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Biomedical subjects

Y Li

Publications and source records attributed to Y Li.

At least 361 records · Page 20Linked to original sources

Predicting caries in permanent teeth from caries in primary teeth: an eight-year cohort study.

Several cross-sectional studies report that caries in primary teeth is correlated with caries in permanent teeth. This eight-year cohort study sought to determine if caries in the primary dentition can predict caries in the permanent dentition of the same individuals and, if so, with what degree of prediction accuracy. A total of 362 Chinese children, from 3 to 5 years old at the time of the 1992 baseline study, were re-examined in 2000. The study found statistically significant associations between caries prevalence in primary and permanent dentitions (p < 0.01). Children having caries in their primary teeth were three times more likely to develop caries in their permanent teeth (relative ratio = 2.6, 95% CI = 1.4-4.7; p < 0.001). Caries on primary molars had the highest predictive value (85.4%). This study demonstrates that caries status in the primary teeth can be used as a risk indicator for predicting caries in the permanent teeth.

Adolescent↗

Retinoic acids promote the action of aromatase and 17beta-hydroxysteroid dehydrogenase type 1 on the biosynthesis of 17beta-estradiol in placental cells.

The biosynthesis of 17beta-estradiol (E(2)) in human placenta involves the actions of aromatase and 17beta-hydroxysteroid dehydrogenase type 1 (17HSD1). Aromatase, an enzyme complex comprised of P450aromatase (P450arom) and NADH-cytochrome P450 reductase, converts androgens to estrogens, whereas 17HSD1 catalyzes the reduction of estrone to E(2). In the present study, the effects of retinoic acids (RAs) on P450arom and 17HSD1 expression in placental cells were investigated. Treatment with all-trans-RA (at-RA) or 9cis-RA increased E(2) production in JEG-3 choriocarcinoma cells and cytotrophoblast (CTB) cells isolated from normal early placentas. Meanwhile, the activity of aromatase and expression of P450arom mRNA were induced by at-RA in JEG-3 cells. Northern blot analysis showed that the effect on P450arom mRNA expression occurs in a dose- and time-dependent fashion. Similar to at-RA and 9cis-RA, Ro40-6055, the retinoic acid receptor alpha (RARalpha)-selective activator, increased the expression of P450arom and 17HSD1 mRNA in JEG-3 cells. On the other hand, Ro41-5253 (Ro41), the RARalpha-selective antagonist, blocked the stimulatory effect of RAs on P450arom expression. Surprisingly, Ro41 induced the activity and mRNA expression of 17HSD1 in JEG-3 cells, which is in contrast to the expected inhibitory effect and, moreover, remarkably potentiated the induction by at-RA and 9cis-RA. However, reporter gene analysis revealed that the influence of Ro41 on the transcription of the HSD17B1 gene, which encodes 17HSD1, is considerably milder in JEG-3 cells, and it only additively enhanced the effect of at-RA. Finally, it was found that at-RA and 9cis-RA increased the expression of P450arom and 17HSD1 mRNA in CTB cells, but to a lesser extent. The data suggest that RAs may play a role in promoting the biosynthesis of E(2 )in the placenta. In addition, Ro41 has divergent effects on gene expression in JEG-3 cells.

17-Hydroxysteroid Dehydrogenases↗

A review of molecular modeling approaches to pharmacophore models and structure-activity relationships of ion channel modulators in CNS.

Through pharmacophore models and providing quantitative analysis of structure-activity relationships (QSAR), molecular modeling techniques can be useful tools to study the interactions of ion channels and their modulators. The present review focuses on molecular modeling approaches that defined pharmacophore models of ion channel modulators in the CNS. The commonality and subtlety of the pharmacophore models of various ion channel modulators are discussed which can be used as a framework for the design of ion channel modulators.

Central Nervous System↗

Cerebral, myocardial and cutaneous ischemic necrosis associated with calcific emboli from aortic and mitral valve calcification in a patient with end-stage renal disease.

We report the case of a 57-year-old diabetic male with chronic renal failure who developed secondary hyperparathyroidism and calcification of mitral and aortic valves and interatrial septum. Multiple ischemic lesions developed in the skin of hands, feet and penis, and in the brain, and these were presumed to be due to septic emboli from cardiac valvular infective endocarditis. Multiple blood cultures were negative, however, and despite antibiotic therapy the patient expired. Autopsy (limited to trunk) demonstrated multiple calcific emboli in the heart and spleen, apparently derived from the prominent calcific deformities in the aortic and mitral valves. These were associated with acute and organizing myocardial infarcts and acute splenic infarcts, suggesting that the multiple ischemic lesions in the brain were also due to calcific emboli. A possible contributory component of infective endocarditis, however, was indicated by postmortem cultures of aortic and mitral valves positive for Enterococcus faecium. Calcific embolism is a rarely recognized but potentially lethal complication of end-stage renal disease, and the clinical diagnosis and the preventive therapeutic options for the control of the product of calcium and phosphate and/or parathyroidectomy should be considered.

