In vivo (31)P-MRS assessment of cytosolic [Mg(2+)] in the human skeletal muscle in different metabolic conditions

Cytosolic free [Mg(2+)] can be assessed in vivo by (31)P-MRS from the chemical shift of beta-ATP. The reliability of in vivo measurements depends on the availability of appropriate in vitro calibration curves obtained by using solutions that mimic the in vivo cytosolic conditions as far as possible. We build a semi-empiric equation that correlates the chemical shift of beta-ATP to free [Mg(2+)] taking into account the amount of Mg(2+) bound to all other ligands in solution. Our experiments resulted in a reliable ten-parameters equation directly usable to assess the cytosolic free [Mg(2+)] of human skeletal muscle at rest, during work and recovery. Our experiments also resulted in a new equation that allows the assessment of cytosolic pH from the chemical shift of Pi taking into account the measured free [Mg(2+)]. To perform simultaneous calculation of free [Mg(2+)] and pH in the skeletal muscle in different metabolic conditions we developed a specific software package available on Internet (http://www.unibo.it/bioclin) together with another program based on the equation previously obtained to calculate cytosolic free [Mg(2+)] in the human brain. The reliability and effectiveness of our equations and software were tested on the calf muscles of healthy volunteers at rest, during work and recovery.     

Impact of aging on cardiac high-energy phosphate metabolism determined by phosphorus-31 2-dimensional chemical shift imaging (31P 2D CSI)

Previous echocardiographic and experimental animal studies have shown that cardiac function, structure, and metabolism change with age. The aim of this study was to evaluate the impact of age on left ventricular high-energy phosphate metabolism. Using a 1.5 Tesla whole-body MR scanner 31P 2D CSI (8 x 8 phase encoding steps, 320 mm field of view) was performed in 76 healthy male volunteers (41.7 +/- 13 years) without any history of coronary heart disease. Fourier interpolation, corrections for T1 saturation effects, the nucleus Overhauser effect, and the blood contamination were applied to the spectroscopic data. The volunteers were divided into two groups, younger (n = 37) and older (n = 39) than 41.7 years. In all volunteers, laboratory specimen were sampled, and transthoracal echocardiography was carried out. Significant differences in left ventricular phosphocreatine (PCr) to beta-adenosine-triphosphate (beta-ATP) ratios (2.16 vs. 1.83, p < 0.001), fasting serum glucose levels (83.3 vs. 98.7 mg/dl, p < 0.001), E/A (1.51 vs. 1.14 p < 0.001), and ejection fraction (EF, 65.3 vs. 59.9%, p = 0.005) were detected between the two groups of volunteers, younger and older than 41.7 years. Moreover, age correlated moderately to well with left ventricular PCr to beta-ATP ratios (r = -0.44), fasting serum glucose levels (r = 0.4), E/A (r = -0.7), left ventricular myocardial mass (r = -0.41), and EF (r = -0.55). In conclusion, our study shows that left ventricular PCr to beta-ATP ratios decrease moderately with age, as suggested by previous experimental animal studies. Additionally, age correlates negatively with E/A, left ventricular myocardial mass, and EF, as reported by previous echocardiography studies. The present study is the first to show the impact of age on left ventricular PCr to beta-ATP values in humans.     

Cardiac phosphorus-31 two-dimensional chemical shift imaging in patients with hereditary hemochromatosis

Hemochromatosis is a hereditary iron overload syndrome characterized by increased iron storage, followed by liver cirrhosis and is often associated with restrictive cardiomyopathy. The purpose of this study was to detect alterations of cardiac high-energy phosphate metabolism in patients with hereditary hemochromatosis (HHC) prior to the development of structural heart diseases. Therefore cardiac phosphorus-31 two-dimensional chemical shift imaging ((31)P 2D CSI) was employed. Twenty-four male patients (mean age 47.2 +/- 12 years) homozygous for the C282Y mutation in the hemochromatosis associated HFE gene and twenty-four male healthy volunteers (mean age 47 +/- 11 years) as age-matched controls were included in this study. Using a 1.5-Tesla whole-body magnetic resonance scanner, electrocardiograph-triggered transversal 31P 2D CSI was performed. Left ventricle mean phosphocreatine (PCr) to beta-adenosine triphosphate (beta-ATP) ratios of patients with HHC (1.60 +/- 0.41) were significantly decreased in comparison to healthy volunteers (1.93 +/- 0.36; p = 0.004). Furthermore, we detected moderate, negative correlations between left ventricular PCr to beta-ATP ratios and transferrin saturation, cholesterol, low-density lipoprotein as well as triglyceride. This study shows that 31P 2D CSI permits the detection of alterations of cardiac high-energy phosphate metabolism in patients with HHC, but without any evidence for heart disease. The decreased PCr to beta-ATP ratios in HHC might be caused by mitochondrial impairment due to cardiac iron overload.     

