Subtypes of adrenergic receptors and intracellular mechanisms involved in modulatory effects of noradrenaline on glutamate

We have previously reported that the response of cultured chick cerebellar neurons to glutamate is enhanced by noradrenaline (NA) or isoproterenol and suppressed by clonidine. The present study was carried out to further specify the adrenergic receptor subtypes involved in the facilitatory effect of NA or isoproterenol and the suppressive effect of clonidine, and to examine the intracellular mechanisms underlying these modulatory effects of NA. The clonidine effect, which was mimicked by NA iontophoresed with large ejecting currents, was blocked by yohimbine and tolazoline (alpha 2 antagonists) and also by dibutyryl cyclic AMP or forskolin which augmented the glutamate response by itself. Prazosin, an alpha 1 receptor antagonist did not block the clonidine effect. NA- or isoproterenol-induced facilitation, which was mimicked by denopamine (beta 1 agonist), was antagonized by acebutolol (beta 1 antagonist) and not by ICI 118,551 (beta 2 antagonist). Pretreatment of neurons with pertussis toxin for more than 24 h blocked the suppressive action of clonidine without affecting the facilitatory action of isoproterenol. Furthermore, intracellular injection of GDP beta S inhibited the modulatory effects of either clonidine or isoproterenol. These results indicate that the facilitatory and inhibitory modulatory effects of NA may be mediated by beta 1 and alpha 2 receptors linked to cAMP systems, respectively, and the former is coupled with the stimulatory G protein (Gs) and the latter is with the inhibitory G protein (Gi).     

尼莫地平对感染性脑水肿的脑保护作用

观察百日咳菌液诱导的感染性脑水肿不同时间大鼠脑含水量和伊文思蓝（ＥＢ）含量的变化，以及Ｎｉｍｏｄｉｐｉｎｅ对感染性脑水肿脑含水量和ＥＢ含量的影响。结果表明：感染性脑水肿在注菌后３０ｍｉｎ，脑含水量和ＥＢ含量已明显升高；应用Ｎｉｍｏｄｉｐｉｎｅ治疗后，脑组织水份含量和ＥＢ含量显著降低，脑水肿明显减轻。     

百日咳菌液致大鼠脑水肿模型脑组织氧化还原酶变化的研究

应用组织化学方法对百日咳菌液所致大鼠急性感染性脑水肿脑组织内乳酸脱氢酶、琥珀酸脱氢酶、单胺氧化酶的活性进行研究，结果显示：注菌组与正常对照组比较，三种氧化还原酶在脑组织内均出现多个局灶性酶活性减弱区，内毒素预处理组比注菌组酶活性强，提示急性感染性脑水肿时，脑组织内三种氧化还原酶活性均减弱，内毒素预处理对脑水肿有保护作用。     

Are murine marginal-zone macrophages the splenic white pulp analog of high endothelial venules?

The entry of lymphocytes into the spleen, in contrast to lymph nodes, does not involve high endothelial venule (HEV) interaction. The precise point of entry, as well as the mechanism by which lymphocytes enter the lymphoid areas of the spleen, remains controversial. We examined in detail the effect of two agents, pertussis toxin (PT) and the sulfated polysaccharide fucoidan, on splenic lymphocyte entry and positioning. These have previously been shown to interfere with lymphocyte extravasation across HEV. PT prevents lymphocyte extravasation, but not binding, to HEV, whereas fucoidan prevents binding and thus subsequent extravasation. Studies presented here show that pretreatment of murine lymphocytes with PT does not numerically affect entry into spleen, but profoundly alters lymphocyte positioning within the spleen. When fluorescently labeled, PT-treated lymphocytes are injected intravenously, they initially accumulate in the marginal zone, in apparent association with the layer of marginal zone macrophages (MZM?) which form a shell around the white pulp. They fail to traverse this layer into the white pulp, and subsequently localize in the red pulp. In contrast, untreated cells initially appear in the marginal zone, then continue to migrate into the white pulp after traversing the MZM? layer. The localization of PT-pretreated lymphocytes adjacent to the MZM? layer is disrupted by intravenous administration of fucoidan. Using a flow cytometric assay of aggregation between MZM? and lymphocytes, we confirmed that fucoidan is also able to inhibit this association in vitro, whereas PT has no effect on this interaction. We propose that MZM? in the mouse are the splenic analog of HEV, forming the port of entry of lymphocytes into the white pulp of the spleen.     

