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Biomedical subjects

R Chen

Publications and source records attributed to R Chen.

At least 217 records · Page 12Linked to original sources
PubMed2000

[Effect of Digan oral liquid on thymic lymphocyte proliferation cycle in immune mediated aplastic anemia in mice].

OBJECTIVE: To study the effect of Digan oral liquid (DGOL) on cell proliferation cycle of thymic lymphocyte in immune mediated aplastic anemia (IMAA) in mice. METHODS: Balb/c mice were used in the experiment, after having exposed under a sublethal amount of radiation, the mice were received injection of mixed cells of thymus and lymph node of DBA/2 mice to form the IMAA models. The model mice were grouped and treated, then their thymus was taken to prepare the single cell suspension for analysis by flow cytometry. RESULTS: Majority of thymocyte of IMAA mice stopped at the G0/G1 phase, and the cells in S and G2 + M phases were significantly less than those in the normal control group, P < 0.01. Both DGOL and Siwu oral liquid could increase the differentiation and proliferation of thymocytes and reduce the apoptosis rate of them, but DGOL showed a better effect, P < 0.05. CONCLUSION: DGOL could significantly promote the differentiation and proliferation of thymocytes and reduce the apoptosis rate of them in IMAA mice, the effect of its is superior to that of Siwu oral liquid.

Anemia, Aplastic↗
PubMed2000

[Effects of fluoride on the expression of c-fos and c-jun genes and cell proliferation of rat osteoblasts].

OBJECTIVE: To investigate the effects of sodium fluoride (NaF) on the expression of c-Fos and c-Jun genes and osteoblast cell proliferation of rat osteoblasts. METHODS: Osteoblastic cells were isolated from baby rat calvaria, and cultured in the presence of different doses of NaF (10(-5) mol/L, 10(-4) mol/L, and 10(-3) mol/L). Cell proliferation was measured by the MTT method, and c-Fos and c-Jun expression was detected by the immunohistochemistry combined with image analysis compute system. RESULTS RESULTS: from the MTT assay showed that NaF increased the proliferation of rat osteoblast and induced the expression of c-Fos and c-Jun genes. The increases of c-Fos and c-Jun expression by the 3 different doses of NaF were 5.4%, 15.4% and 42.3% for the c-Fos gene and 12.1%, 14.4% and 38.6% for c-Jun gene respectively (P < 0.05 and P < 0.01). CONCLUSION: NaF increased rat osteoblastic cell proliferation and the expression of genes involved in cell proliferation.

Animals↗
PubMed2000

[Effects of different cryoprotectants on biological properties of hematopoietic cells derived from cord blood].

OBJECTIVE: To search for effective cryoprotectants that can be used in cord blood bank to cryopreserve hematopoietic cells. METHODS: Four kinds of combined reagents were used to cryopreserve cord blood cells. The effects of these cryoprotectants on biological properties of hematopoietic cells were monitored and compared after the cells were refrigerated for 1 to 4 months. The detected biological properties included the number of total nucleated cells (TNC), CD(34)(+) cells and CFCs. RESULTS: The cryoprotectants of Dextran-40 + 10%DMSO resulted in the highest recovery rates, TNC, CD(34)(+) cells and CFCs were 77.8%, 78.5% and 87.2%, respectively. The combination of 10%DMSO + 6% AB serum + 5%HES led to the lowest recovery rates. CONCLUSION: Dextran-40 + 10%DMSO is an ideal cryoprotectant combination for cryopreserving hematopoietic cells in the cord blood bank.

Antigens, CD34↗
PubMed2000

[The relationship of brainstem auditory evoked potential to cerebral blood flow volume in with vertebrobasilar transient ischemic vertigo].

