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Biomedical subjects

J X Yang

Publications and source records attributed to J X Yang.

At least 19 recordsLinked to original sources
PubMed2001

Chinese life cycle impact assessment factors.

The methodological basis and procedures for determination of Chinese normalization references and weighting factors according to the EDIP-method is described. According to Chinese industrial development intensity and population density, China was divided into three regions and the normalization references for each region were calculated on the basis of an inventory of all of the region's environmental emissions in 1990. The normalization reference was determined as the total environmental impact potential for the area in question in 1990 (EP(j)90) divided by the population. The weighting factor was determined as the normalization reference (ER(j)90) divided by society's target contribution in the year 2000 based on Chinese political reduction plans, ER(j)T2000. This paper presents and discuss results obtained for eight different environmental impact categories relevant for China: global warming, stratospheric ozone depletion, acidification, nutrient enrichment, photochemical ozone formation and generation of bulk waste, hazardous waste and slag and ashes.

China↗
PubMed1999

Long-term inhalable particles and other air pollutants related to mortality in nonsmokers.

Long-term ambient concentrations of inhalable particles less than 10 microm in diameter (PM10) (1973- 1992) and other air pollutants-total suspended sulfates, sulfur dioxide, ozone (O3), and nitrogen dioxide-were related to 1977-1992 mortality in a cohort of 6,338 nonsmoking California Seventh-day Adventists. In both sexes, PM10 showed a strong association with mortality for any mention of nonmalignant respiratory disease on the death certificate, adjusting for a wide range of potentially confounding factors, including occupational and indoor sources of air pollutants. The adjusted relative risk (RR) for this cause of death as associated with an interquartile range (IQR) difference of 43 d/yr when PM10 exceeded 100 microg/m3 was 1.18 (95% confidence interval [CI]: 1.02, 1.36). In males, PM10 showed a strong association with lung cancer deaths-RR for an IQR was 2.38 (95% CI: 1.42, 3.97). Ozone showed an even stronger association with lung cancer mortality for males with an RR of 4.19 (95% CI: 1.81, 9.69) for the IQR difference of 551 h/yr when O3 exceeded 100 parts per billion. Sulfur dioxide showed strong associations with lung cancer mortality for both sexes. Other pollutants showed weak or no association with mortality.

Adult↗
PubMed1998

Gene encoding a human testis Sertoli cell component related to LIM domain protein.

The cDNA (HED-2) encoding a 20 kDa protein found in mammalian epididymal fluid was isolated from a human testis expression library. It is composed of 1908 bp, containing a reading frame of 1479 bp, coding a polypeptide consisting of 493 amino acids, and assigned the accession number: U15158 by GenBank (Biochem. Mol. Biol. Int. 34, 1131-1136, 1994). HED-2 has 99% identity with the zyxin gene in amino acid sequence, a component of cell junction matrix and a member of the LIM domain protein family. Northern blot analysis of RNAs prepared from various human tissues showed that the HED-2 gene was expressed in all tissues analyzed. Sertoli cells of human testis expressed the gene as determined by an in situ hybridization method. The present study shows that the HED-2 gene is a member of the LIM domain protein family.

Amino Acid Sequence↗
PubMed1996

Adenosine diphosphate inhibits the serotonin transporter.

Adenosine 5'-diphosphate (ADP) caused rapid and significant reductions in the rates of [3H]serotonin uptake observed for human platelets, human platelet vesicles, and rat brain synaptic vesicles. Estimated Vmax values in platelets (N = 15). platelet vesicles (N = 3), and synaptic vesicles (N = 3) exposed to 100 microM ADP were 42.3 +/- 11.4%, 78.8 +/- 1.4%, and 56.8 +/- 9.9% of control values, respectively. The EC50 values observed for ADP in platelets and platelet vesicles were 10-24 microM. Exposure to 100 microM ADP had small, inconsistent effects on KM values observed for the platelet transporter. ADP (100 microM) caused only a slight competitive inhibition of the platelet membrane binding of [3H]citalopram, a ligand for the 5HT uptake site of the transporter (5.0% displacement of 1.0 nM [3H]citalopram, 13% increase in apparent KD). The ADP analogue 2-methylthioADP caused similar decreases in the rates of platelet [3H]serotonin uptake, while a number of other related compounds had little or no effect on rates of platelet uptake. The ADP-effect on uptake was rapid, occurring in less than 2.5 s. and was additive with reductions produced by protein kinase C (PKC) activation. The ADP-induced decreases in uptake did not appear to occur through the ADP receptor or known platelet second messenger systems. The exact mechanism of the ADP-effect and its functional significance remain to be determined.

Adenosine Diphosphate↗
PubMed1994

Matrix decompositions of two-dimensional nuclear magnetic resonance spectra.

