Biomedical subjects

B Su

Publications and source records attributed to B Su.

At least 37 records · Page 2Linked to original sources

PubMed2001

Genetic diversity and population history of the red panda (Ailurus fulgens) as inferred from mitochondrial DNA sequence variations.

The red panda (Ailurus fulgens) is one of the flagship species in worldwide conservation and is of special interest in evolutionary studies due to its taxonomic uniqueness. We sequenced a 236-bp fragment of the mitochondrial D-loop region in a sample of 53 red pandas from two populations in southwestern China. Seventeen polymorphic sites were found, together with a total of 25 haplotypes, indicating a high level of genetic diversity in the red panda. However, no obvious genetic divergence was detected between the Sichuan and Yunnan populations. The consensus phylogenetic tree of the 25 haplotypes was starlike. The pairwise mismatch distribution fitted into a pattern of populations undergoing expansion. Furthermore, Fu's F(S) test of neutrality was significant for the total population (F(S) = -7.573), which also suggests a recent population expansion. Interestingly, the effective population size in the Sichuan population was both larger and more stable than that in the Yunnan population, implying a southward expansion from Sichuan to Yunnan.

Animals↗

PubMed2001

Expression of prostaglandin D synthase in ovarian cancer.

Lipocalin-type prostaglandin D synthase (L-PGDS) has recently been shown to be expressed in human brain tumors and breast tumors. However, L-PGDS expression has not been investigated in ovarian cancer. The objective of this study was to determine whether L-PGDS is expressed in human ovarian cancer. Lipocalin prostaglandin D synthase mRNA was cloned and sequenced by RT-PCR. Using in situ hybridization (ISH) technique, the expression of L-PGDS mRNA in 54 ovarian cancer was investigated. Expression of L-PGDS mRNA was found in tumor cells of all various types of ovarian cancers. Patterns of staining of tumor cells varied among different histological types of ovarian cancer. Significant discrepancy between the intensity of the staining and histological types of ovarian cancer could be established (p<0.01). It is reported for the first time that the expression of mRNA of L-PGDS exists in the ovarian cancer, and is related to the cancer type. This may have significance for the progress of ovarian cancer.

Base Sequence↗

PubMed2001

Melting curve analysis of SNPs (McSNP): a gel-free and inexpensive approach for SNP genotyping.

High-throughput methods for assaying DNA variation require two important steps: (i) discriminating the variation and (ii) detecting the signal. In this report, we describe a novel SNP genotyping method that we refer to as melting curve analysis of SNPs (McSNP). McSNP combines a classic approach for discriminating alleles, restriction enzyme digestion, with a more recent method for detecting DNA fragments, melting curve analysis. Melting curve analysis is performed by slowly heating DNA fragments in the presence of the dsDNA-specific fluorescent dye SYBR Green I. As the sample is heated, fluorescence rapidly decreases when the melting temperature of a particular fragment is reached. We show that it is possible to determine the composition of simple mixtures of DNA fragments, such as those that result from restriction enzyme digestions of short PCR products. McSNP is well suited for high-throughput genotyping because 96 samples can be analyzed and automatically scored in 20 min. Our results clearly demonstrate that McSNP is a simple, inexpensive, and accurate means of genotyping SNP variation.

Genotype↗

PubMed2001

Genetic influences on craniofacial outcome in an avian model of prenatal alcohol exposure.

