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Biomedical subjects

F Song

Publications and source records attributed to F Song.

At least 55 records · Page 3Linked to original sources
PubMed2000

Indirect comparison in evaluating relative efficacy illustrated by antimicrobial prophylaxis in colorectal surgery.

This paper aims to explore the potential usefulness and limitations of indirect comparisons in evaluating the relative efficacy of interventions. From a systematic review of antimicrobial prophylaxis in colorectal surgery, we identified 11 sets of randomized trials that can be used to compare antibiotics both directly and indirectly. The discrepancy between the direct and the indirect comparison is defined as the absolute value of difference in log odds ratio. The adjusted indirect comparison has the advantages that the prognostic factors of participants in different trials can be partially taken into account and more uncertainty be incorporated into its result by providing a wider confidence interval. However, considerable discrepancies exist between the direct and the adjusted indirect comparisons. When there is no direct comparison, the adjusted indirect method may be used to obtain some evidence about the relative efficacy of competing interventions, although such indirect results should be interpreted with great caution. Further empirical and methodologic research is needed to explore the validity and generalizability of the adjusted indirect comparison for evaluating different interventions.

Antibiotic Prophylaxis↗
PubMed2000

The causes, consequences and detection of publication bias in psychiatry.

OBJECTIVE: Publication bias threatens the validity of published research, although this topic has received little attention in psychiatry. The purpose of this article is to produce a systematic overview of the causes and consequences of publication bias and to summarize the available methods with which it is detected and corrected. METHOD: Empirical evidence for the existence of publication bias is reviewed and the following methods are applied to an illustrative case example from psychiatry: funnel plot analysis; the 'file drawer method'; linear regression techniques; rank correlation; 'trim and fill'. RESULTS: Small studies are particularly susceptible to publication and related bias. All methods to detect publication bias depend upon the availability of a number of individual studies with a range of sample sizes. Unfortunately, large numbers of studies of varying sample size are not always available in many areas of psychiatric research. CONCLUSION: Where possible researchers should always test for the presence of publication bias. The problem of publication bias will not be solved by anything other than a prospective trials register.

Humans↗
PubMed2000

Expression of IL-10 receptors on epithelial cells from the murine small and large intestine.

The appearance of chronic intestinal inflammation in IL-10 knockout mice suggests IL-10 may inhibit adverse responses to luminal antigen. Moreover, this inflammation is associated with an increase in class II MHC molecule expression on intestinal epithelial cells. Thus, the role of IL-10 regulation in epithelial cell function was investigated. Using RT-PCR, it was shown that intestinal epithelial cells express mRNA for both subunits of the IL-10 receptor-signaling complex. In addition, biotinylated IL-10 was shown to bind to both cultured and freshly isolated intestinal epithelial cells prepared from the small or large intestine. This binding appeared specific as it was blocked by neutralizing antibodies to IL-10 but not the isotype control. Moreover, an excess of native IL-10 also inhibited the binding of radiolabeled IL-10. To evaluate whether IL-10 mediated any functions through this receptor, epithelial cells were cultured with IL-10 alone or with IFN-gamma plus IL-10. IL-10 alone had no detectable effects on epithelial cell growth or their expression of class II MHC molecules but it did antagonize the effect of IFN-gamma on the viability of cultured cells. In addition, IL-10 blocked the IFN-gamma-induced expression of class II MHC molecules on cultured epithelial cells. These results suggest that IL-10 binds to a specific receptor on intestinal epithelial cells and may regulate the contribution of epithelial cells to the inflammatory and immune response in the digestive tract.

Animals↗
PubMed2000

Adaptive changes in insulin secretion by islets from neonatal rats raised on a high-carbohydrate formula.

Artificial rearing of neonatal rats on a high-carbohydrate (HC) milk formula resulted in the immediate onset of hyperinsulinemia. This study examines, in islets of 12-day-old HC rats, adaptive changes that support the hyperinsulinemic state. Increases in plasma glucagon-like peptide-1 (GLP-1) levels and islet GLP-1 receptor mRNA supported increased insulin secretion by HC islets. Isolated HC islets, but not mother-fed (MF) islets, secreted moderate amounts of insulin in a glucose- and Ca(2+)-independent manner. Under stringent Ca(2+)-free conditions and in the presence of glucose, GLP-1 plus acetylcholine augmented insulin release to a larger extent in HC islets. Levels of adenylyl cyclase type VI mRNA and activities of protein kinase A, protein kinase C, and calcium calmodulin kinase II were increased in HC islets. A tenfold increase in norepinephrine concentration was required to inhibit insulin secretion in HC islets compared with MF islets, indicating reduced sensitivity to adrenergic signals. This study shows that significant alterations at proximal and distal sites of the insulin secretory pathway in HC islets may support the hyperinsulinemic state of these rats.