Antibody responses in adult and neonatal BALB/c mice to immunization with novel Bordetella pertussis vaccine formulations

A balanced or Th-1 type immune response is required for effective clearance of many pathogens such as Bordetella pertussis, the causative agent of whooping cough. Since current acellular pertussis vaccines induce limited Th-1 type immune responses, novel vaccine formulations are needed to induce protective immunity in the infant in the earliest stages of life. Here, we developed a novel vaccine platform consisting of genetically detoxified pertussis toxoid (PTd) with multiple adjuvant components including CpG oligodeoxynucleotides, polyphosphazenes, and cationic innate defence regulator peptides. Co-formulation with these immunomodulators increased the serum IgG2a and IgG1 antibody titres in adult mice when compared to immunization with each of the selected adjuvants or immunization with PTd antigen alone. When used in combination, these adjuvants were able to induce a superior IgG2a response in both adult and neonatal mice, when compared to antigen alone or commercial vaccines. The increased response observed when using this adjuvant formulation was also initiated earlier and, moreover, was maintained over a period of greater than 22 months. The adjuvant platform also showed an ability to induce an immune response in a greater number of mice as compared to antigen alone. This suggests that this uniquely adjuvanted vaccine induces a stronger and more balanced immune response with an earlier onset of this response than vaccination with PTd antigen alone.     

Different IgG-subclass distributions after whole-cell and acellular pertussis infant primary vaccinations in healthy and pertussis infected children

The distribution of IgG-subclasses provides insight in the immunological mechanisms of protection against whooping cough. We investigated the effect of Dutch whole-cell pertussis and acellular pertussis vaccines administered in infancy on the IgG-subclass distributions in healthy children aged 12 months, 4 years and 9 years as well as in children who have been infected with Bordetella pertussis.A fluorescent bead-based multiplex immunoassay was used for the measurement of IgG1, IgG2, IgG3 and IgG4 responses against pertussis toxin, filamentous heamagglutinin and pertactin.Although IgG1 was the predominant subclass for all pertussis antigens in both healthy and infected children, elevated IgG4 levels were only present in children who had received repeated number of acellular pertussis vaccinations. IgG2 and IgG3 antibodies did not contribute to the IgG response. No differences in IgG-subclasses between healthy vaccinated or infected children were found.The pertussis vaccine used for priming seems to determine the IgG-subclass composition elicited after a secondary antibody response either induced by pertussis vaccination or infection. The pronounced anti-pertussis IgG4 response might reflect the Th2-skewing of the immune response after aP vaccination.     

Immunogenicity and reactogenicity of co-administered tetanus-diphtheria-acellular pertussis (Tdap) and tetravalent meningococcal conjugate (MCV4) vaccines compared to their separate administration

In the United States, co-administration of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine and tetravalent meningococcal conjugate vaccine (MCV4) is recommended in adolescents. In this clinical study, 1341 adolescents received Tdap (Boostrix® GlaxoSmithKline) and MCV4 (Menactra®, Sanofi-Pasteur) simultaneously or sequentially one month apart. Co-administration of Tdap + MCV4 was well tolerated and immunogenic, resulting in high levels of antibodies against diphtheria, tetanus, pertussis and meningococcal serogroup A,C,W-135 and Y antigens. The data provide support for current recommendations for co-administration of Tdap and MCV4 vaccines at the same office visit.     

