Biomedical subjects

T Cai

Publications and source records attributed to T Cai.

At least 37 records · Page 2Linked to original sources

PubMed2000

Silver Nanowires as Templates for Preparation of Amorphous Carbon Nanotubes.

In this report, we describe a novel method for preparing amorphous carbon nanotubes (ACNT) from silver nanowires using a carbon replica technique. ACNT size and shape are determined by the template silver nanowire. Interspaces between carbon grains present in the ACNT wall cause the wall to act as a permeable membrane through which reactants pass freely. Simple chemical modifications can be used to modify the diameter of the silver filaments within. We anticipate that this method will prove useful in preparing a wide variety of nanometer-sized filaments, perhaps with the replica itself able to serve as a template in casting nanomaterials of assorted shapes. Copyright 2000 Academic Press.

Journal Article↗

PubMed2000

Some nutritional and functional properties of defatted wheat germ protein.

Defatted wheat germ protein (DWGP) was isolated by alkaline extraction at pH 9.5 and subsequent isoelectric precipitation at pH 4.0, and its nutritional and functional properties were studied. The results showed that the amino acid content of defatted wheat germ was as high as 26.793 g/100 g, and the contents of eight essential amino acids were all relatively high. The isoelectric point of DWGP was 4.0. When pH >6.0, the DWGP had high solubility with a nitrogen solubility index of 70%. The emulsifying activity and emulsifying stability of DWGP were similar to those of bovine serum albumin and a little higher than those of casein. DWGP had good foaming capacity, but its foaming stability (FS) was not very good. However, the FS of DWGP can be improved through physical, chemical, or enzymatic methods. Moreover, DWGP had excellent water retention (WR); especially at pH 8.0 and a temperature of 70 degrees C, the WR of DWGP was the highest at 229.4%. DWGP offers is a potential source of functional protein isolate for possible food applications.

Chemical Phenomena↗

PubMed2000

Agrobacterium-mediated sorghum transformation.

Agrobacterium tumefaciens was used to genetically transform sorghum. Immature embryos of a public (P898012) and a commercial line (PHI391) of sorghum were used as the target explants. The Agrobacterium strain used was LBA4404 carrying a 'Super-binary' vector with a bar gene as a selectable marker for herbicide resistance in the plant cells. A series of parameter tests was used to establish a baseline for conditions to be used in stable transformation experiments. A number of different transformation conditions were tested and a total of 131 stably transformed events were produced from 6175 embryos in these two sorghum lines. Statistical analysis showed that the source of the embryos had a very significant impact on transformation efficiency, with field-grown embryos producing a higher transformation frequency than greenhouse-grown embryos. Southern blot analysis of DNA from leaf tissues of T0 plants confirmed the integration of the T-DNA into the sorghum genome. Mendelian segregation in the T1 generation was confirmed by herbicide resistance screening. This is the first report of successful use of Agrobacterium for production of stably transformed sorghum plants. The Agrobacterium method we used yields a higher frequency of stable transformation that other methods reported previously.

Agrobacterium tumefaciens↗

PubMed2000

The cross-cultural generalizability of Axis-II constructs: an evaluation of two personality disorder assessment instruments in the People's Republic of China.

We examined the reliability, cross-instrument validity, and factor structure of Chinese adaptations of the Personality Diagnostic Questionnaire (PDQ-4+; N = 1,926) and Personality Disorders Interview (PDI-IV; N = 525) in psychiatric patients. Comparisons with data from Western countries suggest that the psychometric properties of these two instruments are comparable across cultures. Low to modest agreement between the PDQ-4+ and PDI-IV was observed for both dimensional and categorical personality disorder evaluations. When the PDI-IV was used as the diagnostic standard, the PDQ-4+ showed higher sensitivity than specificity, and higher negative predictive power than positive predictive power. Factor analyses of both instruments replicated the four-factor structure O'Connor and Dyce (1998) found in Western samples. Results suggested that conceptions and measures of DSM-IV personality disorders are cross-culturally generalizable to Chinese psychiatric populations.

Adult↗

PubMed2000

[TGF-beta 1 rapidly reduced hepatocarcinoma cells adhesion on to fibronectin and stimulated FAK dephosphorylation].

