The next influenza pandemic: lessons from Hong Kong, 1997

The 1997 Hong Kong outbreak of an avian influenzalike virus, with 18 proven human cases, many severe or fatal, highlighted the challenges of novel influenza viruses. Lessons from this episode can improve international and national planning for influenza pandemics in seven areas: expanded international commitment to first responses to pandemic threats; surveillance for influenza in key densely populated areas with large live-animal markets; new, economical diagnostic tests not based on eggs; contingency procedures for diagnostic work with highly pathogenic viruses where biocontainment laboratories do not exist; ability of health facilities in developing nations to communicate electronically, nationally and internationally; licenses for new vaccine production methods; and improved equity in supply of pharmaceutical products, as well as availability of basic health services, during a global influenza crisis. The Hong Kong epidemic also underscores the need for national committees and country-specific pandemic plans.     

Field detection of Francisella tularensis

A field investigation was undertaken following an outbreak of water-borne tularemia in Northern Norway. Francisella tularensis bacterial cellular components were analysed by rapid immunochromatography (RI)-testing, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). Water from 1 reservoir, fed from a rapid stream, tested negative. From another reservoir, 2 of a chain of 3 wells tested negative. The third well, at the end of the chain, contained lemming (Lemmus lemmus) carcasses and gave ample proof of F. tularensis contamination. We concluded that the origin of the outbreak was dead, infective lemming carcasses in the water sources. For the various sampling materials, the RI-test proved itself particularly handy and versatile, compared with the ELISA and the PCR.     

A comparison of the humoral and cellular immune responses at different immunological sites after split influenza virus vaccination of mice

The spleen, bone marrow and lymph nodes are all known to be important organs for the initiation and maintenance of an immune response after vaccination. To investigate the differences and similarities in the humoral and cellular immune responses between these tissues, we vaccinated mice once or twice with the conventional human dose (15 microg HA) of influenza A (H3N2) split virus vaccine and analysed the sera and lymphocytes collected from the different sites. We found that the response of antibody secreting cells (ASC) in the lymph nodes appeared to be more transient than in the spleen, possibly because the influenza-specific IgM ASC in particular might have migrated from the lymph nodes immediately after activation. The serum antibody response was found to initially correspond with the ASC response elicited in the spleen and the lymph nodes, whereas the later serum IgG reflected the ASC response in the bone marrow. Proliferation of influenza-specific CD4(+) and CD8(+) cells was predominantly observed in the spleen and was associated with higher concentrations of cytokines than in the lymph nodes. The finding of influenza-specific CD8(+) cell proliferation in the spleen indicates that a split influenza virus vaccine may stimulate a cytotoxic T-cell response. Our results also showed that the primary response elicited a mixed Th1/Th2 profile, whereas the secondary response was skewed towards a Th2 type. Each of the three tissues had a different immunological pattern, suggesting that in preclinical vaccine studies, there is a case for investigating a range of immunological sites.     

Oxidative metabolism of the human eosinophil

We have compared the oxidative metabolism of human eosinophils (80%-90% purity) to that of neutrophils. Hexose monophosphate (HMP) shunt activity of eosinophils was higher than that of neutrophils under either resting or phagocytizing conditions. Eosinophil HMP shunt activity also was stimulated by phorbol myristate acetate, a membrane- active agent. Eosinophils showed a marked incorporation of 125I into trichloroacetic acid-insoluble material under resting conditions, which increased markedly during phagocytosis. Eosinophils likewise showed a greater reduction of nitroblue tetrazolium dye during phagocytosis than did neutrophils. Measurement of other parameters of oxidative metabolism indicated that eosinophils generated superoxide anion following phagocytosis and also elicited a burst of chemiluminescence similar to that observed during phagocytosis by neutrophils. Measurement of NADPH oxidase activity demonstrated that this enzyme was 3-6 times more active in fractions isolated from eosinophils than in corresponding fractions isolated from neutrophils; this was observed over a range of substrate concentrations. The eosinophil enzyme sedimented differently than the neutrophil enzyme with differential centrifugation; neither showed sedimentation characteristics of peroxidase. These data indicate that eosinophils possess a similar, although in some ways more potent, oxidative burst than neutrophils and are consistent with a role for NADPH oxidase in the initiation of that burst.     

