the elution fractionation were determined by the light-scattering method in tetrahydrofuran. The width of fractions was determined by the GPC method (average Mw/Mn = 1.37); the [η] values and the Mark-Houwink constants (K = 5.3 × 10-3, a = 0.84) for tetrahydrofuran at 25°C were determined. The calibration curve for the GP method was constructed by means of the fractions thus obtained; it was demonstrated that the universal calibration curve according to Benoit can also be used. It was demonstrated that the molecular weight distribution of cellulose can be conveniently determined by conversion into CTC followed either by the elution fractionation (for preparative purposes) or by fractionation by the GPC method (for analytical purposes).
TL;DR: In this paper, the authors construct sets of canonical realizations for all classical Lie algebras (An,Bn,Cn,Dn) which depend ond parameters,d=1, 2, 3, n; all Casimir operators are realized by multiples of identity.
Abstract: We construct sets of canonical realizations for all classical Lie algebras (An,Bn,Cn,Dn) These realizations depend ond parameters,d=1, 2, 3,,n; all Casimir operators are realized by multiples of identity For most of the real forms of these algebras we give sets of realizations which are, moreover, in well-defined sense skew-Hermitian Further we study extremal cases of the presented realizations The realizations with minimal numbers of canonical pairs are discussed from the point of view of general results concerning minimal realizations On the other hand, a connection is found between our “maximal” realizations ofAn and the Gel'fand-Kirillov Conjecture
TL;DR: The clinical features consisting mainly of enophthalmos, beaked nose, narrow palpebral fissures, receding chin, long fingers and toes, typical for chromosomal syndrome of partial trisomy 9q, were confirmed in a new case.
Abstract: The clinical features consisting mainly of enophthalmos, beaked nose, narrow palpebral fissures, receding chin, long fingers and toes, typical for chromsomal syndrome or partial trisomy 9q, were confirmed in a new case.
TL;DR: The haemopoietic tissue of mice was damaged by different cell‐cycle‐stage specific and cell‐ cycle‐stage non‐specific cytostatic agents and the proliferation rate among the surviving pluripotential stem cells, i.e. those cells forming colonies in spleens of lethally irradiated mice (CFUs), was investigated.
Abstract: The haemopoietic tissue of mice was damaged by different cell-cycle-stage specific and cell-cycle-stage non-specific cytostatic agents. The proliferation rate among the surviving pluripotential stem cells, i.e. those cells forming colonies in spleens of lethally irradiated mice (CFUs), was then investigated.
The results suggest that, at least in the CFUs population, the cells which synthesize DNA in the S phase of the cell cycle inhibit the entry of the non-proliferating G0 cells into cell cycle. This evidence was based on the ability of three cytostatic agents, hydroxyurea, cytosine arabinoside and methotrexate, which are toxic specifically to the S phase cells to increase the proliferation in the CFUs population. This increase was quite out of proportion to the small amount of damage they caused to the population. Colchicine, which kills cells in mitosis, and ionizing irradiation, damaging cells in all stages, proved to be much weaker stimulators of proliferation.
It has been suggested that a mechanism for the control of cellular proliferation might be based on the negative feedback in the cell cycle. In this feedback control loop the cells which are preparing for cell division in the S phase of the cell cycle inhibit the entry of the non-proliferating G0 cells into cell cycle.
TL;DR: The optimum silylation conditions have been found and the chromatographic behaviour of the trimethylsilyl derivatives formed has been studied and the results make possible the determination of biologically active substances in pharmaceuticals.
TL;DR: Human diploid BAMB cells with epitheloid morphology, which had been derived from amniotic fluid cells, were capable of supporting the replication of human cytomegalovirus (CMV), without prior treatment of the cells with halogenated pyrimidines.
Abstract: Human diploid BAMB cells with epitheloid morphology, which had been derived from amniotic fluid cells, were capable of supporting the replication of human cytomegalovirus (CMV), without prior treatment of the cells with halogenated pyrimidines. The growth of this virus in BAMB cells and in human diploid fibroblastoid (LEP) cells was compared in parallel tests. Virus replication was slower and less efficient in the former than in the latter system. The most characteristic morphological feature of the CMV-infected BAMB cells was the formation of multinucleated giant cells which frequently contained more than a hundred nuclei; such cells were not seen in LEP cultures. The development of ultrastructural changes was slower in BAMB cells than in LEP cells. The additional most marked differences concerned the place of viral envelopment and the production of cytoplasmic dense bodies. While in LEP cells most nucleocapsids were enveloped from the inner leaflet of the nuclear membrane, in the other system a great majority of the particles acquired their envelopes by budding into vacuoles. Cytoplasmic dense bodies were rare in infected LEP cells but very frequent in BAMB cells. Budding of these structures into vacuoles was also observed.
