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Biomedical subjects

W X Li

Publications and source records attributed to W X Li.

At least 73 records · Page 4Linked to original sources
PubMed1993

Low-dose-rate irradiation of rat embryo cells containing the Ha-ras oncogene.

Rat embryo cells and derived transfectants containing the Ha-ras oncogenes were irradiated with 60Co gamma rays at dose rates of 0.72, 0.066, 0.035, and 0.018 Gy/min. The measured dose response of cell survival shows that the oncogene-containing cells exhibit higher survival levels at all doses than the parental cells at every dose rate. The response of the cells containing the ras oncogene also became dose-rate independent at a higher dose rate, perhaps indicative of a greater repair capability relative to that of the primary cells.

Animals↗
PubMed1993

[Serum cholesterol and cancer mortality: eleven-year prospective cohort study on more than nine thousand persons].

Nine thousand and twenty-one employees aged 35-64 years were investigated in the 70s in the meantime with serum cholesterol and other measurements taken, and followed up for 11 years on the average. There were 595 deaths and 64 loss of follow-up. The total number of cancer death was 263 that of primary liver cancer was 51. Subjects were divided into 4 similar sized groups according to serum cholesterol level at basal measurement. No evidence of association of serum cholesterol level with total cancer mortality was seen by Log-rank trend test. But negative correlation was significant between serum cholesterol level and liver cancer (P < 0.05). By Cox regression analysis such negative correlation was found to be independent of other variables (Z = -2.18, P < 0.05). This negative correlation persisted even after 14 deaths of primary liver cancer which occurred within 3 years after measurement of serum cholesterol was discounted. Similar negative correlation also existed between serum cholesterol level and chronic hepatitis and liver cirrhosis.

Adult↗
PubMed1992

CD36 peptides enhance or inhibit CD36-thrombospondin binding. A two-step process of ligand-receptor interaction.

CD36 (glycoprotein IV or IIIB) is an integral plasma membrane protein of wide cellular distribution and functions as a receptor site for thrombospondin (TSP), an adhesive protein important in cell-cell and cell-matrix interactions. OKM5, a monoclonal anti-CD36 antibody, has been reported to block CD36 cell adhesive functions suggesting that the OKM5 epitope on CD36 is functionally important. A panel of 10 synthetic CD36 peptides was made. One peptide, P139-155, specifically inhibited the immunoadsorption of CD36 by OKM5, and P139-155 was directly immunoadsorbed by OKM5, indicating that CD36 sequence 139-155 represents part of the OKM5 epitope. TSP bound to immobilized P139-155 in a dose-dependent and saturable manner. Surprisingly, P139-155 significantly augmented, instead of inhibited, binding of CD36 to TSP. This peptide did not induce platelet aggregation but augmented ADP- and collagen-induced aggregation in platelet-rich plasma. Another CD36 peptide, P93-110, which had no effect on OKM5 immunoadsorption, blocked binding of CD36 to immobilized TSP and partially inhibited collagen-induced platelet aggregation. P93-110 by itself did not bind to TSP; however, in the presence of P139-155, there was a marked enhancement of P93-110 binding to TSP, with a stoichiometry consistent with the trimeric nature of TSP. The data suggest that CD36-TSP interaction is a two-step process; the sequence 139-155 region of CD36 binds first to TSP, triggering a change in TSP to reveal a second site, which binds the 93-110 region of CD36 with high affinity. CD36 peptides can be used as stimulators or inhibitors in cellular adhesive events involving TSP-CD36 interaction. Conformational changes leading to the exposure or activation of high affinity binding sites may occur in both the receptor and the ligand upon cell-cell and cell-matrix adhesion.

Amino Acid Sequence↗
PubMed1992

Visually perceived eye level: changes induced by a pitched-from-vertical 2-line visual field.

The physical elevation corresponding to visually perceived eye level (VPEL) changes linearly with the pitch of a visual field. Deviations from true eye level average more than 0.5 times the angle of pitch over a 65 degrees pitch range. A visual field consisting of 2 dim, isolated vertical lines in darkness is more than 4/5 as effective as that of a complexly structured visual field; 2 horizontal lines have a small and inconsistent effect. Differences in influence on VPEL between pitched-from-vertical and horizontal lines were predicted from an analysis that extracted differences in retinal perspective resulting from changes in pitch. The Great Circle Model (GCM), based on a spherical approximation to the erect, stationary eye, predicts the present results and results of 8 other sets of experiments. The model treats the influence of a single line on VPEL as systematically related to the elevation of the intersection between the great circle containing the image of the line and the central vertical retinal meridian; generalized GCM combines visual inputs with inputs from the body-referenced mechanism and maps onto the central nervous system.