In order to investigate whether TGF-beta 1 could rapidly regulate integrin induced signaling, we treated SMMC-7721 human hepatocellular carcinoma cells with human recombinant TGF-beta 1 for 10 min, and examined cell adhesion, integrin amount and FAK tyrosine phosphorylation. We used cell adhesion assay to estimate the affinity of alpha 5 beta 1 integrin with fibronectin, and analyzed the amount of integrin alpha 5 and beta 1 subunits by performing FACS analysis. Then western blot analysis was carried out to examine tyrosine phosphorylation level of FAK. Our results showed that TGF-beta 1 could rapidly attenuated cell adhesion onto Fn without changing the expression of alpha 5 beta 1 integrin, and at the meantime dephosphorylated FAK. It suggested that TGF-beta 1 rapidly regulated the activation of integrin, and stimulated FAK dephosphorylation, which might induce depolarization in SMMC-7721 hepatocellular carcinoma cells, then facilitates the detachment of tumor cells at early stages of migration.

Carcinoma, Hepatocellular↗

PubMed1999

Duplication of 7p21.2-->pter due to maternal 7p;21q translocation: implications for critical segment assignment in the 7p duplication syndrome.

We describe a 1-year-old boy with mental and physical retardation, a large anterior fontanel, brachycephaly with flat occiput, short and stubby fingers, generalized hypotonia, ocular hypertelorism, low-nasal bridge, long philtrum, high-narrow palate, apparently low-set ears, and a small mandible. Cytogenetic analysis utilizing high resolution chromosome banding technique showed an unbalanced karyotype consisting of 46,XY,add(21)(q22.3) that originated from maternal balanced translocation between chromosomes 7 and 21. Fluorescence in situ hybridization (FISH) using micro-dissected library probe pool from chromosome 7 confirmed the additional material on 21q was derived from chromosome 7. Our results indicated that the patient had an unbalanced translocation, 46,XY, der(21)t(7;21)(p21.2;q22.3)mat, which resulted in duplication for distal 7p. Our patient is similar to reported cases with a 7p15-->pter or larger duplication of 7p, suggesting that the critical segment causing the characteristic phenotype of 7p duplication syndrome, including large anterior fontanel, exists at 7p21.2 or 7p21.2-->pter.

Abnormalities, Multiple↗

PubMed1999

Elf3 encodes a novel 200-kD beta-spectrin: role in liver development.

beta-spectrins are crucial for the maintenance of cell shape, the establishment of cell polarity, and the formation of distinct membrane domains. Our strategy for identifying genes important for hepatocyte polarity has been to utilize subtractive hybridization of early embryonic mouse cDNA liver libraries. As a result, we have cloned three isoforms of a novel beta-spectrin elf (embryonic liver beta-fodrin), and here we report the analysis of elf3, the longest isoform (8172 nt). ELF3 comprises 2154 residues with an overall similarity of 89.0% and 95.3% to mouse beta-spectrin (betaSpIIsigma1) at the nucleotide and amino acid level, respectively. ELF3 is characterized by an actin-binding domain, a long repeat domain, and a short regulatory domain remarkable for the absence of a PH domain. Linkage analysis reveals that elf3 maps to mouse chromosome 11 between D11Bir6 and D11Xrf477, a different chromosomal locus from that of the other four spectrin genes. Northern blot analysis utilizing an elf3 3'-UTR probe demonstrates an abundant 9.0-kb transcript in brain, liver, and heart tissues. Western blot with a polyclonal antibody against ELF identifies a 200 kD protein in mouse liver, brain, kidney, and heart tissues. Immunohistochemical studies demonstrate ELF labeling of the basolateral or sinusoidal membranes surface as well as a granular cytoplasmic pattern in hepatocytes. Antisense studies utilizing cultured liver explants show a vital role of elf3 in hepatocyte differentiation and intrahepatic bile duct formation. The differential expression, tissue localization, and functional studies demonstrate the importance of elf3 in modulating interactions between various components of the cytoskeleton proteins controlling liver and bile duct development.

Amino Acid Sequence↗

PubMed1999

Issues in genomic screening: critical values, sample sizes, and the ability to detect linkage.

The aims of this study were to empirically investigate the ability of affected sib pairs (ASPs) to localize a gene through screening and to explore estimation of lod score critical values through resampling. To do so, we repartitioned 25 replicates of 100 simulated nuclear families into six data sets of sizes 100, 200, 300, 400, 500, and 1,000 and chose at most one mildly ASP per family. Using all marker data, we calculated maximum lod scores across the six-chromosome genome for each set. Then, we determined the cutoff value corresponding to a 5% genome-wide false positive rate using both the method of Lander and Kruglyak [1995] and a simple resampling algorithm that allows greater scan-specific flexibility. For chromosome 1, the ability of the ASPs to detect the region between markers 9 and 10 clearly increases with the sample size, and genome-wide significance is achieved for samples of size 400 or greater. Also, as expected, the critical values based on the less conservative resampling approach are generally slightly smaller than those from theoretical calculations based on the Ornstein-Uhlenbeck diffusion process of Lander and Kruglyak.

