Influenza vaccine: the effects of the 1986/1987 viral strains

Summary

One hundred and twenty healthy volunteers were recruited for a study to evaluate the reactogenicity and serological response of differing doses of the 1986/87 World Health Organization-recommended influenza viral strains. Each vaccine was prepared by Institut Merieux and contained A/Mississippi/1/85, A/Chile/1/83 and B/Ann Arbor/1/86. One vaccine was formulated as a 10/10/10 μg HA and the other as a 15/10/15 μg HA. No significant advantage could be found with the 15/10/15 μg HA combination and it was recommended, therefore, that a 10/10/10 μg HA formulation was to be preferred. This vaccine demonstrated a minimal cross-sensitivity to the A/Singapore/6/86 influenza strain. In view of the prevalence of the A/Singapore strain, a second study was subsequently undertaken with a monovalent A/Singapore/6/86-like vaccine in a further 62 volunteers. This demonstrated an overall sero-conversion rate of 90%. Local side-effects with both vaccines were lower than in a similar study in 1984 and this may reflect a reduction in endotoxin levels achieved by a minor modification in the manufacturing technique. These studies confirmed the efficacy of a trivalent A/Mississippi, A/Chile, B/Ann Arbor influenza vaccine and the efficacy of, and necessity for, an additional A/Singapore vaccine.     

Influenza vaccine: the effects of the 1986/1987 viral strains

One hundred and twenty healthy volunteers were recruited for a study to evaluate the reactogenicity and serological response of differing doses of the 1986/87 World Health Organization-recommended influenza viral strains. Each vaccine was prepared by Institut Merieux and contained A/Mississippi/1/85, A/Chile/1/83 and B/Ann Arbor/1/86. One vaccine was formulated as a 10/10/10 micrograms HA and the other as a 15/10/15 micrograms HA. No significant advantage could be found with the 15/10/15 micrograms HA combination and it was recommended, therefore, that a 10/10/10 micrograms HA formulation was to be preferred. This vaccine demonstrated a minimal cross-sensitivity to the A/Singapore/6/86 influenza strain. In view of the prevalence of the A/Singapore strain, a second study was subsequently undertaken with a monovalent A/Singapore/6/86-like vaccine in a further 62 volunteers. This demonstrated an overall sero-conversion rate of 90%. Local side-effects with both vaccines were lower than in a similar study in 1984 and this may reflect a reduction in endotoxin levels achieved by a minor modification in the manufacturing technique. These studies confirmed the efficacy of a trivalent A/Mississippi, A/Chile, B/Ann Arbor influenza vaccine and the efficacy of, and necessity for, an additional A/Singapore vaccine.     

Histamine-induced excitation of spontaneously active medullary neurones in the rat brain is mediated by H2-receptors : A microiontophoretic study using H1 and H2-agonists and antagonists

The effects of histamine, applied by microiontophoresis onto spontaneously-active medullary neurones were investigated in the rat. Histamine caused current-dependent excitation of these neurones, an action that is at variance with previous studies in the cat. The nature of the receptor mediating these effects was examined using a number of agonists with differing potencies at peripheral H₁- and H₂-receptors. The precursor of histamine, l-histidine and the metabolite, N-telemethylhistamine did not mimic the effects of histamine while the H₂-agonist, 4-methylhistamine caused similar but weaker excitation. The extent of excitations produced by the H₁-agonists, 2-pyridylethylamine, 2-methylhistamine and 2-thiazolylethylamine could be related to their activity at H₂-receptors. Metiamide was ineffective in antagonising responses to histamine and related agonists as was mepyramine. The H₂-antagonist ranitidine, however, proved a good antagonist of responses to histamine and the H₁- and H₂-agonists, despite an unrelated excitatory action which may be linked to inhibition of cholinesterase. It is concluded that the excitatory effects of microiontophoretically-applied histamine and the agonists on medullary neurones in the rat is probably a result of activation of H₂-receptors.     

Depression of rat cerebral cortical neurones by H1 and H2 histamine receptor agonists

Histamine (H) and H₁ agonists-2-pyridylethylamine (PEA) adn 2-methylhistamine (2-MH) produced a greater depression of the corticospinal and unidentified rat cerebral cortical neurones than did 4-methylhistamine (4-MH), an H₂ agonist. Mepyramine antagonized teh effects of 2-MH, PEA and H, adn partially antagonized the depression induced by 4-MH. Metiamide and cimetidine, H₂ antagonists, blocked 4-MH and H but not 2-MH- and PEA-induced depression. These results indicate that H-induced depression of cortical neurones involves activation of H₁ and H₂ receptors.     

