PubMed Health⌕ Search

Biomedical subjects

J Yang

Publications and source records attributed to J Yang.

At least 163 records · Page 9Linked to original sources
PubMed2001

Exclusion of SIX6 hemizygosity in a child with anophthalmia, panhypopituitarism and renal failure.

We report a patient who presented with anophthalmia, panhypopituitarism, early onset of end stage renal failure, and craniofacial abnormalities. MRI at age 3 revealed that the pituitary was absent and renal biopsy demonstrated nephronophthisis as the cause of the renal failure. A similar syndrome has been associated with interstitial deletions of chromosome 14q22 and in one case hemizygosity for SIX6 was demonstrated. The patient reported here had a normal karyotype and Southern blot did not reveal loss of one copy of SIX6. We discuss other possible candidate genes that could be implicated in this syndrome.

Abnormalities, Multiple↗
PubMed2001

Induction of melanoma in murine macrophage inflammatory protein 2 transgenic mice heterozygous for inhibitor of kinase/alternate reading frame.

The molecular and genetic events that contribute to the genesis and progression of cutaneous malignant melanoma are poorly understood, attributable in large part to the different genetic alterations accompanying tumorigenesis. Inhibitor of kinase 4a (INK4a) is often inactivated in families with hereditary melanoma. Loss of INK4a/alternate reading frame (ARF) in mice is associated with increased incidence of other tumors such as lymphoma and fibrosarcoma. However, the incidence of melanoma in INK4a/ARF-deficient mice is very low. Our previous studies have revealed that the CXC chemokine, CXCL1, is overexpressed in human malignant melanoma cells and is linked to transformation of immortalized murine melanocytes. To study the direct role of CXCL1 on the genesis of primary melanoma lesions, transgenic mouse lines were established that express the murine homologue of CXCL1, murine macrophage inflammatory protein 2 (MIP-2), under the transcriptional control of the tyrosinase promoter/enhancer (Tyr-MIP-2) in the mice that were deficient or not deficient for INK4a/ARF. Strong MIP-2 immunoreactivity was associated with pigmented melanocytes in the hyperproliferative hair follicles in the Tyr-MIP-2 transgenic mice, and the level of MIP-2 expression was similar in both INK4a/ARF heterozygous or wild-type mice. After treatment of mice with 7,12-dimethylbenz(a)anthracene, cutaneous melanomas formed in 12% (17/145) of the Tyr-MIP-2 transgene-positive mice, whereas only 2% (3/146) of the Tyr-MIP-2 transgene-negative mice developed melanoma. When melanocytes cultured from MIP-2 transgenic mice null for INK4a/ARF were transplanted into nude mice, melanoma formation occurred in 83% (10/12) of the cases with a latency period of 3 months. However, no melanoma lesions arose in nude mice injected with INK4a/ARF -/- melanocytes, which did not express the MIP-2 transgene. Our results demonstrate that constitutive expression of MIP-2 in INK4a/ARF-deficient melanocytes facilitates formation of malignant melanoma.

Animals↗
PubMed2001

The shorter zinc finger protein ZNF230 gene message is transcribed in fertile male testes and may be related to human spermatogenesis.

The zinc finger gene family represents one of the largest in the mammalian genome, with several of these genes reported to be involved in spermatogenesis. A newly discovered gene has been identified that is expressed abundantly in the testicular tissue of fertile men as determined by mRNA differential display. The gene encodes a C(3)HC(4)-type zinc finger protein motif (ring finger motif) consistent with a role in pre-meiotic or post-meiotic sperm development. The gene was named ZNF230 and mapped to the short arm of chromosome 11 (11p15). ZNF230 has two transcripts, of 1 kb and 4.4 kb in length. The shorter 1 kb transcript was only detected in testicular tissue whereas the longer 4.4 kb transcript was not detected in testis but was found in several other tissues. The lack of detectable ZNF230 expression in azoospermic patients by reverse transcriptase-mediated PCR analysis is interpreted to mean that this gene is involved in maintaining normal human male fertility.

