Biomedical subjects

J Z Hu

Publications and source records attributed to J Z Hu.

At least 19 recordsLinked to original sources

PubMed2001

[Expressions of p-MAPK, cyclin D1, p53 protein and their relationship in osteosarcoma].

OBJECTIVE: To detect the expressions of p-MAPK, cyclin D1 and p53 protein, and investigate their relationship in osteosarcomas. METHODS: SP immunohistochemical technique was used to detect the expressions of of p-MAPK, cyclin D1 and p53 protein among the 58 osteosarcomas and 14 osteoid osteomas samples. RESULTS: The positive rates of p-MAPK, cyclin D1 and p53 protein were 77.6% (45/58), 60.3% (35/58) and 44.8% (26/58) respectively in 58 osteosarcomas, and 21.4% (3/14), 21.4% (3/14) and 7.1% (1/14) in 14 osteoid osteomas. Their positive rates and expressive intensities in osteosarcomas were higher than those in osteiod osteomas. Their positive correlation was significantly observed between p-MAPK and cyclin D1 proteins (P < 0.01), and wasn't observed between p-MAPK and p53 proteins (P < 0.05) in osteosarcomas. CONCLUSIONS: MAPK phosporylation may be one of causes for activation of cyclin D1, which play an important role in osteosarcogenesis. The mutation of p53 oncogene may not result in osteosarcogenesis by MAPK signaling pathway. Detecting p-MAPK by immunohistochemistry may be one of diagnostic indexes for osteosarcoma and benign osteoma.

Adolescent↗

PubMed2001

High-resolution (1)H NMR spectroscopy in organs and tissues using slow magic angle spinning.

It is shown that high-resolution (1)H NMR spectra of intact excised tissues and organs can be obtained by rotating the sample slowly about an axis at the magic angle of 54 degrees 44' with the external magnetic field. In this way tissue and cellular damage invoked by standard magic angle spinning (MAS) experiments, where spinning speeds of several kHz are typically employed, are minimized. Special RF pulse sequences, developed originally in solid state NMR, can be used to produce a spinning sideband-free isotropic spectrum. In this article the first results are shown of the brain, heart, liver, gluteus muscle, and kidney excised from mice using the 2D-phase-altered spinning sidebands (PASS) technique and employing MAS spinning speeds of 43-125 Hz. It was found that with slow sample spinning similar, and in some cases even better, spectral resolutions are obtained as compared with fast MAS.

Animals↗

PubMed2001

A novel dipolar dephasing method for the slow magic angle turning experiment.

Complete suppression of the resonances from protonated carbons in a slow magic angle spinning experiment can be achieved using five dipolar dephasing (Five-DD) periods distributed in one rotor period. This produces a spectrum containing only the spinning sidebands (SSB) from the nonprotonated carbons. It is shown that the SSB patterns corresponding to the nonprotonated carbons are not distorted over a wide range of dipolar dephasing times. Hence, this method can be used to obtain reliable principal values of the chemical shift tensors for each nonprotonated carbon. The Five-DD method can be readily incorporated into isotropic-anisotropic 2D experiments such as FIREMAT and 2D-PASS to facilitate the measurement of the (13)C chemical shift tensors in complex systems.

Carbon Isotopes↗

PubMed2001

[Observation on effect of radiotherapy and antike capsule combination therapy in treating nasopharyngeal cancer patients].

OBJECTIVE: To compare the effect of radiotherapy (RT) combined with Antike capsule (AC) and RT alone in treating nasopharyngeal cancer (NPC) patients. METHODS: Eighty-nine patients with pathologically confirmed NPC (stage II-IV) were randomly divided into two groups: group A (46 cases) were treated with RT, receiving 65-70 Gy/6.5-7 weeks to nasopharynx region and the same dosage to neck region, and AC was given in combination. Group B (43 cases) received the same RT alone. The total dosis of RT for complete remission (CR) of primary nasopharyngeal tumor and neck lymph nodes, the CR rate and the changes of peripheral NK cell, T lymphocyte subsets in the two groups were compared. RESULTS: The total dosis of RT for CR in group A and B were 41.6 +/- 8.9 Gy vs 50.7 +/- 9.2 Gy for primary nasopharyngeal tumor, P < 0.05 and 47.4 +/- 10.3 Gy vs 56.2 +/- 9.7 Gy for neck lymph nodes, P < 0.05. The CR rate of primary nasopharyngeal tumor in group A and B were 93.5% and 88.4% respectively, P < 0.05. The activity of NK cell as well as T3, T4 in peripheral blood increased significantly in the group A after treatment, P < 0.05, while in group B, T3, T4 lowered significantly, P < 0.05. CONCLUSION: RT combined with AC could be helpful in elevating and promoting the remission rate of primary tumor and neck lymph nodes, and AC has some effects in improving the immune function and general condition in NPC patients during RT.