TL;DR: GC methods of analysis of 3H- and 14C-labelled compounds that have been published in the period from 1955 to mid-1976, together with important applications, are reviewed.
TL;DR: Using the technic of semipermeable membranes activities of these enzymes were demonstrated beside cells of the interstitial tissue in muscle fibers themselves as well, and acid phosphatase displayed the highest activity which appeared in many small dots dispersed in the fiber.
Abstract: The distribution of acid phosphatase, β-n-acetylglucosaminidase, β-glucuronidase, and acid β-galactosidase was studied in mm. extensor digitorum longus, soleus, and diaphragm of rats. Using the technic of semipermeable membranes activities of these enzymes were demonstrated beside cells of the interstitial tissue in muscle fibers themselves as well. Acid phosphatase displayed the highest activity which appeared in many small dots dispersed in the fiber. The activity of acid phosphatase was about 1.2 x higher in the m. soleus than in the m. extensor digitorum longus. In the latter muscle a somewhat higher activity was often found in muscle fibers displaying a higher staining for NADH tetrazolium reductase. The activity of β-n-acetylglucosaminidase was slightly lower, that of β-glucuronidase very weak but still discernible. The activity of acid β-galactosidase was not ascertained in the majority of fibers. The ratio of activities measured in an area of the same size in cells of the interstitial tissue and in muscle fibers amounted in average to 2.6: 1 in the case of acid phosphatase, 2.5:1 in the case of β-n-acetylglucosaminidase, 5.7: 1 in the case of β-glucuronidase, and 44.3:1 in the case of acid β-galactosidase. The importance of the histochemical technic in studies concerned with acid hydrolases in striated muscle fibers in normal and pathological conditions is pointed out.
TL;DR: The results showed that unexposed control mice excreted one-half of the administered As(III) in the form of As(V), and the authors discussed the possibility of participation of the biotransformation of As (III) to As (V) on arsenic tolerance.
Abstract: The paper deals with the excretion of As(III) and As(V) in the urine of mice exposed to a toxic concentration of As(III) (250 mg/1) in drinking water. After the exposures of 2, 6, and 8 days, the mice were given i.m. a solution of 74As(III) labeled sodium arsenite in a dose of 1.3 mg As(III)/kg b.w. and an activity of 3 μCi/l ml. After the sacrifice of the animal, the urine was drawn off directly from the bladder. The urine samples were subjected to separation of As(III) from As(V) by using a paper radiochromatography technique.
TL;DR: There was significant improvement in all registered parameters of avoidance learning and a significant increase of sexual acts was recorded in adult LC rats.
Abstract: Low protein (LP) or low calorie (LC) dietary regimens were applied in early postnatal life(1st-40th day of life) in male rats. After nutritional rehabilitation, open-field behavior in larger more illuminated boxes (HI, high intensity stimulus), and smaller, less illuminated boxes (HI, high intensity stimulus), and smaller, less illuminated boxes (HI, high intensity stimulus), and smaller, less illuminated boxes (HI, high intensity stimulus), dyadic interactions, and learning ability were investigated in these animals as adults (between the 200th to 300th day of life). LP malnutrition induced an increase of open-field activity with features of sterotypy both in LI and HI situations, an increase number of intersignal reactions during learning procedures without changes in other registered criteria of learning ability (latency, number of correct responses), and an increase of aggressive behavior in pair interaction. LC rats revealed only significant inhibition in LI--open-field activity and a slightly increased number in intersignal reactions during avoidance learning. With the aim of preventing previously described long-term deviations in early malnourished rats, some groups of animals with the above-mentioned early calorie or protein deficits were treated with pyrithioxine (Encephabol Merck) or pyridoxine in 10 doses of 40 mg/kg i.p. administered in the period when nutritional rehabilitation was carried out (between the 40th--50th day of life). The treatment with pyrithioxine reduced significantly behavioral disturbances in adult LP rats except the increase of intersignal reactions which was even potentiated. Pyridoxine was less effective but normalized the increase number of intersignal reactions both in LP and LC rats. The effect of pyridoxine of adult LC rats was interesting. There was significant improvement in all registered parameters of avoidance learning and a significant increase of sexual acts was recorded.