BACKGROUND: Understanding the basis for ethanol's teratogenic effects may inform the etiology of fetal alcohol syndrome. Here we investigate how genetic background and susceptibility to ethanol-induced neural crest apoptosis contribute to the distinctive craniofacial phenotype observed after prenatal alcohol exposure. METHODS: Nine different chick strains were exposed to ethanol at gastrulation. The sensitivity of these embryos to ethanol-induced neural crest apoptosis was reported elsewhere (Debelak and Smith, 2000). Here, these embryos were permitted to develop until embryonic day 10, when facial morphogenesis was largely complete, and cephalometric measurements were made on cleared skulls. Shifts in facial growth were correlated against the severity of ethanol-induced apoptosis in facial precursors. RESULTS: The facial shape produced by ethanol exposure was a function of the embryos' genetic strain. Three general responses were observed: apparent midfacial flattening (Babcock B300 x Hampshire Red, ISA-Babcock, HyLine W98, and HyLine W36 strains), overall facial expansion (Spafas and Babcock B300 strains), or overall facial hypoplasia (DeKalb strains). When dose and timing of exposure were held constant, the embryo's genetic background predicted the facial outcome. For ethanol-sensitive strains, apoptosis of facial precursor populations was required to produce the facial defects. That some strains had essentially normal faces despite extensive cell death indicated a capacity to recover from the earlier neural crest losses. CONCLUSIONS: We propose that ethanol's effects on craniofacial development are multifactoral, and these influences may include susceptibility to apoptosis, regenerative capacity, and compensatory outgrowth of the facial primordia. The embryo's genetic background may modulate these events. The high and low responder chick strains are useful tools to dissect these contributions.

Animals↗

PubMed2001

[A preliminary study of the combination of noninvasive parameters in the diagnosis of liver fibrosis].

OBJECTIVE: To explore the combination of noninvasive parameters and its significance in the diagnosis of liver fibrosis. METHODS: Liver biopsy was performed on 200 patients with chronic liver diseases, and the biochemical parameters, serum fibrotic markers, and B ultrasound, CT, and MRI were detected in the corresponding period. Then, by the regression, we obtained the combination of the noninvasive parameters and evaluated the significance in the diagnosis of liver fibrosis. RESULTS: Three combinations have been obtained. The parameters in the first combination which was used to differentiate fibrosis and no fibrosis(S0 vs S1+S2+S3+S4) were the parameter of blood flow of portal vein per minute by B ultrasonography, age, the maximum oblique line of right liver by B ultrasound, the wave expression of the surface of liver by CT/MRI and GGT. The parameters in the second combination which was used to evaluated the degree of fibrosis(S1+S2 vs S3+S4) were HA, A/G and the longest length of spleen by B ultrasound. The third combination which was used to distinguish fibrosis with cirrhosis (S1+S2+S3 vs S4) was composed by HA, the little cyst-like change near the intrahepatic duct, thickness of liver capsule by B ultrasound, age and the index of symptoms. All the three combinations were sensitive, specific, and accurate. CONCLUSIONS: The combinations of noninvasive parameters is more valuable than single parameter in the diagnosis of liver fibrosis.

Adolescent↗

PubMed2001

Epithelial maturation and extracellular matrix in reduced enamel epithelium.

OBJECTIVE: To evaluate epithelial-mesenchymal interactions in morphological homeostasis through histologically orientated observations on the reduced enamel in epithelium. STUDY DESIGN: Specimens were taken from impacted molar sites in 20 patients using the surgery. These were processed using standard histological, pathological and biochemical techniques. Slides were observed with a Nikon Eclipse E-600, Plan Apo piece, Microscopy, and photography was done using a Nikon Coolpix 990 digital camera. RESULTS: Radiolucent lesions displayed the supporting fibrous connective tissue wall with stratified squamous epithelium lining mostly. None of the specimens displayed prominent CAM 5.2, and anti-human K7 reacuvity, and PAS positive staining. CONCLUSION: While the results of this study suggest that the reduced enamel epithelium showed a lower tendency in cell cycle, it does indicate that a histologically oriented study of reduced enamel epithelium is needed for the understanding of epithelial-mesenchymal interactions in morphogenesis.

Dental Enamel↗

PubMed2000

Polynesian origins: insights from the Y chromosome.