Adult↗

PubMed2000

Modified spectral editing methods for (13)C CP/MAS experiments in solids.

The spectral editing approach of Zilm and coworkers utilizes polarization, polarization inversion, and spin depolarization methods for enhancing or suppressing NMR spectral lines in solids. The proposed pulse sequences allow nonprotonated C, CH, CH(2), and CH(3) types of carbon resonances to be separated from one another and identified accordingly. The former method tentatively separates the nonprotonated C and CH(3) peaks with a cutoff shift of 35 ppm. This shift is a reasonable demarcation shift for a preponderance of organic molecules, but exceptions do exist that could constitute a serious drawback in a few instances. The new approach separates the nonprotonated C and CH(3) carbon peaks unequivocally using modified pulse sequences similar to those of Zilm. Further, both the CH only and CH(2) only spectra, respectively, can be acquired directly from combining so called (+) and (-) sequences using different spectral delay periods and pulse parameters. The (+) and the (-) pulse sequences produce signals for the nonprotonated and methyl carbons that have essentially the same amplitude but opposite phases. These spectra, combined with the previously reported CH(3) and nonprontonated C only spectra, offer a complete spectral editing technique for solid samples. Examples of these spectral editing methods are provided for 3-methylglutaric acid, fumaric acid monoethyl ester, and two complex natural products: methyl o-methylpodocarpate and 10-deacetylbaccatin III.

Magnetic Resonance Spectroscopy↗

PubMed2000

1H dynamic nuclear polarization in supercritical ethylene at 1.4 T.

(1)H dynamic nuclear polarization (DNP) has been measured in supercritical ethylene in the pressure range 60-300 bar in an external field of 1.4 T. A single-cell sapphire tube was used as a high-pressure cell, and powdered 1,3-bisdiphenylene-2-phenyl allyl (BDPA) free radicals were added and distributed at the wall of the cell. At all pressures the dominant DNP mechanism was a positive Overhauser enhancement, caused by proton-electron contact interactions at the fluid/solid radical interface. The observed enhancements varied from 12 at 60 bar to 17 at 300 bar. Besides the Overhauser enhancement, small solid state and thermal mixing enhancements also were observed, indicating that part of the ethylene was adsorbed at the radical surface for a prolonged time. The impacts of the experimental conditions on the Overhauser enhancement factors are discussed, and enhancements of at least 40-60 are estimated when the EPR saturation factor and the leakage factor become maximal. These data indicate that DNP-enhanced NMR has the potential of extending the impact of NMR in research areas involving supercritical fluids.

Ethylenes↗

PubMed2000

A high-resolution (13)C 3D CSA-CSA-CSA correlation experiment by means of magic angle turning.

It is shown in this paper that a previously reported 90 degrees sample flipping (13)C 2D CSA-CSA correlation experiment may be carried out alternatively by employing constant slow sample rotation about the magic angle axis and by synchronizing the read pulse to 13 of the rotor cycle. A high-resolution 3D CSA-CSA-CSA correlation experiment based on the magic angle turning technique is reported in which the conventional 90 degrees 2D CSA-CSA powder pattern for each carbon in a system containing a number of inequivalent carbons may be separated according to the isotropic chemical shift value. The technique is demonstrated on 1,2,3-trimethoxybenzene in which all of the overlapping powder patterns that cannot be segregated by the 2D CSA-CSA experiment are resolved successfully by the 3D CSA-CSA-CSA experiment, including even the two methoxy groups (M(1) and M(3)) whose isotropic shifts, confirmed by high-speed MAS, are separated by only 1 ppm. A difference of 4 ppm in the principal value component (delta(33)) between M(1) and M(3) is readily obtained.

Algorithms↗

PubMed1998

CP/MAS 13C spectral editing of dried pine leaves.

The recently developed CP/MAS 13C spectral editing technique is applied to the study of the structure of the dried Australian pine leaves. Subspectra of quaternary carbon C, methenyl CH, methylene CH2 and methyl CH3 for Australian pine leaves have been obtained. Simple formulae for spectral editing are proposed.

Carbon Isotopes↗

PubMed1997

Technique for importing greater evolution resolution in multidimensional NMR spectrum.