This study was aimed at the relationship of brain-stem auditory evoked potential(BAEP) with cerebral blood flow(CBF) volume and vascular pathological changes in patients with vertebro-basilar transient ischemic vertigo (VBTIV). 65 patients were examined by magnetic resonance angiography(MRA), transcranial Dopplar(TCD) and BAEP; 26 controls were examined by MRA and TCD. In the patient group, MRA showed that vascular pathological changes were obvious in 50 patients, and obscure or absent in 15 patients. The CBF volume [112.3-278.9 ml/min (2s)] of control group was higher than that (48.0-262.0 ml/min) of the patients group (t = 2.43, P < 0.01) in which 15 patients had low CBF volume and 50 patients had normal CBF volume. The BAEP of 47(72.3%) patients was abnormal. Out of 15 patients with low CBF volume, 14(93.3%) had abnormal BAEP, but out of 50 patients with normal CBF volume, only 33(66%) patients had abnormal BAED (chi 2 = 4.34, P < 0.05). In the 50 patients with obscure obvious vascular pathological changes, 40(80%) patients had abnormal BAEP, but in the 15 patients with obscure or without the changes, only 7(43.3%) patients had abnormal BAEP (chi 2 = 4.86, P < 0.05). These results suggested that there might be a close relationship of BAEP with CBF volume and vascular pathological changes.

Adult↗
PubMed2000

[Effect of sub-acute low level exposure to lead on cellular immune function in rats].

In order to observe the influence of low level exposure to lead on cellular immune functions in rats, sixty rats were randomly divided into six groups and were received diets with different levels of lead for eight weeks. Blood lead, serum tumor necrosis factor-alpha(TNF-alpha) level and the distribution of T lymphocyte subsets were measured. The pathological and ultrastructural changes of spleen were investigated. It was shown that lead exposure resulted in a significant increase of blood lead and decrease of the number of CD4 T-cells. But no significant difference was found in CD8 T-cell among all groups. Serum TNF-alpha at the lowest exposure group was significantly increased but that in other groups was lower than the control group. Electron microscopy for splenic immune cells indicated no significant difference between the lowest lead exposure group and the control group. The mitochondria of other groups were swollen, vaculated and pyknotic, endoplasmic reticulum were swollen and degranulated, nuclear chromatin were loosen. It was suggested that sub-acute exposure to lead, even at relative low exposure, would impair cell-mediated immunity and be harmful to spleen and thymus.

Animals↗
PubMed2000

[Result of orthokeratology for treatment of young people with myopia].

PURPOSE: To evaluate the effectiveness of orthokeratology (Ortho-K) for treatment of myopia in youngths. METHODS: 110 eyes of 56 young peoples with myopia received Ortho-K were studied. The patients were divided into 3 groups according to preoperative diopters. No. I: -1.00(-)-3.00 D, No. II: -3.25(-)-6.00 D, NO. III: -6.25(-)-7.50 D. The uncorrected visual acuities, residual diopters and corneal refractive powers at various time of three months after the operation were statistically analyzed and compared with that of preoperation. Correlation analysis and linear regression analysis were performed between the corneal refractive reduction (X) and clinical refractive reduction (Y) after 3 months of the operation. RESULTS: In 110 eyes, the uncorrected visual acuities in the first day, first week, first month, second month and third month after operation were significantly improved than that of the preoperation (P < 0.01). The mean residual diopters were significantly reduced than that of preoperation (P < 0.01). The mean refractive powers of cornea were significantly decreased than that of the preoperative (P < 0.01). There was significant correlation between the corneal refractive reduction and clinical refractive reduction. (r = 0.3181, P < 0.001). CONCLUSION: Orthokeratology is a safe and effective therapeutic method for treatment of myopia in youngths. The long term effect of Orthokeratology need further observation.

Adolescent↗
PubMed2000

[Spectroscopy and structure of the zinc complexes with mixed ligands].

The negative ion, MS4(2-) (M = Mo, W, V ect.), is used widely in molecule designed as construction fragment because of its various ligand mode. The IR and Raman spectra of the crystals Zn(phen)2 WS4 and Zn(phen)2MoS4 with mixed ligands MS4(2-) and 1, 10-phenanthroline have been investigated, and the coincidence between the spectrum and the structure has been discussed as well.