Absence of IFNγ expression induces neuronal degeneration in the spinal cord of adult mice

Background  

Interferon gamma (IFNγ) is a pro-inflammatory cytokine, which may be up-regulated after trauma to the peripheral or central nervous system. Such changes include reactive gliosis and synaptic plasticity that are considered important responses to the proper regenerative response after injury. Also, IFNγ is involved in the upregulation of the major histocompatibility complex class I (MHC class I), which has recently been shown to play an important role in the synaptic plasticity process following axotomy. There is also evidence that IFNγ may interfere in the differentiation and survival of neuronal cells. However, little is known about the effects of IFNγ absence on spinal cord neurons after injury.     

TDI技术评价卡维地洛对高血压患者左室舒张功能的影响

目的:应用组织多普勒显像(TDI)技术评价卡维地洛对高血压患者左室舒张功能的影响.方法:对30例高血压给予卡维地洛治疗24周.治疗前、治疗后12周、24周用TDI技术测量左室收缩期二尖瓣环平均舒张早期运动速度(Ea)、舒张晚期运动速度(Aa)及Ea/Aa,并与血流多普勒指标E波速度(E)、A波速度(A)、E/A进行比较,观察降压效果及对左室舒张功能的影响.结果:卡维地洛治疗12周后收缩压(SBP)、舒张压(DBP)、心率(HR)均较治疗前下降(P＜0.05),Ea、Ea/Aa均较治疗前升高(P＜0.05),治疗24周后E、E/A较治疗前升高(P＜0.05),Aa较治疗前降低(P＜0.05),Ea、Ea/Aa有进一步改善的趋势(P＜0.05).结论:TDI技术在评价左室舒张功能方面较二尖瓣血流频谱更敏感;卡维地洛对轻、中度高血压具有良好的降压作用,且能改善患者左室舒张功能.     

PCR colorimetric dot-blot assay and clinical pretest probability for diagnosis of Pulmonary Tuberculosis in Smear-Negative patients

Background  

Smear-negative pulmonary tuberculosis (SNPTB) accounts for 30% of Pulmonary Tuberculosis (PTB) cases reported annually in developing nations. Polymerase chain reaction (PCR) may provide an alternative for the rapid detection of Mycobacterium tuberculosis (MTB); however little data are available regarding the clinical utility of PCR in SNPTB, in a setting with a high burden of TB/HIV co-infection.     

TDI技术评价卡维地洛对高血压患者左室舒张功能的影响

目的:应用组织多普勒显像(TDI)技术评价卡维地洛对高血压患者左室舒张功能的影响.方法:对30例高血压给予卡维地洛治疗24周.治疗前、治疗后12周、24周用TDI技术测量左室收缩期二尖瓣环平均舒张早期运动速度(Ea)、舒张晚期运动速度(Aa)及Ea/Aa,并与血流多普勒指标E波速度(E)、A波速度(A)、E/A进行比较,观察降压效果及对左室舒张功能的影响.结果:卡维地洛治疗12周后收缩压(SBP)、舒张压(DBP)、心率(HR)均较治疗前下降(P＜0.05),Ea、Ea/Aa均较治疗前升高(P＜0.05),治疗24周后E、E/A较治疗前升高(P＜0.05),Aa较治疗前降低(P＜0.05),Ea、Ea/Aa有进一步改善的趋势(P＜0.05).结论:TDI技术在评价左室舒张功能方面较二尖瓣血流频谱更敏感;卡维地洛对轻、中度高血压具有良好的降压作用,且能改善患者左室舒张功能.     

Rapid quality evaluation of hybridomas using ELISPOT and cell-ELISA techniques.

We have used the ELISPOT assay in combination with ELISA procedures for rapid evaluation of properties of three different murine hybridoma cell lines, 104-I, -B and -G, secreting IgG1 kappa monoclonal antibodies against a 104-mer synthetic peptide from the C-terminal part of HIV-1 p24. By conventional ELISA we obtained data suggesting that the three monoclonal antibodies had different affinities. By cell-ELISA we found that the IgG1 kappa secretion rate varied between cells (4,000 to 14,000 antibody molecules/cell/min), and ELISPOT showed that only 4-5% of 104-I cells gave antigen-specific spots, indicating a cell population with diverse properties. We recommend that the ELISPOT and cell-ELISA techniques should be used routinely to supplement conventional ELISA procedures for rapid evaluation of hybridoma properties.