Two-dimensional NMR spectra are rectangular arrays of real numbers, which are commonly regarded as digitized images to be analyzed visually. If one treats them instead as mathematical matrices, linear algebra techniques can also be used to extract valuable information from them. This matrix approach is greatly facilitated by means of a physically significant decomposition of these spectra into a product of matrices--namely, S = PAPT. Here, P denotes a matrix whose columns contain the digitized contours of each individual peak or multiple in the one-dimensional spectrum, PT is its transpose, and A is an interaction matrix specific to the experiment in question. The practical applications of this decomposition are considered in detail for two important types of two-dimensional NMR spectra, double quantum-filtered correlated spectroscopy and nuclear Overhauser effect spectroscopy, both in the weak-coupling approximation. The elements of A are the signed intensities of the cross-peaks in a double quantum-filtered correlated spectrum, or the integrated cross-peak intensities in the case of a nuclear Overhauser effect spectrum. This decomposition not only permits these spectra to be efficiently simulated but also permits the corresponding inverse problems to be given an elegant mathematical formulation to which standard numerical methods are applicable. Finally, the extension of this decomposition to the case of strong coupling is given.

Algorithms↗
PubMed1994

An evaluation of least-squares fits to COSY spectra as a means of estimating proton-proton coupling constants. I. Simulated test problems.

A computational method is described that takes an initial estimate of the chemical shifts, line widths and scalar coupling constants for the protons in a molecule, and refines this estimate so as to improve the least-squares fit between an experimental COSY spectrum and the spectrum simulated from these parameters in the weak-coupling approximation. In order to evaluate the potential of such refinements for estimating these parameters from COSY experiments, the method has been applied to a large number of sample problems which were themselves simulated from standard conformations of the amino acids, along with 25 near-native conformations of the protein bovine pancreatic trypsin inhibitor. The results of this evaluation show that: (i) if the chemical shifts are known to within ca. 0.01 ppm and no noise or artifacts are present in the data, the method is capable of recovering the correct coupling constants, starting from essentially arbitrary values, to within 0.1 Hz in almost all cases. (ii) Although the precision of these estimates of the coupling constants is degraded by the limited resolution, noise and artifacts present in most experimental spectra, the large majority of coupling constants can still be recovered to within 1.0 Hz; the local minimum problem is not made significantly worse by such defects in the data. (iii) The method assigns an 'effective' line width to all the resonances, and in the process can resolve overlapping cross peaks. (iv) The method is not capable of determining the chemical shifts a priori, due to the presence of numerous local minima in the least-squares residual as a function of these parameters.

Computer Simulation↗
PubMed1994

An evaluation of least-squares fits to COSY spectra as a means of estimating proton-proton coupling constants. II. Applications to polypeptides.

A new computational method for simultaneously estimating all the proton-proton coupling constants in a molecule from COSY spectra [Yang, J.-X. and Havel, T.F. (1994) J. Biomol. NMR, 4, 807-826] is applied to experimental data from two polypeptides. The first of these is a cyclic hexapeptide denoted as VDA (-D-Ala1-Phe2-Trp3-Lys(Z)4-Val5-Phe6-), in deuterated DMSO, while the second is a 39-residue protein, called decorsin, in aqueous solution. The effect of different data processing strategies and different initial parameter values on the accuracy of the coupling constants was explored. In the case of VDA, most of the coupling constants did not depend strongly on the initial values chosen for the optimization or on how the data were processed. This, together with our previous experience using simulated data, implies strongly that these values are accurate estimates of the coupling constants. They also differ by an average of only 0.36 Hz from the values of the 14 coupling constants that could be measured independently by established methods. In the case of decorsin, many of the coupling constants exhibited a moderate dependence on their initial values and a strong dependence on how the data were processed. With the most successful data processing strategy, the amide-alpha coupling constants differed by an average of 1.11 Hz from the 21 values that could be measured by established methods, while two thirds of the three-bond coupling constants fell within 1.0 Hz of the ranges obtained by applying the Karplus relation to an independently computed ensemble of distance geometry structures. The averages of the coupling constants over multiple optimizations using random initial values were computed in order to obtain the best possible estimates of the coupling constants. Most clearly incorrect averages can be identified by large standard deviations in the coupling constants or the associated line widths and chemical shifts, and can be explained by strong coupling and/or overlap with the water signal, the diagonal peaks or other cross peaks.

Amino Acid Sequence↗
PubMed1994

[A pharmacokinetic study of subconjunctival polyphase liposome 5-fluorouracil].

5-Fu polyphase liposome was prepared by fusing the drug with lecithin and cholesterol, the rate of encapsulation being 52%, and 97% of the particles were less than 2 microns in diameter and stable against heat and cold. 5 mg of tritiated 5-Fu in 0.5 ml of the polyphase liposome preparation was injected subconjunctivally in rabbits. The concentrations of 5-Fu in the conjunctiva, the sclera, and the conjunctiva-Tenen's capsule-sclera en bloc 180 degrees from the site of injection were measured by the scintillation method 12, 24, 48, 72 and 96 hours after injection to be no less than 0.2 microgram, the ID50 of fibroblast proliferation. These findings suggested that 5-Fu polyphase liposome preparation might be substituted for 5-Fu solution in the filtering operation to reduce the frequency of injections and to attenuate the side effects.

