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Biomedical subjects

L Li

Publications and source records attributed to L Li.

At least 91 records · Page 5Linked to original sources
PubMed2005

Response of crayfish, Procambarus clarkii, haemocytes infected by white spot syndrome virus.

White spot syndrome virus (WSSV) is a serious pathogen of aquatic crustaceans. Little is known about its transmission in vivo and the immune reaction of its hosts. In this study, the circulating haemocytes of crayfish, Procambarus clarkii, infected by WSSV, and primary haemocyte cultures inoculated with WSSV, were collected and observed by transmission electron microscopy and light microscopy following in situ hybridization. In ultra-thin sections of infected haemocytes, the enveloped virions were seen to be phagocytosed in the cytoplasm and no viral particles were observed in the nuclei. In situ hybridization with WSSV-specific probes also demonstrated that there were no specific positive signals present in the haemocytes. Conversely, strong specific positive signals showed that WSSV replicated in the nuclei of gill cells. As a control, the lymphoid organ of shrimp, Penaeus monodon, infected by WSSV was examined by in situ hybridization which showed that WSSV did not replicate within the tubules of the lymphoid organ. In contrast to previous studies, it is concluded that neither shrimp nor crayfish haemocytes support WSSV replication.

Animals↗
PubMed2005

Novel genomic insertion-- deletion in MLH1: possible mechanistic role for non-homologous end-joining DNA repair.

Hereditary non-polyposis colorectal cancer (HNPCC) is an inherited cancer syndrome caused by a defect in the mismatch repair pathway. The majority of HNPCC mutations have been detected in MLH1 and MSH2. Most reported mutations are substitutions, small insertions and deletions, but standard methods of mutation analysis do not detect large rearrangements. It is now established that large deletions, insertions and rearrangements account for a significant proportion of MLH1 and MSH2 mutations. We report an unusual rearrangement resulting in the deletion of exons 6, 7 and 8 of MLH1, with the retention of part of intron 6 and insertions of two nucleotides each flanking the retained sequence. The 349-bp-retained sequence is made up of two closely spaced Alu sequences. The mutation was initially detected by protein truncation test and cDNA sequencing. Multiplex ligation-dependent probe amplification confirmed the deletion of three exons. PCR and sequencing were used to characterize the breakpoint. Despite the high density of Alu elements in MLH1, there is no homology at the deletion breakpoints or insertion junctions in this case to suggest that homologous recombination has occurred. We propose a mechanism involving non-homologous end joining to explain the occurrence of this complex deletion.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Identification of a novel HLA-DRB1 allele (HLA-DRB1*111902*).

In this paper, we report a new HLA-DRB1 allele identified in a male acute myeloid leukaemia Chinese patient. This sample was initially typed as DRB1*11XX using commercial polymerase chain reaction-sequence-specific primers kit. When it was typed using a chip-based sequence-specific oligonucleotide technique, a novel hybridization pattern that does not match any known alleles was observed. Through sequencing, we have identified this allele as a new HLA-DRB1 allele, which was later named HLA-DRB1*111902 by the WHO Nomenclature Committee. The sequence of this new allele differs from DRB1*111901 by one nucleotide (from G to C) at 203nt of exon 2 but does not cause any amino acid substitution.

Alleles↗
PubMed2005

Cyclin D1, E2F1 expression levels are associated with characteristics and prognosis of esophageal squamous cell carcinoma.

SUMMARY. We performed a multi-institutional analysis of E2F1 and cyclin D1 expression in cases of esophageal squamous cell carcinoma (ESCC). Cyclin D1 and E2F1 are involved in the transition of cell cycle phases and associated with tumor progression. However, no previous studies have concurrently analyzed combined E2F1 and cyclin D1 expression. The purpose of this study was to clarify the relationship of E2F1 and cyclin D1 in ESCC. We studied 122 patients with primary ESCC who underwent surgical tumor resection. Immunohistochemical analyses were performed for E2F1 and cyclin D1. A statistical analysis of immunohistochemistry results, clinicopathological features, and prognosis was performed. E2F1/cyclin D1 (-/-) tumors were present in 31 patients (25.4%) and correlated with reduced tumor progression. In these patients, pT (P=0.0001), pN (P<0.0001), p-Stage (P=0.0019), and survival rates were better than in patients who were positive for either E2F1 or cyclin D1 (P=0.0232). The expression of E2F1 and cyclin D1 is an indicator of tumor progression and prognosis in patients with ESCC. Combined analysis of E2F1 and cyclin D1 expression helps to determine the characteristics and prognosis of ESCC.

