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Biomedical subjects

G Li

Publications and source records attributed to G Li.

At least 973 records · Page 54Linked to original sources
PubMed1991

Contribution of multiple rounds of viral entry and reverse transcription to expression of human immunodeficiency virus type 1. A quantitative kinetic study.

Human immunodeficiency virus 1 (HIV-1) infection in vitro has been analyzed by the kinetics of expression of HIV-1 RNA and antigens during treatment with antiviral agents. Intracellular HIV-1 RNA rose from input values of 15 molecules per cell to 28 molecules per cell within 3 h after infection and reached a peak of 13,125 in 5 days. The first detectable increase in levels of HIV-1 capsid protein production was 1 day after infection. Virus infection was interrupted at different time points by the introduction of either 2',3'-dideoxycytidine, 3'-azido-3'-deoxythymidine, or suramin to block reverse transcription, or recombinant soluble CD4 to block binding and re-entry of progeny virus. Two results are noteworthy. First, the three inhibitors of reverse transcription blocked viral expression when added up to 48 h after infection. Second, the extent of infection, although postponed, is not greatly altered by culture of infected cells in recombinant soluble CD4. These data imply that reinfection with progeny virus, while necessary for rapid virus expression, is not required for the establishment of productive HIV-1 infection.

CD4 Antigens↗
PubMed1991

A three-year follow-up study of age-related dementia in an urban area of Beijing.

A 3-year follow-up study of 1090 people aged 60 years or over in an urban area of Beijing, China, was conducted to determine the incidence of dementia and its characteristics of distribution. This cohort has been studied first in a cross-sectional survey of dementia in 1986. The follow-up examination employed the same interviewers, psychiatrists, instruments (Mini-Mental State Examination and the Crichton Royal Behavior Rating Scale) and diagnostic criteria for dementia (modified DSM-III) in 1989. The respondent rate in this study was 75.7%. The average annual incidence rate of moderate and severe dementia for greater than or equal to 60 years was 0.3% (95% confidence interval 0.08-0.52%). As expected, the rate increased sharply with aging. No sex difference was found. The prevalence rate of moderate and severe dementia was 1.10% among those aged greater than or equal to 65 years, similar to that (1.82%) in the first survey. Our results showed that the multi-infarct dementia was somewhat more common than primary degenerative dementia (ratio 3:2), both among incident cases and current prevalent ones. The average duration of dementia in the community was 8.0 years (SD 3.4). The risk for death in demented patients was 3 times higher than in the whole cohort (standardized mortality ratio = 2.95), and no specific cause of death was observed. In addition, our study showed that elderly people with less education, a history of consistent unemployment, limited physical activity and stroke history had a higher risk for developing dementia.

Aged↗
PubMed1991

Retinoblastoma protein and simian virus 40-dependent immortalization of human fibroblasts.

Transformation and immortalization of human diploid fibroblasts by simian virus 40 (SV40) is at least a two-stage process, since transformants have a limited lifespan in culture. We have isolated immortalized derivatives (AR5 and HAL) from transformants generated with an origin-defective SV40 genome encoding a heat-labile large T protein (T antigen) and reported that both preimmortal and immortal transformants are continuously dependent on T antigen function for growth as determined by temperature shift experiments. In this study, we demonstrate complex formation between T antigen and the retinoblastoma susceptibility gene product (Rb) at 35 degrees C and observed a reduction in complexes under conditions of loss of T antigen function and growth inhibition at 39 degrees C. Viral oncogenes (polyomavirus large T protein and adenovirus E1A 12S protein) known to bind Rb were introduced into AR5 and HAL cells, both stably by gene transfer and transiently by virus vectors. Such double transformants are still unable to proliferate at 39 degrees C, although complex formation with the newly introduced oncogenes was demonstrated. We suggest that T antigen interacts with other cellular processes in addition to Rb to transform and immortalize human cells in culture. Our finding that p53-T antigen complexes are also temperature dependent in AR5 and HAL cells could provide such an additional mechanism.

Antigens, Viral, Tumor↗
PubMed1991

[A study on characters of liver isoferritin].

The characters of liver isoferritin from Wistar rat, normal human and patient with hepatocellular carcinoma (HCC) were studied. The ratio of iron to protein of liver isoferritin from patient with HCC were 0.021, which accounts for about one-twelfth of that of liver isoferritin from normal human. The molecular weights of liver isoferritin from normal human and the patient with HCC were 20.5 kd and 21.5 kd, respectively. The electrophoresis patterns of liver isoferritin from both Wistar rat and patient with HCC showed one band, but two bands from normal human. There was cross reaction in immunity among isoferritins from normal human liver, Wistar rat liver and horse spleen by double immunodiffusion. The PAGE patterns of liver isoferritin from different sources could be clearly differentiated. The data presented may serve as a good reference for further study of the relationship between the structure and function of ferritin and may be used practically in clinical medicine.

Animals↗
PubMed1991

[Clinical value of the Chengdu classification of non-Hodgkin's lymphomas].

Two hundred forty-nine cases of non-Hodgkin's lymphomas (NHL) were reviewed by using the working classification of NHL (Chengdu, 1985). The results showed that the patients of 249 cases of NHL ranging in age from 5 to 76 years, with the mean age of 42 of the types were separated into three major prognostic groupings as follows: 1. low (41 of 249 cases, small lymphocytic 27 cases, lymphoplasmacytoid 2 cases, follicular cleaved 7 cases, follicular cleaved and noncleaved 5 cases); 2. intermediate (58 of 249 cases, diffuse cleaved 28 cases, diffuse cleaved and noncleaved 27 cases, follicular noncleaved 3 cases); and 3. high grade malignancy (150 of 249 cases, diffuse noncleaved 49 cases, lymphoblastic 41 cases, immunoblastic 13 cases, polymorphic 39 cases, clear cell 2 cases, histiocytic 6 cases). Each group was significantly different from the others (P less than 0.05). The prognosis of patients with angioimmunoblastic lymphadenopathy like T-cell lymphoma (9 of 249 cases) was not more significant (P greater than 0.05) than that of patients with other polymorphic lymphoma (30 of 249 cases). The results showed this Chengdu classification of NHL is good for practice and usage in clinical evaluation and routine surgical pathology.

Adolescent↗
PubMed1991

Synthesis of (+/-)-N-2-methylpropyl-N-1'-methylacetonyl-nitrosamine.

N-2-methylpropyl-N-1-methylacetonyl-nitrosamine (NMAMPA), first isolated from moldy and normal foods, was synthesized by chemical means. The structure and molecular weight of the synthetic NMAMPA were elucidated by spectrometry. A combination of spectral and chromatographic data indicated that the synthetic NMAMPA is identical to that obtained naturally. Synthetic NMAMPA is a racemic modification, and a carcinogen which can induce esophageal and forestomach cancer in rats.

Carcinogens↗
PubMed1991

Inhibition of bone marrow immature B lymphocytes from zinc deficient mice by methionine enkephalin.

Bone marrow cells (BMC) from Zn deficient mice were used to measure the anti-TNP plaque forming cell (PFC) response in the presence of methionine enkephalin (Met-Enk). The results demonstrated that the PFC response of BMC was suppressed by Met-Enk. In the case of Zn deficient group, the inhibitions were up to 51% compared to 27% for the control and became higher as the increasing concentration of Met-Enk. It seems that the sensitivity to Met-Enk was related to degree of Zn deficiency. These findings suggest that Zn may interfere with the role of Met-Enk on BMC.

Animals↗