Phosphorus-31 MR spectroscopic imaging (MRSI) of normal and pathological human brains.

The goals of this study were to evaluate 31P MR spectroscopic imaging (MRSI) for clinical studies and to survey potentially significant spatial variations of 31P metabolite signals in normal and pathological human brains. In normal brains, chemical shifts and metabolite ratios corrected for saturation were similar to previous studies using single-volume localization techniques (n = 10; pH = 7.01 +/- 0.02; PCr/Pi = 2.0 +/- 0.4; PCr/ATP = 1.4 +/- 0.2; ATP/Pi = 1.6 +/- 0.2; PCr/PDE = 0.52 +/- 0.06; PCr/PME = 1.3 +/- 0.2; [Mg2+]free = 0.26 +/- 0.02 mM.) In 17 pathological case studies, ratios of 31P metabolite signals between the pathological regions and normal-appearing (usually homologous contralateral) regions were obtained. First, in subacute and chronic infarctions (n = 9) decreased Pi (65 +/- 12%), PCr (38 +/- 6%), ATP (55 +/- 6%), PDE (47 +/- 9%), and total 31P metabolite signals (50 +/- 8%) were observed. Second, regions of decreased total 31P metabolite signals were observed in normal pressure hydrocephalus (NPH, n = 2), glioblastoma (n = 2), temporal lobe epilepsy (n = 2), and transient ischemic attacks (TIAs, n = 2). Third, alkalosis was detected in the NPH periventricular tissue, glioblastoma, epilepsy ipsilateral ictal foci, and chronic infarction regions; acidosis was detected in subacute infarction regions. Fourth, in TIAs with no MRI-detected infarction, regions consistent with transient neurological deficits were detected with decreased Pi, ATP, and total 31P metabolite signals. These results demonstrate an advantage of 31P MRSI over single-volume 31P MRS techniques in that metabolite information is derived simultaneously from multiple regions of brain, including those outside the primary pathological region of interest. These preliminary findings also suggest that abnormal metabolite distributions may be detected in regions that appear normal on MR images.     

尿酸结石患者尿液中的微晶组分及其与结石形成的关系

采用X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、纳米粒度仪、扫描电子显微镜(SEM)和透射电子显微镜(TEM)研究了10例尿酸结石患者尿微晶的组分、Zeta电位、形貌及其与尿酸结石形成的关系.结果表明,尿酸结石患者的尿pH值较低,大都在4.8～5.7之间;尿微晶的主要成分为尿酸.其粒度分布很不均匀,从几纳米到几十微米不等,并有聚集现象.相比健康对照者尿纳米微品的Zeta电位(-10.1mV),尿酸结石患者的Zeta电位负值更小(-6.02 mV).对这些患者进行药物治疗(服用柠檬酸钾)后,尿pH可上升到6.5左右,此时尿液中的大部分尿酸转变为溶解度显著增加的尿酸盐,因此,尿酸结石形成的危险性显著降低.本文结果表明,尿石组分、尿微晶组分及尿pH三者之间存在密切的联系.     

GFAAS测定微量铍的阳离子干扰研究

石墨炉原子吸收光谱法(GFAAS)是测定微量铍的主要方法,但干扰因素很多.本文在没有背景校正和基体改进的情况下,建立了一个一次多元线性回归模型,并采用正交回归设计方法定量研究了常见阳离子钾、钠、钙、镁和铝对测量铍的干扰.结果表明,GFAAS法测定微量铍时,钾和钠对测量的影响可以忽略不计,而钙、镁和铝对测量有增敏作用,镁和铝还存在交互效应,对测量有抑制作用.离子干扰的 定量回归方程为:A＝-0.0059 0.0104(Ca2 ) 0.0874(Mg2 ) 0.1077(Al3 )-0.0239(Mg2 )(Al3 ),式中(Ca2 )表示lg([Ca2 ]/[Be2 ]),以此类推.     

