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  • Articles  (26)
  • Animals
  • Chemical Engineering
  • Rat
  • pharmacokinetics
  • phytoplankton
  • Springer  (26)
  • Geography  (19)
  • Technology  (7)
  • 1
    Electronic Resource
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    Springer
    Annals of biomedical engineering 28 (2000), S. 128-134 
    ISSN: 1573-9686
    Keywords: Hippocampus ; Vigilance states ; Paired-pulse ; Dentate gyrus ; Dentate granule cells ; Evoked response ; Rat ; In vivo studies ; Perforant path ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract This study examined the effect of normal development and vigilance state on the modulation of dentate granule cell activity in the freely moving rat at 15, 30, and 90 days of age across three vigilance states: quiet waking, slow-wave sleep, and rapid eye movement sleep. Using paired-pulse stimulation, the paired-pulse index (PPI) was obtained for the dentate evoked field potentials elicited by the stimulation of the medial perforant path. Although significant differences in PPI values were observed during development, no significant vigilance state related changes were obtained. Preweaning infant rats, i.e., 15-day old, exhibited significantly less early (interpulse intervals, IPI= 20–50 ms) and late (IPI = 300–1000 ms) inhibition, and less facilitation (IPI = 50–150 ms) when compared to the 90-day old adult rats during all three vigilance states. PPI values obtained from the 30-day old group fell intermediate between the 15- and 90-day old animals. These changes in PPI values provide a quantitative measure of changes in the modulation of dentate granule cell excitability during normal maturation. They can now can be used to evaluate the impact of various insults, such as prenatal protein malnutrition or neonatal stress, on hippocampal development. © 2000 Biomedical Engineering Society. PAC00: 8717Nn, 8719La, 8719Nn
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  • 2
    ISSN: 1573-9686
    Keywords: Heart ; Left ventricle ; LV contractility ; ESPVR ; Pig ; Rat ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The end systolic pressure–volume relation (ESPVR) has been shown to be a relatively load independent measure of left ventricular (LV) contractility. Recently, several single-beat ESPVR computation methods have been developed, enabling the quantification of LV contractility without the need to alter vascular loading conditions on the heart. Using a single-beat ESPVR method, which has been validated previously in humans and assumes that normalized elastance is constant between individuals of a species, we studied the effects of myocardial infarction on LV contractility in two species, the rat and the pig. In our studies, LV pressure was acquired invasively and LV volume determined noninvasively with magnetic resonance imaging, at one week postinfarction in pigs and at 12 weeks postinfarction in rats. Normalized systolic elastance curves in both animal species were not statistically different from that of humans. Also, the slope of the ESPVR $$\left( {E_{es} } \right)$$ decreased significantly following infarction in both species, while the volume-axis intercept $$\left( {V_0 } \right)$$ was unaffected. These results indicate that a single-beat ESPVR method can be used to measure the inotropic response of the heart to myocardial infarction, and that the basis for this method (i.e., constant normalized elastance) is applicable to a variety of mammalian species. © 2000 Biomedical Engineering Society. PAC00: 8719Uv, 8761Lh, 8719Hh, 8719Rr, 8719Ff
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  • 3
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    Annals of biomedical engineering 28 (2000), S. 1101-1115 
    ISSN: 1573-9686
    Keywords: Time–frequency analysis ; Coherence ; Cross correlation ; Nonstationary persistent signals ; Central pattern generator ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract We present a novel time-varying phase spectrum (TVPS) method to quantify the dynamics of coevolution of two persistent nonstationary coupled signals. Based on the TVPS, an instantaneous intersignal phase shift is defined within the primary frequency range in which the two signals are highly correlated. The TVPS is estimated using a fixed-window method or an adaptive-window method. In the latter method, the window length changes dynamically and automatically as a function of change in frequency of the signals. The effects of altering window types and lengths on the accuracy of the estimation of the primary phase shift is assessed by analyzing synthesized linear chirp signals with decaying amplitude and constant relative phase shift or decaying amplitude and changing relative phase shifts. The methods developed are also used for determining the evolution of the primary phase shift among ventral root activities during fictive locomotion in an in vitro rat spinal cord preparation. The analyses indicate that the TVPS method in conjunction with the determination of the primary frequency range, allows determination of both the evolution of the coupling strength and the evolution of the phase shift between two persistent nonstationary rhythmic signals in the joint time–frequency domain. An adaptive window reduces the estimation bias and the estimation variability. © 2000 Biomedical Engineering Society. PAC00: 0230-f, 8780Tq
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  • 4
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    International journal of salt lake research 8 (1999), S. 7-18 
    ISSN: 1573-8590
    Keywords: coastal waters ; production ; decomposition ; phytoplankton ; Aral Sea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The species composition, population density, biomass and main functional characteristics of the phytoplankton community near Cape Tastubec, northern Aral Sea in September 1993 were investigated. The characteristics investigated were daily primary production, decomposition, and photosynthetic intensity. The data indicate that certain changes in the structure and function of the phytoplankton have recently taken place.