Adult↗
PubMed2005

Usage of an intronic promoter for stable gene expression in Saccharomyces cerevisiae.

AIMS: To construct expression vectors capable of switching promoters under different metabolic circumstances to obtain stable gene expression. METHODS AND RESULTS: In this study, we designed a series of constructs for the expression of the chicken lactate dehydrogenase (cldh) gene under the control of galactose-inducible GAL1 promoter and the high glucose-inducible HXT1 promoter in Saccharomyces cerevisiae. In one construct, the HXT1 promoter was placed between artificial splicing sequences to function as an intronic promoter. We checked all constructs for the usage of promoters by reverse transcriptional polymerase chain reaction and assayed the expression level of the reporter gene under different culturing conditions. In the presence of galactose, when the GAL1 promoter was linked with the intronic HXT1 promoter, the cldh gene showed 1.5-fold activity compared with single GAL1 promoter, while in the presence of glucose, the construct showed over twofold activity compared with that without splicing sequences. CONCLUSION: The intronic HXT1 promoter could be induced by the presence of high glucose concentration. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report detailing the use of an intronic promoter in the construction of stable expression vectors and the novel system could serve as a model of expression vectors for fermentation or other purposes.

Animals↗
PubMed2005

Rose (Rosa rugosa)-flower extract increases the activities of antioxidant enzymes and their gene expression and reduces lipid peroxidation.

The effects of rose-flower extract on antioxidant enzymes were studied. The activities of catalase (CAT) and glutathione peroxidase (GPx) in 9-month-old senescence-accelerated mice (SAM mice) were lower than those in 6-month-old SAM mice. Therefore, 9-month-old SAM mice were the most appropriate targets for treatment with the rose-flower extract. The activities of CAT and GPx in SAM mice treated with rose-flower extract showed a marked increase in whole blood and liver. At the same time, the gene-expression level of CAT and GPx was upregulated in the liver, while malondialdehyde content in liver and brain decreased. Male SAM mice were more sensitive than female SAM mice. The mean and the longest lifespan of SAM mice were longer after treatment with rose-flower extract.

Aging↗
PubMed2005

Antineutrophil cytoplasmic antibodies (ANCA) in Chinese patients with anti-GBM crescentic glomerulonephritis.

OBJECTIVE: To study the prevalence of ANCA and their target antigen in Chinese patients with anti-GBM crescentic glomerulonephritis (CGN), and to evaluate the possible role of ANCA in Chinese anti-GBM CGN patients with coexisting serum ANCA by studying clinicopathologic features of this disease. MATERIAL AND METHODS: Twenty-three sera were collected from 23 renal biopsy-proven anti-GBM CGN patients. According to the standardized procedures, all of the sera were determined by both, indirect immunofluorescence (IIF) ANCA, and enzyme-linked immunosorbent assay (ELISA) MPO-ANCA, PR3-ANCA and BPI-ANCA. The patients were divided into two groups according to serum ANCA positivity (Group A) or negativity (Group B). Thirty-three ANCA-associated pauci-immune CGN patients were regarded as control group (Group C). Their clinicopathologic features were compared to reveal whether ANCA correlated with disease activity. RESULTS: There were 11 (47.8%) cases with positive serum ANCA in 23 anti-GBM glomerulonephritis patients. There were 4/11 MPO-ANCA (one with positive PR3-ANCA and C-ANCA, three with negative IIF-ANCA), 1/11 PR3-ANCA (with positive MPO-ANCA and C-ANCA), 3/11 P-ANCA (with negative ELISA-ANCA) and 5/11 C-ANCA (one with positive PR3-ANCA and MPO-ANCA, and the other four with negative ELISA-ANCA). No BPI-ANCA was detected. No different clinicopathologic features were found between Groups A and B. Both were different from Group C in age, sex ratio, frequence of anuria and ESRD, variety of crescents, glomerular sclerosis, vessel lesion and prognosis. CONCLUSION: Our data demonstrate that ANCA in Chinese patients with anti-GBM CGN is not rare. The major target antigen of ANCA is MPO. ANCA seems not to be correlated with disease activity.