Chelating Agents↗
PubMed2000

[The comparison of luminescence properties for Ce3+, Tb3+ ions in the fluorides].

The matrix K3AlF6 was prepared with a reaction of mixture of solution K2CO3 upon certain solution of Al(OH)3 plus HF (40%), dehydrating at 100 degrees C and annealing for 48 h at 600 degrees C. A series of phosphors for Ce3+, Tb3+ ions in complex fluorides KBF4 and K3AlF6 were synthesized by a solid reaction method. Their excitation and emission spectra were determined, compared with phosphors KAlF4: Ce, Tb, CaF2: Ce, Tb and AlF3: Ce, Tb. The results indicated that Ce3+ could only effectively sensitize Tb3+ in KAlF4 and enhance the emission of Tb3+ significantly. Ce3+ can not effectvely transfer energy to Tb3+ in matrixes CaF2, AlF3, KBF4 and K3AlF6.

Cerium↗
PubMed2000

[IR spectra and structures of two trinuclear molybdenum cluster compounds coordinated by binary carboxylates].

Two trinuclear molybdenum cluster compounds coordinated by binary carboxylates compounds Mo3S4 (DTP)3(phthalate) (Py)(A) and Mo3S4 (DTP)3(malonate)(Py)(B) have been synthesized. IR absorption peaks of Mo3S4 core and the ligands are assigned with reference to those of Mo3S4(DTP)4(Py)(C). The assignment of stretching vibrations of carboxylate (COO-) for both (A) and (B) reveals much information corresponding to their molecular structures.

English Abstract↗
PubMed2000

[Infrared spectra and Raman spectra of monoclinic RblnS2 and CsInS2].

Monoclinic RbInS2 and CsInS2 were prepared by the traditional flux method and their IR and Raman spectra were studied. The IR and Raman absorption bands of CsInS2 shift to lower frequency compared with RbInS2. IR and Raman spectra show that monoclinic RbInS2 and CsInS2 exhibit good infrared transmission.

English Abstract↗
PubMed2000

[Luminescence properties and energy transfer between Ce3+ and Gd3+ ions in KAlF4:Ce, Gd].

The matrix KAlF4 was prepared with a reaction of mixtures of solution K2CO3 upon certain solution of Al(OH)3 plus HF (40%), dehydrating at 100 degrees C and annealing for 48 h at 450 degrees C. A series of phosphors KAlF4:Ce, Gd were synthesized by a solid reaction method. Their excitation and emission spectra were determined. It was observed that Ce3+ could sensitize Gd3+ in KAlF4 effectively, so as to enhance the emission of Gd3+ significantly. But emission intensity of Gd3 + 6 P1/2-->8S7/2 decreased with the concentration of Gd3+ increased when the concentration of Ce3+ was constant.

English Abstract↗
PubMed1999

The cumulative q interval curve as a starting point in disease cluster investigation.

Statistical analyses aimed at detection and investigation of clustering are associated with inherent difficulties. Both types of statistical errors are large in these analyses. The results of the analyses should indicate whether or not at least some of the cases are clustered, and if they are, whether or not the cluster is related to an exposure. The temporal changes in the incidence rate of the disease may alleviate the difficulties associated with the large statistical errors. Because of the sparse data, estimates of the incidence rates over time are not reliable. In this study we present the q interval statistic that has the uniform (0,1) distribution. It can be viewed as a standardized time interval between consecutive diagnoses of the disease. As such, it reflects the reciprocal of the incidence rates. Since it is measured for each diagnosis, it is sensitive to gradual change in the incidence rate, and in general to a true clustering that is due to exposure, even when the test result is not significant. When clustering is detected, it may indicate which of the possible reasons leading to a cluster has a sound basis. As a result, the epidemiological search for exposure is limited to situations indicated by the q intervals. In addition, the q interval presents a useful survival statistic in a follow-up study when no control group is available. Software programs in SAS and in SYSTAT are available.

