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31.
Takeshi Minami Masayo Ichii Yoshiyuki Tohno Setsuko Tohno Masako Utsumi Masa-oki Yamada Yuko Okazaki 《Biological trace element research》1996,55(1-2):199-205
The purpose of this study was to determine the extent of aluminum (Al) accumulation in the human aorta and cerebral arteries.
The Al contents in the aortae and in the cerebral arteries from 23 human subjects was determined by inductively coupled plasma
atomic emission spectrophotometry (ICP-AES). The subjects' age range was 45–99-yr-old; 15 of the subjects were males and 8
were females. Al was detected in twelve aortae and in six cerebral arteries, when the entire specimen was analyzed. Two specimens
where Al was found in the cerebral arteries contained no Al in the aorta. No relationship to the subject's sex was found.
When related to age, two groups were established. Group L (45–75 yr old) and group H (>75 yr old), which exhibited aortal
Al concentrations of 33.3 and 72.7%, respectively. When the aortic wall was dissected into the tunica intima, media, and adventitia,
Al was found mainly in the tunica media. In the aorta, significant relationships were found between Al and phosphorus (P)
levels (r=0.801,p<0.01) and between Al and calcium (Ca) (r=0.661,p<0.05). We have concluded that Al accumulation is age-dependent and that it occurs both in the aorta and in the cerebral artery.
In the aorta, accumulation occurs mainly in the tunica media. Both P and Ca appear to enhance aortal Al accumulation. 相似文献
32.
Douglas A. Burns 《Biogeochemistry》1996,32(3):339-362
Calcite treatment of chronically acidic lakes has improved fish habitat, but the effects on downstream water quality have not previously been examined. In this study, the spatial and temporal effects of watershed CaCO3 treatment on the chemistry of a lake outlet stream in the Adirondack Mountains of New York were examined. Before CaCO3 treatment, the stream was chronically acidic. During spring snowmelt before treatment, pH and acid-neutralizing capacity (ANC) in the outlet stream declined, and NO
3
–
and inorganic monomeric aluminum (AlIM) concentrations increased sharply. During that summer, SO
4
–
and NO
3
–
concentrations decreased downstream, and dissolved organic carbon (DOC) concentrations and ANC increased, in association with the seasonal increase in decomposition of organic matter and the attendant SO
4
–
-reduction process. A charge-balance ANC calculation closely matched measured downstream changes in ANC in the summer and indicated that SO
4
–
reduction was the major process contributing to summer increases in ANC. Increases in Ca2+ concentration and ANC began immediately after CaCO3 application, and within 3 months, exceeded their pretreatment values by more than 130 eq/L. Within 2 months after treatment, downstream decreases in Ca2+ concentration, ANC, and pH, were noted. Stream mass balances between the lake and the sampling site 1.5 km downstream revealed that the transport of all chemical constituents was dominated by conservative mixing with tributaries and ground water; however, non-conservative processes resulted in significant Ca2+ losses during the 13-month period after CaCO3 treatment. Comparison of substrate samples from the buffered outlet stream with those from its untreated tributaries showed that the percentage of cation-exchange sites occupied by Ca2+ as well as non-exchangeable Ca, were higher in the outlet-stream substrate than in tributary-stream substrate. Mass-balance data for Ca2+ H+, AlIM, and DOC revealed net downstream losses of these constituents and indicated that a reasonable set of hypothesized reactions involving AlIM, HCO
3
–
, Ca2+, SO
4
–
NO
3
–
, and DOC could have caused the measured changes in stream acid/base chemistry. In the summer, the sharp decrease in ANC continued despite significant downstream decreases in SO4
2– concentrations. After CaCO3 treatment, reduction of SO
4
–
was only a minor contributor to ANC changes relative to those caused by Ca2+ dilution from acidic tributaries and acidic ground water, and Ca2+ interactions with stream substrate. 相似文献
33.
Susan H. McKiernan Murray K. Clayton Barry D. Bavister 《Molecular reproduction and development》1995,42(2):188-199
Hamster embryo development to the blastocyst stage in vitro can be modulated by amino acids. This series of experiments employed both empirically and statistically designed approaches to elucidate which of 20 amino acids inhibit or stimulate development and to devise a complement of amino acids that best supports in vitro development of hamster 1-cell embryos. Development and/or mean cell number were significantly inhibited by the presence of leucine, tyrosine, valine, isoleucine, phenylalanine, arginine, methionine, or cysteine (at 0.5 mM) and isoleucine, phenylalanine, or tryptophan (at 0.05 mM). Three amino acids—glutamine, taurine, and glycine—were stimulatory and in combination improved development; the culture medium containing these amino acids was designated Hamster Embryo Culture Medium-5. Moreover, addition of another eight amino acids—asparagine, aspartic acid, serine, glutamic acid, histidine, lysine, proline and cysteine (medium designated HECM-6)—had a significant stimulatory effect on development over previously formulated culture media for hamster embryos. These results demonstrated that amino acids, alone and in combination, can markedly stimulate or inhibit hamster embryo development in vitro up to the blastocyst stage. Embryo transfer experiments showed that HECM-5 and ?6 (chemically defined, protein-free culture media) supported normal preimplantation embryo development in vitro. This study also indicates that empirically designed embryo culture media formulations can be as effective as those obtained by application of statistical methodologies. © 1995 wiley-Liss, Inc. 相似文献
34.