A very simple and general procedure that extracts constant-evolution-frequency data from a truncated multidimensional (2D, 3D, 4D, etc.) FID is described, generalized, analyzed, and illustrated. The method replaces Fourier transformation of the evolution dimension with a linear model created from a separate, high-quality 1D FID. The equivalent of high resolution in the evolution dimension can be achieved without obtaining an extensive multidimensional FID. The analysis of the 1D FID can also be used to predict the signal to noise ratio of the extracted slices that will result from various evolution dimension sampling protocols, making it possible to develop a priori an optimal sampling strategy for the multidimensional FID. The evolution dimension need not be sampled periodically. The procedure has a potential signal-to-noise ratio advantage because it extracts usable information from a multidimensional FID at short evolution times before the magnetization has decayed significantly.

Data Interpretation, Statistical↗

PubMed1997

Dynamic nuclear polarization of nitrogen-15 in benzamide.

A 15N dynamic nuclear polarization (DNP) experiment is reported in which a 15N DNP enhancement factor of approximately 2.6 x 10(2) is obtained on free radical doped samples of 99% 15N labeled benzamide. The free radicals BDPA (1:1 complex of alpha, gamma-bisdiphenylene-beta-phenylallyl with benzene) and DPPH (2,2-Di(4-tert-octylphenyl)-1-picrylhydrazyl) are used as dopants and the spin relaxation effects of adding these dopants are studied by means of changes in proton and nitrogen T1 values of the samples. The combination in solids of a very low natural abundance, 0.37%, a small gyromagnetic ratio, and a long spin-lattice relaxation time for 15N nuclei create severe sensitivity problems that, in large part, are ameliorated by the signal enhancement observed in the 15N DNP experiment on samples containing free electrons.

Benzamides↗

PubMed1997

Measurement of spin-lattice relaxation times of 13C in organic solids.

A transient nuclear Overhauser effect (NOE) makes measurements of the 13C spin-lattice relaxation times in organic solids complicated. Extended Solomon equations are applied in order to describe 13C spin-lattice relaxation with 1H r.f. field irradiation. Spin-lattice relaxation under r.f. irradiation is shown to be generally a triple-exponential process, but it can be reduced to be single-exponential under stronger r.f. field irradiation as well as in the absence of 1H initial magnetizations. Based on numerical calculations, the difference between spin-lattice relaxation curves obeying T1C < T1H and those obeying T1C > T1H is clearly indicated. The methyl group resonances in solid-state L-valine are examined, and the experimental results agree well with the theoretical results.

Carbon Isotopes↗

PubMed1996

Spectral editing in 13C CP/MAS experiments at high magnetic field.

We show that the spinning side-bands of protonated and non-protonated carbon atoms can be well separated by means of the standard SCP and LCPD experiments at a relatively slow sample spinning rate or at high magnetic field. These experiments offer a promising way of measuring the principal values of chemical shift anisotropies via spinning side-band analysis in a moderately complex system. General spectral editing in 13C cross-polarization magic-angle spinning (CP/MAS) experiments at high field is achieved by incorporating the total side-band suppression (TOSS) pulse sequence into the standard series of spectral editing pulse sequences. It is confirmed that the relative signal intensity for a certain kind of functional group obtained at different polarization, polarization-inversion and depolarization times is about the same as that obtained at low magnetic field, and that the signal intensity distortion introduced by the TOSS sequence for resonances having different chemical shift anisotropies does not interfere with the spectral editing process. However, quantitative results can only be expected in those cases where full restoration of the intensity of the central band can be achieved by the TOSS sequence. This new strategy at high field is demonstrated by using fumaric acid monoethyl ester as a model compound. A typical application to a Chinese resin is presented, where the relative ratio of each functional group in the aliphatic portion to the total number of aliphatic carbon atoms is determined from only three experimental spectra.

Anisotropy↗

PubMed1996

The use of differential transverse relaxation to detect mobile species in solids.

Delayed acquisition of the proton NMR in selected organic molecular solids (L-alanine, durene, ethyl fumarate, and p-hydroxybenzoic acid) is shown to allow the observation of mobile species in the presence of relatively rigid bulk molecules. The mobility is found to be thermally activated. The combination of the thermally activated motion and magic-angle spinning leads to a fraction of these species moving nearly isotropically on the time scale of the inverse of the homonuclear dipolar splitting. In the case of ethyl fumarate and alanine, there exist populations with differing values of T1 and T1 row. This indicates the co-existence of relatively rigid and relatively mobile molecules in the same sample. The intensities under delayed acquisition cannot always be trusted to yield quantitative information. Comparison of spectra taken under delayed acquisition and under the CRAMPS (B.C. Gerstein, R.G. Pembleton, R.C. Wilson and L.M. Ryan, J. Chem. Phys., 66 (1977)361) technique is made.