Adolescent↗
PubMed2004

Steady-state fluorescence study on release of camptothecin from agar hydrogel.

The slow drug release processes from agar hydrogel were studied by steady-state fluorescence (SSF) measurement. An anticancer drug, camptothecin (CPT), was used as the release drug and the fluorescence probe for the real-time monitoring of the release processes by measuring the fluorescence intensity of the probe. The release kinetics of CPT at different temperatures was investigated. The Fickian diffusion model was adopted to fit the results and a good linear relationship could be observed between the logarithmic release fraction and the releasing time. The diffusion coefficients (D) at these conditions were thus obtained from the slopes of the fitting curves. By plotting D against temperature, the diffusion coefficient of CPT was found to obey the Arrhenius relation and the activation energy was then obtained to be 70.6 kJ mol(-1).

Agar↗
PubMed2004

Human albumin solution for resuscitation and volume expansion in critically ill patients.

BACKGROUND: Human albumin solutions are used in a range of medical and surgical problems. Licensed indications are the emergency treatment of shock and other conditions where restoration of blood volume is urgent, burns, and hypoproteinaemia. Human albumin solutions are more expensive than other colloids and crystalloids. OBJECTIVES: To quantify the effect on mortality of human albumin and plasma protein fraction (PPF) administration in the management of critically ill patients. SEARCH STRATEGY: We searched the Cochrane Injuries Group trials register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and BIDS Index to Scientific and Technical Proceedings. Reference lists of trials and review articles were checked, and authors of identified trials were contacted. The search was last updated in August 2004. SELECTION CRITERIA: Randomised controlled trials comparing albumin/PPF with no albumin/PPF, or with a crystalloid solution, in critically ill patients with hypovolaemia, burns or hypoalbuminaemia. DATA COLLECTION AND ANALYSIS: We collected data on the participants, albumin solution used, mortality at the end of follow up, and quality of allocation concealment. Analysis was stratified according to patient type. MAIN RESULTS: We found 32 trials meeting the inclusion criteria and reporting death as an outcome. There were 1632 deaths among 8452 trial participants. For hypovolaemia, the relative risk of death following albumin administration was 1.01 (95% confidence interval 0.92, 1.10). This estimate was heavily influenced by the results of the SAFE trial which contributed 91% of the information (based on the weights in the meta-analysis). For burns, the relative risk was 2.40 (1.11, 5.19) and for hypoalbuminaemia the relative risk was 1.38 (0.94, 2.03). There was no substantial heterogeneity between the trials in the various categories (chi-square = 21.86, df = 25, p =0.64). The pooled relative risk of death with albumin administration was 1.04 (0.95, 1.13). REVIEWERS' CONCLUSIONS: For patients with hypovolaemia there is no evidence that albumin reduces mortality when compared with cheaper alternatives such as saline. There is no evidence that albumin reduces mortality in critically ill patients with burns and hypoalbuminaemia. The possibility that there may be highly selected populations of critically ill patients in which albumin may be indicated remains open to question. However, in view of the absence of evidence of a mortality benefit from albumin and the increased cost of albumin compared to alternatives such as saline, it would seem reasonable that albumin should only be used within the context of well concealed and adequately powered randomised controlled trial.

Blood Proteins↗
PubMed2004

Kinetic study on the epimerization of trityloxymethyl butyrolactol by liquid chromatography.

The epimerization of trityloxymethyl butyrolactol has been investigated using dynamic chromatography and an approximation function introduced by Trapp and Schurig that is based on stochastic and theoretical plate models. The epimerization rate constants and Gibbs activation energies of epimerization are directly calculated from chromatographic peak parameters, i.e. retention times of the interconverting species, peak width at half height and the relative plateau height by using the approximation function. The relationships between peak shape and chromatographic conditions, such as flow-rate, temperature and pH are investigated.

4-Butyrolactone↗
PubMed2004

Acid phosphatase role in chickpea/maize intercropping.