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  • 5
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    International journal of salt lake research 8 (1999), S. 7-18 
    ISSN: 1573-8590
    Keywords: coastal waters ; production ; decomposition ; phytoplankton ; Aral Sea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The species composition, population density, biomass and main functional characteristics of the phytoplankton community near Cape Tastubec, northern Aral Sea in September 1993 were investigated. The characteristics investigated were daily primary production, decomposition, and photosynthetic intensity. The data indicate that certain changes in the structure and function of the phytoplankton have recently taken place.
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  • 6
    ISSN: 1573-8590
    Keywords: bacterioplankton ; blue-green algae ; meromictic salt lake ; phytoplankton ; vertical structure ; zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The specific composition, vertical distribution and daily migration of plankton in a meromictic salt lake, Lake Shira, have been investigated. The main structural components of the ecosystem are bacteria, algae and crustaceans. Since the late 1970s, blue-green algae are reported as dominant. Nowadays the phytoplankton is dominated by Lyngbya contorta, Microcystis ichtyoblabe (Cyanophyta), Cyclotella tuberculata (Bacillariophyta) and Dictyosphaerium tetrachotomum (Chlorophyta). The zooplankton of Lake Shira comprises Arctodiaptomus salinus (Copepoda), Brachionus plicatilis and Hexarthra oxiuris (Rotatoria). Investigation revealed a stratified vertical distribution of all dominant species except Cyclotella with a maximum at a depth of 12--15 m during the summer growth period. Zooplanktons differ in the pattern of distribution and daily migration, but most zooplankton tend to concentrate near the surface. The possible reasons for the vertical distribution of the plankton are discussed.
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  • 7
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    International journal of salt lake research 8 (1999), S. 211-232 
    ISSN: 1573-8590
    Keywords: bacterioplankton ; blue-green algae ; meromictic salt lake ; phytoplankton ; vertical structure ; zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The specific composition, vertical distribution and daily migration of plankton in a meromictic salt lake, Lake Shira, have been investigated. The main structural components of the ecosystem are bacteria, algae and crustaceans. Since the late 1970s, blue-green algae are reported as dominant. Nowadays the phytoplankton is dominated byLyngbya contorta, Microcystis ichtyoblabe (Cyanophyta),Cyclotella tuberculata (Bacillariophyta) andDictyosphaerium tetrachotomum (Chlorophyta). The zooplankton of Lake Shira comprisesArctodiaptomus salinus (Copepoda),Brachionus plicatilis andHexarthra oxiuris (Rotatoria). Investigation revealed a stratified vertical distribution of all dominant species exceptCyclotella with a maximum at a depth of 12–15 m during the summer growth period. Zooplanktons differ in the pattern of distribution and daily migration, but most zooplankton tend to concentrate near the surface. The possible reasons for the vertical distribution of the plankton are discussed.