Adaptation, Physiological↗
PubMed2000

Modelling publication bias in meta-analysis: a review.

Meta-analysis is now a widely used technique for summarizing evidence from multiple studies. Publication bias, the bias induced by the fact that research with statistically significant results is potentially more likely to be submitted and published than work with null or non-significant results, poses a threat to the validity of such analyses. The implication of this is that combining only the identified published studies uncritically may lead to an incorrect, usually over optimistic, conclusion. How publication bias should be addressed when carrying out a meta-analysis is currently a hotly debated subject. While statistical methods to test for its presence are starting be used, they do not address the problem of how to proceed if publication bias is suspected. This paper provides a review of methods, which can be employed as a sensitivity analysis to assess the likely impact of publication bias on a meta-analysis. It is hoped that this will raise awareness of such methods, and promote their use and development, as well as provide an agenda for future research.

Bayes Theorem↗
PubMed2000

The effectiveness and cost-effectiveness of prophylactic removal of wisdom teeth.

BACKGROUND: Removal of wisdom teeth is one of the most common surgical procedures performed in the UK. Little controversy surrounds the removal of impacted third molars when they are associated with pathological changes such as infection, non-restorable carious lesions, cysts, tumours, and destruction of adjacent teeth and bone. However, the justification for prophylactic removal of impacted third molars is less certain and has been debated for many years. OBJECTIVES: To provide a summary of existing evidence on prophylactic removal of impacted wisdom teeth, in terms of the incidence of surgical complications associated with prophylactic removal, and the morbidity associated with retention. METHODS: A systematic review of the research literature was undertaken. METHODS - DATA SOURCES: An existing review formed the basis of this report, and additional literature searches were undertaken, including searches of electronic databases (MEDLINE, 1984-99; EMBASE, 1984-99; Science Citation Index, Cochrane Controlled Trials Register, National Research Register; Database of Abstracts of Reviews of Effectiveness), paper sources (including Clinical Evidence), and web-based resources. Relevant organisations and professional bodies were contacted for further information. METHODS - STUDY SELECTION: Studies were selected for inclusion if they met the following criteria: (1) design - randomised controlled trials (RCTs), literature reviews, or decision analyses; (2) participants - people with unerupted or impacted third molars, or those undergoing surgical removal of third molars either as prophylaxis or due to associated pathological changes; (3) reported outcomes - either the pathological changes associated with retention of third molars, or post-operative complications following extraction. There were no language restrictions on study selection. METHODS - DATA EXTRACTION AND SYNTHESIS: Data from included studies were extracted into structured tables and individual study validity was assessed against methodological checklists. Data were summarised descriptively. Decisions relating to study selection, data extraction and validity assessment were made by two independent reviewers, and disagreements were resolved by discussion. For non-English papers, translators were recruited to assist with study selection and data extraction. RESULTS: Forty studies were included in the review: two RCTs, 34 literature reviews, and four decision analysis studies. One RCT in the UK focused on the effects of retained third molars on incisor crowding (predominantly a cosmetic problem) in patients who had previously undergone orthodontic treatment. The results of this trial suggested that the removal of third molars to prevent late incisor crowding cannot be justified. Another on-going RCT in Denmark compares the effects and costs of prophylactic removal of third molars with removal according to morbidity. So far, this trial has recruited 200 participants, and preliminary results indicate that watchful waiting may be a promising strategy. However, more data and longer follow-up of patients are needed to conclude which treatment strategy is the most cost-effective. It is also known that a trial is on-going in the USA but no results are available so far. The methodological quality of the literature reviews was generally poor, and none of the reviews was systematic. Conclusions from nine reviews on anterior crowding suggested that there was only a weak association between retention of third molars and crowding. Six out of 21 reviews with a more general scope also concluded that the prophylactic removal of third molars was unjustified. Twelve general reviews did not conclude with a clear message about the management of third molars. Three reviews suggested that prophylactic removal of third molars is appropriate, but these reviews were of poorer methodological quality than the majority of other reviews. Three out of four papers focusing on surgical management expressed

Cost-Benefit Analysis↗
PubMed2000

Factors influencing the expression of Fas and Fas ligand on newborn murine keratinocytes and fibroblasts.