Protective efficacy of an H1N1 cold-adapted live vaccine against the 2009 pandemic H1N1, seasonal H1N1, and H5N1 influenza viruses in mice

Vaccination is a key strategy for preventing influenza virus infections. Here, we generated a reassortant virus (SC/AAca) containing the hemagglutinin and neuraminidase genes from a 2009 pandemic influenza virus A/Sichuan/1/2009 (H1N1) (SC/09) and six internal genes from the cold-adapted virus A/Ann Arbor/6/60 (H2N2) (AAca). The SC/AAca reassortant induced a sound humoral immune response and complete protection against homologous SC/09 virus challenge in mice after intranasal administration of an at least 10(6) 50% egg infectious dose (EID(50)) of SC/AAca. SC/AAca inoculation also induced significant CD4+ and CD8+ T cell responses and provided solid protection against heterologous H1N1 and H5N1 virus challenge. Our results suggest that this 2009 H1N1 live vaccine will provide protection against both 2009 pandemic and seasonal H1N1 virus infection and might reduce the severity of H5N1 virus infection in humans. The induction of cross-reactive virus-specific T cell responses may be an effective approach to develop universal influenza vaccines.     

Comparison of amantadine and rimantadine for prevention of type A (Russian) influenza

The efficacies of 200 mg daily doses of amantadine and of rimantadine for prevention of infection and illness due to influenza A/USSR/77 (H1N1) virus were compared in a double-blind, placebo-controlled study on a college campus. Frequencies of symptoms that might have been side effects of the drugs were not significantly different from those in placebo recipients. Analyses indicated that the trial was initiated late in the epidemic and that an age-related protective effect against A/USSR virus existed; seroconversion frequencies were $\text{52}\text{139}$ (37%) among 18–19-year-olds, $\text{33}\text{130}$ (25%) among 20–21-year-olds, and $\text{5}\text{39}$ (12.8%) among 22–24-year-olds. Among initially antibody-negative (<1 : 4 in complement fixing and neutralizing tests and <1 : 8 in hemagglutination inhibition tests) 18–19-year-old students, amantadine was associated with significantly fewer seroconversions (P = 0.01) and both less infection and milder illness than occurred in placebo recipients (P<0.05). Although rimantadine was not accompanied by reduction in frequency of seroconversions in the same age group, illness frequency and severity among seroconverters were significantly reduced when compared to placebo recipients (P<0.01). Amantadine and rimantadine appear suitable for use in young adults. Although other studies have suggested greater effectiveness of rimantadine than of amantadine against influenza, no evidence for this was seen in the present study which used both drugs at the same dose.     

Synthesis and Preliminary Antiviral Activities of Piperidine‐substituted Purines against HIV and Influenza A/H1N1 Infections

We have developed a series of N²‐(1‐(substituted‐aryl)piperidin‐4‐yl)‐N⁶‐mesityl‐9H‐purine‐2,6‐diamine derivatives as potent antiviral agents. Preliminary biological evaluation indicated that nearly half of them possessed remarkable HIV inhibitory potencies in cellular assays. In particular, FZJ 13 appeared to be the most notable one, which displayed anti‐HIV‐1 activity compared to 3TC. Moreover, an unexpected finding was that FZJ 05 displayed significant potency against influenza A/H1N1 (strain A/PR/8/34) in Madin–Darby canine kidney cells with EC₅₀ values much lower than those of ribavirin, amantadine, and rimantadine. The results suggest that these novel purine derivatives have the potential to be further developed as new therapeutic agents against HIV‐1 or influenza virus.     