Aortic Valve↗

Reconstructing the mechanics of quadrupedalism in an extinct hominoid.

Traditionally, analogising comparative anatomical approaches, working on features of individual bony elements, have led to the Miocene hominoids Proconsul heseloni and P. nyanzae being described as arboreal, with a variety of possible locomotion modes. Whilst most researchers seemingly agree that quadrupedal was one of the most frequently adopted modes, any deeper knowledge about the kinematical characteristics of such quadrupedalism is very limited. Based on the previous studies and a computer simulation technique developed in our laboratory, a set of alternative models for Proconsul quadrupedalism was created. The body measurements and initial properties for the different models were held constant, using data from published literature if available, or otherwise estimated from data for Pan. Judged by the power output of joints, the results of computer simulation indicate that the style of quadrupedal locomotion typical of living macaques fits the body proportions of Proconsul better than that of Canis domesticus, Varecia variegata, Cebus albifrons or Pan troglodytes. It may reasonably be assumed that Proconsul's quadrupedal mode was similar to that of living macaques.

Animals↗

The role of (111)In Capromab Pendetide (Prosta-ScintR) immunoscintigraphy in the management of prostate cancer.

(111)In Capromab Pendetide (ProstaScintR) is a whole murine antibody that is reactive with prostate specific membrane antigen (PSMA), a glycoprotein on the surface of normal and abnormal prostate epithelium. It has proven to be of great value in assisting management decisions in prostate cancer patients who initially present with high risk for metastatic spread, or who develop a picture of recurrent disease after surgery or radiation therapy. Patterns of metastatic lymphatic spread have correlated well with autopsy reports in the literature. Unfortunately, other imaging study and/or histologic confirmation of scintigraphic findings has been difficult to obtain. Prostascint's role in predicting durable complete response (DCR) in postoperative patients having salvage radiotherapy to their prostate fossa is very promising. Further investigative work in larger patient populations is needed to confirm these early results.

Antibodies, Monoclonal↗

Serum cholesterol changes from 1983-1984 to 1993-1994 in the People's Republic of China.

BACKGROUND AND AIM: Increasing cardiovascular disease (CVD) mortality in the People's Republic of China (PRC) led to the 1981 establishment of the PRC-USA Study of Cardiovascular and Cardiopulmonary Epidemiology which, among other objectives, is concerned with the correlates of CVD morbidity and mortality in Chinese populations among other objectives. This report describes changes in total cholesterol (TC) levels in four PRC populations from 1983 to 1993 and identifies factors related to the changes. METHODS AND RESULTS: Population screenings carried out in 1983-1984, 1987-1988 and 1993-1994 involved the collection of demographic data, specimens (including blood), medical history and physical examination data. The data from cohort and independent samples were used to assess TC changes in urban and rural men and women over the decade, with and without adjustment for age and body mass index (BMI) changes. For Guangzhou men and women, the cohort analyses (aged 35-54 at baseline) showed increases in TC of 10-20 mg/dL after adjustment for age and changes in BMI; the independent sample analyses (aged 35-44) also showed higher average TC levels in 1993-1994 than in 1983-1984. For the Beijing cohorts, the results showed decreases in TC during the decade in men, an increase in TC in urban women and no change in rural women; the independent sample analyses indicated declines in TC for Beijing men and women. Possible reasons for the Guangzhou TC increases are economic growth, and dietary and BMI changes. The mean age-adjusted BMI significantly increased (5-10%) over the 10-year period in all of the studied groups. CONCLUSIONS: TC increased 10-20 mg/dL in Guangzhou men and women, probably as a result of socioeconomic development during the decade. The inconsistent patterns of TC changes in Beijing require further study.

Adult↗

[A novel erythroid differentiation related gene EDRF1 upreguated globin gene expression in HEL cells].