Genetic Linkage↗

PubMed1999

Genomic structure, chromosomal mapping, and muscle-specific expression of a PH domain-associated intronless gene, cded/lior.

The aim of our study was to isolate novel gene(s) involved in cell differentiation and embryonic liver development. Mouse cded/lior was identified from subtraction hybridization of embryonic liver cDNA libraries as well as an adult mouse liver genomic DNA library. The full open reading frame of cded/lior encodes a 131-amino acid protein with 71.88% overall similarity to the PH domain of rat PLC-gamma1. A gapped search with the C-terminal region of CDED/LIOR revealed a 36-41% similarity to several proteins related to signal transduction and cell replication, such as ORC1 and KSR. Northern blot analysis of adult mouse tissues shows a strong 2.6-kb transcript restricted to heart and skeletal muscle. RT-PCR utilizing cded/lior-specific primers demonstrates cded/lior mRNAs in heart, brain, and liver tissue throughout mid-embryonic mouse gestation. cded/lior maps to the distal end of mouse Chromosome (Chr) 2. Analysis of the genomic structure for cded/lior demonstrated a single exon gene that is not an alternatively spliced isoform of PLC-gamma1. Analysis of the cded/lior promoter region revealed a high GC-content, high ratio of CpG/GpC, multiple GC-boxes, the lack of a TATA box, CTF/NFI element, and two MyoD-MCK binding sites. These characteristics are also found in several genes important in the regulation of cell growth or DNA synthesis, such as transforming growth factor-beta1, c-Ha-ras, nerve growth factor, epidermal growth factor receptor, and DNA polymerase beta. These results suggest that cded/lior is a mesoderm/muscle-specific transcript that may be involved in the mesodermal inductive and regulatory interactions required for liver formation and embryonic development.

Amino Acid Sequence↗

PubMed1999

Processing effect on soybean storage proteins and their relationship with tofu quality.

Tofu was prepared from 13 soybean varieties according to three different methods (bench, pilot, and production methods). Different soybean varieties showed significant differences in storage protein composition (glycinin and beta-conglycinin). The beta-conglycinin (7S) and glycinin (11S) contents were 7.3-9.9 and 14.1-22.9% on the dry matter basis, respectively. The 11S/7S protein ratio varied from 1.64 to 2.51 among the varieties. Glycinin content and 11S/7S protein ratio of the 13 varieties did not change significantly from soy milk to tofu for the production and pilot methods. Soybean 11S/7S protein ratio positively correlated with the 11S/7S ratio of soy milk and tofu (0.57 < or = r < or = 0.83, p < or = 0.01). The correlation coefficient depended on the processing method. Processing method affected 7S and 11S protein contents of tofu and their contribution to tofu hardness, yield, and sensory quality. This may explain in part the contradictory findings of the relationships between storage proteins and tofu quality because processing methods differed in various studies.

Electrophoresis, Polyacrylamide Gel↗

PubMed1999

Somatostatin controls Kaposi's sarcoma tumor growth through inhibition of angiogenesis.

Somatostatin and its analogs are active in the inhibition of SST receptor-positive endocrine neoplasms, but their activity and mechanism in nonendocrine tumors is not clear. Somatostatin potently inhibited growth of a Kaposi's sarcoma xenograft in nude mice, yet in vitro the tumor cells did not express any known somatostatin receptors and were not growth inhibited by somatostatin. Histological examination revealed limited vascularization in the somatostatin-treated tumors as compared with the controls. Somatostatin was a potent inhibitor of angiogenesis in an in vivo assay. In vitro, somatostatin inhibited endothelial cell growth and invasion. Migration of monocytes, important mediators of the angiogenic cascade, was also inhibited by somatostatin. Both cells types expressed somatostatin receptor mRNAs. These data demonstrate that somatostatin is a potent antitumor angiogenesis compound directly affecting both endothelial and monocytic cells. The debated function of somatostatin in tumor treatment and the design of therapeutic protocols should be reexamined considering these data.

Animals↗

PubMed1999

Mutagenesis of SNM1, which encodes a protein component of the yeast RNase MRP, reveals a role for this ribonucleoprotein endoribonuclease in plasmid segregation.

