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Biomedical subjects

S D Li

Publications and source records attributed to S D Li.

At least 19 recordsLinked to original sources
PubMed2006

Large low-field magnetoresistance in nanocrystalline magnetite prepared by sol-gel method.

Nanocrystalline magnetite Fe3O4 samples with a grain size of about 40 nm have been synthesized by an optimized sol-gel method. The single phase of spinel magnetite was confirmed by both X-ray diffraction and transmission electron microscopy. It has been found that the magnetoresistance of the samples at low field (LFMR) is relatively large, and with the decrease of temperature its value at a field of 0.5 T changes dramatically from -2.5% at 300 K to -17.0% at 55 K. With the further decrease of temperature a sharp drop occurs for the magnitude of the magnetoresistance (MR), regarded as a spin (cluster) glass transition in the surface region of the grains that can be confirmed by the zero-field-cooled and field-cooled magnetization and ac susceptibility measurement. The mechanism of the magnetic and transport properties was discussed.

Journal Article↗
PubMed2000

Use of orbicularis oculi muscle flap for undercorrected blepharoptosis with previous frontalis suspension.

The frontalis muscle and its fascia are connected with the orbicularis oculi muscle at the level of the eyebrow. Therefore, the superiorly based orbicularis oculi muscle flap, when advanced and attached to the tarsal plate, can dynamically elevate the upper lid and correct blepharoptosis with previous frontalis sling. Six patients with undercorrected blepharoptosis after frontalis sling suspension were included in this study. The superiorly based orbicularis oculi muscle flap was advanced to the tarsal plate in these patients and the redundant portion of the distal flap was resected. Postoperative results were satisfactory after 1-year follow-up.

Adolescent↗
PubMed2000

Nutrition support for individuals with liver failure.

The prevalence of liver diseases is increasing in the United States, particularly as a result of the recent hepatitis C epidemic. In the past, patients who developed fulminant hepatic failure or cirrhosis owing to a chronic liver disease were likely to expire. During the last 15-20 years, liver transplantation has given these patients a chance at survival. Progressive nutrition deficiencies and muscle wasting are universal problems in these patients. Left untreated, the progressive wasting of liver disease leads to infection and an increased risk of death owing to infection both before and after transplantation. Aggressive nutritional support is essential to optimize the care of these patients and to enable them to obtain and survive a liver transplant and gain access to a new life following a successful liver engraftment.

Aged↗
PubMed2000

Association between body mass index and adenocarcinoma of the esophagus and gastric cardia.

Obesity is an increasing problem for industrialized nations. The incidence of adenocarcinoma of the esophagus and gastric cardia has also risen during the past two decades. A recently published population-based study attempted to relate this rise to increases in obesity or body mass index. Obesity may not only increase the risk for adenocarcinoma of the upper gastrointestinal tract, but it may also increase the risk of colon cancer and overall mortality. More research is needed to understand obesity's health impact and ways to control this epidemic.

Adenocarcinoma↗
PubMed2000

[Genescan for STR analysis and genetic distribution in a population sample from Han, China].

Genetic distributions for nine STR loci and Amelogenin locus were determined in a Chinese Han population based on DNA sequencing. The databanks in Chinese Population were generated by using Genescan, genotype and genetic distribution analysis. Allele frequency distribution was determined for 10 loci, such as D3S1358, VWA, FGA, Amelogenin, THO1, TPOX, CSF1PO, D5S818, D13S317 and D7S820. The results show significant differences between ethnic groups (African-American, US-Caucasian and Chinese Han) in the pattern of distribution as well as in the related frequency of the most common alleles of their STR loci. The probabilities of identity values for the population described in this section are 2.79 x 10(-10) (U.S-Caucasian), 1.23 x 10(-10) (African-American) and 0.5 x 10(-10) (Chinese Han). The results show the probability of Paternity Exclusion (PPE) values of 0.9998 (Chinese Han), 0.9996 (African-American) and 0.9994 (U.S-Caucasian). These results suggested that the nine STR loci and the Amelogenin locus are very useful for human identification, such as analyzing forensis casework, establishing DNA databanks, processing paternity test, evaluation linkage genetics, studying gene natural resources and monitoring bone marrow transplants.

Asian People↗
PubMed2000

[STR polymorphisms in five Chinese ethnic groups(2)].