注射用丹参多酚酸对H2O2诱导的人脐静脉内皮细胞损伤的保护作用

目的 研究注射用丹参多酚酸（SAFI）对过氧化氢（H₂O₂）诱导的人脐静脉内皮细胞（HUVEC）损伤的保护作用及机制。方法 体外培养HUVEC,设置对照组、模型组、SAFI（0.05、0.10、0.20、0.40、0.80 mg/mL）组,对照组及模型组不加药,继续培养24 h,模型组及SAFI组分别加入1 mmol/L H₂O₂作用1 h,对照组不加H₂O₂。CCK-8法检测HUVEC增殖;酶联免疫吸附法（ELISA）测定细胞间黏附因子（ICAM-1）、血管细胞黏附因子（VCAM-1）、丙二醛（MDA）、乳酸脱氢酶（LDH）、超氧化物歧化酶（SOD）的含量;TUNEL染色法观察HUVEC凋亡状态;Western blotting法检测凋亡相关蛋白Bcl-2、Bax的变化。结果 与模型组比较,质量浓度大于0.1 mg/mL的SAFI组细胞存活率显著增加（P<0.05）;质量浓度大于0.2 mg/mL的SAFI组LDH、MDA水平显著降低,SOD水平显著增加（P<0.05）;0.4、0.8 mg/mL的SAFI组ICAM-1、VCAM-1水平显著降低（P<0.05）;TUNEL染色结果显示,0.4、0.8 mg/mL的SAFI显著抑制凋亡;Western blotting结果显示,0.4、0.8 mg/mL的SAFI组Bcl-2蛋白表达显著升高（P<0.05）,Bax蛋白表达显著下降（P<0.05）。结论 SAFI对H₂O₂诱导的HUVEC损伤有保护作用,主要是通过提高SOD含量,降低氧化指标LDH、MDA以及炎症因子ICAM-1、VCAM-1水平,调节凋亡蛋白Bax、Bcl-2的表达发挥作用。     

Comparative therapeutic effect of aerosolized and oral rimantadine HC1 in experimental human influenza A virus infection

Thirty-six adult volunteers were inoculated intranasally with 7.2 log₁₀ egg infectious doses 50% of an attenuated A/Khabarovsk/77/H1N1 virus. Twenty-four hours later volunteers were begun on both aerosol treatments (rimantadine HC1 25 mg in saline or saline, 10 min exposure twice daily) and oral medications (rimantadine HC1 50 mg or placebo every 6 h, three times daily) which were administered for 5 days. Virus-positive volunteers receiving placebo by both of the two routes had a peak in clinical illness scores on the second treatment day (mean score 5.3), which was not observed in either the aerosol rimantadine (0.6) or oral rimantadine (0.9) treated volunteers. On the second treatment day, the proportion of virus-positive volunteers with elevated axillary temperature measurements and the mean peak temperature measurement were also significantly reduced in both drug groups. No significant effects on the duration of virus shedding were noted.In experimental influenza A virus infection, characterized by mild clinical illness and short duration of virus shedding, low doses of aerosolized rimantadine had a therapeutic effect comparable to that found with larger doses of oral rimantadine.     

乙型脑炎减毒活疫苗SA14-14-2在BHK21细胞上传代后的基因序列研究

目的：研究乙型脑炎减毒活疫苗SA14-14-2在BHK₂₁细胞上传代后的病毒基因序列,以深入控制乙型脑炎减毒活疫苗的安全性。方法：将乙型脑炎减毒活疫苗SA14-14-2在BHK₂₁细胞上连续传代,选取第二代病毒（P2）、第五代病毒（P5）、第十五代病毒（P15）提取RNA,反转录为cDNA后,进行各代病毒全基因序列分析,分析与乙型脑炎病毒毒力密切相关的关键位点基因是否发生改变。结论：乙型脑炎减毒活疫苗SA14-14-2在BHK₂₁细胞上传5代后,病毒E蛋白上关键基因第279位（E279）氨基酸由甲硫氨酸（M）突变为赖氨酸（K）。     

Cerebral cortical 5-HT1, and 5-HT2, receptors of morphine tolerant-dependent rats