BACKGROUND AND AIMS: Organic P comprises 30-80 % of the total P in most agricultural soils. It has been proven that chickpea facilitates P uptake from an organic P source by intercropped wheat. In this study, acid phosphatase excreted from chickpea roots is quantified and the contribution of acid phosphatase to the facilitation of P uptake by intercropped maize receiving phytate is examined. METHODS: For the first experiment using hydroponics, maize (Zea mays 'Zhongdan No. 2') and chickpea (Cicer arietinum 'Sona') were grown in either the same or separate containers, and P was supplied as phytate, KH2PO4 at 0.25 mmol P L(-1), or not at all. The second experiment involved soil culture with three types of root separation between the two species: (1) plastic sheet, (2) nylon mesh, and (3) no barrier. Maize plants were grown in one compartment and chickpea in the other. Phosphorus was supplied as phytate, Ca(H2PO4)2 at 50 mg P kg(-1), or no P added. KEY RESULTS: In the hydroponics study, the total P uptake by intercropped maize supplied with phytate was 2.1-fold greater than when it was grown as a monoculture. In the soil experiment, when supplied with phytate, total P uptake by maize with mesh barrier and without root barrier was 2.2 and 1.5 times, respectively, as much as that with solid barrier. In both experiments, roots of both maize and chickpea supplied with phytate and no P secreted more acid phosphatase than those with KH2PO4 or Ca(H2PO4)2. However, average acid phosphatase activity of chickpea roots supplied with phytate was 2-3-fold as much as maize. Soil acid phosphatase activity in the rhizosphere of chickpea was also significantly higher than maize regardless of P sources. CONCLUSIONS: Chickpea can mobilize organic P in both hydroponic and soil cultures, leading to an interspecific facilitation in utilization of organic P in maize/chickpea intercropping.

Acid Phosphatase↗
PubMed2004

Laparoscopic versus open total mesorectal excision with anal sphincter preservation for low rectal cancer.

BACKGROUND: The Laparoscopic approach has been applied to colorectal surgery for many years; however, there are only a few reports on laparoscopic low and ultralow anterior resection with construction of coloanal anastomosis. This study compares open versus laparoscopic low and ultralow anterior resections, assesses the feasibility and efficacy of the laparoscopic approach of total mesorectal excision (TME) with anal sphincter preservation (ASP), and analyzes the short-term results of patients with low rectal cancer. METHODS: We analyzed our experience via a prospective, randomized control trail. From June 2001 to September 2002, 171 patients with low rectal cancer underwent TME with ASP, 82 by the laparoscopic procedure and 89 by the open technique. The lowest margin of tumors was below peritoneal reflection and 1.5-8 cm above the dentate line (1.5-4.9 cm in 104 cases and 5-8 cm in 67 cases). The grouping was randomized. RESULTS: Results of operation, postoperative recovery, and short-term oncological follow-up were compared between 82 laparoscopic procedures and 89 controls who underwent open surgery during the same period. In the laparoscopic group, 30 patients in whom low anterior resection was performed had the anastomosis below peritoneal reflection and more than 2 cm above the dentate line, 27 patients in whom ultralow anterior resection was performed had anastomotic height within 2 cm of the dentate line, and 25 patients in whom coloanal anastomosis was performed had the anastomosis at or below the dentate line. In the open group, the numbers were 35, 27, and 27, respectively. There was no statistical difference in operation time, administration of parenteral analgesics, start of food intake, and mortality rate between the two groups. However, blood loss was less, bowel function recovered earlier, and hospitalization time was shorter in the laparoscopic group. CONCLUSION: Totally laparoscopic TME with ASP is feasible, and it is a minimally invasive technique with the benefits of much less blood loss during operation, earlier return of bowel function, and shorter hospitalization.

Adult↗
PubMed2004

Glucagon-like peptide-1 regulates proliferation and apoptosis via activation of protein kinase B in pancreatic INS-1 beta cells.