(MgC)n (n=1~10)团簇结构稳定性及金属性第一性原理研究

采用基于密度泛函理论的第一性原理对同比例二元团簇(MgC)n (n=1~10)的结构稳定性和金属性进行比较系统的研究。结果显示：当原子总数N=2, 4, 6, 8, 12时,二元团簇的结构为平面形状,其余为对称性较低的三维构型,且Mg3C3为幻数结构。另外,在二元团簇的形成过程中,镁、碳原子并不是均匀分布于空间中,而是首先形成各自倾向的构型,再结合成团簇。同时,(MgC)n (n=1~10)二元团簇的基态结构在原子总数N=10时发生突变,由平面形向三维结构转变。此外,最高占据轨道和最低未占据轨道间的能隙值除N=8外呈逐渐降低的趋势,说明在同比例二元团簇随尺寸增加的演化中出现半导体性与金属性间的相互转变行为。     

磷酸铵镁结石患者尿微晶组分分析及其与结石形成的关系

采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、纳米粒度仪、扫描电子显微镜(SEM)和透射电子显微镜(TEM)研究了磷酸铵镁结石患者尿液中微晶的组分、形貌、粒径和Zeta电位,并对其结石进行了组分分析.结果表明,结石类型、尿微晶组分和尿液pH三者之间存在密切的联系:磷酸铵镁结石病人的尿液pH值较高,通常在6....     

The metabolic effect of resistant starch and yoghurt on the renal and faecal nitrogen and ammonia excretion in humans as measured by lactose-[15N2]ureide

Resistant starch (RS) and Lactobacillus acidophilus yoghurt (LC1) were supplemented simultaneously in healthy adults to evaluate the effect on the urinary and faecal nitrogen and ammonia excretion by means of lactose-[¹⁵N₂]ureide (¹⁵N-LU) degradation. Nineteen subjects received a regular daily diet either without or with supplementation of an RS-LC1-mixture composed of fibre of potatoes (RS type 1), wrinkle pea starch (RS type 2), and LC1 over a 20-day period in randomised order. Thereafter, ¹⁵N-LU was administered together with breakfast. Urine and faeces were collected over a period of 48 and 72 h, respectively. The ¹⁵N abundances were measured by isotope ratio mass spectrometry. The intake of the pre- and probiotic mixture composed of RS of type 1, type 2 and of LC1 significantly lowered the colonic generation and the renal excretion of toxic ¹⁵NH₃ and functioned as an ammonia shift from urinary to faecal ¹⁵N excretion when using ¹⁵N-LU as a xenobiotic marker.     

Inhibition of urinary calculi—a spectroscopic study

Although herbal medicine is widely employed in inhibition of urinary calculi as an alternative and complementary curative method, the lack of detailed scientific studies that could provide insights into this complex process weakens its validity. The present work targets multitechnique spectroscopic investigations by Raman, infrared absorption, X‐ray photoelectron spectroscopy (XPS), and photoluminescence on the effects of the herb Rotula Aquatica Lour (RAL) on the growth of synthetically prepared magnesium‐based calculi. In addition to the standard magnesium phosphate‐based sample, two other samples were prepared with incorporation of 1 and 2wt% RAL herbal extract. Both, Raman and infrared data show a newberyite structure for the crystals without and with inhibitor. The XPS measurements reveal an unexpected presence of Zn in the sample with bfRAL inhibitor, which, as suggested in the literature, may initiate rapid stone formation, and consequently, contribute to the inhibition process. Furthermore, the existence of metallic Zn can explain the reflectance of the incident light observed in the infrared transmission studies of the unground crystals. A significant increase in magnesium with addition of herbal extract is observed in the XPS data. Also, evidence for Mg O binding between the inhibitor and the phosphate units of urinary calculus is found in XPS and Raman results. Similarity between our photoluminescence measurements and those of in vivo chlorophyll a corroborates to provide additional evidence of Mg‐related inhibition. Copyright © 2009 John Wiley & Sons, Ltd.     

