Molecular dynamics and information on possible sites of interaction of intramyocellular metabolites in vivo from resolved dipolar couplings in localized H NMR spectra

Proton NMR resonances of the endogenous metabolites creatine and phosphocreatine ((P)Cr), taurine (Tau), and carnosine (Cs, β-alanyl-l-histidine) were studied with regard to residual dipolar couplings and molecular mobility. We present an analysis of the direct ¹H–¹H interaction that provides information on motional reorientation of subgroups in these molecules in vivo. For this purpose, localized ¹H NMR experiments were performed on m. gastrocnemius of healthy volunteers using a 1.5-T clinical whole-body MR scanner. We evaluated the observable dipolar coupling strength SD₀ (S = order parameter) of the (P)Cr-methyl triplet and the Tau-methylene doublet by means of the apparent line splitting. These were compared to the dipolar coupling strength of the (P)Cr-methylene doublet. In contrast to the aliphatic protons of (P)Cr and Tau, the aromatic H2 (δ = 8 ppm) and H4 (δ = 7 ppm) protons of the imidazole ring of Cs exhibit second-order spectra at 1.5 T. This effect is the consequence of incomplete transition from Zeeman to Paschen-Back regime and allows a determination of SD₀ from H2 and H4 of Cs as an alternative to evaluating the multiplet splitting which can be measured directly in high-resolution ¹H NMR spectra. Experimental data showed striking differences in the mobility of the metabolites when the dipolar coupling constant D₀ (calculated with the internuclear distance known from molecular geometry in the case of complete absence of molecular dynamics and motion) is used for comparison. The aliphatic signals involve very small order parameters S ≈ (1.4 − 3) × 10⁻⁴ indicating rapid reorientation of the corresponding subgroups in these metabolites. In contrast, analysis of the Cs resonances yielded S ≈ (113 − 137) × 10⁻⁴. Thus, the immobilization of the Cs imidazole ring owing to an anisotropic cellular substructure in human m. gastrocnemius is much more effective than for (P)Cr and Tau subgroups. Furthermore, ¹H NMR experiments on aqueous model solutions of histidine and N-acetyl-l-aspartate (NAA) enabled the assignment of an additional signal component at δ = 8 ppm of Cs in vivo to the amide group at the peptide bond. The visibility of this proton could result from hydrogen bonding which would agree with the anticipated stronger motional restriction of Cs. Referring to the observation that all dipolar-coupled multiplets resolved in localized in vivo ¹H NMR spectra of human m. gastrocnemius collapse simultaneously when the fibre structure is tilted towards the magic angle (θ ≈ 55°), a common model for molecular confinement in muscle tissue is proposed on the basis of an interaction of the studied metabolites with myocellular membrane phospholipids.     

RO-heparin Inhibits L-Selectin-mediated Neutrophils Adhesion to Vascular Endothelium Under Flow Conditions

Introduction Migrationandrecruitmentofleukocytesfromblood toinflammatorylesionsitesaresequentiallyregulated byadhesionmoleculesandtheirreceptors[1].These lectinfamilyplaysamajorroleininitiatingattachement ofneutrophilstotheactivatedendothelium.P selectin,…     

A structured light-based system for human heads

The 3-D modeling of heads by using optical triangulation techniques is of great interest in the context of virtual reality, telecommunication and computer animation. This paper presents a structured light-based system mainly for human heads. It is named “3-D Laser Color Scanner” (3DLCS). A 3-D model is obtained with a cylindrical scan. The laser beam is switched on and off using a “light valve” and two successive CCD frames are captured, one with the laser line showing and one without. We can simplify the laser line extracting by subtracting these two images.In this system, two CCD cameras are used to avoid occlusion problems. Color information is read from the CCD when the laser light is absent. Since traditional laser scanner will miss the range data in the low-reflectance areas such as the hair area of human head, a shape from silhouette algorithm is presented to overcome this problem. Finally, we give some results using our system. The resulting model is suitable for many applications.     

荧光猝灭法测定人发中微量锰

异丙肾上腺素在pH9.91的伯瑞坦 罗比森缓冲溶液中被MnO-4氧化,导致其荧光强度显著减弱。最大激发及发射波长为278nm和616nm,MnO-4浓度在0.01～0.64mg·L-1范围内,荧光强度与浓度呈良好线性关系。将其用于人发中微量锰的测定,得到满意的结果。     

散射背景下激光热透镜光谱分析法测定人体血清中锌量

建立了散射背景下测定人体血清中Zn^2＋含量的激光热透镜光谱分析方法。比较了蛋白质微粒散射对于分光光度法和激光热透镜光谱分析法测定的影响。结果表明，激光热透镜光谱分析方法能够避免溶液中存留蛋白质微粒散射的影响。Zn^2＋量在0～1．6μg/mL范围内呈线性关系（r=0．9986），检出限为1ng/mL。应用于人体血清中Zn^2＋含量的测定，与原子吸收法测定结果基本一致。     

Human insulin and desamido human insulin isotherms in ethanol-water reversed phase systems