Animals↗
PubMed1994

[Study of clinical pathology and discussion of surgical strategy in comprehensive mitral valvuloplasty].

The results of clinical pathologic study of 162 mitral valves (MV) intraoperatively and pathologic anatomy of 8 excised MV were reported. Type I 64 cases, type II 23 cases and type III 75 cases. The pathogenic causes were congenital heart disease in 22 cases degeneration in 27 cases infective endocarditis in 1 case and rheumatic disease in 112 cases. Of the excised MV, 7 rheumatic lesion with type III. All valve components were involved. The valve leaflets thickened significantly and valve orifice changed like a funnel or semi-funnel shape. Under light microscope there was no interface between the increased collagen fibers and the valve tissue. Some superficial collagen fibers appeared hyalinosis. The calcification, local necrosis and inflammatory cell infiltration could be seen in some cases but the rheumatic bodies and the chordae tendineae wrapped up in the thickened valve tissue only in one case respectively degenerative lesion with thin chordae tendineae which appeared muco-hyalinosis and ruptured in three points. According to the clinical pathology of MV the indication and surgical technique are discussed.

Adolescent↗
PubMed1993

SESAME: a least-squares approach to the evaluation of protein structures computed from NMR data.

A method is proposed for defining a probability distribution on an ensemble of protein conformations from a 2D NOE spectrum, while at the same time back-calculating the experimental spectrum from the ensemble. This enables one to assess the relative quality and significance of the conformations, and to test the consistency of the ensemble as a whole with the experimental spectrum. The method eliminates the need to integrate the cross-peak intensities and is surprisingly insensitive to random noise in the spectrum. In this communication, these advantages are demonstrated by applying the method to simulated data, for which the correct result is already known.

Magnetic Resonance Spectroscopy↗
PubMed1992

Platelet dense granule release reaction monitored by high-performance liquid chromatography-fluorometric determination of endogenous serotonin.

The platelet dense granule release reaction was monitored by measuring the serotonin content of platelets collected by filtration following release. Sensitive HPLC-fluorometric analysis permitted release to be assessed using small (25-50 microliters) volumes of plasma and whole blood. Release could be examined for periods as short as 1 s due to the rapid stoppage effected by filtration. The half-life of thrombin-stimulated (1 U/ml) release was 2-3 s, the EC50 values observed for thrombin-stimulated release over a 60-s release period were 0.01-0.03 U/ml for diluted whole blood and plasma samples.

Blood Platelets↗
PubMed1991

Dialectic classification of syndrome diagnosis in traditional Chinese medicine used as new criterion for evaluating prognosis of patients with cervical cancer.

254 patients with cervical cancer were treated by radiotherapy from Jan 1979 to Dec 1984. All the patients were followed up at least for more than 3 years, of them 180 for over 5 years. According to various symptoms, picture of the tongue and pulse condition, the disease was classified into 4 types, namely: 1) deficiency of liver-yin and kidney-yin, 2) deficiency of splenic qi, 3) internal retention of damp-heat, and 4) stagnation of qi and blood or stagnation of liver qi. The survival rate of the various types was quite different. The patients of type 4 had the worst prognosis. The prognosis of patients with type 1 was significantly better than that of patients with type 4. The difference was of statistical significance (P less than 0.01).

Carcinoma, Squamous Cell↗
PubMed1989

[The efficacy of electromyographic biofeedback treatment on cardiovascular disease and the correlation of type A behavior and traditional Chinese medicine syndrome differentiation].

Using the method of trilineal relaxation training, electromyographic biofeedback technic (EMGBT) in the treatment of 400 cases of cardiovascular disease was reported. There were 274 (68.5%) cases of hypertension and coronary heart disease, more than other diseases. After treatment, average systolic blood pressure reduced 1.85 Kpa (13.86 mmHg), and average diastolic blood pressure reduced 1.29 Kpa (9.73 mmHg). The treatment was more effective for the type A behavior patients, so was it in the treatment of various extrasystoles (75%). To analyse the correlation between TCM syndrome differentiation and behavior pattern, it was found that there were 90.66% of Heart Yin deficiency and Liver Yang ( ) associated with Phlegm among type A behavior patients and 82.5% of Heart Qi ( ) Yang deficiency and Qi Yin deficiency among non-type A behavior patients. By means of relaxation training, EMGBT might reduce sympathetic tone, dilate blood vessels, so as to reduce blood pressure and treat arrhythmia.

Adolescent↗