(MgC)n (n=1~10)团簇结构稳定性及金属性第一性原理研究

采用基于密度泛函理论的第一性原理对同比例二元团簇(MgC)n (n=1~10)的结构稳定性和金属性进行比较系统的研究。结果显示：当原子总数N=2, 4, 6, 8, 12时,二元团簇的结构为平面形状,其余为对称性较低的三维构型,且Mg3C3为幻数结构。另外,在二元团簇的形成过程中,镁、碳原子并不是均匀分布于空间中,而是首先形成各自倾向的构型,再结合成团簇。同时,(MgC)n (n=1~10)二元团簇的基态结构在原子总数N=10时发生突变,由平面形向三维结构转变。此外,最高占据轨道和最低未占据轨道间的能隙值除N=8外呈逐渐降低的趋势,说明在同比例二元团簇随尺寸增加的演化中出现半导体性与金属性间的相互转变行为。     

Effect of creatine monohydrate in improving cellular energetics and muscle strength in ambulatory Duchenne muscular dystrophy patients: a randomized,placebo-controlled P MRS study

Randomized, placebo-controlled single blinded study was carried out to evaluate the effect of oral creatine supplementation on cellular energetics, manual muscle test (MMT) score and functional status in steroid-naive, ambulatory boys suffering with Duchenne muscular dystrophy (DMD; n=33). Eighteen patients received creatine monohydrate (Cr; 5 g/day for 8 weeks), while 15 received placebo (500 mg of vitamin C). Phosphorus metabolite ratios were determined from the right calf muscle of patients using phosphorus magnetic resonance spectroscopy (³¹P MRS) both prior to (baseline) and after supplementation of Cr or placebo. In addition, metabolite ratios were determined in normal calf muscle of age and sex matched controls (n=8). Significant differences in several metabolite ratios were observed between controls and DMD patients indicating a lower energy state in these patients. Analysis using analysis of covariance adjusted for age and stature showed that the mean phosphocreatine (PCr)/inorganic phosphate (Pi) ratio in patients treated with Cr (4.7; 95% CI; 3.9–5.6) was significantly higher (P=.03) compared to the placebo group (3.3; 95% CI; 2.5–4.2). The mean percentage increase in PCr/Pi ratio was also more in patients <7 years of age compared to older patients after Cr supplementation indicating variation in therapeutic effect with the age. In the placebo group, significant reduction in PCr/Pi (P=.0009), PCr/t-ATP (P=.05) and an increase in phosphodiester (PDE)/PCr ratios was observed after supplementation. Further, in the placebo group, patients <7 years showed reduction of PCr/t-ATP and Pi/t-ATP compared to older patients (>7 years), after supplementation. These results imply that the significant difference observed in PCr/Pi ratio between the Cr and the placebo groups after supplementation may be attributed to a decrease of PCr in the placebo group and an increase in PCr in the Cr group. Changes in MMT score between the two groups was significant (P=.04); however, no change in functional scale (P=.19) was observed. Parents reported subjective improvement on Cr supplementation versus worsening in placebo (P=.02). Our results indicated that Cr was well tolerated and oral Cr significantly improved the muscle PCr/Pi ratio and preserved the muscle strength in short term. However, this study provides no evidence that creatine will prove beneficial after long-term treatment, or have any positive effect on patient lifespan.     

Spectroscopic investigations on kidney stones using Fourier transform infrared and X‐ray fluorescence spectrometry

