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Biomedical subjects

F Song

Publications and source records attributed to F Song.

At least 109 records · Page 6Linked to original sources
PubMed1996

[The cloning and expression of salmon calcitonin gene in Escherichia coli].

The DNA fragment encoding salmon calcitonin was separated from the salmon DNA with PCR method. It was recombined into the fusion expression vector (pGEX-2T) which included a Glutathion-S-Transferase (GST) gene and was transformed into E. coli JM109 and then expression was induced with IPTG. The fusion protein (GST-sCT) accounted for 38%-40% of the total cellular protein and was purified from the soluble expression products by glutathion sepharose 4B affinity chromatography. The purity of GST-sCT is about 80% and it showed a positive immunological reaction in calcitonin enzyme immunoassay.

Amino Acid Sequence↗
PubMed1996

[A simple technique of somatic cell hybridization].

Since the first report on the use of mutants lacking enzymes and HAT medium for hybrid selection (Littlefield, 1964), enormous similar techniques, at least, have been basically established. These techniques have opened new avenues to assigning genes, analysing gene regulation in eukaryotic cells and studying mechanisms which govern cell growth and differentiation during normal embryonic development, wound healing and tumor formation. But some problems still remain. For instance, such techniques need about one year to mutate both kinds of cells before fusion and selection, A simple technique of somatic cell hybridization without cell mutation has been developed, and by utilizing different appearances of cells before and after trypsinization, two kinds of cells may be fused and selected in some hours. Up-to-date six kinds of cells have been tested and found successful. Some hundreds of tests have been repeated, and modified, and the analyses by different methods have shown that the technique is both stable and reliable.

3T3 Cells↗
PubMed1995

Early appearance of T cell receptor alpha beta + CD4- CD8- T cells with a skewed variable region repertoire after infection with Listeria monocytogenes.

We found that the number of T cell receptor (TCR) alpha beta + CD4- CD8- T cells increased in the peritoneal cavity on day 5 after an intraperitoneal infection with Listeria monocytogenes strain EGD together with TCR gamma delta + CD4- CD8- T cells. Thereafter, the TCR alpha beta + CD4- CD8- T cells decreased to a normal level by day 14. The TCR alpha beta + CD4- CD8- T cells showed an activated T cell phenotype (L-selectin CD44 +) and expressed CD45/B220 and interleukin-2 receptor beta, but did not express heat stable antigen, which is expressed by the immature CD4- CD8- thymocytes. Furthermore, 20-30% of the TCR alpha beta + CD4- CD8- T cells expressed the NK1.1 natural killer cell marker. Analysis of the TCR V region repertoire of the TCR alpha beta + CD4- CD8- T cells induced by L. monocytogenes infection showed that more than 80% of the TCR alpha beta + CD4- CD8- T cells expressed TCR V beta 8 detected by anti-TCR V beta 8.1 and 8.2 mAb, and a reverse transcription-polymerase chain reaction analysis of V alpha 14 relative to V alpha 11 expression revealed that the TCR alpha beta + CD4- CD8- T cells expressed a higher level of V alpha 14, which was reported to be preferentially expressed by TCR alpha beta + CD4- CD8- thymocytes rather than conventional CD4+ T cells. The TCR alpha beta + CD4- CD8-T cells showed a proliferative response to anti-TCR alpha beta mAb stimulation. In contrast, they showed no response to stimulation with either Listeria antigen or 65-kDa heat shock protein of Mycobacterium bovis, which do stimulate the Listeria-specific TCR alpha beta + CD4- CD8- T cells and the Listeria-induced TCR gamma delta + T cells, respectively. These results suggest that the TCR alpha beta + CD4- CD8- T cells may recognize a restricted set of self antigens induced by L. monocytogenes infection, and that they contribute to host protection at an early stage of infection.

Animals↗
PubMed1995

In vitro generation of IFN-gamma-producing Listeria-specific T cells is dependent on IFN-gamma production by non-NK cells.