The effect of chronic administration of morphine to rats on 5-HT₁ and 5-HT₂ receptors in the cerebral cortex was determined. Male Sprague-Dawley rats were implanted subcutaneously with 6 pellets of morphine (each containing 75 mg of morphine free base) during a 7 day period. Animals which served as controls were implanted with placebo pellets. The procedure for implantation of pellets produced a high degree of tolerance to and physical dependence on morphine in the rat. The tolerance to the analgesic and hyperthermic effects of morphine was demonstrated by decreased responses in the rats implanted with morphine pellet in comparison to the placebo-treated controls. The physical dependence was shown by the greater weight loss after removal of the pellet in the rats implanted with morphine pellets when compared to rats implanted with placebo pellets. The pellets were removed (withdrawn) and, after 6–8 h, the rats were sacrificed and the cerebral cortex was isolated. In another experiment the pellets were left in place (tolerant-dependent rats). The 5-HT₁ and 5-HT₂ receptors were characterized by using [^3H]5-HT and [^3H]spiroperidol as the ligands and unlabelled 5-HT and ketanserin, respectively, to determine non-specific binding. The [^3H]5-HT bound to 5-HT₁ receptors on membranes from the cerebral cortex of rats implanted with placebo pellets, at a single high affinity site, with a B_max of 102 ± 10 fmol/mg protein and a K_d of 6.02 ± 0.98 nM. Implantation of morphine pellets, followed by removal of the pellets resulted in a 50% increase in the B_maxvalue of [^3H]5-HT but the K_d values did not change. In rats from which the pellets were not removed, the B_max and K_d values of [^3H]5-HT in placebo- and morphine-treated groups did not differ. [^3H]Spiroperidol bound to 5-HT₂ receptors on cortical membranes of rats implanted with placebo pellet at a single high affinity site with B_max and K_d values of 131 ± 5 fmol/mg protein and 0.22 ± 0.01 nM, respectively. The implantation of pellets of morphine followed by removal of the pellets did not alter the characteristics of 5-HT₂, receptors, however in rats with the pellets in place, the B_max for 5-HT₂ receptors in placebo- and morphine-treated groups did not differ but the K_d values were much smaller in morphine-treated rats compared to rats implanted with placebo pellets. It is concluded that the development of tolerance to, and physical dependence on, morphine by implantation of pellets results in up-regulation of 5-HT₂ receptors whereas in morphine-abstinent rats there is a selective up-regulation of 5-HT₁ receptors on the membranes in the cerebral cortex.     

Comparison of the effect of the antacid Rennie versus low-dose H2-receptor antagonists (ranitidine, famotidine) on intragastric acidity

Background:

Symptoms of functional dyspepsia are common and patients often self-medicate with antacids, or with low-dose H₂-antagonists which are available as over-the-counter medications. To date, there has been limited information available comparing the effects on intragastric acidity of these two types of over-the-counter medication. Therefore we studied the effect of the antacid Rennie and two H₂-antagonists on the intragastric pH of fasting volunteers.

Methods:

Sixteen healthy, fasting volunteers were randomized into a double-blind, placebo-controlled, four-way crossover study comparing Rennie (calcium-magnesium carbonate) 1360 mg, ranitidine 75 mg, famotidine 10 mg and placebo. Their effect on gastric pH was monitored by a 4-h gastric pH-metry. The primary efficacy parameter was the time lag before an intragastric pH > 3.0 was reached after drug administration.

Results:

The median time lag before pH > 3.0 was reached after drug administration was 5.8 min for Rennie, 64.9 min for ranitidine, 70.1 min for famotidine and 240.0 min for placebo. The percentage of time with values of pH > 3.0 was 10.4% for Rennie, 61.4% for ranitidine, 56.6% for famotidine and 1.4% for placebo.

Conclusion:

The onset of action in fasting volunteers was significantly faster with the antacid than with the two H₂-antagonists. The duration of action was significantly longer with an H₂-antagonist than with the antacid. This suggests that the two products should be used for different indications: antacids are superior for rapid pain relief, whereas H₂-antagonists might be better for symptom prophylaxis—for example for nocturnal dyspepsia.

     

Regional vascular resistance and heart rate responses mediated through H1- and H2-histamine receptors in the unanaesthetised rabbit

The effects of histamine infusions (10—100 μg/kg/min) on heart rate and hindlimb, carotid, mesenteric and renal vascular resistance were investigated in unanaesthetised rabbits after “total” autonomic effector block to abolish reflex effects. Histamine caused a rise in heart rate that was predominately due to stimulation of H₂-receptors (blocked by metiamide). Hindlimb and carotid vascular resistance did not change significantly during histamine infusion. However, after blocking H₂-receptors with metiamide histamine infusions produced dose-related vasoconstriction in these beds while after H₁-receptor block with mepyramine histamine caused dose-related vasodilatation indicating that H₁- and H₂-receptors mediated opposite vascular effects which were of similar magnitude. By contrast, histamine infusion caused vasodilatation in both the mesenteric and renal vasculature before giving antagonists. This dilatation was mediated by both H₁- and H₂-receptors as either receptor antagonist attenuated the response. These studies suggest that H₁-receptors in the same species mediate vasoconstriction in some beds and vasodilatation in others while H₂-receptors mediate vasodilatation in all the beds studied and also account for most of the increase in heart rate.     