OBJECTIVE: To investigate the expression of Fas, FasL mRNA and proteins on keratinocytes and fibroblasts, and the influence by retinoid acid (RA) and dexamethasone (Dex). METHODS: RNase protection assay and flow cytometry were used. RESULTS: Fas mRNA was expressed on neonatal murine keratinocytes and was up-regulated by all-trans retinoid acid and down-regulated by Dex. RA and Dex also increased the Fas protein expression on keratinocytes. Newborn murine keratinocytes express FasL mRNA, which was up-regulated by RA and Dex, while its protein expression was moderately induced by RA. Newborn murine fibroblasts also expressed Fas and FasL mRNA, which were up-regulated by the RA and Dex. CONCLUSIONS: The results indicated that RA and Dex might regulate apoptosis of keratinocytes and fibroblasts via the Fas-FasL system.

Animals↗
PubMed2000

[Identification of cry-type genes of 31 Bacillus thuringiensis isolates and analysis of their expression product].

In this study, cry-type gene of 31 isolates of Bt had been identified using PCR-RFLP identification system, and SDS-PAGE analysis and bioassay had been performed. 25 strains containing cry1 type gene express 130-150 kD protein and 16 of them contain cry1I gene, which codes 80 kD protein and is larvicidal to both lepidopteran and coleopteran species. 15 strains contain both cry1 and cry2 type gene; 10 strains contain unknown cry-type gene; 6 strains don't contain seven identified cry-type gene. Result of bioassay shows that the strains containing both cry1 and cry2 gene have high toxicity to lepidopteran order, 7 of them are strongly insecticidal to Pristiphora beijingensis and Lymantria dispar larvae; the strains containing cry1Ab + 1Ac + 2A or cry1Aa + 1Ac + 2A have high activity to Heliothis armigera; no cry gene, no activity. It is indicated that identification of cry-type gene and its analysis of SDS-PAGE protein can predict insecticidal activity of Bt isolates, and it is no pertinency between cry-type gene and serotype of Bt strain.

Animals↗
PubMed2000

[Activities of superoxide dismutase in Xanthomonas oryzae pv. oryzae and its induction].

The activities of superoxide dismutase(SOD) in Xanthomonas oryzae pv. oryzae were determined to demonstrate the correlation of SOD activities with the bacterial virulence. In liquid culture, SOD activities of the tested strains reached the maxima at the end of lag phase and then declined. The virulent strain PXO99A showed higher SOD activities than the avirulent strain PXO99A (pBUavr Xa10.F1). Analysis on the subcellular location indicated that SOD activities detected from the cytoplasm and periplasm were over 70% and 20%-30% of the total, respectively. Treatment of the bacterial culture for 1 h with exogenous O2- at concentration of 50-800 mumol/L induced SOD activities of both the strains. The treatment with 200 mumol/L resulted in the highest SOD activities. The effect of exogenous O2- on SOD induction was more significant in 12 h-culture than in 24 h-culture, and more notable for the virulent strain PXO99A. The treatment with exogenous O2- resulted in significantly decreased survival rate off both the strains. The decreases of survival rate were greater in 24 h-culture than in 12 h-culture, and more significantly for the virulent strain than for the avirulent one.

Oryza↗
PubMed2000

[Expression and synergism of two cry insecticidal protein genes in Pseudomonas fluorescens].

Several engineered Pseudomonas fluorescens(Pf) strains were constructed mainly based on a Pseudomonas plasmid pJMS6 alpha-lac and two insecticidal crystal protein genes of Bacillus thuringiensis, cry1Ac and cry2Aa, and the host Pf strain, P303, which was with highly antifungal activity to some plant disease fungi and colonizing ability on a wide range of plants. The DNA introduction was confirmed by PCR-RFLP and Southern blot. The 132 kD insecticidal protein was detected in IPP101 and IPP202 by SDS-PAGE and rhombic insecticidal protein crystals of them were observed through electron microscope, also indicating that cry1Ac gene was highly expressed. The results of insecticidal bioassay indicated that IPP101 was more toxic than IPP201, and IPP202 was the most toxic among the 3 strains. LC50 to the neonates of cotton boll worm(Helicoverpa armigera) were 0.02604, 0.00812 and 0.00186 mL/g feed, consecutively. In IPP202, two gene products showed significant synergism, with the co-toxicity coefficient of 332.8.

Animals↗
PubMed2000

[Laryngostroboscopy in the monitoring of precancerous lesion of vocal cord and in canceration tracing].

OBJECTIVE: To evaluate the value of laryngostroboscopy in the monitoring of precancerous lesion of vocal cord and in the canceration tracing. METHODS: Fifty-two cases of precancerous lesion of vocal cord were examined under Laryngostroboscope. The modifications of mucosal wave and amplitude of vocal cord vibration were observed. All cases were monitored for 1-6 years. RESULTS: The mucosal wave was weak in 45 of 52 cases (86.3%) and the amplitude of vocal cord vibration was weak in 4 of 52 cases (9.6%) with precancerous lesions. However, the mucosal wave disappeared and the amplitude of vocal cord vibration weakened in all 14 cases with early glottic cancer. CONCLUSION: Laryngostroboscopy can be used in diagnosis of glottic precancerous lesion and distinguishing it from the early glottic cancer. It is also an effective means of canceration tracing.