The question surrounding the colonization of Polynesia has remained controversial. Two hypotheses, one postulating Taiwan as the putative homeland and the other asserting a Melanesian origin of the Polynesian people, have received considerable attention. In this work, we present haplotype data based on the distribution of 19 biallelic polymorphisms on the Y chromosome in a sample of 551 male individuals from 36 populations living in Southeast Asia, Taiwan, Micronesia, Melanesia, and Polynesia. Surprisingly, nearly none of the Taiwanese Y haplotypes were found in Micronesia and Polynesia. Likewise, a Melanesian-specific haplotype was not found among the Polynesians. However, all of the Polynesian, Micronesian, and Taiwanese haplotypes are present in the extant Southeast Asian populations. Evidently, the Y-chromosome data do not lend support to either of the prevailing hypotheses. Rather, we postulate that Southeast Asia provided a genetic source for two independent migrations, one toward Taiwan and the other toward Polynesia through island Southeast Asia.

Biological Evolution↗

PubMed2000

MEK kinase 1 is critically required for c-Jun N-terminal kinase activation by proinflammatory stimuli and growth factor-induced cell migration.

Exposure of eukaryotic cells to extracellular stimuli results in activation of mitogen-activated protein kinase (MAPK) cascades composed of MAPKs, MAPK kinases (MAP2Ks), and MAPK kinase kinases (MAP3Ks). Mammals possess a large number of MAP3Ks, many of which can activate the c-Jun N-terminal kinase (JNK) MAPK cascade when overexpressed, but whose biological function is poorly understood. We examined the function of the MAP3K MEK kinase 1 (MEKK1) in proinflammatory signaling. Using MEKK1-deficient embryonic stem cells prepared by gene targeting, we find that, in addition to its function in JNK activation by growth factors, MEKK1 is required for JNK activation by diverse proinflammatory stimuli, including tumor necrosis factor alpha, IL-1, double-stranded RNA, and lipopolysaccharide. MEKK1 is also essential for induction of embryonic stem cell migration by serum factors, but is not required for activation of other MAPKs or the IkappaB kinase signaling cascade.

Animals↗

PubMed2000

Multiple origins of Tibetan Y chromosomes.

The genetic origin of Tibetans was investigated using Y chromosome markers. A total of three populations were studied, two from central Tibet speaking central Tibetan and one from Yunnan speaking Kham. Two dominant paternal lineages (>80%) were identified in all three populations with one possibly from central Asia (YAP+) and the other from east Asia (M122C). We conclude that Tibetan Y chromosomes may have been derived from two different gene pools, given the virtual absence of M122C in central Asia and YAP+ in east Asia, with drift an unlikely mechanism accounting for these observations.

Alu Elements↗

PubMed2000

Y chromosome haplotypes reveal prehistorical migrations to the Himalayas.

By using 19 Y chromosome biallelic markers and 3 Y chromosome microsatellite markers, we analyzed the genetic structure of 31 indigenous Sino-Tibetan speaking populations (607 individuals) currently residing in East, Southeast, and South Asia. Our results showed that a T to C mutation at locus M122 is highly prevalent in almost all of the Sino-Tibetan populations, implying a strong genetic affinity among populations in the same language family. Furthermore, the extremely high frequency of H8, a haplotype derived from M122C, in the Sino-Tibetan speaking populations in the Himalayas including Tibet and northeast India indicated a strong bottleneck effect that occurred during a westward and then southward migration of the founding population of Tibeto-Burmans. We, therefore, postulate that the ancient people, who lived in the upper-middle Yellow River basin about 10,000 years ago and developed one of the earliest Neolithic cultures in East Asia, were the ancestors of modern Sino-Tibetan populations.

China↗

PubMed2000

Natives or immigrants: modern human origin in east Asia.

East Asia is one of the few regions in the world where a relatively large number of human fossils have been unearthed--a discovery that has been taken as evidence for an independent local origin of modern humans outside of Africa. However, genetic studies conducted in the past ten years, especially using Y chromosomes, have provided unequivocal evidence for an African origin of East Asian populations. The genetic signatures present in diverse East Asian populations mark the footsteps of prehistoric migrations that occurred tens of thousands of years ago.

Africa↗

PubMed2000

Mekk3 is essential for early embryonic cardiovascular development.