Amino Acid Sequence↗
PubMed2001

Altering the GTP binding site of the DNA/RNA-binding protein, Translin/TB-RBP, decreases RNA binding and may create a dominant negative phenotype.

The DNA/RNA-binding protein, Translin/Testis Brain RNA-binding protein (Translin/TB-RBP), contains a putative GTP binding site in its C-terminus which is highly conserved. To determine if guanine nucleotide binding to this site functionally alters nucleic acid binding, electrophoretic mobility shift assays were performed with RNA and DNA binding probes. GTP, but not GDP, reduces RNA binding by approximately 50% and the poorly hydrolyzed GTP analog, GTPgammaS, reduces binding by >90% in gel shift and immunoprecipitation assays. No similar reduction of DNA binding is seen. When the putative GTP binding site of TB-RBP, amino acid sequence VTAGD, is altered to VTNSD by site directed mutagenesis, GTP will no longer bind to TB-RBP(GTP) and TB-RBP(GTP) no longer binds to RNA, although DNA binding is not affected. Yeast two-hybrid assays reveal that like wild-type TB-RBP, TB-RBP(GTP) will interact with itself, with wild-type TB-RBP and with Translin associated factor X (Trax). Transfection of TB-RBP(GTP) into NIH 3T3 cells leads to a marked increase in cell death suggesting a dominant negative function for TB-RBP(GTP) in cells. These data suggest TB-RBP is an RNA-binding protein whose activity is allosterically controlled by nucleotide binding.

3T3 Cells↗
PubMed2001

Adiabatic interaction of N ultrashort solitons: universality of the complex Toda chain model.

Using the Karpman-Solov'ev method we derive the equations for the two-soliton adiabatic interaction for solitons of the modified nonlinear Schrödinger equation (MNSE). Then we generalize these equations to the case of N interacting solitons with almost equal velocities and widths. On the basis of this result we prove that the N MNSE-soliton train interaction (N>2) can be modeled by the completely integrable complex Toda chain (CTC). This is an argument in favor of universality of the complex Toda chain that was previously shown to model the soliton train interaction for nonlinear Schrödinger solitons. The integrability of the CTC is used to describe all possible dynamical regimes of the N-soliton trains that include asymptotically free propagation of all N solitons, N-soliton bound states, various mixed regimes, etc. It allows also to describe analytically the manifolds in the 4N-dimensional space of initial soliton parameters that are responsible for each of the regimes mentioned above. We compare the results of the CTC model with the numerical solutions of the MNSE for two and three-soliton interactions and find a very good agreement.

Journal Article↗
PubMed2001

[Association between DLST gene polymorphism and Alzheimer's disease].

OBJECTIVE: To investigate the association between the polymorphic alleles of dihydrolipoamide succinyltransferase (DLST) gene cDNA at position A19117G in intron 13 and C19183T in exon 14 and the risk for sporandic Alzheimer's disease (SAD). METHODS: The polymorphism of DLST gene was detected using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques in 105 patients with sporadic Alzheimer disease and 109 normal controls. RESULTS: The frequency of AT/AC genotype was found to be significantly higher in SAD patients (21%) than in controls (10%) with an odds ratio of 2.36 (P < 0.05). The frequencies of AC/AC, AT/AT genotypes and AC allele were slightly decreased in cases with SAD as compared with controls. While the frequencies of the GC/GC genotype and GC allele were slightly higher in SAD patients than in controls. However, these differences were not statistically significant (P > 0.05). CONCLUSION: The AT/AC genotype of DLST gene is associated with an increased risk for SAD.

Acyltransferases↗
PubMed2001

[Persistent ectopic pregnancy, report of seven cases].

