节能减排，高新技术是关键——访中国电器工业协会常务副会长邢玉久

2007年4月27日,温家宝总理在全国节能减排工作电视电话会议上的讲话,强调充分认识节能减排工作的重要性和迫切性。“十一五”以来,节能减排工作取得了积极进展,但必须清醒地看到,全国节能减排面临的形势仍然相当严峻。中国电器工业协会常务副会长邢玉久对此感触颇深,他提倡用更新换代的技术来促进节能减排。     

Proton chemical shift imaging,metabolic maps,and single voxel spectroscopy of glial brain tumors

Seventeen patients with presumed glial brain tumors were examined with proton chemical shift imaging and single voxel spectroscopy that used different echo times. Metabolite resonances were evaluated by metabolic ratios and absolutely by correcting for coil load and comparison to phantom measurements. Metabolic images were created to visualize the metabolic changes. All patients showed spectra that were different from those measured in healthy control subjects. Spectral changes were also present in normal-appearing matter (NAM) that was distant from lesions. The resonance at 3.55 ppm which is usually assigned to bothmyo-inositol and glycine, was the only one to allow a discrimination between healthy volunteers, astrocytoma grade II, and glioblastoma multiforme (GBM) (p<0.02). From the different echo times used we conclude that an increase inhis resonance has to be assigned to glycine rather thanmyo-inositol. This resonance might be used to grade human gliomas more reliably. Total creatine (Cr) decreased more drastically with malignancy than N-acetylated metabolites (NA). This led to a higher NA/Cr ratio in GBM compared to astrocytoma grade II. NA/Cr was thus pseudonormal in GBM due to a change in both nominator and denominator. This study reveals the importance of comparing magnetic resonance spectroscopy data of lesions to spectra measured in identical localizations in healthy control subjects instead of NAM and the importance of quantifying single metabolic peaks instead of creating metabolic ratios in clinical magnetic resonance spectroscopy.     

Extinction coefficients of hemoglobin for near-infrared spectroscopy of tissue.

Extinction coefficients of hemoglobin have been studied for five decades by clinical chemists and biochemists, particularly for laboratory spectrophotometric measurements. In the last ten to 15 years, near infrared spectroscopy (NIRS) and imaging for tissue vascular oxygenation, breast tumor detection, and functional brain imaging have been intensively developed for in vivo measurements by groups of physicists, biomedical engineers, and mathematicians. In the approach of NIRS, NIR light in the wavelength range of 650-900 nm is utilized to illuminate tissue in vivo, and the transmitted or reflected light through tissue is recorded for the quantification of hemoglobin concentrations of the measured tissue vasculature. In order to achieve mathematical conversion from the detected light intensity at different wavelengths to hemoglobin concentration, extinction coefficients of hemoglobin, /spl epsiv/, must be used. While the engineers and physicists working in the NIR field have found the correct /spl epsiv/ values to use, there has been controversy on what /spl epsiv/ values should be used for in vivo NIRS in comparison with the conventional e/spl epsiv/ that most biochemists have used in the laboratories for in vitro measurements. The purpose of this article is to address this issue and help biomedical engineers and physicists gain a better understanding of e to be used for NIRS and NIR imaging.     

High-resolution magic-angle spinning 13C NMR spectroscopy of cerebral tissue

Monitoring the metabolism of ¹³C-labelled substrates by biological tissues allows both the rate of metabolism and the relative importance of metabolic pathways to be determined. In this study high-resolution magic-angle spinning (HRMAS) ¹³C NMR spectroscopy is assessed as a technique for determining the labelling of metabolites in brain slices. Freshly prepared rat brain slices were superfused in isotonic salt solution containing [1-¹³C] glucose. HRMAS ¹H and ¹³C NMR spectra were acquired of the slices (10 mg) at 3°C. Using ¹H NMR spectroscopy it was demonstrated that the concentration of key metabolites indicative of metabolic degradation, including N-acetyl aspartate and lactate, did not change significantly across the 11 h time period required for ¹³C NMR spectra. The approach produced high-resolution spectra of intact tissue with the labelling patterns of tissues being indicative of both labelling via pyruvate dehydrogenase found in both neuronal and glial cells, and pyruvate carboxylase, found only within glial cells. This approach is a versatile tool for monitoring the compartmentation of metabolites directly, and will also allow the investigation of aqueous and lipid metabolites simultaneously.     