Darkness↗
PubMed1992

Regulation of a beta-galactoside-binding lectin and potential ligands during postnatal maturation of rat brain.

Variations in expression and activity of a beta-galactoside-specific lectin were quantified during postnatal maturation of the rat brain. Lectin expression, estimated from enzymatic immunoassay data, and lectin activity, evaluated by rabbit erythrocyte agglutination, are higher in the brains of young animals (5 days after birth) than in older ones (2 months of postnatal life). Concurrently, modifications in glycosylation during cellular differentiation were detected by affinoblotting using a biotinylated derivative of a beta-galactoside-specific brain lectin. This study shows that membrane and cytosolic glycoconjugates of the rat brain bear appropriate beta-galactoside moieties which may be recognized by an endogenous lectin expressed in the tissue itself in relation to brain maturation. The observed variations in the expression of lectin and complementary glycoconjugates can be correlated with significant events of rat brain development.

Aging↗
PubMed1992

[Alveolar echinococcosis in China: current data].

Very few information about alveolar echinococcosis in China is available outside the country. The aim of the authors is to give some precisions about the human cases and the infection in the natural animal hosts. It occurs in 3 distinct foci which comprise poor and remote rural areas. Approximately, 420 cases of human disease have been detected, and the most intense focus is Ningxia province in central China. In all areas, the adult tapeworm is frequently found in V. vulpes, V. corsac, and in the domestic dog. The intermediate hosts differ from an area to the others. Their infection rate is high in the central and the northern foci. More researches are needed for improving our knowledge about the epidemiology of the disease. But the actual major requirement is to apply control measures as health education and medical information.

Animals↗
PubMed1991

Improved synthesis of [1-14C]acyl-sphingosine-galactose-3-sulfate (sulfatide) for diagnosis of metachromatic leukodystrophy: usefulness of radioscanning.

We report an improved method for the radiolabelling of [1-14C 00acyl-sphingosine-galactose-3-sulfate (sulfatide), requiring preparation of lysosulfatide (sulfogalactosyl-sphingosine) by alkaline hydrolysis of sulfatide and reacylation of the sphingosine amino group with a [1-14C]stearoyl chloride. We found that the yield of labeled sulfatide could be considerably increased using stringent chromatographic conditions for the preparation of lysosulfatide and strict anhydrous conditions for the formation of the acylchloride and its coupling to lysosulfatide. Radioscanning was used at different steps to check the purity of the labeled compounds. Radioscanning was also used to determine the formation of cerebroside when measuring cerebroside sulfate sulfatase activity and sulfatide metabolism in intact fibroblasts in controls and patients with metachromatic leukodystrophy. It could demonstrate and measure with accuracy the cerebroside sulfate storage characteristic of the disease.

Carbon Radioisotopes↗
PubMed1991

Transferrin inhibits aromatase activity of rat granulosa cells in vitro.

The effect of transferrin on basal and FSH-stimulated aromatase activity of granulosa cells from immature female rats treated with diethylstilboestrol (DES) was examined in vitro by a radiometric method. The basal activity of the enzyme was very low after 3 days of incubation. Treatment with FSH (20 ng/ml) resulted in a 9.6-fold increase in activity, whereas coincubation with increasing doses of transferrin (3-300 micrograms/ml) produced a dose-dependent inhibition of FSH-stimulated aromatase activity with a projected minimal effective dose of less than 2 micrograms/ml. A time-course study showed that the inhibitory effect of transferrin on aromatase activity has become significant at 48 h of incubation. The inhibitory action of transferrin on the enzyme complex was further confirmed by showing that the FSH dose-response curve was significantly suppressed by concomitant treatment with 100 micrograms transferrin/ml with a maximum suppression of 54.1% at a dose of 30 ng FSH/ml. The possibility that transferrin may act through a non-specific inhibitory effect seems unlikely, as no changes in cell number and DNA content per well were observed. In fact, protein synthesis was enhanced after treatment with transferrin. Aromatase activity, stimulated by several promoters of cyclic AMP (cAMP), such as prostaglandin E2 (PGE2), forskolin and 8-bromo-cAMP, was significantly suppressed by 100 micrograms transferrin/ml (36.6, 47.4 and 23.4% inhibition respectively), suggesting that the effect of transferrin on FSH action may involve a site(s) distal to cAMP generation. These findings indicated that transferrin, present in follicular fluid, may play an important role in the regulation of granulosa cell differentiation.