Population genetic studies were performed in Chinese Han, Hui, Mongolian, Tibetan and Uygur. Allele frequency distributions were analyzed for ten loci, i.e., D3S1358, VWA, CSF1PO, FGA, THO1, TPOX, D5S818, D13S317 and D7S820 by GeneScan. The results showed that there were 60 STR alleles and 149 genotypes in Han; 63 STR alleles and 144 genotypes in Hui; 69 STR alleles and 173 genotypes in Mongolian; 77 STR alleles and 168 genotypes in Tibetan; 70 STR alleles and 148 genotypes in Uygur. Significant differences were identified among ethnic groups (African-American, US-Caucasian and Chinese-Oriental), but similarity was found among the five Chinese populations, and immunogenomics and pharmacogenomics studied in this report. These findings indicated that the nine STR loci and amelogenin locus were very useful for individual identification in forensic science.

Alleles↗
PubMed1999

Multiple genes in the left half of the cag pathogenicity island of Helicobacter pylori are required for tyrosine kinase-dependent transcription of interleukin-8 in gastric epithelial cells.

Helicobacter pylori strains that contain the cag pathogenicity island (PAI) elicit increased synthesis of gastric C-X-C chemokines, promote neutrophilic infiltration into the gastric epithelium, and stimulate the synthesis of interleukin-8 (IL-8) in cultured gastric epithelial cells. To investigate the effects of cag PAI genes on the transcription of the IL-8 gene, the Kato-3 gastric epithelial cell line was stably transfected with plasmid DNA containing the IL-8 gene promoter fused to a luciferase reporter gene. The resulting reporter cell line, L5F11, was used to monitor the effects of infection in cell culture by H. pylori 26695 and isogenic derivatives with null mutations in genes in the cag PAI on transcription of the IL-8 gene. We found that null mutations in eight open reading frames, including homologs of the Agrobacterium virB9, virB10, and virB11 genes, in the left half of the cag PAI abrogated the induction of IL-8 gene transcription. Further studies with the L5F11 cell line showed that IL-8 gene transcription induced by H. pylori was blocked by the protein tyrosine kinase inhibitor herbimycin A but not by the protein kinase C inhibitor calphostin C or by the protein kinase G inhibitor KT5823. IL-8 gene transcription in L5F11 cells could also be induced by the cytokine tumor necrosis factor alpha (TNF-alpha) without exposure to H. pylori. This TNF-alpha-induced IL-8 transcription was inhibited by the protein kinase A inhibitor H7, which had no significant effect on H. pylori-induced IL-8 transcription. These studies show that multiple genes in the left half of the cag PAI are essential for the transcription of the IL-8 gene in gastric epithelial cells and that this depends on protein tyrosine kinase activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1999

Modulation of Helicobacter pylori induced interleukin-8 synthesis in gastric epithelial cells mediated by cag PAI encoded VirD4 homologue.

BACKGROUND: Strains of Helicobacter pylori carrying the virulence associated cag pathogenicity island (PAI) induce gastric epithelial synthesis of the chemokine interleukin-8 (IL-8), a neutrophil chemoattractant, and thereby a strong inflammatory response during chronic infection of the human gastric mucosa. Previous mutational analyses have shown that many genes in the cag PAI are needed to elicit IL-8 synthesis in gastric epithelial cells, and also that some genes are not involved. AIM: To test the possibility that certain genes in the cag PAI also downregulate (modulate) the inflammatory response elicited by cag+ H pylori infection. METHODS: Cells of L5F11, a derivative of the Kato-3 gastric epithelial cell line that carries an engineered IL-8 promoter-luciferase reporter gene fusion, were cocultured with H pylori strain 26695 or with an isogenic mutant in which most of the cag PAI ORF 10 gene, an Agrobacterium virD4 homologue, was deleted. Luciferase activity was measured to assess IL-8 gene transcription and secreted IL-8 was measured by enzyme linked immunosorbent assay to assess synthesis and release of IL-8 protein from gastric epithelial cells. RESULTS: Inactivation of ORF10 led to a 2.8-fold increase in IL-8 gene transcription and a 3.6-fold increase in IL-8 synthesis and secretion. CONCLUSIONS: The results suggest that this VirD4 homologue participates in the control of inflammation that H pylori infection elicits by downregulating (modulating) the strong induction of IL-8 synthesis mediated by other cag encoded proteins.

Bacterial Proteins↗
PubMed1997

Breast-conserving radiation therapy: potential of inverse planning with intensity modulation.