Alanine↗

PubMed1996

High resolution 1H spectra of powdered solids observed by Hahn echo pulse sequence with magic-angle spinning.

The 1H magic-angle spinning (MAS) spectrum for a typical powdered solid is composed of a high resolution component and a broadline component. The high resolution component can be well isolated from the broadline component by the Hahn echo sequence with a long echo time. Compared with CRAMPS experiment, which measures the proton system as a whole, the high resolution echo-MAS method measures only a fraction of the solid, which is usually small at room temperature and quite different from the majority of the solid in both molecular motion and chemical environment. It is shown that for a sample of fumaric acid monoethyl ester, the chemical shifts of the high resolution component are apparently distinguishable from the isotropic chemical shifts of the broadline component in the CRAMPS spectrum as the temperature approaches the melting point. In addition, for a sample of malonic acid, the echo-MAS spectrum is sensitive to moisture and temperature, while its corresponding CRAMPS spectrum is not. It is suggested that the molecules which produce the high resolution component are related to the lattice defects in a solid, including the surface disorder of the polycrystallites, while the molecules that generate the broadline component are located on the rigid lattice of the solid.

Chemical Phenomena↗

PubMed1995

Use of relaxation agent doping to shorten very long spin-lattice relaxation times in a magic-angle turning experiment.

A practical method is described for measuring the principal values of the chemical shift tensors in compounds with very long proton spin-lattice relaxation times (T1). This technique involves shortening the effective proton T1. by mixing a compound of interest with another compound having a much shorter T1 value. The doped mixture, partly consisting of a monophasic glass, allows efficient intermolecular spin diffusion between the two compounds. Using a slow magic-angle turning (MAT) experiment, we have successfully used such mixtures to measure the principal values of the chemical shift tensors of all the carbons in dibenzofuran in just four days. Without using this technique the experimental time required for the pure compound would have been several months.

Benzofurans↗

PubMed1994

Measurement of 13C chemical shift tensor principal values with a magic-angle turning experiment.

The magic-angle turning (MAT) experiment introduced by Gan is developed into a powerful and routine method for measuring the principal values of 13C chemical shift tensors in powdered solids. A large-volume MAT probe with stable rotation frequencies down to 22 Hz is described. A triple-echo MAT pulse sequence is introduced to improve the quality of the two-dimensional baseplane. It is shown that measurements of the principal values of chemical shift tensors in complex compounds can be enhanced by using either short contact times or dipolar dephasing pulse sequences to isolate the powder patterns from protonated or non-protonated carbons, respectively. A model compound, 1,2,3-trimethoxybenzene, is used to demonstrate these techniques, and the 13C principal values in 2,3-dimethylnaphthalene and Pocahontas coal are reported as typical examples.

Anisoles↗

PubMed1993

Improvements to the magic angle hopping experiment.

Several improvements to the magic angle hopping experiment first introduced by Bax et al. [J. Magn. Reson., 52 (1983) 147] are presented. A dc servo motor driven sample hopping mechanism which requires less than 60 ms to accomplish a 120 degrees sample rotation is described. Modifications to the data acquisition process, including starting the acquisition period immediately after the second hop and acquiring a hypercomplex data set, are also presented. Principal values of the 13C chemical shielding tensor are measured for 1,2,3-trimethoxybenzene and 2,6-dimethoxynaphthalene.

Magnetic Resonance Spectroscopy↗

PubMed1993

[Fibrobronchoscopy in the diagnosis of middle lobe syndrome].

236 cases with middle lobe syndrome were examined with fibrobronchoscope. The total rate of positive finding was 92.8% (219/236). Inflammation (167 cases), lung cancer (47 cases), tuberculosis (17 cases) accounted for most of the cases. The diagnostic rate for the three above-mentioned diseases were 97.6%, 87.2% and 58.8% respectively. Fibrobronchoscopy was also of significant diagnostic value in determining other uncommon cases such as broncholithiasis, lipoid pneumonia, lung infiltration in leukemia, etc. The etiology, chest X-ray (including CT) presentations of this middle lobe syndrome and the diagnostic value of fibrobronchoscopy were discussed. Our experience suggests that this procedure is both safe and effective in the diagnosis of patients with middle lobe syndrome.

Adenocarcinoma↗