Animals↗
PubMed1991

[Eighty cases of alveolar hydatid disease treated with albendazole].

Alveolar hydatid disease occurs frequently in Xiji County of Ningxia. 80 cases of the disease were treated orally with albendazole from 1985 to 1988 and the short-term results proved satisfactory. The treatment consisted of two groups. Group I included 72 cases which were orally given 8-10 mg/kg.d of albendazole 2 to 3 times a day after each meal for 30 days and then stop taking the medicine for 10 days as one treatment course. The treatment continued 3-12 months comprising about 24 courses were given with the highest dosage of 412g. Group II included 8 cases who were given 15.6-20 mg/kg.d of the medicine for 14 days (one course) and every two weeks with a 10 days interval. The treatment of group II continued 3-6 months which totalled 19-24 courses with the highest dosage of 270g. All the treated patients tolerate well except that a few of them felt giddy and had diarrhoea which disappeared after the withdrawal of medicine. Through 3-5 years, follow-up observation, it was found that the gener alsymptoms of the treated patients improved and their body weight increased by 2-9.5 kg, some of them could take part in light physical labour. The jaundice index in 80% of them returned to normal. SGPT in 86.4% decreased to within normal range. The enlarged livers in half of the patients decreased by 1-6 cm. 23.7% of the patients were reexamined by B ultrasound scanning which revealed that their enlarged liver reduced in size while the liquifaction area and the shadows of calcification in the livers in 42.5% patients increased obviously.

Adolescent↗
PubMed1991

[Histopathological and immunohistochemical studies of generalized amyloidosis].

Histopathological and immunohistochemical studies were performed on 10 autopsy cases of generalized amyloidosis. The results showed that there were 3 cases of secondary amyloidosis (AA protein), 4 cases of primary amyloidosis (AL protein) and 3 cases of amyloidosis associated with multiple myeloma (AL protein); no familial amyloidosis (AF protein) was identified. Amyloid substances detected in all of the cases were similar in appearance morphologically, and differentiation of different types of amyloid proteins could not be depended on whether the disease is primary in nature or there is amyloid deposition in various organs or tissues. Anyhow, the differentiation could be made by pre-treatment with KMnO4 in Congo red stain or by immunoperoxidase stain, and the latter one is considered to be more reliable in identifying amyloid protein types.

Adult↗
PubMed1990

Saccadic suppression of displacement: influence of postsaccadic exposure duration and of saccadic stimulus elimination.

The threshold for detection of stimulus displacement, which is normally raised in the presence of voluntary saccades relative to its value during steady fixation ("saccadic suppression of displacement"), decreases from 50x to 25x its value during steady fixation when the duration of the second display is experimentally increased from 33 to 461 msec; further increase of the duration of the second display has no additional effect. It might be expected that this improvement in sensitivity to displacement is a consequence of the elimination from perception of the visible smear corresponding to the saccadic stimulus by the action of metacontrast from the postsaccadic stimulus. That this is not so is shown by the fact that the improvement in displacement sensitivity with increased postsaccadic exposure duration is unaffected by experimental elimination of the retinal stimulus normally present during the saccade, even under conditions for which the saccadic stimulus is normally visible and appears smeared. The results demonstrate that the basis for saccadic suppression of displacement lies in the transient saccade-related modification of extraretinal eye position information.

Darkness↗
PubMed1990

The influence of saccade length on the saccadic suppression of displacement detection.