OBJECTIVE: To investigate and evaluate the occurrence, diagnosis and treatment of persistent ectopic pregnancy. METHODS: 411 patients with ectopic pregnancy treated via laparoscopy or laparotomy between July 1995 and June 2000 were reviewed. The clinic manifestations of patients who were successfully treated by laparoscopic surgery and those with persistent ectopic pregnancy were analyzed by multivariate stepwise logistic regression. RESULTS: Seven cases with persistent ectopic pregnancy occurred after laparoscopic surgery with an incidence rate of 3.5%. Six cases had been treated by conservative approach and one case by tubectomy. Persistent ectopic pregnancy was diagnosed in two cases because of abdominal pain and intra-abdominal hemorrhage and in five cases because of plateauing beta-hCG titers. Two of the seven cases underwent a second time laparoscopic surgery and five were treated with methotrexate. The size of ectopic mass and the absence of villi by pathologic finding were relevant factors of persistent ectopic pregnancy. CONCLUSION: Small mass of ectopic pregnancy, short amenorrhea time, and biopsy specimens in which no villi are found are all warning indicators of persistent ectopic pregnancy. Close postoperative beta-hCG surveillance is critical for diagnosis and treatment.

Chorionic Gonadotropin, beta Subunit, Human↗
PubMed2001

Complexity and regularity of vector-soliton collisions.

In this paper, we extensively investigate the collision of vector solitons in the coupled nonlinear Schrödinger equations. First, we show that for collisions of orthogonally polarized and equal-amplitude vector solitons, when the cross-phase modulational coefficient beta is small, a sequence of reflection windows similar to that in the phi(4) model arises. When beta increases, a fractal structure unlike phi(4)'s gradually emerges. But when beta is greater than one, this fractal structure disappears. Analytically, we explain these collision behaviors by a variational model that qualitatively reproduces the main features of these collisions. This variational model helps to establish that these window sequences and fractal structures are caused entirely or partially by a resonance mechanism between the translational motion and width oscillations of vector solitons. Next, we investigate collision dependence on initial polarizations of vector solitons. We discovered a sequence of reflection windows that is phase induced rather than resonance induced. Analytically, we have derived a simple formula for the locations of these phase-induced windows, and this formula agrees well with the numerical data. Last, we discuss collision dependence on relative amplitudes of initial vector solitons. We show that when vector solitons have different amplitudes, the collision structure simplifies. Feasibility of experimental observation of these results is also discussed at the end of the paper.

Journal Article↗
PubMed2001

A genomewide search for quantitative-trait loci underlying asthma.

A genomewide screen for quantitative-trait loci (QTLs) that underlie asthma was performed on 533 Chinese families with asthma, by the unified Haseman-Elston method. Nine asthma-related phenotypes were studied, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), airway responsiveness as indicated by methacholine (MTCH)-challenge test, serum total immunoglobulin E (TIgE), serum-specific immunoglobulin E, eosinophil count in peripheral blood, and skin-prick tests with three different allergens (cockroach, Dermatophagoides pteronyssinus, and D. farinae). Our study showed significant linkage between airway responsiveness to MTCH and D2S1780 on chromosome 2 (P<.00002) and provided suggestive evidence (P<.002) for six additional possible QTLs: D10S1435 and D22S685, for FEV1; D16S412, for FVC; D19S433, for airway responsiveness to MTCH; D1S518, for TIgE; and D4S1647, for skin reactivity to cockroach. No significant or suggestive evidence of linkage for the other four traits was found.

Adult↗
PubMed2001

Endostatin regulates branching morphogenesis of renal epithelial cells and ureteric bud.

