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71.
Age-related changes of elements and relationships among elements in the common bile and pancreatic ducts 总被引:1,自引:0,他引:1
Tohno Y Tohno S Yamada MO Azuma C Moriwake Y Minami T Maruyama H Omura T 《Biological trace element research》2004,101(1):47-60
To elucidate compositional changes of the common bile and main pancreatic ducts with aging, the authors investigated age-related
changes of element contents in the common bile and pancreatic ducts by inductively coupled plasma-atomic emission spectrometry.
After ordinary dissection by medical students was finished, the common bile ducts and main pancreatic ducts (pancreatic ducts)
were resected and the element contents were determined. The Mg content increased significantly only in the pancreatic duct
with aging, but the other element contents did not change significantly in both the common bile and pancreatic ducts with
aging. Regarding the relationship among the elements, significant direct correlations were found among the contents of Ca,
P, S, and Mg in the common bile ducts, with some exceptions between P and either S or Mg contents. In the pancreatic ducts,
significant direct correlations were found between S and Mg contents and between P and Na contents. The relationships in the
elements between the common bile and pancreatic ducts were examined. It was found that there were significant direct correlations
in the Ca, Mg, and Fe contents between the common bile and pancreatic ducts; that is, as Ca, Mg, and Fe increased in the common
bile duct, they increased simultaneously in the pancreatic duct. 相似文献
72.
73.
Differentiation of the slow-binding mechanism for magnesium ion activation and zinc ion inhibition of human placental alkaline phosphatase
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The binding mechanism of Mg(2+) at the M3 site of human placental alkaline phosphatase was found to be a slow-binding process with a low binding affinity (K(Mg(app.)) = 3.32 mM). Quenching of the intrinsic fluorescence of the Mg(2+)-free and Mg(2+)-containing enzymes by acrylamide showed almost identical dynamic quenching constant (K(sv) = 4.44 +/- 0.09 M(-1)), indicating that there is no gross conformational difference between the M3-free and the M3-Mg(2+) enzymes. However, Zn(2+) was found to have a high affinity with the M3 site (K(Zn(app.)) = 0.11 mM) and was observed as a time-dependent inhibitor of the enzyme. The dependence of the observed transition rate from higher activity to lower activity (k(obs)) at different zinc concentrations resulted in a hyperbolic curve suggesting that zinc ion induces a slow conformational change of the enzyme, which locks the enzyme in a conformation (M3'-Zn) having an extremely high affinity for the Zn(2+) (K*(Zn(app.)) = 0.33 microM). The conformation of the M3'-Zn enzyme, however, is unfavorable for the catalysis by the enzyme. Both Mg(2+) activation and Zn(2+) inhibition of the enzyme are reversible processes. Structural information indicates that the M3 site, which is octahedrally coordinated to Mg(2+), has been converted to a distorted tetrahedral coordination when zinc ion substitutes for magnesium ion at the M3 site. This conformation of the enzyme has a small dynamic quenching constant for acrylamide (K(sv) = 3.86 +/- 0.04 M(-1)), suggesting a conformational change. Both Mg(2+) and phosphate prevent the enzyme from reaching this inactive structure. GTP plays an important role in reactivating the Zn-inhibited enzyme activity. We propose that, under physiological conditions, magnesium ion may play an important modulatory role in the cell for protecting the enzyme by retaining a favorable geometry of the active site needed for catalysis. 相似文献
74.
To examine whether an accumulation of elements in the arteries with aging differs between human and animal, the authors investigated
the relationships among element contents in the arteries of the Japanese monkeys. The Japanese monkeys consisted of five males
and four females, ranging in age from 2 to 29 yr. The aorta, common and external iliac, femoral, common carotid, subclavian,
and axillary arteries were resected from the monkeys and element contents were determined by inductively coupled plasma-atomic
emission spectrometry. It was found that there were very high correlations between calcium and phosphorus contents, between
calcium and magnesium contents, and between phosphorus and magnesium contents in all of the monkey arteries. In addition,
significant correlations were found among the other element contents in some, but not all of the arteries. These results were
consistent with the foregoing findings of the human arteries. It is likely that magnesium forms compounds with phosphorus
or calcium in the monkey arteries. 相似文献
75.