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  • 8
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    International journal of biometeorology 41 (1998), S. 101-104 
    ISSN: 1432-1254
    Keywords: Key words Space flight ; Rat ; Plantaris muscle ; GLUT-4 ; Citrate synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract  The effects of 14 days of space flight on the glucose transporter protein (GLUT-4) were studied in the plantaris muscle of growing 9-week-old, male Sprague Dawley rats. The rats were randomly separated into five groups: pre-flight vivarium ground controls (PF-VC) sacrificed approximately 2 h after launch; flight groups sacrificed either approximately 5 h (F-R0) or 9 days (F-R9) after the return from space; and synchronous ground controls (SC-R0 and SC-R9) sacrificed at the same time as the respective flight groups. The flight groups F-R0 and F-R9 were exposed to micro-gravity for 14 days in the Spacelab module located in the cargo bay of the shuttle transport system – 58 of the manned Space Shuttle for the NASA mission named ”Spacelab Life Sciences 2”. Body weight and plantaris weight of SC-R0 and F-R0 were significantly higher than those of PF-VC. Neither body weight nor plantaris muscle weight in either group had changed 9 days after the return from space. As a result, body weight and plantaris muscle weight did not differ between the flight and synchronous control groups at any of the time points investigated. The GLUT-4 content (cpm/µg membrane protein) in the plantaris muscle did not show any significant change in response to 14 days of space flight or 9 days after return. Similarly, citrate synthase activity did not change during the course of the space flight or the recovery period. These results suggest that 14 days of space flight does not affect muscle mass or GLUT-4 content of the fast-twitch plantaris muscle in the rat.
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  • 9
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    International journal of salt lake research 7 (1998), S. 13-24 
    ISSN: 1573-8590
    Keywords: Artemia ; bacteria ; benthic microbial communities ; ecology ; feeding biology ; grazing ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Primary production in Lake Hayward, Western Australia, is dominated by benthic microbial communities, with limited planktonic primary production. This study investigated the question of how Artemia, commonly regarded as simple, obligate, non-selective filter feeders, were able to survive in this system. Bacteria (heterotrophic and autotrophic, filamentous and unicellular) were the major components in the diet of the Artemia in Lake Hayward. These bacteria were derived from bacterial aggregates in the water column and also from benthic mat material (both still attached to the substrate and from pieces floating in the water column). Benthic diatoms were a substantial dietary component of animals living in the unstratified shallow regions. Photosynthetic eukaryotic nanoplankton comprised a minor component of the diet of this Artemia population. Gut contents of a large number of animals and the results of a simple laboratory test indicated that these animals utilise substrate-bound food resources. The results of the present study raises the question of the ecological significance of surface grazing by brine shrimps in other shallow, benthos dominated saline systems.
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  • 10
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    International journal of salt lake research 7 (1998), S. 45-80 
    ISSN: 1573-8590
    Keywords: aquatic flora and fauna ; circum-lacustrine vegetation ; cormophytes ; microphytobenthos ; pelogenous/non-pelogenous lakes ; phytoplankton ; Romania ; saline lakes ; zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract An inventory of the aquatic and circum-lacustrine flora and aquatic fauna of 23 karst- and anthroposaline lakes formed on Miocene rock salt bodies in Romania was undertaken. Simultaneous field determinations of water and sediment pH, total dissolved solids, Secchi transparency and lake maximum depth were also made. Environmental conditions for phytoplankton, microphytobenthos, macrophyte and cormophyte species were defined. Relations between the numbers of plankton, microbenthos, macrophyte and cormophyte species differentiated pelogenous (usually, therapeutic) and non-pelogenous lakes. High densities and occurrence frequencies characterized the most representative species. For three of these species, Amphora veneta, Artemia sp. and Potamogeton pectinatus, ecological conditions were noted. In the circum-lacustrine vegetation, glycophytes were more important than halophytes.
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  • 11
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    International journal of salt lake research 7 (1998), S. 13-24 
    ISSN: 1573-8590
    Keywords: Artemia ; bacteria ; benthic microbial communities ; ecology ; feeding biology ; grazing ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Primary production in Lake Hayward, Western Australia, is dominated by benthic microbial communities, with limited planktonic primary production. This study investigated the question of howArtemia, commonly regarded as simple, obligate, non-selective filter feeders, were able to survive in this system. Bacteria (heterotrophic and autotrophic, filamentous and unicellular) were the major components in the diet of theArtemia in Lake Hayward. These bacteria were derived from bacterial aggregates in the water column and also from benthic mat material (both still attached to the substrate and from pieces floating in the water column). Benthic diatoms were a substantial dietary component of animals living in the unstratified shallow regions. Photosynthetic eukaryotic nanoplankton comprised a minor component of the diet of thisArtemia population. Gut contents of a large number of animals and the results of a simple laboratory test indicated that these animals utilise substrate-bound food resources. The results of the present study raises the question of the ecological significance of surface grazing by brine shrimps in other shallow, benthos dominated saline systems.