Proton MR spectroscopy of human pancreas allografts

Objective

To estimate pancreas graft relaxation times and concentrations of total fat, and the intracellular lipids of non-adipose pancreatic cells (NAPC) using proton (¹H) magnetic resonance spectroscopy (MRS) during cold preservation.

Materials and methods

Grafts from 11 human donors were investigated. Each pancreas was perfused in situ with histidine-tryptophan-ketoglutarate (HTK) or with University of Wisconsin solution and placed into a transport container. Temperature of the grafts was maintained at 4 ± 2 °C during transport to our hospital and MR scanning. A 1.5 T clinical scanner was used for the measurements. Single-voxel PRESS spectra were acquired using transmit–receiver head coil.

Results

Relaxation times were measured for lipid (–CH₂–)_n (T₁, 287 ± 60 ms; T₂, 27 ± 4 ms), and tissue water (T₁, 670 ± 69 ms; T₂, 77 ± 17 ms). Average total fat, and intracellular lipids of NAPC concentrations were 79.2 ± 100.8 (range 2.4–304.4), and 2.9 ± 1.2 mmol/kg ww, respectively.

Conclusion

We have shown that ¹H-MRS is a useful tool for the estimation of pancreas graft lipid concentrations. Total pancreatic fat and especially content of intracellular lipids of NAPC are valuable measures for inspection of graft quality prior to transplantation or islet of Langerhans isolation.

     

In vivo 13C chemical shift imaging of the human liver

Chemical shift imaging (CSI) was applied to measure natural abundance proton-decoupled¹³C-NMR spectra of the human liver. Large surface coils were designed for¹³C spectra acquisition (16-cm-diameter circular coil) as well as for proton imaging and decoupling (21×20-cm butterfly coil). Such sizes allowed deep observations of the abdomen. A space matrix of 8×4 voxels (4×8 cm each) was defined using 32 phase-encoding steps. Magnetic field gradients were adjusted on multicompartment phantoms to limit contamination between voxels. Spectral maps containing {¹H}-¹³C spectra of liver from healthy volunteers with an acceptable signal-to-noise ratio were recorded within 20 min. Liver spectra exhibited well-defined resonances corresponding to fatty acyl chains, carbonyl groups, and sugars. The (C-l)-glycogen resonance was also detected under such conditions. Such a technique would be of interest in the development of metabolic investigations on the human liverin vivo.     

Detection of polyunsaturated omega-6 fatty acid in human malignant prostate tissue by 1D and 2D high-resolution magic angle spinning NMR spectroscopy

Object  

Polyunsaturated omega-6 fatty acids (PUFAs) have been shown to promote prostate cancer. Here, we describe the use of HRMAS NMR spectroscopy to detect omega-6 PUFA species in prostate tissues.     

In vivo1H-MR spectroscopy of the human heart

4. Conclusions Combined respiratory and cardiac triggering improves the localization accuracy and spectral quality in cardiac¹H-MRS dramatically leading to substantially increased spectral reproducibility. The best practical realization of double triggering turned out to be the use of the ECG amplitude when making use of the fact that it is modulated by respiration. In spite of the spectral quality achieved in most subjects, we still fail to record satisfactory spectra in a minority of subjects. The reasons for this are not understood at present but must be some particulars of either a given subject or the experimental setup. The cardiac¹H-MR spectra contain quantifiable contributions from creatine, TMA, lipids, and probably taurine. It is possible that the spectral contributions of creatine are subject to dipolar coupling similar to the observations for skeletal muscle.     

PASADENA hyperpolarization of 13C biomolecules: equipment design and installation

Object  The PASADENA method has achieved hyperpolarization of 16–20% (exceeding 40,000-fold signal enhancement at 4.7 T), in liquid samples of biological molecules relevant to in vivo MRI and MRS. However, there exists no commercial apparatus to perform this experiment conveniently and reproducibly on the routine basis necessary for translation of PASADENA to questions of biomedical importance. The present paper describes equipment designed for rapid production of six to eight liquid samples per hour with high reproducibility of hyperpolarization. Materials and methods  Drawing on an earlier, but unpublished, prototype, we provide diagrams of a delivery circuit, a laminar-flow reaction chamber within a low field NMR contained in a compact, movable housing. Assembly instructions are provided from which a computer driven, semi-automated PASADENA polarizer can be constructed. Results  Together with an available parahydrogen generator, the polarizer, which can be operated by a single investigator, completes one cycle of hyperpolarization each 52 s. Evidence of efficacy is presented. In contrast to competing, commercially available devices for dynamic nuclear polarization which characteristically require 90 min per cycle, PASADENA provides a low-cost alternative for high throughput. Conclusions  This equipment is suited to investigators who have an established small animal NMR and wish to explore the potential of heteronuclear (¹³ C and ¹⁵ N) MRI, MRS, which harnesses the enormous sensitivity gain offered by hyperpolarization.     