The early development of blood vessels consists of two phases, vasculogenesis and angiogenesis, which involve distinct and also overlapping molecular regulators, but the intracellular signal transduction pathways involved in these processes have not been well defined. We disrupted Map3k3 (also known as Mekk3), which encodes Mekk3, a member of the Mekk/Ste11 family, in mice. Map3k3-/- embryos died at approximately embryonic day (E) 11, displaying disruption of blood vessel development and the structural integrity of the yolk sac. Angiogenesis was blocked at approximately E9.5 in mutant embryos. Map3k3 disruption did not alter the expression of the genes encoding Vegf-1, angiopoietin or their receptors. The development of embryonic, but not maternal, blood vessels in the placentas of Map3k3-/- embryos was impaired, revealing an intrinsic defect in Map3k3-/- endothelial cells. Moreover, Mekk3 activated myocyte-specific enhancer factor 2C (Mef2c), a transcription factor crucial for early embryonic cardiovascular development through the p38 mitogen-activated protein kinase (Mapk) cascade. We conclude that Mekk3 is necessary for blood vessel development and may be a possible target for drugs that control angiogenesis.

Animals↗

PubMed2000

Distribution of three HIV-1 resistance-conferring polymorphisms (SDF1-3'A, CCR2-641, and CCR5-delta32) in global populations.

Chemokine receptors (CCR5, CXCR4 and CCR2) have been shown to be important co-receptors for HIV infection. Mutations at CCR5 (CCR5-delta2), CCR2 (CCR2-641), and stromal-derived factor SDF1 (SDF1-3'A), a primary ligand for CXCR4, are known to have protective effects against HIV-1 infection and the onset of AIDS symptoms. We studied the three-locus genotype frequency distributions in 70worldwide populations from a sample of 2341 individuals without any known history of HIV-1 infection and AIDS symptoms. From these data, we estimated the risk of AIDS onset (relative hazard, RH) of each population. This survey shows that the substantial allele frequency differences of each of these mutations translate into an extensive variation in relative hazards for AIDS in worldwide populations. However, no evidence of natural selection against the mutant gene carriers is detected. Finally, the combined three-locus genotype data predict the highest relative hazard (RH) in South-East Asia and Africa where AIDS is known to be more prevalent.

Chemokine CXCL12↗

PubMed2000

Synergistic interaction of MEK kinase 2, c-Jun N-terminal kinase (JNK) kinase 2, and JNK1 results in efficient and specific JNK1 activation.

Mitogen-activated protein kinases (MAPKs) are activated through cascades or modules consisting of a MAPK, a MAPK kinase (MAPKK), and a MAPKK kinase (MAPKKK). Investigating the molecular basis of activation of the c-Jun N-terminal kinase (JNK) subgroup of MAPK by the MAPKKK MEKK2, we found that strong and specific JNK1 activation by MEKK2 was mediated by the MAPKK JNK kinase 2 (JNKK2) rather than by JNKK1 through formation of a tripartite complex consisting of MEKK2, JNKK2, and JNK1. No scaffold protein was required for the MEKK2-JNKK2-JNK1 tripartite-complex formation. Expression of JNK1, JNKK2, and MEKK2 significantly augmented the coprecipitation of, respectively, MEKK2-JNKK2, MEKK2-JNK1, and JNKK2-JNK1, indicating that the interaction of MEKK2, JNKK2, and JNK1 is synergistic. Finally, the JNK1 was activated more efficiently in the MEKK2-JNKK2-JNK1 complex than was the JNK1 excluded from the complex. Thus, formation of a signaling complex through synergistic interaction of a MAPKKK, a MAPKK, and a MAPK molecule like MEKK2-JNKK2-JNK1 is likely to be responsible for the efficient, specific flow of information via MAPK cascades.

Animals↗

PubMed2000

RAPD analysis of Astragalus medicines marketed in Taiwan.

The genetic variability of Astragalus medicine materials sold by twenty randomly selected stores in Taiwan was investigated using RAPD analysis in order to obtain available primers which could clearly differentiate among them. Total DNA isolated from the rhizomes of the samples were used as templates, and sixty 10 mer arbitrary primers were used in the analysis. The aim of the present study is to construct an identification model of molecular biotechniques applicable to Chinese herbal medicines in RAPD analysis. Three of the primers, OPT-03, OPT-13, and OPT-17, revealed polymorphic RAPD fingerprints among the samples of Astragalus membranaceus, and between Astragalus membranaceus and Hedysarum polybotrys samples. SSCP analysis was also conducted on PCR products from the ITS-1 region of ribosomal DNA in order to differentiate the two species.