OBJECTIVE: To observe the differentiation-inducing properties of the novel erythroid differentiation related gene EDRF1, and demonstrate its functioning pathway involved in regulation of alpha- and gamma-globin gene expression. METHODS: EDRF1 sense and antisense constructs were transfected into HEL cells, then the expression of globin and erythropoietin receptor gene was identified by Northern blot analysis. RT-PCR and electrophoresis mobility shift assay (EMSA) were carried out to monitor the expression and DNA-binding activity of erythroid specific transcription factor GATA-1 and NF-E2. RESULTS: In HEL cells with transfection of sense expression carrier, the experssion of EDRF1 mRNA was upregulated. In HEL cells with transfection of antisense expression carrier, the experession of EDRF1 mRNA was downregulated. In HEL cells with overexpression of EDRF1, production of alpha-globin was increased. In antisense EDRF1 overexpressed HEL cells, significant loss of alpha- and gamma-globin mRNA synthesis was observed. The expression of erythropoietin receptor was unchanged in HEL cells transfected with EDRF1 sense and antisense expression carriers. No significant change was found in expression of transcription factors GATA-1 and NF-E2 in HEL cells transfected with empty carrier, sense expression carrier, and antisense expression carrier. However, the transcription activity of GATA-1 was severely impaired. Expression of erythropoietin receptor gene was not influenced by EDRF1 gene overexpression. CONCLUSION: EDRF1 regulates alpha- and gamma-globin gene synthesis by modulating DNA-binding activity of GATA-1 transcription factor. Overexpression and underexpression of EDRF1 do not significantly regulate the expression of GATA-1 and NF-E2 mRNA. Monitoring the EPOR signal pathway is not the mechanism by which EDRF1 influences the differentiation of erythrocyte.

Blood Proteins↗

Delayed-onset ataxia in mice lacking alpha -tocopherol transfer protein: model for neuronal degeneration caused by chronic oxidative stress.

alpha-Tocopherol transfer protein (alpha-TTP) maintains the concentration of serum alpha-tocopherol (vitamin E), one of the most potent fat-soluble antioxidants, by facilitating alpha-tocopherol export from the liver. Mutations of the alpha-TTP gene are linked to ataxia with isolated vitamin E deficiency (AVED). We produced a model mouse of AVED by deleting the alpha-TTP gene, which showed ataxia and retinal degeneration after 1 year of age. Because the brain alpha-TTP functions in maintaining alpha-tocopherol levels in the brain, alpha-tocopherol was completely depleted in the alpha-TTP(-/-) mouse brain, and the neurological phenotype of alpha-TTP(-/-) mice is much more severe than that of wild-type mice when maintained on an alpha-tocopherol-deficient diet. Lipid peroxidation in alpha-TTP(-/-) mice brains showed a significant increase, especially in degenerating neurons. alpha-Tocopherol supplementation suppressed lipid peroxidation and almost completely prevented the development of neurological symptoms. This therapy almost completely corrects the abnormalities in a mouse model of human neurodegenerative disease. Moreover, alpha-TTP(-/-) mice may prove to be excellent animal models of delayed onset, slowly progressive neuronal degeneration caused by chronic oxidative stress.

Animals↗

Functional regulatory regions of human transcription factor MEF2C.

Myocyte enhancer-binding factor 2C (MEF2C), a transcription factor expressed at high levels in muscle and brain, is implicated in the terminal differentiation and post-mitotic survival of neurons. In this study MEF2C deletion mutants and naturally-occurring isoforms were transfected into COS and P19 cells with two different reporter genes, to test the relative transcriptional activities of the MEF2C constructs. Deletion of parts of the carboxy terminus, in particular amino acids 387-473, enhanced transcriptional activation. A region rich in serine, threonine, proline, and tyrosine from amino acids 312-367 was sufficient to activate transcription at low levels when coupled to amino acids 1-86, which contain the DNA-binding (MADS/MEF) domain of MEF2C, but also depended on amino acids 87-311 for full effect. A construct with amino acids 312-350 missing showed significantly less transcriptional activation than proteins containing this sequence. MEF2C constructs were uniformly localized to the cell nucleus by immunostaining with an antibody to the constant N-terminal region of MEF2C. Western blot and gel shift studies of extracts from transfected cells and from in vitro transcription/translation suggest that variation in the amount of protein expressed or in DNA-binding properties does not account for observed differences in transcriptional activation. This structural information may be useful for elucidating the mechanisms of MEF2C in interacting with other factors to regulate target genes.

Animals↗

Recombinant paramyosin (rec-Sj-97) tested for immunogenicity and vaccine efficacy against Schistosoma japonicum in mice and water buffaloes.