Adult↗
PubMed1999

Differential cytokine modulation and T cell activation by two distinct classes of thalidomide analogues that are potent inhibitors of TNF-alpha.

TNF-alpha mediates both protective and detrimental manifestations of the host immune response. Our previous work has shown thalidomide to be a relatively selective inhibitor of TNF-alpha production in vivo and in vitro. Additionally, we have recently reported that thalidomide exerts a costimulatory effect on T cell responses. To develop thalidomide analogues with increased anti-TNF-alpha activity and reduced or absent toxicities, novel TNF-alpha inhibitors were designed and synthesized. When a selected group of these compounds was examined for their immunomodulatory activities, different patterns of cytokine modulation were revealed. The tested compounds segregated into two distinct classes: one class of compounds, shown to be potent phosphodiesterase 4 inhibitors, inhibited TNF-alpha production, increased IL-10 production by LPS-induced PBMC, and had little effect on T cell activation; the other class of compounds, similar to thalidomide, were not phosphodiesterase 4 inhibitors and markedly stimulated T cell proliferation and IL-2 and IFN-gamma production. These compounds inhibited TNF-alpha, IL-1beta, and IL-6 and greatly increased IL-10 production by LPS-induced PBMC. Similar to thalidomide, the effect of these agents on IL-12 production was dichotomous; IL-12 was inhibited when PBMC were stimulated with LPS but increased when cells were stimulated by cross-linking the TCR. The latter effect was associated with increased T cell CD40 ligand expression. The distinct immunomodulatory activities of these classes of thalidomide analogues may potentially allow them to be used in the clinic for the treatment of different immunopathological disorders.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1999

Amino-substituted thalidomide analogs: potent inhibitors of TNF-alpha production.

Thalidomide, (1), is a known inhibitor of TNF-alpha release in LPS stimulated human PBMC. Herein we describe the TNF-alpha inhibitory activity of amino substituted analogs of thalidomide (1) and its isoindolin-1-one analog, EM-12 (2). The 4-amino substituted analogs were found to be potent inhibitors of TNF-alpha release in LPS stimulated human PBMC.

Blood↗
PubMed1999

Longitudinal association of vascular and Alzheimer's dementias, diabetes, and glucose tolerance.

OBJECTIVE: To assess the relationship between impaired glucose tolerance and both vascular dementia and AD. BACKGROUND: Diabetes and abnormalities of glucose metabolism have been associated with stroke and poor cognitive function. In addition, glycoproteins and glycosylation have been postulated to be associated with the development of neuritic plaques characteristic of AD. METHODS: A historical prospective cohort study of Japanese-American men (n = 3,774), who were examined at ages 45 to 68 (1965 through 1968) and again at ages 71 to 93 (1991 through 1993). Measurements were obtained by clinical and home examinations: assessment of glucose intolerance (nonfasting 1 hour after glucose load) from 1965 through 1968 and history of diabetes diagnosed by a physician at examinations given from 1965 through 1968 and from 1976 through 1978. At the 1991 through 1993 examinations, the Cognitive Assessment Screening Instrument (CASI)-an instrument designed for use in cross-cultural settings combining features of the Folstein Mini-Mental State Examination, the Modified Mini-Mental State Examination, and the Hasegawa Dementia Screening Scale-was used. Diagnosis and classification of AD and vascular dementia were made by a consensus panel using neuropsychologic assessment data, a neurologist's evaluation, and information from a family informant. Diagnostic and Statistical Manual of Mental Disorders, 3rd ed., revised criteria were used to establish dementia, and subclassification by cause was based on other published criteria. RESULTS: No association between AD and diabetes, present either 25 or 15 years previously, was found after adjustment for age and education in a multiple regression model. A significant association was found between impaired glucose tolerance at baseline and vascular dementia (p < 0.01). CONCLUSIONS: These findings confirm expected relationships between impaired glucose tolerance and stroke-related dementia but do not support an association of disordered glucose metabolism with AD.

Aged↗