Endostatin (ES) inhibits endothelial cell migration and has been found to bind to glypicans (Gpcs) on both endothelial cells and renal epithelial cells. We examined the possibility that ES might regulate epithelial cell morphogenesis. The addition of ES to cultured epithelial cells causes an inhibition of both hepatocyte growth factor- and epidermal growth factor-dependent process formation and migration. In contrast, ES does not inhibit epidermal growth factor-dependent morphogenesis in renal epithelial cells derived from Gpc-3 -/mice, whereas expression of Gpc-1 in these cells reconstitutes ES responsiveness. Gpc-3 -/mice have been shown to display enhanced ureteric bud (UB) branching early in development, and cultured UB cells release ES into the media, suggesting that ES binding to Gpcs may regulate UB branching. The addition of ES inhibits branching of the explanted UB, whereas a neutralizing Ab to ES enhances UB outgrowth and branching. Thus, local expression of ES at the tips of the UB may play a role in the regulation of UB arborization.

Animals↗
PubMed2001

Topical application of HIV DNA vaccine with cytokine-expression plasmids induces strong antigen-specific immune responses.

The topical application of DNA vaccine to the skin is a useful method of immunization because of its simplicity, painlessness and economy. But the immune responses that it elicits are relatively low. In this study, we administered human immunodeficiency virus type-1 (HIV-1) DNA vaccine with cytokine-expressing plasmids to the skin of mice by a new topical application technique involving prior elimination of keratinocytes using fast-acting adhesive. Our results revealed that the topical application of HIV-1 DNA vaccine induced high levels of both humoral and cell-mediated immune activity against HIV-1 envelope antigen. Co-administration of the DNA vaccine with cytokine expression plasmids of IL-12 and granulocyte-macrophage colony-stimulating factor (GM-CSF) by this new method raised the levels of both the HIV-specific cytotoxic T lymphocyte (CTL) response and delayed-type hypersensitivity (DTH) and facilitated the induction of substantial immune responses by DNA vaccine. Skin biopsy sections, thus, immunized showed significant increases of S-100 protein-positive dendritic cells (DCs). These results suggest that the topical application method described here is an efficient route of DNA vaccine administration and that the immune response may be induced by DNA plasmids taken in by DCs, Langerhans cells (LCs), or others such as antigen-presenting cells. This new topical application is likely to be of benefit in clinical use.

AIDS Vaccines↗
PubMed2001

Protein phosphatase 2A interacts with and directly dephosphorylates RelA.

Nuclear factor-kappa B (NF-kappa B)/Rel transcription factors are key regulators of a variety of genes involved in inflammatory responses, growth, differentiation, apoptosis, and development. There are increasing lines of evidence that NF-kappa B/Rel activity is controlled to a great extent by its phosphorylation state. In this study, we demonstrated that RelA physically associated with protein phosphatase 2A (PP2A) subunit A (PR65). Both the N- and C-terminal regions of RelA were responsible for the PP2A binding. RelA co-immunoprecipitated with PP2A in melanocytes in the absence of stimulation, indicating that RelA forms a signaling complex with PP2A in the cells. RelA was dephosphorylated by a purified PP2A core enzyme, a heterodimer formed by the catalytic subunit of PP2A (PP2Ac) and PR65, in a concentration-dependent manner. Okadaic acid, an inhibitor of PP2A at lower concentration, increased the basal phosphorylation of RelA in melanocytes and blocked the dephosphorylation of RelA after interleukin-1 stimulation. Interestingly, PP2A immunoprecipitated from melanocytes was able to dephosphorylate RelA, whereas PP2A immunoprecipitated from melanoma cell lines exhibited decreased capacity to dephosphorylate RelA in vitro. Moreover, in melanoma cells in which I kappa B kinase activity was inhibited by sulindac to a similar level as in melanocytes, the phosphorylation state of RelA and the relative NF-kappa B activity were still higher than those in normal melanocytes. These data suggest that the constitutive activation of RelA in melanoma cells (Yang, J., and Richmond, A. (2001) Cancer Res. 61, 4901-4909) could be due, at least in part, to the deficiency of PP2A, which exhibits decreased dephosphorylation of NF-kappa B/RelA.

Humans↗
PubMed2001

Effect of pH and soybean cultivars on the quantitative analyses of soybean rhizobia populations.