RNase MRP is a ribonucleoprotein endoribonuclease that has been shown to have roles in both mitochondrial DNA replication and nuclear 5.8S rRNA processing. SNM1 encodes an essential 22.5-kDa protein that is a component of yeast RNase MRP. It is an RNA binding protein that binds the MRP RNA specifically. This 198-amino-acid protein can be divided into three structural regions: a potential leucine zipper near the amino terminus, a binuclear zinc cluster in the middle region, and a serine- and lysine-rich region near the carboxy terminus. We have performed PCR mutagenesis of the SNM1 gene to produce 17 mutants that have a conditional phenotype for growth at different temperatures. Yeast strains carrying any of these mutations as the only copy of snm1 display an rRNA processing defect identical to that in MRP RNA mutants. We have characterized these mutant proteins for RNase MRP function by examining 5.8S rRNA processing, MRP RNA binding in vivo, and the stability of the RNase MRP RNA. The results indicate two separate functional domains of the protein, one responsible for binding the MRP RNA and a second that promotes substrate cleavage. The Snm1 protein appears not to be required for the stability of the MRP RNA, but very low levels of the protein are required for processing of the 5.8S rRNA. Surprisingly, a large number of conditional mutations that resulted from nonsense and frameshift mutations throughout the coding regions were identified. The most severe of these was a frameshift at amino acid 7. These mutations were found to be undergoing translational suppression, resulting in a small amount of full-length Snm1 protein. This small amount of Snm1 protein was sufficient to maintain enough RNase MRP activity to support viability. Translational suppression was accomplished in two ways. First, CEN plasmid missegregation leads to plasmid amplification, which in turn leads to SNM1 mRNA overexpression. Translational suppression of a small amount of the superabundant SNM1 mRNA results in sufficient Snm1 protein to support viability. CEN plasmid missegregation is believed to be the result of a prolonged telophase arrest that has been recently identified in RNase MRP mutants. Either the SNM1 gene is inherently susceptible to translational suppression or extremely small amounts of Snm1 protein are sufficient to maintain essential levels of MRP activity.

Chromosomes, Fungal↗

PubMed1999

Primary choledochorrhaphy after common bile duct exploration.

AIM: To prove further the safety of primary closure of the common bile duct. METHOD: Twenty patients among 99 common bile duct explorations underwent primary closure. Pre- and postoperative liver function test, ultrasound and intraoperative cholangiography data, operation time, postoperative complications and the length of postoperative stay were recorded. RESULTS: Nineteen patients did not suffer any biliary complication. One had bile leakage and bile peritonitis, and another had duodenal leakage. One case was complicated by gastric ulcer perforation. The mean postoperative hospital stay except for the 2 patients with complications was 8.72 +/- 0.75 days. Preoperative abnormal liver function tests recovered within 2-3 weeks after the operation. Postoperative ultrasound scan of the biliary tract within 2 months revealed no stenosis and residual stone. CONCLUSION: Primary common bile duct closure is a safe alternative to routine biliary drainage in selected patients.

Adult↗

PubMed1999

N-acetylcysteine inhibits endothelial cell invasion and angiogenesis.

The thiol N-acetylcysteine (NAC) is a chemopreventive agent that acts through a variety of mechanisms and can prevent in vivo carcinogenesis. We have previously shown that NAC inhibits invasion and metastasis of malignant cells as well as tumor take. Neovascularization is critical for tumor mass expansion and metastasis formation. We investigated whether a target of the anti-cancer activity of NAC could be the inhibition of the tumor angiogenesis-associated phenotype in vitro and in vivo using the potent angiogenic mixture of Kaposi's sarcoma cell products as a stimulus. Two endothelial (EAhy926 and human umbilical vein endothelial [HUVE]) cell lines were utilized in a panel of assays to test NAC ability in inhibiting chemotaxis, invasion, and gelatinolytic activity in vitro. NAC treatment of EAhy926 and HUVE cells in vitro dose-dependently reduced their ability to invade a reconstituted basement membrane, an indicator of endothelial cell activation. Invasion of HUVE cells was inhibited with an ID50 of 0.24 mM NAC, whereas inhibition of chemotaxis required a 10 fold higher doses, indicating that invasion is a preferential target. NAC inhibited the enzymatic activity and conversion to active forms of the gelatinase produced by endothelial cells. The matrigel in vivo assay was used for the evaluation of angiogenesis; NAC strongly inhibited neovascularization of the matrigel sponges in response to Kaposi's sarcoma cell products. NAC prevented angiogenesis while preserving endothelial cells, implying that it could be safely used as an anti-angiogenic treatment.