Kidney stone is the most painful and prevalent urological disorder of the urinary system throughout the world. Thus, analysis of kidney stones is an integral part in the evaluation of patents having stone disease. Spectroscopic investigations of stones provide an idea about the pathogenesis of stones for its better cure and treatment. Hence, the present work targets multispectroscopic investigations on kidney stones using Fourier transform infrared (FTIR) and wave dispersive X‐ray fluorescence (WD‐XRF) spectroscopy which are the most useful analytical methods for the purpose of bio‐medical diagnostics. In the present study, FTIR spectral method is used to investigate the chemical composition and classification of kidney stones. The multicomponents of kidney stones such as calcium oxalate, hydroxyl apatite, phosphates, carbonates, and struvite were investigated and studied. Qualitative and quantitative determination of major and trace elements present in the kidney stones was performed employing WD‐XRF spectroscopy. The wide range of elements determined in the kidney stones were calcium (Ca), magnesium (Mg), phosphorous (P), sodium (Na), potassium (K), chlorine (Cl), sulfur (S), silicon (Si), iodine (I), titanium (Ti), iron (Fe), ruthenium (Ru), zinc (Zn), aluminum (Al), strontium (Sr), nickel (Ni), copper (Cu), and bromine (Br). For the first time, ruthenium was detected in kidney stone samples employing WD‐XRF in very low concentration. Our results revealed that the presence and relative concentrations of trace elements in different kinds of stones are different and depend on the stone types. From the experiments carried out on kidney stones for trace elemental detection, it was found that WD‐XRF is a robust analytical tool that can be useful for the diagnosis of urological disorders. We have also compared our findings with the results reported using XRF technique. The results obtained in the present paper show interesting prospects for FTIR and WD‐XRF spectrometry in nephrolithiasis. Copyright © 2017 John Wiley & Sons, Ltd.     

Micro‐Raman spectroscopy identification of urinary stone composition from ureteroscopic lithotripsy urine powder

Urolithiasis is a prevalent, disturbing, and highly recurrent disease. Knowing the composition of a urinary stone is important for prevention purposes. Traditional urinary stone analysis methods need large stone fragments for analysis. However, the advancement of ureteroscopic lithotripsy (URSL) has resulted in micro‐stone fragments and unapparently expelled urinary stone powder. In this study, we developed a micro‐Raman spectroscopy (MRS) based diagnosis method for detecting micro‐stones or stone powders in urine after URSL. In our experiment, urine samples of 10 ml each were collected from 12 patients over the fragmented stone site in the ureter after the URSL procedure. The post‐URSL urine sediments extracted from urine were analyzed by MRS. The small urinary stones caught by grasping forceps were analyzed by both MRS and Fourier‐transform infrared (FTIR) spectroscopy. We have identified common urinary stone compositions: calcium oxalate monohydrate (COM), calcium oxalate dihydrate (COD), dicalcium phosphate dihydrate (DCPD), calcium phosphate hydroxide (hydroxyl apatite or HAP), and uric acid, by using a 632.8 nm He‐Ne laser for excitation, a 100× microscope objective lens for irradiation and collection, and a short photobleaching time for fluorescent background reduction. Thus, we developed an MRS‐based method for analyzing the composition of urinary stone powders directly from the urine samples after the URSL procedure. This approach provides a quick and convenient method for urinary stone analysis. Copyright © 2009 John Wiley & Sons, Ltd.     

AlnMgm (n+m=6,7;m=1,2)团簇的稳定性与电子结构

用遗传算法结合经验势对AlnMgm(n+m=6,7; m=1,2)的低能结构进行全局搜索,用从头计算方法研究了其稳定性和电子结构。计算表明AlnMgm存在多个能量相近的异构体,在AlMg团簇中Mg-Mg相互作用远弱于Al-Al作用,稳定结构中Mg原子倾向于形成更多的Mg-Al键。NBO电荷分析表明Mg向Al转移电子,Al原子上的电荷大小强烈依赖于相连的Mg原子个数。电子结构分析表明随着原子数目的增大,占据轨道能级略有降低,同尺寸下掺杂一个Mg时能级更低;AlMg团簇的能隙约为5.30 eV。     

Al_nMg_m(n+m=6,7;m=1,2)团簇的稳定性与电子结构

用遗传算法结合经验势对AlnMgm(n+m=6,7;m=1,2)的低能结构进行全局搜索,用从头计算方法研究了其稳定性和电子结构.计算表明AlnMgm存在多个能量相近的异构体,在Al Mg团簇中Mg-Mg相互作用远弱于Al-Al作用,稳定结构中Mg原子倾向于形成更多的Mg-Al键.自然键轨道(NBO)电荷分析表明Mg向Al转移电子,Al原子上的电荷大小强烈依赖于相连的Mg原子个数.电子结构分析表明随着原子数目的增大,占据轨道能级略有降低,同尺寸下掺杂一个Mg时能级更低;Al Mg团簇的能隙约为5.30 e V.     