The multi-component isotherms for human insulin (HI) and desamido human insulin (dHI) over reversed phase packing (C18) and with 29.8% (w/w) ethanol-water as mobile phase have been determined experimentally. The isotherms of HI in ethanol-water differ from those obtained with the more commonly applied methanol-water and acetonitrile-water mobile phase, as described in this paper. The isotherm exhibits anti Langmuirian behavior and can be very well modeled by an anti Langmuir isotherm presented in this paper. The HI and dHI anti Langmuir isotherm are determined as: qHI = (8.4C(HI) + 3C(HI)CdHI)/(1 - 0.05C(HI) - 0.14CdHI + 0.04C(HI)CdHI) and qdHI = (11.4CdHI + 2C(HI)CdHI)/ (1 - 0.05C(HI) - 0.14CdHI + 0.04C(HI)CdHI)     

刚果红与血清白蛋白相互作用的极谱分析

在pH4．7HAc-NaAc缓冲溶液中，刚果红与蛋白质(BSA或HSA)作用形成络合物，使刚果红-0．35V(vs SCE)的还原峰电流下降，峰电流的降低值同所加的BSA或HSA质量浓度在一定范围内呈线性关系；BSA和HSA的线性范围分别为0．5～12mg／L和0．5～11mg／L，检出限分别为0．25和0．20mg／L；运用该法测定了人血清白蛋白样品，结果令人满意。     

A comparison of double-focusing sector field ICP-MS, ICP-OES and octopole collision cell ICP-MS for the high-accuracy determination of calcium in human serum

Human serum is routinely measured for total calcium content in clinical studies. A definitive high-accuracy and low-uncertainty method is required for reference measurements to underpin medical diagnoses. This study presents a novel octopole collision cell ICP-MS, high-accuracy, methodology and comparison of that technique with double-focusing sector field ICP-MS and an ICP-OES method. Double-matched isotope dilution mass spectrometry (IDMS) was employed for ICP-MS techniques and an exact matching bracketing technique using scandium as an internal standard was used for ICP-OES analysis. Medium resolution mode was utilised for double-focusing sector field ICP-MS analysis to resolve the dominant interferences on the ⁴⁴Ca/⁴²Ca isotope pair. Hydrogen reaction gas was employed to chemically resolve a number of polyatomic interferences predominantly through charge transfer reactions in the octopole collision cell. Comparison data presented for NIST CRM 909b human serum analysis from all three techniques demonstrates highest accuracy (99.6%) and lowest uncertainty (1.1%) for octopole collision cell ICP-MS. Data from ICP-OES using a non-IDMS technique produces comparably accurate data and low-uncertainties. The much higher total expanded uncertainties for double-focusing sector field ICP-MS compared with octopole collision cell data are explained by lower precision on the measurement of the ⁴⁴Ca/⁴²Ca isotope ratio. Data for octopole collision cell ICP-MS submitted for an international blind trial comparison (CCQM K-14) demonstrated excellent agreement with the mean of all participants with a low expanded uncertainty.     

Inclusion of molybdenocene dichloride (Cp2MoCl2) in 2-hydroxypropyl- and trimethyl-β-cyclodextrin: Structural and biological properties

Organometallic-cyclodextrin inclusion compounds were obtained by the treatment of molybdenocene dichloride (Cp₂MoCl₂) with the modified cyclodextrins (CDs) heptakis-2,3,6-tri-O-methyl-β-CD (TRIMEB) and 2-hydroxypropyl-β-CD (HPβCD) in aqueous solution. The products were isolated by liophilisation and characterised in the solid-state by powder XRD, thermogravimetric analysis, Raman and FTIR spectroscopy, and ¹³C CP MAS NMR spectroscopy. The results are consistent with inclusion of Cp₂MoCl₂, rather than hydrolysis products such as [Cp₂Mo(H₂O)X]⁺ (X = Cl, OH) or [Cp₂Mo(H₂O)₂]²⁺. The pure non-included metallocene Cp₂MoCl₂ and its inclusion compounds with unmodified β-CD, TRIMEB and HPβCD were screened for their potential antiproliferative and cytotoxic activity, in both human cancer and healthy cell lines. Inclusion in CD was found to enhance the cytotoxic effect of Cp₂MoCl₂, with the TRIMEB adduct displaying the highest anti-tumour activity, along with the lowest toxicity towards non-neoplastic cells.     

Determination of doxorubicin in human plasma by excitation-emission matrix fluorescence and multi-way analysis

Direct determination of doxorubicin (DXR), a cytotoxic anthracycline antibiotic, in human plasma was accomplished based on excitation-emission matrix (EEM) fluorescence measurements and multi-way chemometric methods based on parallel factor analysis (PARAFAC) and N-PLS. Several different procedures, such as residual analysis, core consistency diagnostic (CONCORDIA) and split-half analysis were employed to determine the correct number of factors in PARAFAC. These procedures converged to a choice of two factors, attributed to DXR and to the sum of two fluorescence species present in the plasma. Sample PARAFAC loadings were employed to build a regression model against concentration, resulting in a RMSECV of 0.060 μg ml⁻¹. N-PLS using two factors produced a RMSECV of 0.045 μg ml⁻¹. Figures of merit (FOM), such as sensitivity (SEN), selectivity (SEL) and limit of detection (L_D) were determined for both PARAFAC and N-PLS.