The decrease in sensitivity to spatial displacement which accompanies a voluntary horizontal saccadic eye movement was measured as a function of the length of the saccade. Threshold for detecting the displacement increased linearly from about 0.3 degrees to 1.2 degrees as saccade length increased from 4 degrees to 12 degrees. The variability (standard deviation) of the discrimination increased linearly with saccade length as well, and hence also linearly with the displacement threshold. These results, along with our previous finding that the increase is not a consequence of the saccadically generated spatiotemporal smearing of the retinal image (Li & Matin, 1990), support the proposal that displacement detection is based on a constant internal signal/noise ratio whose denominator is a measure of the variability of the extraretinal signal regarding eye position, and that the reduction in sensitivity is a result of a transient increase of this variability in the temporal neighborhood of a saccade.

Attention↗
PubMed1989

Smoking, occupational exposure to rubber, and lung cancer.

A cohort of 1624 employees (957 men, 667 women) in a rubber factory in Shanghai have been followed up since 1972 and their 12 year mortality experience is presented. The relative risk of lung cancer for smokers was 8.5 for men and 11.4 for women and for rubber workers exposed to curing agents or talc powder 3.2 for men and 4.6 for women.

China↗
PubMed1989

[A case-control study of female lung cancer at XuHui district in Shanghai].

All the 57 female lung cancer patients in Xu-Hui District, Shanghai discovered during 1985 were used as subjects of this study, each was matched with 2 of her near neighbours of same sex and within 5 years of age difference. Smoking, chronic bronchitis, pulmonary tuberculosis and family history of tumour were found to be related with lung cancer in single variable analysis. Upon stratification, smoking and pulmonary tuberculosis were still found related to lung cancer and considered as risk factors with OR and its 95% confidence interval 6.996, 3.23-15.14 and 4.82, 1.37-19.97 respectively. But chronic bronchitis failed to relate with lung cancer and was considered as a confounding factor. Of all the female lung cancer cases only 49.1% and 19.3% were smokers and TB patients respectively, hence smoking and TB could be responsible only for a small portion. In cancer cytology, squamous-cell carcinoma appeared to show association with smoking while adenocarcinoma did not. Among female lung cancer cases the proportion of adenocarcinoma exceeded that of squamous-cell carcinoma, and appeared unrelated with smoking. More family members of the lung cancer cases seem to have had malignant histories, suggesting that a hereditary factor of cancer susceptibility might be involved.

Adenocarcinoma↗
PubMed1988

Chang-Ning epidemiological study of children's health: I: Passive smoking and children's respiratory diseases.

The effects of household exposure to cigarette smoke on hospitalization and incidence of respiratory illness were examined among 2227 children at Chang-Ning District, Shanghai Municipality, People's Republic of China. The passive smoking quantity was estimated by total daily cigarette consumption of family members and number of cigarettes smoked in the home. No mothers who smoked were found. A significant dose-response relationship of passive smoking to hospitalization for respiratory illness during the children's first 18 months of life was found, for which no confounding factors were discovered. The incidence density ratio of hospitalization for respiratory illness was 2.1 for children living in families including people who smoked 20 or more cigarettes a day compared with those living in non-smoking families. The children appeared to be more vulnerable in the first six months of life than in the 7-18 month period, and those with lower birth weight and the artificially fed were more susceptible. The cumulative incidence of bronchitis or pneumonia increased significantly with increasing cigarette smoking of family members, which persisted when sex, birthweight, nursery care, father's education, coal for cooking, and adult cases with chronic respiratory disease were taken into account. Family smoking status was not found to be significantly associated with the incidence of asthma, whooping cough, sinusitis and measles.

Birth Weight↗
PubMed1988

Artificial feeding and hospitalization in the first 18 months of life.

The association between type of feeding and hospitalization during the first 18 months of life was examined among 1,058 infants from Jing-An district, Shanghai, People's Republic of China. Infants who had never been fed with mother's milk were categorized as artificially fed; the remainder were breast-fed. The rate of hospitalization for first episodes of respiratory infections during the first 18 months of life for the artificially fed infants was 18.0% v 11.2% for the breast-fed infants (P less than .01). Multiple logistic regression analysis demonstrated that the adverse effect of artificial feeding on the hospitalization rate for respiratory infections was independent of birth weight, father's education, passive smoking, and any case(s) of chronic respiratory disease in the family. The adjusted odds ratio for the artificially fed infants compared with the breast-fed infants was 2.11. The artificially fed infants were also hospitalized more frequently for gastroenteritis and other conditions, but the differences were not significant.

Birth Weight↗