In vitro 5-day cultures of naive spleen cells with viable Listeria monocytogenes (VLM), but not heat-killed L. monocytogenes, induced CD4+ T cells that produced IFN-gamma upon secondary antigen stimulation. The VLM-induced Listeria-specific T cells produced IFN-gamma but lacked expression of IL-2 and IL-4. To study the role of IFN-gamma in the induction of the IFN-gamma-producing T cells, we added anti-IFN-gamma mAb to the primary culture and analyzed IFN-gamma production upon secondary antigen stimulation. Addition of anti-IFN-gamma mAb to the culture suppressed generation of IFN-gamma-producing CD4+ T cells, suggesting that IFN-gamma is important in the induction of IFN-gamma-producing CD4+ T cells. Furthermore, our results showed that depletion of NK cells from spleen cells by anti-asialo GM1 antibody plus complement before culture enhanced induction of IFN-gamma-producing CD4+ T cells. Although NK cells are known to produce IFN-gamma, the results indicate that NK cell-derived IFN-gamma may not be important in induction of the Listeria-specific IFN-gamma-producing CD4+ T cells in the culture system. In addition, we demonstrated that IFN-gamma expression was high in CD4+ T cells from cultures of spleen cells with VLM at the primary culture level. These results suggest that IFN-gamma derived from T cells may enhance production of IFN-gamma by CD4+ T cells, while NK cells rather suppress the induction of IFN-gamma producing CD4+ T cells.

Animals↗
PubMed1994

Prescribing selective serotonin reuptake inhibitors as strategy for prevention of suicide.

OBJECTIVE: To evaluate a policy to reduce the incidence of suicide by means of changing the prescribing of antidepressants from the older tricyclic antidepressants to the routine first line use of selective serotonin reuptake inhibitors or newer tricyclic and related antidepressants. DESIGN: Cost effectiveness analysis with sensitivity analyses using observational data on costs, volume of prescribing, deaths, and toxicity. SETTING: United Kingdom primary care. INTERVENTIONS: Selective serotonin reuptake inhibitors or newer tricyclic and related antidepressants compared with the use of older tricyclics. MAIN OUTCOME MEASURES: Cost per life saved and cost per life year saved. RESULTS: The potential number of lives which may be saved from a switch to the routine first line use of selective serotonin reuptake inhibitors is between 300 and 450 each year. The cost per life year gained ranges from 19,000 pounds to 173,000 pounds, depending on the assumptions used. The cost per life year gained through the use of the newer tricyclic and related antidepressants is considerably lower. CONCLUSIONS: The cost per life year gained through avoiding suicides by the routine first line use of serotonin reuptake inhibitors is likely to be high. The new tricyclics and related drugs are of similar toxicity to the serotonin reuptake inhibitors but are considerably cheaper and so are most cost effective for this purpose. Further research is required on such prescribing. Because of the great uncertainties the shift to considerably more expensive options must be further investigated.

Antidepressive Agents, Tricyclic↗
PubMed1994

The role of B cells in in vitro induction of IFN-gamma-producing CD4+ T cells specific to Listeria monocytogens: positive and IL-10-mediated negative regulation.

We have reported that Listeria monocytogenes-specific IFN-gamma-producing CD4+ T cells are induced by in vitro 5-day culture of naive spleen cells with viable L. monocytogenes (VLM), but not induced by culture with heat-killed L. monocytogenes (HKLM). In the present study, the role of B cells in the regulation of induction of IFN-gamma-producing CD4+ T cells in the in vitro system was investigated. We found that L. monocytogenes-specific IFN-gamma-producing CD4+ T cells were not generated when B cells were depleted from spleen cells before culture with VLM although Ag-specific proliferative response was retained. IFN-gamma production by CD4+ T cells was restored by addition of B cells cultured with VLM to the culture of B cell-depleted spleen cells and VLM. In contrast, B cells cultured with HKLM could not restore the induction of IFN-gamma production when added in culture of B cell-depleted spleen cells and VLM. Analysis of cytokine gene expression by reverse transcription-polymerase chain reaction method revealed that expression of interleukin-10 (IL-10) was higher but TNF-alpha was lower in B cells cultured with HKLM when compared with that in B cells cultured with VLM. Furthermore, addition of neutralizing anti-IL-10 mAb into culture of naive spleen cells with HKLM resulted in appearance of IFN-gamma-producing cells. These results suggest that B cells have positive and negative roles in the induction of IFN-gamma-producing CD4+ T cells. The inhibition of induction of IFN-gamma-producing CD4+ T cells may depend on B cell-derived IL-10.

Animals↗
PubMed1994

Anatomic considerations in botulinum toxin type A therapy for spasmodic dysphonia.

Chemodenervation by injection of botulinum toxin type A into the vocal fold(s) has become the preferred treatment for patients with adductor spasmodic dysphonia. Injection may be done either perorally or transcutaneously; each method has its advocates and advantages. The authors have used the transcutaneous transcricothyroid membrane route exclusively with satisfactory results in more than 50 patients. Temporary breathliness and aspiration are common. The preferred injection site should be as close as possible to the motor end plates of the affected muscle. The thyroarytenoid muscle end plates are distributed throughout the muscle, whereas in the lateral cricoarytenoid muscle they are located in band in the center of the muscle. The transcutaneous injection site is below and posterior to the midpoint of the vibrating vocal fold as visualized by indirect laryngoscopy. The proximity of this site to the lateral cricoarytenoid muscle suggests that postinjection breathiness and aspiration may be related to spread of botulinum toxin type A to the lateral cricoarytenoid muscle. However, it is likely that thyroarytenoid muscle paresis is mainly responsible for this side effect and that the rapid clearing of the breathy dysphonia in the face of prolonged relief of spasmodic dysphonia symptoms suggests the action of an adaptive neural response, such as axonal sprouting. Further research of this subject is warranted.

