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Biomedical subjects

G Li

Publications and source records attributed to G Li.

At least 991 records · Page 55Linked to original sources
PubMed1991

Environmental determinants of lung cancer in Shenyang, China.

To investigate determinants of the high rates of lung cancer in Shenyang, an industrial city in north-eastern China, a case-control study was conducted. Interviews with 1249 lung cancer patients and 1345 population-based controls revealed that cigarette smoking was the main cause of lung cancer. Smoking accounted for 55% of the lung tumours in men and 37% in women. In addition, air pollution from coal-burning heating and cooking devices was significantly linked to lung cancer, with risks rising in proportion to duration of exposure to indoor pollutants. Measurement of benzo[a]pyrene revealed average wintertime levels in air that were nearly 60 times the recommended upper limit for US cities, with even higher concentrations indoors in traditional single-storey homes using coal-burning kang (stoves). Occupational factors were also involved, the risk being elevated by three fold among smelter workers. Soil levels of arsenic and other metals rose with increasing proximity to the Shenyang copper smelter, and elevated risks of lung cancer were found among men, but not women, living within 1 km of its central stacks. Prior nonmalignant lung disease was common and was reported more often among the lung cancer patients than among controls. The findings suggest that cigarette smoking and environmental pollutants combine to account for most of the excess risk of lung cancer in this population.

Adult↗
PubMed1991

[Preliminary infection source of downy mildew of Corydalis yanhusuo W. T. Wang].

The downy mildew of Corydalis yanhusuo caused by Peronospora corydalis usually brings about devastating harm in Anhui Province. In the past, it was generally held that the spores in diseased remains buried in soil were the main source of preliminary infection. But, according to our test, it is the mycelia in tubers that are mainly the preliminary infections source.

Oomycetes↗
PubMed1991

[Isolation of bilirubin oxidase from Myrothecium verrucaria and the optimum conditions of enzyme production].

A bilirubin oxidase (EC 1.3.3.5) producing strain, Mv 2.1089, was isolated from several strains of Myrothecium verrucaria by dilution method. The optimum conditions of enzyme production were investigated and the results were as follows: the suitable medium was cultured at 25 degrees C on a rotating shaker glucose and peptone, at pH 6.0. The strain was cultured at 25 degrees C on a rotating shaker (150 r/min) for 96 h. Bilirubin oxidase with 0.5-1.5 u/ml was obtained in the culture medium.

Mitosporic Fungi↗
PubMed1991

Clinical genetic studies of Alzheimer's disease.

In this article, the authors review the genetic investigations in Alzheimer's disease employing epidemiologic study techniques--mainly case-control, twin, and cumulative risk studies--as well as pedigree and genetic linkage studies and discuss the implications these studies have for identifying and characterizing a possible genetic etiology of Alzheimer's disease. Some of the methodologic issues associated with each of these techniques and the more general problems associated with identifying genetic factors in Alzheimer's disease are discussed, and some directions and prospects for future research in this area are indicated.

Aged↗
PubMed1991

Carpal kinematics of lunotriquetral dissociations.

The purpose of this study is to investigate the carpal kinematics after serial arthroscopic sectioning of the ligaments at the lunotriquetral joint, without damaging the capsule and other soft tissues of the wrist. Six cadaver wrists were studied and a custom designed three-dimensional mechanical digitizer was utilized. Three sets of digitization were performed for a normal state, after arthroscopic sectioning of lunotriquetral interosseous ligament (stage A), and after further sectioning of volar radiolunotriquetral ligament (stage B). Motion of the scaphoid, lunate, triquetrum, capitate and hamate was studied. The results indicated that the motion of the triquetrum was significantly increased at stage A, particularly after 15 degrees of ulnar deviation. An increased motion at the lunotriquetral joint was observed at stage B, which was mainly due to the significantly decreased lunate extension motion and the increased triquetrum extension motion during wrist extension. This study suggested that the lunotriquetral interosseous ligament plays the most important role for the stabilization of the lunotriquetral joint during wrist ulnar deviation, while the volar radiolunotriquetral ligament may function as a stabilizer for the lunotriquetral joint during wrist extension.

Adult↗
PubMed1990

Lipid-protein interactions in thylakoid membranes of chilling-resistant and -sensitive plants studied by spin label electron spin resonance spectroscopy.

Lipid-protein interactions in thylakoid membranes from lettuce, pea, tomato, and cucumber have been studied using spin-labeled analogues of the thylakoid membrane lipid components, monogalactosyl diglyceride and phosphatidylglycerol. The electron spin resonance spectra of the spin-labeled lipids all consist of two components, one corresponding to the fluid lipid environment in the membranes and the other to the motionally restricted lipids interacting with the integral membrane proteins. Comparison of the spectra from the same spin label in thylakoid membranes from different plants shows that the overall lipid fluidity in the membranes decreases with chilling sensitivity. Spectral subtraction has been used to quantitate the fraction of the membrane lipids in contact with integral membrane proteins. Thylakoid membranes of cucumber, a typical chilling-sensitive plant, have been found to have a higher proportion of motionally restricted lipids and a different lipid selectivity for lipid-protein interaction, as compared with those of pea, a typical chilling-resistant plant. This correlation with chilling sensitivity holds generally for the different plants studied. It seems likely that the chilling sensitivity in thylakoid membranes is not determined by lipid fluidity alone, but also by the lipid-protein interactions which could affect protein function in a more direct manner.

Cold Temperature↗
PubMed1990

Lipid-protein interactions in stacked and destacked thylakoid membranes and the influence of phosphorylation and illumination. Spin label ESR studies.