A simple and unified proof of dyadic shift invariance and theextension to cyclic shift invariance

A simple and unified proof of the dyadic shift invariance and an extension to cyclic shift invariance are presented. First, the concept of the dyadic shift invariance (DSI) and cyclic shift invariant (CSI) functions is proposed. Basic properties of the DSI and CSI functions are considered. Then it is shown that the Walsh-Hadamard transform (WHT) and discrete Fourier transform (DFT) are, in fact, special cases of the DSI and CSI functions, respectively. Many properties of the WHT and DFT can then be obtained easily from DSI and CSI points of view. The proposed unified approach is simple and rigorous. It is also shown that the properties of the WHT and DFT are the consequence of the basic principles of the DSI and CSI functions     

实施战略性人力资源规划是企业成功的关键

人力资源规划,对于企业总体发展战略规划的实施具有举足轻重的作用,尤其是在企业内外部环境瞬息万变的今天,好的规划有助于减少未来的不确定性。科学制定和实施人力资源规划,实现人力资源与其他资源有效配置,可使现代企业在激烈的市场竞争中经得起考验。     

A comparison of the proton relaxation in human epithelial tumors and associated uninvolved tissue

Longitudinal and transverse proton relaxation from several sets of paired surgical samples of human epithelial tumors and associated histologically uninvolved tissues were studied at 37°C and at 20 MHz. Broad distributions of exponential terms fit allT ₁ andT ₂ decays well. The tumor times showed over twice the scatter of the associated tissue times but no clear trends. Although the nontumor relaxation show little variability, the tumor curves can have either longer or shorter times and different shapes.     

CDMA移频直放站的规划和应用

本文通过对CDMA移频直放站的分析介绍,讨论了直放站对基站接受灵敏度的影响,并利用上下链路分析提出了移频直放站规划设计的思路和方法.     

卫星通信的发展及其关键技术

由于科学技术的发展和多媒体业务的需求,现代通信技术发展异常迅速。文章通过对卫星通信应用现状的介绍,分析了卫星通信技术在当今全球信息化浪潮中所处的地位、作用及遇到的挑战,探讨了其在未来的应用竞争环境中所具有的优势和劣势,总结了演变趋势及需要解决的关键技术问题,给出了它在未来通信网中的主要应用模式。     

Quantitative metabolic profiles of 2nd and 3rd trimester human amniotic fluid using 1H HR-MAS spectroscopy

Object

To establish and compare normative metabolite concentrations in 2nd and 3rd trimester human amniotic fluid samples in an effort to reveal metabolic biomarkers of fetal health and development.

Materials and methods

Twenty-one metabolite concentrations were compared between 2nd (15–27 weeks gestation, N = 23) and 3rd (29–39 weeks gestation, N = 27) trimester amniotic fluid samples using ¹H high resolution magic angle spinning (HR-MAS) spectroscopy. Data were acquired using the electronic reference to access in vivo concentrations method and quantified using a modified semi-parametric quantum estimation algorithm modified for high-resolution ex vivo data.

Results

Sixteen of 21 metabolite concentrations differed significantly between 2nd and 3rd trimester groups. Betaine (0.00846±0.00206 mmol/kg vs. 0.0133±0.0058 mmol/kg, P < 0.002) and creatinine (0.0124±0.0058 mmol/kg vs. 0.247±0.011 mmol/kg, P < 0.001) concentrations increased significantly, while glucose (5.96±1.66 mmol/kg vs. 2.41±1.69 mmol/kg, P < 0.001), citrate (0.740±0.217 mmol/kg vs. 0.399±0.137 mmol/kg, P < 0.001), pyruvate (0.0659±0.0103 mmol/kg vs. 0.0299±0.286 mmol/kg, P < 0.001), and numerous amino acid (e.g. alanine, glutamate, isoleucine, leucine, lysine, and valine) concentrations decreased significantly with advancing gestation. A stepwise multiple linear regression model applied to 50 samples showed that gestational age can be accurately predicted using combinations of alanine, glucose and creatinine concentrations.

Conclusion

These results provide key normative data for 2nd and 3rd trimester amniotic fluid metabolite concentrations and provide the foundation for future development of magnetic resonance spectroscopy (MRS) biomarkers to evaluate fetal health and development.     