Increased responsiveness to JNK1/2 mediates the enhanced H2O2-induced stimulation of Cl/HCO3 exchanger activity in immortalized renal proximal tubular epithelial cells from the SHR

We have previously demonstrated that exogenous H₂O₂ stimulates Cl⁻/HCO₃⁻ exchanger activity in immortalized renal proximal tubular epithelial (PTE) cells from both the Wistar-Kyoto (WKY) rat and the spontaneously hypertensive rat (SHR), this effect being more pronounced in SHR cells. The aim of the present study was to examine the mechanism of H₂O₂-induced stimulation of Cl⁻/HCO₃⁻ exchanger activity in WKY and SHR cells. It is now reported that the SHR PTE cells were endowed with an enhanced capacity to produce H₂O₂, comparatively with WKY cells and this was accompanied by a decreased expression of SOD2, SOD3, and catalase in SHR PTE cells. The stimulatory effect of H₂O₂ on the exchanger activity was blocked by SP600125 (JNK inhibitor), but not by U0126 (MEK1/2 inhibitor) or SB203580 (p38 inhibitor) in both cell lines. Basal JNK1 and JNK2 protein expression was higher in SHR PTE cells than in WKY PTE cells. H₂O₂ had no effect on p-JNK1/2 in WKY PTE cells over time. By contrast, H₂O₂ treatment resulted in a rapid and sustained increase in JNK1/2 phosphorylation in SHR PTE cells, which was completely abolished by apocynin. Treatment of SHR PTE cells with apocynin significantly decreased the H₂O₂-induced stimulation of Cl⁻/HCO₃⁻ exchanger activity. It is concluded that H₂O₂-induced stimulation of Cl⁻/HCO₃⁻ exchanger activity is regulated by JNK1/2, particularly by JNK2, in SHR PTE cells. The imbalance between oxidant and antioxidant mechanisms in SHR PTE cells enhances the response of JNK1/2 to H₂O₂, which contributes to their increased sensitivity to H₂O₂.     

trans-Resveratrol inhibits H2O2-induced adenocarcinoma gastric cells proliferation via inactivation of MEK1/2-ERK1/2-c-Jun signalling axis

In this report we investigate the signalling pathway activated by H₂O₂ in human adenocarcinoma gastric cells (AGS) and we evaluate the anti-proliferative action of the natural stilbene trans-resveratrol. We demonstrate that H₂O₂ accelerates cell growth and induces a prompt MEK1/2-ERK1/2 activation. Such events are also associated with the activation of c-Jun and its translocation into the nuclear compartment. A specific inhibitor of ERK1/2 phosphorylation by MEK1/2 (U0126) abrogates these phenomena. On the contrary, specific inhibition of JNK activity does not influence H₂O₂-mediated growth, suggesting that cell proliferation likely proceeds via MEK1/2-ERK1/2-Jun signalling axis. trans-Resveratrol is also able to completely suppress the increase in proliferation. We demonstrate that this property is not due to its antioxidant capacity but rather due to a specific inhibition of ERK1/2 phosphorylation by MEK1/2 and repression of c-Jun activation.     

Activation of adenosine1 (A1) receptors suppresses head shakes induced by a serotonergic hallucinogen in rats

Modulation of glutamatergic neurotransmission by metabotropic glutamate2/3 (mGlu2/3) receptor agonists effectively treats seemingly diverse neuropsychiatric illness such as generalized anxiety disorder and schizophrenia. Activation of adenosine A₁ heteroceptors, like mGlu2 autoreceptors, decreases glutamate release in the medial prefrontal cortex (mPFC) and other limbic brain regions. Previously, we have reported electrophysiological, neurochemical and behavioral evidence for interactions between the 5-hydroxytryptamine_2A (5-HT_2A) and mGlu2/3 receptors in the mPFC. The present studies were designed to investigate the effects in rats of adenosine A₁ receptor activation/blockade on a behavior modulated by 5-HT_2A receptor activation/blockade in the mPFC: head shakes induced in the rat by phenethylamine hallucinogens. An adenosine A₁ receptor agonist, N⁶-cyclohexyladenosine (CHA) suppressed head shakes induced by activation of 5-HT_2A receptors with the phenethylamine hallucinogen (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI). An adenosine A1 receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), enhanced DOI-induced head shakes and blocked the suppressant action of an adenosine A₁ receptor agonist on DOI-induced head shakes. Thus, the pattern of activity for an agonist and antagonist at the adenosine A1 receptor with respect to modulating DOI-induced head shakes is similar to the pattern observed with mGlu2/3 receptor agonists and antagonists. These novel observations with an adenosine A₁ receptor agonist suggest that this pharmacological action could contribute to antipsychotic effects in addition to thymoleptic effects.     