The Global Pertussis Initiative: report from a round table meeting to discuss the epidemiology and detection of pertussis, Paris, France, 11-12 January 2010

Pertussis remains endemic worldwide and is an important public health problem, even in countries with sustained high vaccination coverage. Resurgence of pertussis in the post-vaccination era has been reported in many areas of the world. The Global Pertussis Initiative (GPI) was established in 2001 to evaluate the ongoing problem of pertussis worldwide and to recommend appropriate pertussis control strategies. In addition to primary vaccinations, the GPI currently recommends a pertussis booster vaccination to pre-school children, adolescents and those adults at risk of transmitting Bordetella pertussis infection to infants. At a meeting in Paris, France, in January 2010, GPI members discussed pertussis surveillance and testing then prepared recommendations on the implementation and utilisation of these activities. Issues and projects discussed included: national surveillance systems and their suitability for other countries; seroprevalence studies; ideal surveillance methodologies; ongoing efforts in obtaining biological samples; standardisation of sample treatment; culture; real-time polymerase chain reaction (PCR); and likely future advances such as antibody detection in saliva. Previous regional meetings of the GPI have confirmed that many countries have limited laboratory facilities for the detection of pertussis. The GPI hopes that the future introduction of increased laboratory capabilities and greater harmonisation of clinical definitions and detection methods will lead to enhanced surveillance and a better estimate of the burden of pertussis infection worldwide. This article provides a current guide on the appropriate use of laboratory diagnostics and optimal surveillance methodologies to assist countries in the control of pertussis disease.     

Enhanced memory B-cell immune responses after a second acellular pertussis booster vaccination in children 9 years of age

Whooping cough has made its comeback and the incidence of pertussis in countries with widespread pertussis vaccination is most prominent in individuals above 9 years of age. To control the burden of infection, several countries already introduced acellular pertussis (aP) booster vaccination in adolescents and/or adults. However, antibody levels wane rapidly after vaccination even at older age. In this longitudinal study we investigated the effect of a second aP booster on the pertussis-specific memory B-cell immunity in children 9 years of age that have previously been vaccinated according to the national immunization program. Longitudinal blood samples were taken before, one month and one year after the booster. Purified B-cells were polyclonally stimulated and frequencies of memory B-cells were identified by ELISPOT-assays specific for various pertussis antigens. In addition, IgG levels and avidity indices were measured with fluorescent bead-based multiplex immunoassays.Starting with low pertussis-specific antibody and memory B-cell levels, a typical booster response was measured at one month after vaccination with increased antibody and memory B-cell responses. Although these responses declined slightly after one year, they substantially exceeded pre-booster levels and the avidity indices of the anti-pertussis antibodies remained high. Furthermore, high numbers of pertussis-specific memory B-cells at one-month post-booster correlate quite reliably with the corresponding high antibody response at one-year follow-up. In conclusion, booster vaccination in children 9 years of age induced an enhanced pertussis-specific memory immune response that sustained at least for one year. Therefore, this study supports the introduction of booster vaccination in older age groups.     

Impact of infant and preschool pertussis vaccinations on memory B-cell responses in children at 4 years of age

Whooping cough, caused by Bordetella pertussis, is reemerging in the vaccinated population. Antibody levels to pertussis antigens wane rapidly after both whole-cell (wP) and acellular pertussis (aP) vaccination and protection may largely depend on long-term B- and T-cell immunity. We studied the effect of wP and aP infant priming at 2, 3, 4 and 11 months according to the Dutch immunization program on pertussis-specific memory B-cell responses before and after a booster vaccination with either a high- or low-pertussis dose vaccine at 4 years of age.Purified B-cells were characterized by FACS-analysis and after polyclonal stimulation, memory B-cells were detected by ELISPOT-assays specific for pertussis toxin, filamentous haemagglutinin and pertactin.Before and after the booster, higher memory B-cell responses were measured in aP primed children compared with wP primed children. In contrast with antibody levels, no dose-effect was observed on the numbers of memory B-cell responses. In aP primed children a fifth high-dose aP vaccination tended to induce even lower memory B-cell responses than a low-dose aP booster. In both wP and aP primed children, the number of memory B-cells increased after the booster and correlated with the pertussis-specific antibody concentrations and observed affinity maturation.This study indicates that aP vaccinations in the first year of life induce higher pertussis-specific memory B-cell responses in children 4 years of age compared with Dutch wP primary vaccinations. Since infant aP vaccinations have improved protection against whooping cough in children despite waning antibody levels, this suggests that an enhanced memory B-cell pool induction may have an important role in protection. However, the pertussis-dose of the preschool booster needs to be considered depending on the vaccine used for priming to optimize long-term protection against whooping cough.