AIMS/HYPOTHESIS: The incretin hormone glucagon-like peptide-1 augments islet cell mass in vivo by increasing proliferation and decreasing apoptosis of the beta cells. However, the signalling pathways that mediate these effects are mostly unknown. Using a clonal rat pancreatic beta cell line (INS-1), we examined the role of protein kinase B in mediating beta-cell growth and survival stimulated by glucagon-like peptide-1. METHODS: Immunoblot analysis was used to detect active (phospho-) and total protein kinase B. Proliferation was assessed using (3)H-thymidine incorporation, while apoptosis was quantitated using 4'-6-diamidino-2-phenylindole staining and APO percentage apoptosis assay. Kinase-dead and wild-type protein kinase B was introduced into cells using adenoviral vectors. RESULTS: Glucagon-like peptide-1 rapidly activated protein kinase B in INS-1 cells (by 2.7+/-0.7-fold, p<0.05). This effect was completely abrogated by inhibition, with wortmannin, of the upstream activator of protein kinase B, phosphatidylinositol-3-kinase. Glucagon-like peptide-1 also stimulated INS-1 cell proliferation in a dose-dependent manner (by 1.8+/-0.5-fold at 10(-7) mol/l, p<0.01), and inhibited staurosporine-induced apoptosis (by 69+/-12%, p<0.05). Both of these effects were also prevented by wortmannin treatment. Ablation of protein kinase B by adenovirus-mediated overexpression of the kinase-dead form of protein kinase Balpha prevented protein kinase B phosphorylation and completely abrogated both cellular proliferation ( p<0.05) and protection from drug-induced cellular death ( p<0.01) induced by glucagon-like peptide-1. CONCLUSIONS/INTERPRETATION: These results identify protein kinase B as an essential mediator linking the glucagon-like peptide-1 signal to the intracellular machinery that modulates beta-cell growth and survival.

Animals↗
PubMed2004

Salt-assisted and salt-suppressed sol-gel transitions of methylcellulose in water.

The effects of various salts on the sol-gel transition of aqueous methylcellulose (MC) solutions have been studied systematically by means of a micro differential scanning calorimeter. It was found that the heating process was endothermic while the cooling process was exothermic for both MC solutions with and without salts. The addition of salts did not change the patterns of gelation and degelation of MC. However, the salts could shift the sol-gel transition and the gel-sol transition to lower or higher temperatures from a pure MC solution, depending on the salt type. These opposite effects were termed the salt-assisted and salt-suppressed sol-gel transitions. Either the salt-assisted transition or the salt-suppressed sol-gel transition was a function of salt concentration. In addition, each salt was found to have its own concentration limit for producing a stable aqueous solution of MC at a given concentration of MC, which was related to the anionic charge density of the salt. Cations were proved to have weaker effects than anions. The "salt-out strength", defined as the salt effect per mole of anion, was obtained for each anion studied. The thermodynamic mechanisms involved in the salt-assisted and salt-suppressed sol-gel transitions are discussed.

Anions↗
PubMed2004

[Calcifying epithelial odontogenic tumor of the maxilla (Pindborg tumor)].

A male patient presented with an extraordinarily large calcifying epithelial odontogenic tumor (CEOT or Pindborg-tumor) that affected the maxilla. The disease became evident due to alterations in the facial aspect, in particular of the perioral region, caused by the expanding tumor. CEOT is characterised by the slowly growing mass of part of the jaws. Multilocular or extraosseous manifestations are extremely rare. Malignant transformation with metastases is rare. Radiography depicts characteristic, but not obligatory, areas of calcification inside the tumor. The surgical therapy for CEOT is complete local resection with safe margins. If tooth bearing parts of the jaws are affected, these teeth almost always have to be removed. The prognosis is excellent for overall survival. Local recurrences have rarely been reported but may be found even decades after primary treatment. Three years following surgical therapy there is no evidence of local recurrence. A long-term follow-up control is recommended.

Calcinosis↗
PubMed2004

C-peptide fragments stimulate glucose utilization in diabetic rats.

Studies of C-peptide cellular effects show that not only the full-length native peptide but also specific C-terminal fragments are biologically active in in vitro systems. In the present study, the effect of five C-peptide fragments and the native peptide on whole-body glucose turnover was studied in streptozotocin diabetic rats using the insulin clamp technique. Insulin was infused intravenously at 18 pmol kg(-1) min(-1) for 90 min and blood glucose concentration was clamped at 8 and 4 mM in diabetic and non-diabetic animals. A steady state was reached during the last 30 min of the study period. Rat C-peptide II and fragments comprising residues 27-31 and 28-31 were effective in augmenting glucose turnover in diabetic rats (+100% to 150%), while no significant effects were seen for segments 1-26, 11-19 and 11-15. The metabolic clearance rate for glucose during infusion of C-peptide or fragments 27-31 and 28-31 in diabetic rats was similar to that seen in non-diabetic animals. We conclude that C-terminal tetra- and pentapeptides, but not fragments from the middle segment of C-peptide, are as effective as the full-length peptide in stimulating whole-body glucose turnover in diabetic rats.

Animals↗