A primary vaccine candidate antigen against schistosomiasis is paramyosin (pmy), a myofibrillar protein found exclusively in invertebrates. Here we report the results of vaccine trials against the Asian schistosome undertaken on inbred and outbred mice and water buffaloes using a bacterially expressed and purified form of Schistosoma japonicum pmy (rec-Sj-97). Vaccination of the mice resulted in high levels of specific anti-pmy IgG antibodies when compared with adjuvant controls and significant reduction in worm burdens and in liver eggs. Furthermore, a significant reduction in liver eggs was recorded in two of the three water buffalo vaccine trials undertaken and, in all three trials, high levels of specific anti-pmy IgG antibodies were generated. There was no evidence of any toxic effects and the vaccine preparations and Quil A adjuvant were clearly well tolerated. The development of a vaccine intended for livestock animals such as bovines would be beneficial in two ways; directly by blocking transmission of schistosomiasis to humans and economically by contributing to healthier livestock. We are encouraged by the consistent efficacy in the mouse and the buffalo vaccine trials that resulted in a significant decrease in liver eggs. Indeed, predictions from mathematical models indicate that an egg reduction effect of 42-45% in buffaloes would be sufficient when combined with human treatment to control schistosomiasis japonica in the marshes and lakes along the middle and upper reaches of the Yangtze River, the most highly endemic areas for the disease in China.

Animals↗

[Screening for the new variant of defective receptor-binding apolipoprotein B-100].

OBJECTIVE: To detect possibly existing unknown mutation(s) in nucleotide sequence coding amino acid residues 2,980 to 3,084, that may lead to familial defective apo B-100, and to provide evidence for evaluating the putative receptor binding domain of apo B-100. METHODS: The nucleotide sequence coding the amino acid resudues 2,980-3,084 of apo B gene in 341 patients with primary hypercholesteremia and of 50 controls was amplified by PCR and subjected to single strand conformational polymorphism analysis under optimized conditions. RESULTS: No abnormal electrophoretic figure was found in the samples from 341 hypercholesterlemic patients and 50 controls. CONCLUSION: (1) Point mutation causing hypercholesterlemia is unlikely to exist, or rare, if any, in the codons 2,980-3,084 of apo B-100 in Chinese. (2) Amino acid residues 2,980-3,084 may not be involved in the receptor-binding of apo B-100.

Adult↗

Phylogenetic comparison of classical swine fever virus in China.

An N-terminal fragment of the E2 gene of classical swine fever (CSF) virus encoding major immunogenic sites was amplified by RT-PCR directly from 110 clinical specimens representing 109 epizootic sites during the last decade in China. Phylogenetic relationships between these viruses as well as 20 reference strains were determined by comparison of their nucleotide sequences. A phylogenetic tree showed that 103 of the 110 field viruses (93.6%) were clustered within group 2 and subdivided into three subgroups, while the remaining seven viruses (6.4%), along with two Chinese reference strains, Shimen and HCLV (attenuated vaccine strain), were clustered into subgroup 1.1 within group 1. However, none of the Chinese CSF viruses were members of subgroup 1.2 (represented by reference strain Brescia). This is the first report on the distribution of CSF virus genotypes in China. Results indicated that CSF viruses predominating in recent epizootics within China are genetically divergent from the reference strain Shimen and the vaccine strain HCLV.

Animals↗

Substance P enhances HIV-1 replication in latently infected human immune cells.

Substance P (SP) is a potent modulator of neuroimmunoregulation. SP receptors are present on human monocytes and T lymphocytes, and SP alters the function of these immune cells. We investigated the effects of SP on HIV-1 replication in latently infected human immune cells. SP significantly enhanced HIV-1 replication in the latently infected promonocytic cell line (U1) and T lymphocyte line (ACH-2) stimulated with tumor necrosis factor (TNF-alpha). When added to these cells in combination with TNF-alpha, SP also enhanced HIV-1 gag gene expression in U1 and ACH-2 cells. This stimulatory effect of SP was associated with the activation of HIV-LTR (long terminal repeat) driven chloramphenicol acetyltransferase (CAT) gene expression, and could be blocked by pretreatment of U1 and ACH-2 cells with an SP receptor antagonist RP-67,580, indicating specific SP receptor-mediated regulation. Furthermore, the addition of SP to the cultures of latently infected peripheral blood mononuclear cells isolated from HIV-1-infected patients enhanced HIV-1 gag gene expression. Thus, SP may play a potentially important role as a positive regulator of HIV-1 replication in latently infected monocytes and lymphocytes. These observations may have significant implications toward understanding the role of neuropeptide SP in the immunopathogenesis of HIV-1 infection and AIDS.

Adult↗

Translational regulation is a control point in RUNX2/Cbfa1 gene expression.