Jürgen Vormann Michael Worlitschek Thomas Goedecke Burton Silver 《Journal of trace elements in medicine and biology》2001,15(2-3):179-183
The cause of low back pain is heterogeneous, it has been hypothesised that a latent chronic acidosis might contribute to these symptoms. It was tested whether a supplementation with alkaline minerals would influence symptoms in patients with low back pain symptoms. In an open prospective study 82 patients with chronic low back pain received daily 30 g of a lactose based alkaline multimineral supplement (Basica) over a period of 4 weeks in addition to their usual medication. Pain symptoms were quantified with the "Arhus low back pain rating scale" (ARS). Mean ARS dropped highly significant by 49% from 41 to 21 points after 4 weeks supplemention. In 76 out of 82 patients a reduction in ARS was achieved by the supplementation. Total blood buffering capacity was significantly increased from 77.69 +/- 6.79 to 80.16 +/- 5.24 mmol/L (mean +/- SEM, n = 82, p < 0.001) and also blood pH rose from 7.456 +/- 0.007 to 7.470 +/- 0.007 (mean +/- SEM, n = 75, p < 0.05). Only intracellular magnesium increased by 11% while other intracellular minerals were not significantly changed in sublingual tissue as measured with the EXA-test. Plasma concentrations of potassium, calcium, iron, copper, and zinc were within the normal range and not significantly influenced by the supplementation. Plasma magnesium was slightly reduced after the supplemenation (-3%, p < 0.05). The results show that a disturbed acid-base balance may contribute to the symptoms of low back pain. The simple and safe addition of an alkaline multimineral preparate was able to reduce the pain symptoms in these patients with chronic low back pain. 相似文献
76.
硫酸镁对大鼠海马CA1区神经元钠电流的抑制作用 总被引:5,自引:2,他引:3
利用全细胞膜片钳技术研究了硫酸镁 (MgSO4 )对大鼠海马CA1区神经元钠电流的影响。结果表明 ,MgSO4 可浓度依赖和电压依赖地抑制钠电流 ,半数抑制浓度为 4 0 5mmol/L。这一抑制作用与刺激频率无关。结果还表明 ,4mmol/LMgSO4 不影响钠电流的失活过程 ,却使半数激活电压由 - 5 5 8± 6 8mV变为 - 3 4 2± 6 2mV (n =8,P <0 0 1) ,而激活曲线的斜率因子不变。结果提示 ,MgSO4 抑制大鼠海马CA1区神经元的钠电流可能是其抗缺血缺氧造成的中枢神经系统损伤的机制之一 相似文献
77.
The aragonite constructions of the Black Sea are formed in a stable anaerobic zone and are a perfect object to study the natural mechanism of anaerobic methane oxidation. The most probable pathway of methane oxidation is its methanogen-mediated reaction with bicarbonates, dissolved in seawater, with the formation of water and acetate, which is then consumed by other components of the anaerobic community. Comparison of the 13C values of carbonate minerals and organic matter once more demonstrated that the formation of the organic matter of biomass is accompanied by intense fractionation of carbon isotopes, as a result of which the total organic matter of biomass acquires an extremely light isotopic composition, characterized by 13C values as low as –83.8. 相似文献
78.
Zorbas YG Kakurin VJ Denogradov SD Luzhkov SH Neofitov AC 《Biological trace element research》2002,90(1-3):155-173
Hypokinesia (diminished movement) induces muscle mineral depletion. However, the mechanism of muscle mineral depletion during
hypokinesia (HK) remains unknown. Measuring electrolyte retention and electrolyte values in muscle, plasma, and urine during
and after HK, the aim of this study was to discover if HK could depress mineral retention and lead to muscle mineral depletion.