Carcinoma, Squamous Cell↗
PubMed1999

Expression of the neutrophil chemokine KC in the colon of mice with enterocolitis and by intestinal epithelial cell lines: effects of flora and proinflammatory cytokines.

IL-10 plays an important role in preventing excessive inflammation to the normal flora in the intestinal lumen. The purpose of this study was to compare the effect of normal flora on inflammation in mice in which the IL-10 gene was disrupted. IL-10 knock-out mice housed in germfree conditions remained healthy while those housed in conventional conditions developed colitis after weaning, suggesting that IL-10 inhibits the adverse responses to luminal Ag. Crypt abscesses were present in virtually all of the diseased animals as evidenced by flattening of the epithelial cells and a large number of neutrophils in the lumen of the crypt. Since KC is a chemokine that is capable of recruiting neutrophils in mice, mRNA and protein for KC was measured. Increased levels of both KC mRNA and protein were detected in the colon of diseased mice. To determine whether the epithelial cells were capable of synthesizing KC and contributing to neutrophil accumulation in the crypts, a murine intestinal epithelial cell line (Mode-K) was shown to express mRNA and protein for KC. Two cytokines induced in association with colitis in these mice, TNF-alpha and IFN-gamma, increased the expression of KC mRNA and protein in murine epithelial cells. However, IL-10 was incapable of decreasing the induction of KC, even though the cells expressed the IL-10 receptor. These results suggest that the neutrophil chemokine KC is produced by gastrointestinal epithelial cells in response to inflammatory mediators that are expressed following exposure to normal flora in animals lacking IL-10.

Age Factors↗
PubMed1999

Quantitative analysis of pethidine using liquid secondary ion and tandem mass spectrometry.

A method for the quantatitive determination of pethidine in human urine by liquid secondary ion and tandem mass spectrometry is presented. Quantification was carried out by using ketamine as internal standard. It was found that the collision-induced dissociation (CID) spectrum of the [M + H]+ ion of pethidine exhibited a prominent daughter ion at m/z 220 and ketamine also yielded the same daughter ion at m/z 220. For ((quadrupole)) quantitative analysis, the first quadrupole mass filter was set to transmit m/z 220 and a narrow-range magnet scan yielded a spectrum of parents, including m/z 238 and 248, correspending to ketamine and pethidine, respectively.

Chromatography, Liquid↗
PubMed1999

Application of capillary nongel sieving electrophoresis for gene analysis.

Capillary electrophoresis (CE) has proved to be a strong tool for DNA analysis and has found abundant applications in the fields of restriction fragment sizing, mutation screening, polymerase chain reaction (PCR) product characterizing and forensic identifying. CE may be the main alternative to slab gel electrophoresis. Capillary nongel electrophoresis is the most favorable mode when aiming for this purpose because of its advantages of long lifetime, easy operation, good reproducibility, and low expense. In this paper, a new kind of sieving matrix, with mannitol as the additive for capillary electrophoresis, as well as related methods and their application for gene analysis were reported. Nine DNA fragments amplified by multiplex PCR from a normal dystrophin gene were well separated by this system. Three different deletions were found in Duchenne muscular dystrophy (DMD) patients. Three to four copies of the sex-determination region of the Y chromosome (SRY) gene, as well as the phenylalanine hydroxylase (PAH) gene, could be detected in mixed samples. The frequencies of short tandem repeats (STR) in PAH genes was analyzed in 61 normal Chinese individuals and 6 phenylketonuria families. One case of prenatal gene diagnosis was performed. By using this matrix, CE coupled with reverse transcription PCR (RT-PCR), the analysis of the alternative splicing expression pattern of the fragile X mental retardation 1 (FMR1) gene in adult lung tissue was achieved.

Adult↗
PubMed1999

Exploring heterogeneity in meta-analysis: is the L'Abbé plot useful?

By using a published meta-analysis as an example, this paper discusses the use of L'Abbe plot for investigating the potential sources of heterogeneity in meta-analysis. As compared with other graphic procedures, the L'Abbe plot is useful to identify not only the studies having different results from other studies, but also the study arms that are responsible for such differences. This may be important for determining the focus of heterogeneity investigations. Results of stochastic simulation indicate that, purely because of random variation, studies with event rates of around 50% are more likely to be identified as outliers in a L'Abbe plot. This paper also demonstrates that different methods may identify different trials as "outliers" in meta-analysis.

Computer Simulation↗