Runt-related transcription factor-2 (RUNX2)/core binding factor a1 (Cbfa1) is implicated in the regulation of osteoblast differentiation and osteoblast-specific gene expression. Mutations in RUNX2 cause the bone disease cleidocranial dysplasia, which is characterized by multiple skeletal defects. RUNX2 is expressed as two isoforms (type-I and type-II) encoded by two different mRNAs. We report here the detection of both mRNAs in osteoblastic cells and osteoblast precursors as well as nonosteoblastic cells. Surprisingly, however, osteoblast precursors and nonosteoblastic cells express no RUNX2 protein; mature osteoblasts express both isoforms, while less mature osteoblastic cells express only type-I protein. Northern blot analysis of RNA isolated from polysomes and ribonucleoprotein particles demonstrated that RUNX2 mRNA is polysome-associated in osteoblastic cells but polysome-free in osteoblast precursors. These results suggest that (a) RUNX2 mRNAs are expressed but dormant in osteoblast precursors and nonosteoblastic cells, (b) RUNX2 gene expression is controlled at the translational level, and (c) the expression of individual protein isoforms of RUNX2 is differentiation stage specific. Thus, differentiation of cells along the osteoblast lineage appears to be regulated at the level of RUNX2 mRNA translation.

3T3 Cells↗

Regulation of the Bub2/Bfa1 GAP complex by Cdc5 and cell cycle checkpoints.

During mitosis, a ras-related GTPase (Tem1) binds GTP and activates a signal transduction pathway to allow mitotic exit. During most of the cell cycle, Tem1 function is antagonized by a GTPase-activating protein complex, Bfa1/Bub2. How the Bfa1/Bub2 complex is regulated is not well understood. We find that Polo/Cdc5 kinase acts upstream of Bfa1/Bub2 in the mitotic exit network. Cdc5 phosphorylates Bfa1 and acts to antagonize Bfa1 function to promote mitotic exit. Bfa1 is regulated by multiple cell cycle checkpoints. The spindle assembly and spindle orientation checkpoints inhibit Bfa1 phosphorylation. DNA damage does not inhibit Bfa1 phosphorylation and instead causes a Rad53- and Dun1-dependent modification of Bfa1. Regulation of Bfa1 may therefore be a key step controlled by multiple checkpoint pathways to ensure a mitotic arrest.

Amino Acid Sequence↗

[Phenotypic and functional alterations of mesangial cells in patients with diabetic nephropathy].

OBJECTIVE: To explore the phenotypic and functional changes of glomerular mesangial cells (MC) in the development of diabetic nephropathy (DN). METHODS: Renal biopsy specimens were obtained from patients with type II DN. MC from microdissected glomeruli were cultured in vitro. Both the cells deriving from minute piece of renal biopsy specimen of type 2 DN with overt proteinuria and from transplanted donors' kidneys were investigated. Cell volume, RNA/DNA ratio and the production of fibronectin and glucose transporter 1 (GLUT1) was analyzed by flow ctrometry. Cell proliferation was determined by 3H-Tdr incorporation assay and doubling time. Immunofluorescence staining and flow ctrometry were used to examine the expression of alpha-smooth muscle actin and extracellular matrix. The mRNA expression of GLUT1 was determined by Northern blotting and flow cytometry. Glucose uptake rate by MC was detected using the [3H]-2-DG. The activity of glutamine: fructose-6-P aminotransferase (GFAT), the key enzyme of hexosamine pathway, was measured by spetrophotometry method. Specimens from transplanted kidneys were used a s controls. RESULTS: In specimens from patients with type II DN, increase in volume of MC (in arbitrary units) and RNA/DNA ratio (0.29 +/- 0.05 vs. 0.17 +/- 0.03, P < 0.01) accompanied with high 3H-Tdr incorporation rate (1,898 +/- 421 vs. 1,221 +/- 262, P < 0.05) and shorter doubling time (31.6 +/- 1.84 h vs. 35.0 +/- 5.37 h, P < 0.05) was found in comparison with the control. The synthesis of alpha-smooth muscle actin and extracellular matrix, including fibronectin and laminin, increased. Enhanced mRNA and protein expression of GLUT1 were verified in MC from DN. 2-DG uptake assay showed increased glucose uptake rate in MC from DN compared to the control(1,592 cpm x 10(5) cell-1 vs. 1,275 cpm x 10(5) cell-1, P < 0.05). Furthermore, MC from DN demonstrated a higher GFAT activity as compared to control. CONCLUSION: Dramatic phenotypic and functional changes, including cell hypertrophy, increased cell turnover, excessive formation of ECM, enhanced expression of GLUT1 as well as alterration in cell glucose uptake, excessive flux of glucose metabolism through the hexosamine pathway, occur in MC from type II DN. The above mentioned phenotypic and functional changes may be the basis of pathogenesis of MC in DN.

Actins↗