Acetylcysteine↗

PubMed1998

Identification of a novel domain of HIV tat involved in monocyte chemotaxis.

Human immunodeficiency virus (HIV) Tat is chemotactic for monocytes and dendritic cells, an activity that could play a key role in the expansion of HIV infection of accessory cells. To date, domains of Tat previously found to interact with cell surface molecules have shown only partial chemotactic activity toward monocytes. Using overlapping Tat peptides, we identify a novel region of Tat with a potent chemotactic activity for monocytes, reaching levels equal to Tat itself. This peptide also provokes monocyte polarization similar to Tat and is able to compete with Tat for induction of monocyte migration. Specific high affinity (kd = 3 x 10(-9) M) cell surface binding sites on monocyte cell surfaces for this region of Tat are demonstrated. These data indicate that the majority of Tat effects on monocytes are mediated by a novel region in the cysteine-rich and core domains. These domains are highly conserved among different HIV isolates, suggesting an important role in the establishment of HIV infection.

Cell Polarity↗

PubMed1998

Identification of mouse itih-4 encoding a glycoprotein with two EF-hand motifs from early embryonic liver.

An essential feature of cell differentiation is the specificity of signal transduction events from extracellular cues, which are considered to be conferred by scaffold, anchoring and adaptor proteins. Our aim was to identify important scaffolding proteins required for liver development. Utilizing subtraction hybridization of embryonic liver cDNA libraries, here we report the full length cDNA sequence for mouse itih-4 (Inter-alpha-trypsin inhibitor H4). Itih-4 encodes a 942 amino acid protein containing two EF-hand (helix-loop-helix) motifs with an unique short loop, with a potential calcium-binding function. Itih-4 is expressed as a strong 3.1-kb transcript in liver, to a lesser extent in lung and heart tissue. RT-PCR demonstrates itih-4 mRNAs abundantly in liver, less in heart and brain, during mid-embryonic gestation. These results suggest that itih-4 is a potential regulator for extracellular matrix proteins and plays a role during early embryonic liver development.

Amino Acid Sequence↗

PubMed1998

Trinucleotide repeat expansion of spinocerebellar ataxia (SCA1) found in a Chinese family.

OBJECTIVE: To investigate the gene mutation and the ratio of the spinocerebellar ataxia type 1 (SCA1) in Chinese patients with autosomal dominant spinocerebellar ataxia (ADSCA). METHOD: The family material and DNA samples were collected from thirteen families with ADSCA. To determine the characteristics of the CAG trinucleotide repeats in SCA1 gene, the PCR products of the Rep1 and Rep2 primers were analyzed, and the bands with CAG repeat expansion were cloned by PCR2. 1 vector and sequenced. RESULTS: One family was found to have an expanded CAG repeat in the 13 families with ADSCA. The clinically affected individual was heterozygous with one disease allele being 55 CAG repeats, whereas the mean size of the CAG repeats on 104 chromosomes generated from unrelated control Chinese individuals is 29.3 (ranging from 18 to 34). CONCLUSIONS: The frequency of the SCA1 mutation is about 7% in the 13 Chinese families with ADSCA, suggesting that this type of genetic defect is not the main cause involved in the pathogenesis of ADSCA in China. Since the mutation has also been found in Caucasian, Japanese, Malaysian, and Bangladeshi kindreds, it is suggested that this genetic defect may well have multiple origins in different ethnic groups.

Adult↗

PubMed1998

Identification of elf1, a beta-spectrin, in early mouse liver development.

Beta-spectrins play essential roles in cell-cell interactions and in the maintenance of cell polarity. Our aim was to identify beta-spectrin genes important for the establishment of hepatocyte polarity and differentiation. Using subtractive screening of cDNA libraries from early embryonic mouse livers (post-coital days 10, 11, and 12), we have isolated elf1 (embryonic liver fodrin 1), a differentially expressed beta-spectrin or fodrin (betaSpIIsigmaI). Elf1 encodes a 220-amino acid protein with an NH2 terminal actin-binding domain. In situ hybridization studies demonstrate elf1 expression initially in day 10 embryonic heart tissue, then in day 11-11.5 hepatic tissue. These studies suggest that elf1 may play a role in the emergence of hepatocyte polarity during liver development.

Amino Acid Sequence↗