Studies were done on 204 13-wk-old male Wistar rats (370–390 g) during 10 d pre-HK period, 98 d HK period, and 15 d post-HK
period. Rats were equally divided into two groups: vivarium control rats (VCR) and hypokinetic rats (HKR). All hypokinetic
rats were kept for 98 d in small individual cages, which restricted their movements in all directions without hindering food
and water intakes. All control rats were housed for 98 d in individual cages under vivarium control conditions. Both groups
of rats were pair-fed.
During the HK period skeletal muscle sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and water content and electrolyte
retention decreased significantly (p < 0.05), while urinary and plasma electrolyte levels increased significantly (p < 0.05) in HKR compared with their pre-HK values and their respective VCR. During the initial days of the post-HK period,
mineral retention increased significantly (p < 0.05), plasma and urinary electrolyte level decreased significantly (p < 0.05), while muscle electrolyte and water content remained significantly (p < 0.05) depressed in HKR compared with VCR. Muscle mineral and water content, electrolyte retention, plasma, and urinary
electrolyte values did not change in VCR compared with their pre-HK values.
It was concluded that during HK decreased muscle mineral content may suggest muscle mineral depletion, while increased urinary
electrolyte loss and muscle mineral depletion may demonstrate reduced mineral retention. Reduced electrolyte excretion and
depressed muscle mineral content during post-HK may indicate skeletal muscle mineral depletion during HK. Dissociation between
electrolyte retention and muscle mineral depletion may demonstrate the presence of decreased electrolyte retention as the
mechanism of muscle electrolyte depletion during prolonged HK. 相似文献
79.
Shiraiwa Y 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2003,136(4):775-783
Emiliania huxleyi and Gephyrocapsa oceanica are the predominant coccolithophorid species that produce blooms in the ocean and affect the global environment. These species are capable of carbon fixation by both photosynthesis for organic matter production and by intracellular calcification for coccolith production. Both processes were strongly affected by the nutrient status in a laboratory culture. The coccolith production was stimulated by the addition of a high concentration of sodium bicarbonate and by the depletion of phosphate. Interestingly, when the calcification was stimulated, the increase in cell number during algal growth was greatly suppressed and then the cell volume increased. When the growth rate was increased under nutrient-sufficient conditions, the cells became very small in size and most of them bore few or no coccoliths. The data from laboratory experiments show that the cell growth and calcification proceeded apparently independently at different phases. We, therefore, assume that the coccolithophorid blooms in the ocean might be separated into two phases; firstly, the increase in cell population might be triggered by an adequate supply of nutrients to enhance algal growth and then the calcification might subsequently be stimulated when the nutrients become depleted by substantial algal growth. 相似文献
80.
Yamada M Tohno Y Takakura Y Tohno S Moriwake Y Minami T 《Biological trace element research》2003,91(1):57-66
To elucidate compositional changes of the tendons with aging, the authors investigated age-related changes of element contents
in the tendon of the iliopsoas muscle by inductively coupled plasma-atomic emission spectrometry. The subjects consisted of
14 men and 14 women, ranging in age from 4 to 102 yr. The insertion tendons of the iliopsoas were removed from the cadavers
after ordinary dissection and also surgically from patients with congenital dislocation of the hip. It was found that both
Mg and P in the tendon of the iliopsoas muscle increased significantly with aging, but the other elements, such as S, Ca,
Na, Zn, Fe, and Si, hardly changed with aging.
With regard to the relationship among element contents, extremely significant correlations were found between P and S contents,
between Mg and Na contents, and between S and Zn contents. In addition, very significant correlations were found between Si
and either S or Zn contents. However, there was no significant correlation between Ca and P contents. These results revealed
that with regard to age-related changes of element contents and the relationships among element contents, the tendon of the
iliopsoas muscle was different from the Achilles tendon, in which both Mg and P decreased significantly with aging and there
were significant correlations each other among the contents of S, Mg, and P. 相似文献