PURPOSE: To evaluate inverse planning with beam-intensity modulation in breast-conserving radiation therapy. MATERIALS AND METHODS: A prototype inverse treatment-planning system was used in five patients with early-stage breast tumors. The prescription for the breast was 5,040 cGy in 180-cGy fractions, with the primary tumor site receiving 6,000 cGy in 214-cGy fractions. Isodose distributions from the prototype were compared section by section with those from conventional three-dimensional planning. RESULTS: The inverse planning system showed dose variation of 84%-98% to 111%-113% in the primary tumor site. For whole-breast irradiation, 95% of the target volume received at least 4,000 cGy. High-dose areas were adjacent to the primary site. Lower-dose areas were in the most medial part of the breast. Compared with the conventional system, target doses were similar. The volume of lung and heart that received high doses was smaller; however, larger lung and heart volumes received doses of less than 1,200 cGy. CONCLUSION: Intensity modulation may accomplish "concomitant boost" treatment. Acceptable dose gradients are achieved in the target volumes, with lower volumes of high-dose treatment in normal tissue. Plans that required comprehensive nodal radiation, in particular, were improved relative to conventional plans. Optimization of the planning system is needed to minimize the lung and heart volumes that receive low-dose radiation.

Breast↗
PubMed1995

A method of analyzing rectal surface area irradiated and rectal complications in prostate conformal radiotherapy.

PURPOSE: To develop a method of analyzing rectal surface area irradiated and rectal complications in prostate conformal radiotherapy. METHODS AND MATERIALS: Dose-surface histograms of the rectum, which state the rectal surface area irradiated to any given dose, were calculated for a group of 27 patients treated with a four-field box technique to a total (tumor minimum) dose ranging from 68 to 70 Gy. Occurrences of rectal toxicities as defined by the Radiation Therapy Oncology Group (RTOG) were recorded and examined in terms of dose and rectal surface area irradiated. For a specified end point of rectal complication, the complication probability was analyzed as a function of dose irradiated to a fixed rectal area, and as a function of area receiving a fixed dose. Lyman's model of normal tissue complication probability (NTCP) was used to fit the data. RESULTS: The observed occurrences of rectal complications appear to depend on the rectal surface area irradiated to a given dose level. The patient distribution of each toxicity grade exhibits a maximum as a function of percentage surface area irradiated, and the maximum moves to higher values of percentage surface area as the toxicity grade increases. The dependence of the NTCP for the specified end point on dose and percentage surface area irradiated was fitted to Lyman's NTCP model with a set of parameters. The curvature of the NTCP as a function of the surface area suggests that the rectum is a parallel structured organ. CONCLUSIONS: The described method of analyzing rectal surface area irradiated yields interesting insight into understanding rectal complications in prostate conformal radiotherapy. Application of the method to a larger patient data set has the potential to facilitate the construction of a full dose-surface-complication relationship, which would be most useful in guiding clinical practice.

Dose-Response Relationship, Radiation↗
PubMed1995

Nucleotide sequence of a 1446 base pair SalI fragment and structure of a novel early gene of Leucania separata nuclear polyhedrosis virus.

A 1446 bp SalI fragment of LsNPV was sequenced by the silver staining method, and two large open reading frames (ORFs, ORF1 and ORF2) were found, both contain typical characteristics of the 5' regulatory elements of baculovirus early genes. ORF1 is 345 bp long with the capacity to encode a putative protein of 114 amino acid residues with MW about 13 kDa and was designated p13 gene, ORF2 comprises 248 bp from the 3' end of the fragment. In the untranslated region (UTR) of ORF1, a 33 bp mini cistron (ORF3), a core recognition sequence (CGTCG) for many bHLHzip transcription factors and a late promoter sequence TTAAG are present. In the UTR of ORF2, two host transcription factor binding elements (CACGTG and GATA motif) and two CGT motifs were found. Some regular leucine zipper-like structures, designated leucine trans-conformation structure and LVT repeat, were found near the N-terminus and the middle of p13 protein. The leucine trans-conformation structure that is near the N-terminus consists of 4 leucines and 7 other amino acids between every two leucines, and every leucine is located at a conformation shift point of the predicted secondary structure of the p13 protein. In LVT repeat, L-6aa-V-6aa-T-6aa is repeated once. The functions of those structures remain unclear, and the two ORFs, not found in the genome of Autographa californica nuclear polyhedrosis virus, are possibly two new genes.