Astragalus propinquus↗

PubMed2000

MEKK1 activation of human estrogen receptor alpha and stimulation of the agonistic activity of 4-hydroxytamoxifen in endometrial and ovarian cancer cells.

Estrogens are mitogens that stimulate the growth of both normal and transformed epithelial cells of the female reproductive system. The effect of estrogens is mediated through the estrogen receptors, which are ligand-regulated transcription factors. Tamoxifen, a selective estrogen receptor modulator, functions as an estrogen receptor antagonist in breast but an agonist in uterus. In the current study, we show that coexpression of a constitutively active MEKK1, but not RAF or MEKK2, significantly increases the transcriptional activity of the receptor in endometrial and ovarian cancer cells. The expression of wild-type MEKK1 and an active Rac1, which functions upstream of MEKK1, also increased the activity of the receptor while coexpression of dominant negative MEKK1 blocked the Rac1 induction, indicating that endogenous MEKK1 is capable of activating the receptor. Additional experiments demonstrated that the MEKK1-induced activation was mediated through both Jun N-terminal kinases and p38/Hog1 and was independent of the known phosphorylation sites on the receptor. p38, but not Jun N-terminal kinases, efficiently phosphorylated the receptor in immunocomplex kinase assays, suggesting a differential involvement of the two kinases in the receptor activation. More importantly, the expression of the constitutively active MEKK1 increased the agonistic activity of 4-hydroxytamoxifen to a level comparable to that of 17beta-estradiol and fully blocked its antagonistic activity. These findings suggest that the uterine-specific agonistic activity of the tamoxifen compound may be determined by the status of kinases acting downstream of MEKK1.

Endometrial Neoplasms↗

PubMed2000

World population data for the HLA-DQA1, PM and D1S80 loci with least and most common profile frequencies for combinations of loci estimated following NRC II guidelines.

All published and unpublished gene frequency data for the PCR-based loci HLA-DQA1, LDLR, GYPA, HBGG, D7S8, GC, and D1S80 that could be located are presented in summary tables. These gene frequencies provide the data necessary for estimating probabilities of chance match according to NRC II guidelines for any DNA profile that includes any combination of these loci for any of the populations. To illustrate the range of polymorphism for combined locus profiles, least and most common profile frequencies were estimated following NRC II guidelines for: the PM loci for all populations for which PM data were available; and for combinations of HLA-DQA1/PM, HLA-DQA1/D1S80, PM/D1S80, and HLA-DQA1/ PM/D1S80 for populations for which data were available for the relevant combinations. The profile frequencies were calculated at theta values of zero and 0.01. Minimum allele frequencies (MAF) were calculated, and are shown, for each data set for which the MAF was greater than the lowest observed allele frequency. Least common profile frequencies were calculated using MAF in those cases to illustrate a conservative estimate. The effect of using MAF versus lowest observed allele frequency in estimating least common profile frequencies is briefly illustrated as well. We finally show that aggregate U.S. gene frequency data for the classical MN and GC polymorphisms for both Caucasian and African-American populations is fully in accord with the DNA-based gene frequency data obtained from PM reverse dot-blot strips for GYPA and GC, respectively.

Alleles↗

PubMed2000

[Advance in soil sampling methods in rhizosphere microzone study].

Soil sampling methods in rhizosphere microzone study since 1960's were reviewed. It was suggested that the trend of rhizosphere soil sampling was from field coarse sampling to fine division of indoor simulated experiment. The simulated equipment was applied for field experiments, and the purpose guiding production practice could be achieved finally. Meanwhile, with the widening of the concept of rhizosphere, such as ecoboundary layer, rhizosphere soil sampling tends to keep unvarnished and fine.

Ecosystem↗