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  • 12
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    International journal of salt lake research 7 (1998), S. 45-80 
    ISSN: 1573-8590
    Keywords: aquatic flora and fauna ; circum-lacustrine vegetation ; cormophytes ; microphytobenthos ; pelogenous/non-pelogenous lakes ; phytoplankton ; Romania ; saline lakes ; zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract An inventory of the aquatic and circum-lacustrine flora and aquatic fauna of 23 karst- and anthroposaline lakes formed on Miocene rock salt bodies in Romania was undertaken. Simultaneous field determinations of water and sediment pH, total dissolved solids, Secchi transparency and lake maximum depth were also made. Environmental conditions for phytoplankton, microphytobenthos, macrophyte and cormophyte species were defined. Relations between the numbers of plankton, microbenthos, macrophyte and cormophyte species differentiated pelogenous (usually, therapeutic) and non-pelogenous lakes. High densities and occurrence frequencies characterized the most representative species. For three of these species,Amphora veneta, Artemia sp. andPotamogeton pectinatus, ecological conditions were noted. In the circum-lacustrine vegetation, glycophytes were more important than halophytes.
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  • 13
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    Annals of biomedical engineering 26 (1998), S. 526-533 
    ISSN: 1573-9686
    Keywords: Rat ; Artery: femoral ; Arterial diameter ; Vasomotion ; Shear stress ; Flow-dependent constriction ; Step flow ; Oscillating flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The effects of flow and flow changes on arterial diameter were investigated in vitro on isolated rat femoral arteries. Segments of femoral arteries were excised, mounted on microcannulas, and perfused with Tyrode's solution (37°C). Perfusion pressure was kept constant at 90 mm Hg. The mean external diameter after equilibration at a transmural pressure of 90 mm Hg was 720 ± 50 μ m (n=12). Vessels were then constricted with norepinephrine (1 μM in the superfusion solution) to 77% ± 13% of the resting diameter; acetylcholine was used to check endothelial function. The external diameter was measured continuously using video microscopy. The arteries were subjected to two different types of flow variations: (a) step changes in flow (increase and decrease, n=6) and (b) low-frequency sinusoidal flow variations (frequencies ranging from 0.002 to 0.1 Hz, n=11). Flow ranged from 0 to 800 μ l/min (shear stress ranging from 0 to 15 dyn/cm2). All measured vessels constricted as flow increased. Flow steps induced exponential-like contractions (flow increase) or relaxations (flow decrease) with mean characteristic time constants 31 ± 4 and 22 ± 2 s, respectively. Sinusoidal flow oscillations induced sinusoidal diameter oscillations with a time delay. An increase in the frequency of the flow led to a decrease of both the amplitude of the flow-induced diameter oscillations and the phase shift between flow and diameter. The dynamic diameter response to flow changes could be characterized by a first-order low-pass filter with a time constant of 22 s. © 1998 Biomedical Engineering Society. PAC98: 8745Hw
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  • 14
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    Annals of biomedical engineering 26 (1998), S. 28-36 
    ISSN: 1573-9686
    Keywords: Mathematical model ; Tissue factor ; Wall shear rate ; FXa generation ; TF:FVIIa ; Rat ; Vascular ; Smooth muscle ; Factor X ; Coagulation ; Clot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A computational model was developed to investigate the contribution of classical mass transport and flow parameters to factor X (FX) activation by the tissue factor–factor VIIa complex (TF:VIIa) on one wall of a parallel-plate flow chamber. The computational results were compared to previously obtained experimental data for the generation of factor Xa (FXa) by TF:VIIa on the surface of cultured rat vascular smooth muscle cells. In this study, the complete steady-state convection–diffusion equation was solved using the commercial software package, FLUENT (Fluent Inc., Lebanon, New Hampshire). A user-defined subroutine interfaced with FLUENT implemented the surface reaction which was modeled using classical Michaelis–Menten reaction kinetics. The numerical solutions were obtained for 12 cases which used combinations of three wall shear rates and four reaction rates. The numerically obtained fluxes for a given reaction rate displayed a wall shear rate dependence which ranged from classical kinetic reaction control (no dependence) to pure diffusional control (maximum dependence). The experimental data, however, were not represented by numerical data generated using a single reaction rate. The three numerically obtained fluxes which corresponded most closely to the experimental fluxes were determined using three different V max values. This finding supports the hypothesis that there may be a direct effect of flow on the TF:VIIa complex or the cell membrane. © 1998 Biomedical Engineering Society. PAC98: 8722-q, 8710+e
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  • 15
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    International journal of salt lake research 6 (1997), S. 217-231 
    ISSN: 1573-8590
    Keywords: saline water-bodies ; phytoplankton ; biomass ; production ; chlorophyll ; P/B ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Phytoplankton and its production in water-bodies of the lower Amu Dar'yawere investigated in 1984–1989. The structure and functional nature ofthe phytoplankton in the water-bodies studied were analogous to those ofthe littoral zone of eutrophic lakes, considering hydrological andhydrochemical conditions. The very high average annual P/B ratios(453–582) are considered as regional features, namely high lightintensity and prolonged light period, the salinity usual for salinewaters under anthropogenic influence, the frequent and discrete incomeof nutrients in drainage water and from sediments.