Cellular/tissue engineering - Cardiomyoplasty: The prospect of human stem cells

Currently, the largest ongoing effort in cellular and tissue cardiomyoplasty therapies is the search for a suitable cell source. The following are the desirable attributes of an ideal cell source: 1) autologous (not requiring immune suppression), 2) able to substantially proliferate in vitro, 3) having a similar function when compared to host cardiomyocytes, and 4) able to couple with the host cells electrically and mechanically. A number of cell types have been attempted for cellular and tissue engineering therapies in the heart.     

Investigation of multidrug resistance in cultured human renal cell carcinoma cells by 31P-NMR spectroscopy and treatment survival assays

KTCTL-26 and KTCTL-2 are renal cell carcinoma (RCC) lines with high and lowexpression of P-170 glycoprotein, respectively. Inherent differences between the two cell lines in terms of phosphate metabolites and growth characteristics in culture were examined for possible association with multidrug resistance (MDR). Differences in response to drug treatment were investigated for 40 h incubations with various doses of vinblastine (VBL) alone or as cotreatments with various concentrations of the calcium antagonist diltiazem (DIL) and/or interferon–α (IFN-α). Treatment effects were quantitated using the MTT survival assay and ³¹P magnetic resonance spectroscopy (MRS) to determine phosphate metabolite profiles in intact cells. KTCTL-2 and KTCTL-26 cells exhibited significant inherent differences in phosphocholine, glycerophosphocholine, glycerophosphoethanolamine, and phosphocreatine levels. KTCTL-26 cells were more sensitive than KTCTL-2 to 0.011μM VBL alone (87% vs. 102% survival) or to 0.011μM BL + 10μM DIL (55% vs. 80% survival). The latter treatment resulted in a significant decrease in the ratio of phosphocholine to glycerophosphocholine in KTCTL-26 cells but no significant changes in phosphate metabolites in KTCTL-2 cells. Metabolomic ³¹P MRS detects different metabolite profiles for RCC cell lines with different MDR phenotypes and may be useful for noninvasive characterization of tumors in a clinical setting.This revised version was published online in August 2005 with a corrected sequence of authors.     

Influence of cytosolic pH onin vivo assessment of human muscle mitochondrial respiration by phosphorus magnetic resonance spectroscopy

The authors present anin vivo phosphorus magnetic resonance spectroscopy systematic study on the effects of cytosolic pH on skeletal muscle mitochondrial respiration in human calf muscle. In 49 normal subjects, the effect of cytosolic pH on kinetics of phosphocreatine and adenosine diphosphate recovery and on maximum rate of mitochondrial adenosine triphosphate production (Q_max) was evaluation. The results show a strong relationship between the rate of postexercise phosphocreatine recovery and the lowest value of cytosolic pH reached during recovery from exercise (termed minimum pH;r=0.89); in constrast, both adenosine diphosphate recovery halftime andQ _max were independent of cytosolic pH at the end of exercise.     

呼叫中心的技术研究和方案实现

呼叫中心是当前发展的一个热点,文中首先介绍了呼叫中心的概念,然后给出了呼叫中心的典型技术及其方案实现,并详细地讨论了IP呼叫中心的关键技术,最后简要地介绍了呼叫中心的未来发展趋势。     

Proton MR spectroscopy of prostatic tissue focused on the etection of spermine, a possible biomarker of malignant behavior in prostate cancer

To investigate whether polyamines may be valuable diagnostic and prognostic markers in prostate cancer, the presence of alyamines was studied in various human prostatic tissues using both proton magnetic resonance (MR) spectroscopy and righ-pressure liquid chromatography (HPLC). The HPLC results showed that normal and benign hyperplastic prostatic tissues re characterized by a high content of spermine. Spermine levels were reduced in tumor tissue, especially in prostatic carcinoma h metastases, and in xenografts of human prostatic carcinoma cells. These preliminary results indicate that spermine may be d as a biomarker for malignant behavior. The MR spectroscopy study showed that it is possible to detect spermine resonances prostatic biopsy material by one-dimensional and two-dimensional J-resolved MR spectroscopy at high field (600 MHz). ocalized one-dimensional in vitro MR spectra obtained at the clinical field strength of 1.5 T showed spermine signals in the region between 3.0 and 3.3 ppm. In in vivo MR spectra of the human prostate, however, these signals were obscured by esonances of choline (3.2 ppm) and creatine (3.0 ppm).