Amino Acid Sequence↗
PubMed1989

[Cytogenetic study on a human colorectal carcinoma cell line (HR-8348)].

Cytogenetics of a human colorectal carcinoma cell line (HR-8348) established in China were described. The early (29th passage) and late passages (93th passage) of this cell line were used for chromosome analysis. HR-8348 was a cell line essentially with near triploid karyotype. The distribution of chromosome number was rather dispersed in the early passage, whereas it was concentrated to 65-70 range in the late passage. G-banding stain showed that the numerical distribution of different chromosomes was also dispersed in the early passage associated with abundant abnormal chromosomes. In the late passage, it turned to be more stable and the number of abnormal chromosomes reduced. In 60 metaphases analysed, 10 marker chromosomes were found. The frequency of M1, M3 and M2 was 100% in both early and late passages. The morphologic characteristics and their possible origin and role in the pathogenesis of colorectal carcinoma were discussed.

Adenocarcinoma↗
PubMed1989

[Studies on cell surface fibronectin of transformed Syrian hamster lung cells induced by butyric acid].

In this paper, Fn was analysed qualitatively and quantitatively in three Syrian hamster cell lines, ie, nontransformed baby hamster lung fibroblasts cell line (BHL), a transformed cell line (BHLB4) and a butyric acid-induced phenotypically reversed cell line (ButB4) respectively. Fn was visualized on cell surface by means of indirect immunofluorescence technique. Immunofluorescence of Fn on the surface of BHL was bright with a stripe-like distribution, while that on the surface of BHLB4 was very dim or dispersed. On ButB4 cell surface, the intensity and distribution of immunofluorescence was similar to that on BHLB4 cells. Fn was isolated by affinity chromatography from the cell surface of the three cell lines. Its molecular weight was 250 kDa on SDS-polyacrylamide electrophoresis. The quantity of Fn isolated from surface of ButB4 was a bit lower than that from BHL, but was much higher than that from BHLB4. The result offers us a useful criterion for transformation and reverse transformation.

Animals↗
PubMed1987

[Establishment of a human colonic carcinoma xenograft in nude mice and its chief biological characteristics].

A human colonic cancer specimen cut into 1-2 mm3 pieces under aseptic condition was heterotransplanted hypodermically by trocar to the inguinal region of BALB/cATcL nude mice bred in our laboratory. 53 days later, a 10 X 9 X 11 mm3 tumor was obtained. The take rate was 100% (48/48). The take rate of liquid nitrogen frozen and recovered tissue pieces was also 100% (13/13). Grossly, the tumor was rich in blood supply and well encapsulated. Within the tumor, the tissue was cream-colored. G-banded chromosome analysis revealed a human chromosome pattern with the mode 70-90. Pathologic diagnosis was signet-ring cell cancer, which was identical to the surgical specimen. No change was found after maintaining 13 passages in nude mice. It was named the human colonic carcinoma xenograft XHCn/w. It provides an ideal tumor model for in vivo or in vitro experiments.

Adenocarcinoma, Mucinous↗
PubMed1987

[Cytogenetic studies on 3 esophageal cancer cell lines].

The cytogenetic studies on three esophageal cancer cell lines established in China were done. Thirty metaphases showing suitable chromosome length and good G-banding pattern from each of the cell lines were chosen and subjected to karyological analysis. The typical karyotypes from these cell lines were listed, and the variation of chromosome number as well as the morphological characteristics, possible sources and the incidence of the marker chromosomes were analysed. Eca 109 is the cell line first established and used extensively in China. A strictly regular karyotype pattern was found in it: the modal number of chromosomes being 63-64; the number of each type of chromosome varying between 1-5; a distal deletion of short arm of chromosome No. 1 being discernible in all metaphases, with break sites located within 1p22-1p33. Also a distal deletion of long arm of chromosome No. 4 was usually visible. There were seven marker chromosomes with high incidence. Among them, M1 marker chromosome was a large subacrocentric chromosome which was observed in the early passages of this cell line. The chromosome number of Ec 17 cell line was usually subtetraploid. In addition to the numerical variation in some of the chromosomes, six marker chromosomes were usually observed. Among them, M1 involved reciprocal translocation between chromosome No. 1 and No. 4. M3 of Ec 17 was in correspondence with M5 of Eca 109. Both were Rob (13q;14q). The chromosome number of Ec 56 was usually subtetraploid, and in addition to the numerical variation in some of the chromosomes, seven marker chromosomes were usually observed.

Cell Line↗