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  • 16
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    International journal of salt lake research 6 (1997), S. 353-371 
    ISSN: 1573-8590
    Keywords: hypersaline lakes ; multivariate methods ; phytoplankton ; seasonality ; shallow lakes ; zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Honda saline lake is located in an endorheic basin in the south of Spain. The lake is very shallow, with frequent seasonal drought and a high degree of unpredictability. It was sampled monthly during a relatively dry year (1994–1995, 5 months permanence). To establish a relationship between environmental variables (temperature, depth, salinity and conductivity), variables related to biological activity (organic matter, total solids suspension, and pH) and the planktonic community in the sampled months, various uni- and multivariate statistical methods were carried out. Dunaliella salina, D. viridis, and ciliates sp. 2 is the principal species group used to average out the dissimilarity between the samples. Multivariate analysis showed that salinity (as TDS), conductivity and pH made major and significant contributions to the explanation of the variance in the sample data.
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  • 17
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    International journal of salt lake research 6 (1997), S. 353-371 
    ISSN: 1573-8590
    Keywords: hypersaline lakes ; multivariate methods ; phytoplankton ; seasonality ; shallow lakes ; zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Honda saline lake is located in an endorheic basin in the south of Spain. The lake is very shallow, with frequent seasonal drought and a high degree of unpredictability. It was sampled monthly during a relatively dry year (1994–1995, 5 months permanence). To establish a relationship between environmental variables (temperature, depth, salinity and conductivity), variables related to biological activity (organic matter, total solids suspension, and pH) and the planktonic community in the sampled months, various uni-and miltivariate statistical methods were carried out.Dunaliella salina, D. viridis, and ciliates sp. 2 is the principal species group used to average out the dissimilarity between the samples. Muttivariate analysis showed that salinity (as TDS), conductivity and pH made major and significant contributions to the explanation of the variance in the sample data.
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  • 18
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    International journal of salt lake research 6 (1997), S. 5-16 
    ISSN: 1573-8590
    Keywords: Aral Sea ; Central Asia ; EC (electrical conductivity) ; Lake Balkhash ; Lake Kamyslybas ; phytoplankton ; saline lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The Aral Sea, Lake Balkhash, and Lake Kamyslybas are closed lakes inCentral Asia. They range from oligosaline to metasaline. The salinity of theAral Sea has increased by more than 30 g L−1 sincewidespread irrigation began in its catchment area. Few studies of thephytoplankton have been conducted on these lakes since extensive irrigationstarted. The investigation reported here compares the flora of phytoplanktonin these saline lakes. In the Small Aral Sea, phytoplankton densitygradually decreased with increasing electrical conductivity (EC) (∼salinity), but there was no such relation in Lake Balkhash and LakeKamyslybas. In the Aral Sea, Dinophyceae and Bacillariophyceae werefrequently observed in most areas of high EC value, and Cyanophyceae weremost conspicuous in the area of medium and lower EC values. In LakeBalkhash, Cyanophyceae were most conspicuous, but Chlorophyceae were alsonoticeable. Most Cyanophyceae in Aral Sea formed filaments with heterocysts.The distinct characteristic of the phytoplankton of the Lake Balkhash wasthat all dominant species form colonies covered with a gelatinous film.Siliceousplankton diversity gradually decreased with increasing EC values inthe Aral Sea and Lake Balkhash.