The effects of membrane destacking, protein phosphorylation, and continuous illumination have been studied in pea thylakoid membranes using ESR spectroscopy of an incorporated spin-labelled phosphatidylglycerol. This spin-labelled analogue of an endogenous thylakoid lipid has previously been shown to exhibit a selectivity of interaction with thylakoid proteins. Neither destacking, phosphorylation nor illumination was found to change the ESR spectra appreciably, suggesting that for phosphatidylglycerol at least, neither the number of protein-associated membrane lipids nor their pattern of selectivity was altered. The redistribution of the thylakoid protein complexes in the membrane, under these various conditions, therefore takes place with conservation of the properties of the lipid/protein interface.

Cell Membrane↗
PubMed1990

The development of the lamprey pattern generator for locomotion.

The life cycle of the lamprey includes a larval stage that can last for several years. The motor behavior of the larval lamprey, the ammocoete, has been only minimally studied and little is known of the neural correlates of that behavior. Comparison of known larval behavior to that of adults leaves unclear whether there are large or small changes in the spinal nervous system during transformation. The motor output of isolated larval and transforming spinal cords when stimulated to "swim" with D-glutamate has some differences from that of comparable adult preparations, but shares many important features with adults. Primarily, the fictive swimming is less well regulated and less stable than adults of the same species. We propose that a major difference in the structure and organization of the central pattern generator for locomotion between adults and ammocoetes is a relative lack or immaturity of some cell types that participate in the coordination of the segments and the generation of the rhythm of the periodic bursting.

Animals↗
PubMed1990

Titration of human immunodeficiency virus type 1 (HIV-1) and quantitative analysis of virus expression in vitro using liquid RNA-RNA hybridization.

An assay is described for titration of human immunodeficiency virus type 1 (HIV-1) and for quantitative analysis of virus expression in vitro. The assay utilizes a liquid RNA-RNA hybridization method coupled with reversible target capture (RTC) on oligo(dT) derivatized magnetic particles. The assay provides a rapid, specific, and sensitive method for quantitation of HIV-1 RNA molecules present either in cells or in viral particles from cell-free culture media. Chronically infected monocytoid U1.1 cells were found to carry 52 pg HIV-1 RNA per 200,000 cells (160 HIV-1 RNA molecules per cell). In contrast, acutely infected CEM and H9 cells carried 3010 and 4370 pg HIV-1 RNA per 200,000 cells (9040 and 13,110 HIV-1 RNA molecules per cell, respectively). No hybridization was observed with uninfected cells or cells infected with HIV-2, HTLV-I, HTLV-II, or EBV. Use of liquid HIV-1 RNA hybridization in association with HIV-1 protein detection methods permits more complete characterization of HIV-1 expression in host cells than either method alone, and also provides a method for standardizing preparations of virus.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Is cyclosporin A an inhibitor of drug metabolism?

1. The potential for a drug interaction between cyclosporin A and midazolam was investigated since both compounds appear to be metabolized by the same cytochrome P-450 isoenzyme. 2. In vitro evaluation of the binding of cyclosporin A to rat microsomal cytochrome P-450 indicated a Ks-value of 0.4 microM. In further studies with rat liver microsomes IC50-values of 6, 8 and 70 microM cyclosporin A were determined for the inhibition of the metabolism of midazolam to its alpha-OH-,4-OH- and di-OH-metabolites, respectively. 3. Comparative studies with human liver microsomes indicated IC50-values of approximately 300 microM for the formation of alpha-OH-midazolam and of 65 microM for the formation of 4-OH-midazolam. 4. The pharmacokinetics of a single intravenous dose of midazolam (0.075 mg kg-1) was studied in nine patients receiving cyclosporin A to prevent rejection of their transplanted kidneys. The average steady state blood concentrations of cyclosporin A, measured by r.i.a. using a specific monoclonal antibody, varied during a dosing interval between 175 and 600 ng ml-1. 5. In these patients the hepatic elimination of midazolam was characterized by a mean t1/2 (+/- s.d.) of 2.3 +/- 1.2 h and a plasma clearance (CL) of 414 +/- 95 ml min-1. These values were not different from those of normal human subjects (t1/2 = 1.5 to 4 h, CL = 350 to 700 ml min-1). 6. From the results of the in vitro experiments it is concluded that cyclosporin A may potentially inhibit drug metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Primary lymphomas of the lung: morphological, immunohistochemical and clinical features.

Sixty-two cases of primary malignant lymphoma of the lung were investigated. Fifty-eight lymphomas were of B- and two of T-cell type. Two cases of high-grade lymphoma could not be further classified. The largest group (43 cases) consisted of low-grade B-cell lymphoma of the bronchus-associated lymphoid tissue. These showed features similar to low-grade B-cell lymphomas of the mucosa-associated lymphoid tissue of the stomach. The low-grade lymphomas showed a peak occurrence in the sixth decade, the high-grade lymphomas in the seventh decade. Males predominated slightly. Three-quarters of the patients with low-grade B-cell lymphoma of the bronchus-associated lymphoid tissue showed solitary or multiple sharply defined nodules of the lung. The prognosis of the B-cell-derived lung lymphomas without constitutional symptoms was relatively favourable, regardless of whether they were of low- or high-grade malignancy, whereas patients with constitutional symptoms and the two patients with T-cell lymphomas showed a bad prognosis. However, recurrences and metastases in the lung, stomach, lymph nodes and salivary glands were seen in about 46% of the cases of low-grade B-cell lymphoma of the bronchus-associated lymphoid tissue.

Age Factors↗
PubMed1990

[Chemical evaluation of vinegar-processing method for fresh rhizoma Corydalis].

Qualitative and quantitative analysis were carried out on the samples of Rhizoma Corydalis in both the locally vinegar-processed (fresh) and traditionally vinegar-processed forms. No difference was found in the main chemical constituents. However, both the total alkaloids and the corydalis B content of the former are higher than those of the latter.

Acetates↗