Quantitative analyses of fast- and slow-growing soybean rhizobia populations in soils of four different provinces of China (Hubei, Shan Dong, Henan, and Xinjiang) have been carried out using the most probable number technique (MPN). All soils contained fast- (FSR) and slow-growing (SSR) soybean rhizobia. Asiatic and American soybean cultivars grown at acid, neutral and alkaline pH were used as trapping hosts for FSR and SSR strains. The estimated total indigenous soybean-rhizobia populations of the Xinjiang and Shan Dong soil samples greatly varied with the different soybean cultivars used. The soybean cultivar and the pH at which plants were grown also showed clear effects on the FSR/SSR rations isolated from nodules. Results of competition experiments between FSR and SSR strains supported the importance of the soybean cultivar and the pH on the outcome of competition for nodulation between FSR and SSR strains. In general, nodule occupancy by FSRs significantly increased at alkaline pH. Bacterial isolates from soybean cultivar Jing Dou 19 inoculated with Xinjiang soil nodulate cultivars Heinong 33 and Williams very poorly. Plasmid and lipopolysaccharide (LPS) profiles and PCR-RAPD analyses showed that cultivar Jing Dou 19 had trapped a diversity of FSR strains. Most of the isolates from soybean cultivar Heinong 33 inoculated with Xinjiang soil were able to nodulate Heinong 33 and Williams showed very similar, or identical, plasmid, LPS and PCR-RAPD profiles. All the strains isolated from Xinjiang province, regardless of the soybean cultivar used for trapping, showed similar nodulation factor (LCO) profiles as judged by thin layer chromatographic analyses. These results indicate that the existence of soybean rhizobia sub-populations showing marked cultivar specificity, can affect the estimation of total soybean rhizobia populations indigenous to the soil, and can also affect the diversity of soybean rhizobial strains isolated from soybean nodules.

China↗
PubMed2001

Short-term exposure to pregnancy levels of estrogen prevents mammary carcinogenesis.

It is well established that pregnancy early in life reduces the risk of breast cancer in women and that this effect is universal. This phenomenon of parity protection against mammary cancer is also observed in rodents. Earlier studies have demonstrated that short-term administration of estradiol (E) in combination with progesterone mimics the protective effect of parity in rats. In this study, the lowest effective E dosage for preventing mammary cancer was determined. Rats were injected with N-methyl-N-nitrosourea at 7 weeks of age; 2 weeks later, the rats were subjected to sustained treatment with 20 microg, 100 microg, 200 microg, or 30 mg of E in silastic capsules for 3 weeks. Treatments with 100 microg, 200 microg, and 30 mg of E resulted in serum levels of E equivalent to those of pregnancy and were highly effective in preventing mammary cancer. E treatment (20 microg) did not result in pregnancy levels of E and was not effective in reducing the mammary cancer incidence. In another set of experiments, we determined the effect of different durations of E with or without progesterone treatments on mammary carcinogenesis. These experiments indicate that a period as short as one-third the period of gestation is sufficient to induce protection against mammary carcinogenesis. The pioneering aspect of our study in contrast to long-term estrogen exposure, which is thought to increase the risk of breast cancer, is that short-term sustained treatments with pregnancy levels of E can induce protection against frank mammary cancer.

Alkylating Agents↗
PubMed2001

Mouse nestin cDNA cloning and protein expression in the cytoskeleton of transfected cells.

Complementary DNA (cDNA) corresponding to mouse nestin intermediate filament protein, a specific marker for neural stem cells, was isolated and characterized. The complete sequence comprised 5983 base pairs encoding 1821 amino acids, and the deduced polypeptide was similar to rat (84%), hamster (73%), and human (62%) nestin. Southern blots showed that mouse nestin was a single-copy gene, and Northern blots detected a 6.0 kilobase mRNA transcript. When the cDNA was overexpressed as an enhanced green fluorescent fusion protein in COS7 cells, nestin immunoreactivity appeared in the filamentous cytoskeletal network. Accordingly, biologically active mouse nestin cDNA may offer an important new tool for stem cell research.