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  • 19
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    International journal of salt lake research 6 (1997), S. 217-231 
    ISSN: 1573-8590
    Keywords: saline water-bodies ; phytoplankton ; biomass ; production ; chlorophyll ; P/B ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Phytoplankton and its production in water-bodies of the lower Amu Dar'ya were investigated in 1984–1989. The structure and functional nature of the phytoplankton in the water-bodies studied were analogous to those of the littoral zone of eutrophic lakes, considering hydrological and hydrochemical conditions. The very high average annual P/B ratios (453–582) are considered as regional features, namely high light intensity and prolonged light period, the salinity usual for saline waters under anthropogenic influence, the frequent and discrete income of nutrients in drainage water and from sediments.
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  • 20
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    International journal of salt lake research 6 (1997), S. 5-16 
    ISSN: 1573-8590
    Keywords: Aral Sea ; Central Asia ; EC (electrical conductivity) ; Lake Balkhash ; Lake Kamyslybas ; phytoplankton ; saline lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The Aral Sea, Lake Balkhash, and Lake Kamyslybas are closed lakes in Central Asia. They range from oligosaline to metasaline. The salinity of the Aral Sea has increased by more than 30 g L−1 since widespread irrigation began in its catchment area. Few studies of the phytoplankton have been conducted on these lakes since extensive irrigation started. The investigation reported here compares the flora of phytoplankton in these saline lakes. In the Small Aral Sea, phytoplankton density gradually decreased with increasing electrical conductivity (EC) (∼ salinity), but there was no such relation in Lake Balkhash and Lake Kamyslybas. In the Aral Sea, Dinophyceae and Bacillariophyceae were frequently observed in most areas of high EC value, and Cyanophyceae were most conspicuous in the area of medium and lower EC values. In Lake Balkhash, Cyanophyceae were most conspicuous, but Chlorophyceae were also noticeable. Most Cyanophyceae in Aral Sea formed filaments with heterocysts. The distinct characteristic of the phytoplankton of the Lake Balkhash was that all dominant species form colonies covered with a gelatinous film. Siliceousplankton diversity gradually decreased with increasing EC values in the Aral Sea and Lake Balkhash.
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  • 21
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    International journal of salt lake research 5 (1996), S. 253-260 
    ISSN: 1573-8590
    Keywords: saline lakes ; chlorophyll ; size-fractions ; phytoplankton ; shallow lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract The size-fractionated distribution of chlorophylla was studied in a temporary hypersaline lake situated in the south of Spain during an annual hydrological cycle characterized by low levels of rainfall. The contribution of each size class to the total chlorophylla concentration indicates that ultraplankton (size class 〈5μm) was the most important fraction of phytoplankton biomass during this year.
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  • 22
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    Lasers in medical science 10 (1995), S. 273-277 
    ISSN: 1435-604X
    Keywords: Ga-As laser ; Myelinated fibre regression ; Rat ; Sciatic nerve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The purpose of the present study was to examine the regeneration of myelinated axons under the effect of laser irradiation at various wavelengths and energy densities. Laser irradiation at 890 nm with an energy dose of 0.33 J cm−2 as well as He-Ne laser irradiation failed to change the number of regenerating myelinated axons in distal nerve stumps on the 30th day after cutting the nerve. An increase of dose delivered to the skin to 9.33 J cm−2 resulted in a 49% decrease in the number of myelinated axons. A 24% suppression of nerve regeneration was also registered using 1220 nm wavelength laser (dose 0.98 J cm−2). This phenomenon is likely to be attributed to the stimulating effect of laser irradiation of the near-infra-red range on proliferation of fibroblasts and scar formation. 1220 nm of 7.2 J cm−2 dose effected neither the growth nor the myelinization of axons in distal nerve stumps on the 20th day following nerve damage.