白光LED用Ca_8Mg(SiO_4)_4Cl_2:Eu~(2+),Dy~(3+)发光粉的发光性能

采用高温固相法合成了白光LED用Ca8Mg(SiO4)4Cl2:Eu和Ca8Mg(SiO4)4Cl2:Eu,Dy绿色发光粉。研究发现:共掺Dy可以明显地提高Ca8Mg(SiO4)4Cl2:Eu发光粉的发光性能,表明Dy3+和Eu2+之间存在着能量传递过程。当Dy3+的最佳掺杂摩尔分数为0.02时,发光粉505nm处绿光发射的强度约提高12%。通过对Dy3+和Eu2+光谱特性的分析,Dy3+和Eu2+之间的能量传递机制可归因于无辐射交叉弛豫。     

Intrinsic photorefractive centers in LiNbO3:Fe

In LiNbO₃:Fe,Me crystals (Me = K, Mg, Zn) elementary holograms are recorded and erased with frequency-doubled, ordinarily polarized pulses of a Q-switched Nd:YAG laser. At high light intensities (I > 10⁹ Wm^–2) holographic sensitivities and saturation values of refractive index changes grow with increasing intensity and a contribution to photo-conductivity appears increasing quadratically withI. The intensity-dependent parts of the holographic quantities are diminished by increasing the lithium content of the samples or by doping the crystals with magnesium or zinc. Experimental results can be described by a two-center charge transport model, which is the Fe^2+/3+ model supplemented by shallow traps, namely niobium ions occupying lithium sites.     

Correlation between metabolite ratios and ADC values of prostate in men with increased PSA level

Proton magnetic resonance spectroscopic imaging (MRSI) and diffusion-weighted imaging (DWI) were carried out in men with increased prostate-specific antigen (PSA) level. Forty subjects [controls (Group I) and patients (Groups II and III with PSA >20 and 4-20 ng/ml, respectively)] were investigated using endorectal coil at 1.5 T prior to transrectal ultrasound (TRUS)-guided biopsy. Metabolite ratio [citrate/(choline+creatine)] and apparent diffusion coefficient (ADC) were calculated for identical voxels. In patients, voxels that showed lower metabolite ratio showed reduced ADC in the peripheral zone (PZ) of the prostate, and voxels with increased metabolite ratio showed higher ADC. Metabolite ratios were used to predict areas of malignancy if the ratio was <1.4 and if ADC value was <1.17 x 10(-3) mm(2)/s. Patients in Group II had lower metabolite ratio and ADC in the PZ compared to controls and Group III. All 13 were positive for malignancy in MR, while 12 of 13 were positive on TRUS-guided sextant biopsy. In Group III, certain voxels of PZ that showed reduced metabolite ratio also showed lower ADC. A positive correlation was observed between metabolite ratio and ADC. MR predicted areas of malignancy in PZ in 15 of 20 patients; however, only six were positive on TRUS-guided biopsy perhaps due to high false-negative rate of TRUS-guided biopsy. Results show positive correlation between MRSI and DWI and their potential in detection of malignancy, thereby improving the diagnosis especially in patients with PSA level of 4-20 ng/ml.     

阈下激励与噪声联合作用下肝细胞系统的内钙时空随机共振问题

研究阈下周期信号激励对耦合肝细胞系统内钙离子浓度（［Ca²⁺］)的时空随机共振性质的影响.当阈下激励的频率等于确定性系统在Hopf分岔点附近的频率时,它就会极大地提高随机耦合系统内发生［Ca²⁺］喷发的细胞的比例,通过对喷发比的自相关函数计算得知阈下激励增强了系统在高斯白噪声作用下［Ca²⁺］的时间共振性.通过数值模拟得知,对于不同耦合强度,都存在最优噪声强度使得随机系统内［Ca²⁺］时间共振达到最佳,并且随着细胞间耦 关键词： 钙振动 噪声 阈下激励 随机共振