Amino Acid Sequence↗
PubMed2001

Total asymmetric synthesis of the putative structure of the cytotoxic diterpenoid (-)-sclerophytin a and of the authentic natural sclerophytins A and B.

An enantioselective synthetic route to the thermodynamically most stable diastereomer of the structure assigned to sclerophytin A (5) has been realized. The required tricyclic ketone 33 was prepared by sequential Tebbe-Claisen rearrangement of lactones 29 and 30, which originated from the Diels-Alder cycloaddition of Danishefsky's diene to (5S)-5-(d-menthyloxy)-2(5H)-furanone (14). An allyl and a cyano group were introduced into the resulting adduct by means of stereocontrolled allylindation under aqueous Barbier-like conditions and by way of cyanotrimethylsilane, respectively. Following stereocontrolled nucleophilic addition of a methyl group to 33, ring A was elaborated by formation of the silyl enol ether, ytterbium triflate-catalyzed condensation with formaldehyde, O-silylation, and Cu(I)-promoted 1,4-addition of isopropylmagnesium chloride. The superfluous ketone carbonyl was subsequently removed and the second ether bridge introduced by means of oxymercuration chemistry. Only then was the exocyclic methylene group unmasked via elimination. An alternative approach to the alpha-carbinol diastereomer proceeds by initial alpha-oxygenation of 37 and ensuing 1,2-carbonyl transposition. Neither this series of steps nor the Wittig olefination to follow induced epimerization at C10. Through deployment of oxymercuration chemistry, it was again possible to elaborate the dual oxygen-bridge network of the target ring system. Oxidation of the organomercurial products with O(2) in the presence of sodium borohydride furnished 72, which was readily separated from its isomer 73 after oxidation to 61. Hydride attack on this ketone proceeded with high selectivity from the beta-direction to deliver (-)-60. Comparison of the high-field (1)H and (13)C NMR properties and polarity of synthetic 5 with natural material required that structural revision be made. Following a complete spectral reassessment of the structural assignments to many sclerophytin diterpenes, a general approach to sclerophytin A, three diastereomers thereof, and of sclerophytin B was devised. The presence of two oxygen bridges as originally formulated was thereby ruled out, and absolute configurations were properly determined. Key elements of the strategy include dihydroxylation of a medium-ring double bond, oxidation of the secondary hydroxyl in the two resulting diols, unmasking of an exocyclic methylene group at C-11, and stereocontrolled 1,2-reduction of the alpha-hydroxy ketone functionality made available earlier.

Antineoplastic Agents↗
PubMed2001

Exposure-response relationship between paternal smoking and children's pulmonary function.

We conducted a cross-sectional study to investigate paternal smoking and children's pulmonary function in rural communities of Anqing, China. Our analysis included 1,718 children 8 to 15 yr of age whose mothers were never-smokers. Multiple linear regression models were used to estimate the effect of paternal smoking on children's pulmonary function, with adjustment for children's age, sex, weight, height, square of height, asthma, and father's education. When compared with children of never-smoking fathers, children of smoking fathers had small, but detectable deficits in FEV(1) (-36 ml, SE = 20) and FVC (-37 ml, SE = 22). When children of smoking fathers were subdivided into two subgroups, father smoked < 30 cigarettes/day and >/= 30 cigarettes/day, we found that children whose fathers smoked >/= 30 cigarettes/day had the largest deficits in both FEV(1) (-79 ml, SE = 30) and FVC (-71 ml, SE = 34). This monotonic exposure-response relationship remained in all strata when we further stratified our analysis by children's sex and asthma status. Our data also suggested that the relationship was greatest among nonasthmatic girls, although neither sex nor asthma interaction terms were statistically significant. We conclude that there is a monotonic exposure-response relationship between paternal smoking and decline of pulmonary function in children in this rural Chinese population.

Adolescent↗