Botulinum Toxins↗
PubMed1994

Stochastic simulation and sensitivity analysis: estimating future demand for health resources in China.

A simulation model has been built to estimate the demand for hospital beds and doctors in China between 1990 and 2010. The model was used to compare deterministic sensitivity analysis and stochastic simulation in assessing inherent uncertainty in health projections. The stochastic simulation method uses information more efficiently, and produces a more reasonable average estimate and a more meaningful range of projections than deterministic sensitivity analysis. However, it may be preferable to combine the use of both approaches because they have different, complementary, advantages and disadvantages. The usefulness of 3 value estimates of input variables and the benefits of the triangular distribution for stochastic simulation should be emphasized in health projections.

China↗
PubMed1993

Cholesterol lowering and mortality: the importance of considering initial level of risk.

OBJECTIVE: To investigate the level of risk of death from coronary heart disease above which cholesterol lowering treatment produces net benefits. DESIGN: Meta-analysis of results of randomised controlled trials of cholesterol lowering treatments. METHODS: Published and unpublished data from all identified randomised controlled trials of cholesterol lowering treatments with six months or more follow up and with at least one death were included in the meta-analysis. The analyses were stratified by the rate of death from coronary heart disease in the control arms of the trials. MAIN OUTCOME MEASURES: Death from all causes, from coronary heart disease, and from causes other than coronary heart disease. RESULTS: In the pooled analysis, net benefit in terms of total mortality from cholesterol lowering was seen only for trials including patients at very high initial risk of coronary heart disease (odds ratio 0.74; 95% confidence interval 0.60 to 0.92). In a medium risk group no net effect was seen, and in the low risk group there were adverse treatment effects (1.22; 1.06 to 1.42). In a weighted regression analysis a significant (p < 0.001) trend of increasing benefit with increasing initial risk of coronary heart disease was shown. Raised mortality from causes other than coronary heart disease was seen in trials of drug treatment (1.21; 1.05 to 1.39) but not in the trials of non-drug treatments (1.02; 0.88 to 1.19). Cumulative meta-analysis showed that these results seem to have been stable as new trials appeared. CONCLUSION: Currently evaluated cholesterol lowering drugs seem to produce mortality benefits in only a small proportion of patients at very high risk of death from coronary heart disease. Population cholesterol screening could waste resources and even result in net harm in substantial groups of patients. Overall risk of coronary heart disease should be the main focus of clinical guidelines, and a cautious approach to the use of cholesterol lowering drugs should be advocated. Future trials should aim to clarify the level of risk above which treatment is of net benefit.

Cholesterol↗
PubMed1993

Selective serotonin reuptake inhibitors: meta-analysis of efficacy and acceptability.

OBJECTIVE: To examine the evidence for using selective serotonin reuptake inhibitors instead of tricyclic antidepressants in the first line treatment of depression. DESIGN: Meta-analysis of 63 randomised controlled trials comparing the efficacy and acceptability of selective serotonin reuptake inhibitors with those of tricyclic and related antidepressants. MAIN OUTCOME MEASURES: Improvement in mean scores on Hamilton depression rating scale for 53 randomised controlled trials. Pooled drop out rates from the 58 trials which reported drop out by treatment group. RESULTS: Among the 20 studies reporting standard deviation for the Hamilton score no difference was found in efficacy between serotonin reuptake inhibitors and tricyclic and related antidepressants (standardised mean difference 0.004, 95% confidence interval -0.096 to 0.105). The difference remained insignificant when the remaining 33 studies that used the 17 item and 21 item Hamilton score were included by ascribing weighted standard deviations. The odds ratio for drop out rate in patients receiving serotonin reuptake inhibitors compared with those receiving tricyclic antidepressants was 0.95 (0.86 to 1.07). Similar proportions in both groups cited lack of efficacy as the reason for dropping out but slightly more patients in the tricyclic group cited side effects (18.8% v 15.4% in serotonin reuptake group). CONCLUSIONS: Routine use of selective serotonin reuptake inhibitors as the first line treatment of depressive illness may greatly increase cost with only questionable benefit.

Antidepressive Agents, Tricyclic↗