Antonietta Bernardo Mario Patrizio Giulio Levi Tamara C. Petrucci 《Cellular and molecular neurobiology》1994,14(2):159-173
Summary 1. We have previously shown that acute exposure to the HIV coat protein gp120 interferes with the -adrenergic regulation of astroglial and microglial cells (Leviet al., 1993). In particular, exposure to 100 pM gp120 for 30 min depressed the phosphorylation of vimentin and glial fibrillary acidic protein (GFAP) induced by isoproterenol in rat cortical astrocyte cultures. In the present study we have extended our analysis on the effects of gp120 on astroglial protein phosphorylation.2. We found that chronic (3-day) treatment of the cells with 100 pM gp120 before exposure to isoproterenol was substantially more effective than acute treatment in depressing the stimulatory effect of the -adrenergic agonist on vimentin and GFAP phosphorylation.3. Even after chronic treatment with gp120, no differences were found in the levels and solubility of these proteins.4. Besides stimulating the phosphorylation of intermediate filament proteins, isoproterenol inhibited the incorporation of32P into a soluble acidic protein of 80,000M
r
, which was only minimally present in Triton X-100-insoluble extracts.5. Treatment of astrocytes with a phorbol ester or exposure to3H-myristic acid indicated that the acidic 80,000M
r
protein is a substrate for protein kinase C (PKC) and is myristoylated, thus suggesting that it is related to the MARCKS family of PKC substrates.6. Acute (30-min) treatment with 100 pM gp120 totally prevented the inhibitory effect of isoproterenol on the phorphorylation of the 80,000M
r
MARCKS-like protein.7. Our studies corroborate the hypothesis that viral components may contribute to the neuropathological changes observed in AIDS through the alteration of signal transduction systems in glial cells. 相似文献
35.
Transport of bacteria in porous media: II. A model for convective Transport and growth 总被引:1,自引:0,他引:1
A model is presented for the coupled processes of bacterial growth and convective transport of bacteria has been modeled using a fractional flow approach. The various mechanisms of bacteria retention can be incorporated into the model through selection of an appropriate shape of the fractional flow curve. Permeability reduction due to pore plugging by bacteria was simulated using the effective medium theory. In porous media, the rates of transport and growth of bacteria, the generation of metabolic products, and the consumption of nutrients are strongly coupled processes. Consequently, the set of governing conservation equations form a set of coupled, nonlinear partial differential equations that were solved numerically. Reasonably good agreement between the model and experimental data has been obtained indicating that the physical processes incorporated in the model are adequate. The model has been used to predict the in situ transport and growth of bacteria, nutrient consumption, and metabolite production. It can be particularly useful in simulating laboratory experiments and in scaling microbial-enhanced oil recovery or bioremediation processes to the field. (c) 1994 John Wiley & Sons, Inc. 相似文献
36.
The influence of short draft tubes covered by perforated plates on gas-liquid mass transfer was examined in external-loop airlift bioreactors. The volumetric mass transfer coefficients in a model external-loop airlift bioreactor were measured with water and non-Newtonian media. It was found that introduction of draft tubes covered with perforated plates in the riser significantly improved the mass transfer rate, particularly in higher viscous non-Newtonian fermentation media. The enhancement of mass transfer rate might be due mainly to an increase in bubble coalescence and redispersion. (c) 1994 John Wiley & Sons, Inc. 相似文献
37.
38.
Chronic Administration of Lithium Chloride Increases Immunodetectable Glial Fibrillary Acidic Protein in the Rat Hippocampus 总被引:3,自引:0,他引:3
Abstract: We studied the effect of treating rats with lithium salts on the content and in vitro phosphorylation rate of the astrocyte cell marker, glial fibrillary acidic protein (GFAP), in brain slices. Rats were fed a diet incorporating lithium chloride until the concentration of Li+ in serum reached 0.6–1.2 m M , a range similar to that achieved in clinical practice. Hippocampal tissue was analyzed for immunoreactive GFAP by a dot assay, and slices of hippocampus and caudate nucleus were labeled with [32 P]-phosphate to determine the in vitro rate of phosphorylation of GFAP. Compared with controls, the level of immunoreactive GFAP in the hippocampus from lithium-treated rats was increased 34%, and GFAP in hippocampal slices incorporated 39% more 32 P. This effect of lithium was apparently not confined to the hippocampus because the in vitro rate of phosphorylation of GFAP in caudate slices was also increased in the treated rats. 相似文献
39.