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  • 23
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    International journal of biometeorology 34 (1990), S. 24-27 
    ISSN: 1432-1254
    Keywords: Cold-induced thermogenesis ; Peripheral nervous system ; Respiratory quotient ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Cold-exposed rats show a reduction in the respiratory quotient which is indicative of a relative shift from carbohydrates to lipids as substrates for oxidative metabolism. In the present study, the effects of food deprivation and cold exposure on the respiratory quotient were observed. In addition, the involvement of the three main branches of the peripheral nervous system (sympathetic, parasympathetic, and somatic) was investigated by means of synaptic blockade with propranolol, atropine, and quinine, respectively. Both propranolol and quinine blocked the cold-induced decrease in respiratory quotient and increase in heat production, whereas atropine had only minor and very brief effects. It is concluded that both the sympathetic and somatic branches are involved in the metabolic changes associated with cold-induced thermogenesis and that the increase in metabolic heat production involves a shift from carbohydrate to lipid utilization irrespective of which of the two branches is activated.
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  • 24
    ISSN: 1435-604X
    Keywords: Brain tumour ; Rat ; Detection ; Fluorescence ; Laser ; Haematoporphyrin derivative
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Laser-induced fluorescence has been used for the identification of brain tumours in rats, which have been previously given tumour-seeking haematoporphyrin derivative. A pulsed nitrogen laser (λ=337 nm) was used in conjunction with an optical multichannel analyzer. For both inoculated RG-2 and TCVC rat-brain-tumour models, the blue autofluorescence was strongly reduced in the tumour compared with normal brain tissue, and at the same time the characteristic red-drug signal increased. The contrast between tumour and normal tissue was strongly enhanced by forming the ratio between the two signals. Implications for possible improvement of tumour delineation in brain tumour surgery are discussed.
    Type of Medium: Electronic Resource
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  • 25
    Electronic Resource
    Electronic Resource
    Springer
    International journal of biometeorology 32 (1988), S. 17-20 
    ISSN: 1432-1254
    Keywords: Epilepsy ; Electromagnetic fields ; Rat ; Audiogenic seizure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract In order to study the possible association between epileptic seizures and natural electromagnetic fields, 32 female audiogenic seizure (AGS)-susceptible rats were exposed to simulated 10 kHz and 28 kHz atmospherics and to a sinusoidally oscillating magnetic field with a frequency of 100 Hz and field strength of 1 A/m. After the electromagnetic exposure, seizures were induced in the rats with a sound stimulus. The severity of the seizure was determined on an ordinal scale, the audiogenic response score (ARS). The time from the beginning of the sound stimulus to the onset of the seizure (seizure latency) and the duration of the convulsion was measured. No differences from the control experiments were found in the experiments with simulated atmospherics, but the 100 Hz magnetic field increased the seizure latency by about 13% (P〈0.02). The results do not support the hypothesis that natural atmospheric electromagnetic signals could affect the onset of epileptic seizures, but they suggest that AGS-susceptible rats may be a useful model for studying the biological effects of electromagnetic fields.
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  • 26
    ISSN: 1432-1254
    Keywords: Atmospherics ; Carrageenan inflammation ; Rat ; Susceptibility ; Correlations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Between the mean daily density of 28 kHz atmospherics and the onset of epileptic fits there is a highly significant correlation coefficient (r) of 0.30; there is a negative coefficient of −0.20 between the fits and the mean daily density of 10 kHz atmospherics. The onset of heart infarction is correlated with 28 kHz atmospherics (r=0.15). Furthermore, we have discovered that sudden deafness is also correlated with certain configurations of atmospherics. In this paper we report the following correlation coefficients between the inflammatory reaction of rats to a carrageenan injection (rci) into a hind paw and the mean daily pulse rate of atmospherics of the same day:r=0.49 for the 8 kHz atmospherics (P〈0.02) andr=0.44 for the 10 kHz atmospherics (P〈0.04). The correlations between rci reaction and other atmospherics (12 and 28 kHz) are smaller and not significant. By the method of multiple linear regression we found a multipleR=0.54 between rci reaction and the 8 and 10 kHz atmospherics (the regression function for the rci reaction is 0.15+0.004×8 kHz+0.002×10 kHz,P〈0.05).
    Type of Medium: Electronic Resource
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