A pharmacokinetic and pharmacodynamic interaction study between nebivolol and the H2-receptor antagonists cimetidine and ranitidine

Aims The study was designed to investigate the effects of the H₂-receptor antagonists, cimetidine and ranitidine on the pharmacokinetics and pharmacodynamics of nebivolol in healthy volunteers. Methods Twelve healthy volunteers took part in a randomized placebo-controlled cross-over study. Each subject received on three separate occasions placebo, cimetidine (400 mg twice daily) or ranitidine (150 mg twice daily) for 24 h before and 48 h after a single oral dose of nebivolol (5 mg). Nebivolol and its individual (+) and (−) enantiomers were determined tby h.p.l.c. Results Ranitidine had no significant effect on nebivolol pharmacokinetics. Cimetidine, however, resulted in a 21–23% increase in C_max of unchanged nebivolol and of each enantiomer plus its hydroxylated metabolites. Cimetidine significantly (P<0.05) increased the AUC [mean±s.d. (95% C.I. of differences in mean)] for unchanged (±)-nebivolol [7.76±3.07 ng ml⁻¹h with placebo; 11.50±5.40 (1.75, 8.76) ng ml⁻¹h with cimetidine], (+)-nebivolol plus its hydroxylated metabolites [73.0±18.0 ng ml⁻¹h with placebo; 91.5±25.7 (1.0, 23.1) ng ml⁻¹h with cimetidine] and (−)-nebivolol plus its hydroxylated metabolites [101±32 ng ml⁻¹h with placebo; 123±38 (3.3, 27.0) ng ml⁻¹h with cimetidine]. Statistical analysis of the resting blood pressure and heart rate and exercise data did not suggest any consistent effects of ranitidine or cimetidine upon the pharmacodynamic effects of nebivolol. Conclusions There was no interaction between ranitidine and nebivolol. Although cimetidine inhibited nebivolol metabolism, it did not have a significant influence on the pharmacodynamics of the drug.     

Identification of endothelial H1, vascular H2 and cardiac presynaptic H3 receptors in the pithed rat

Summary In pithed and vagotomized rats the effects of the H₃ receptor agonist R-(–)--methylhistamine, the H₁ receptor agonist 2-(2-thiazolyl)ethylamine and the H₂ receptor agonist dimaprit on basal diastolic blood pressure, basal heart rate and the electrically induced rise in heart rate were examined.Basal diastolic blood pressure was not altered by low, but increased by high doses of R-(–)--methylhistamine; the latter effect was not affected by selective H₁, H₂ or H₃ receptor antagonists and by prazosin, but was attenuated by rauwolscine. Rauwolscine also unmasked a vasodepressor response to R-(–)--methylhistamine not affected by the H₃ receptor antagonist thioperamide, but counteracted by the H₁ receptor antagonist dimetindene or the H₂ receptor antagonist ranitidine. The vasodepressor responses to 2-(2-thiazolyl)ethylamine and dimaprit were antagonized by dimetindene and ranitidine, respectively. The vasodepressor response to 2-(2-thiazolyl)ethylamine was not altered by indomethacin, but reduced by an inhibitor of endothelial nitric oxide synthase, N-nitro-L-arginine methyl ester (which, by itself, markedly increased blood pressure). Both drug tools did not alter the effect of dimaprit. Basal heart rate was not affected by 2-(2-thiazolyl)ethylamine (examined after administration of propranolol), dimaprit and R-(–)--methylhistamine. The electrically induced increase in heart rate (studied in animals which had received rauwolscine) was decreased by R-(–)--methylhistamine but not affected by 2-(2-thiazolyl)ethylamine and dimaprit. The effect of R-(–)--methylhistamine was abolished by thioperamide. R-(–)--methylhistamine did not influence the increase in heart rate produced by isoprenaline.In conclusion, the pithed rat offers the opportunity to study cardiac presynaptic H₃ receptors, endothelial H₁ receptors and vascular H₂ receptors in the same experimental model. Cardiac presynaptic H₁ and H₂ receptors as well as postsynaptic H₃ receptors in the heart and in the resistance vessels were not found. R-(–)--methylhistamine is a weak agonist at ₂, H₁ and H₂ receptors.Correspondence to E. Schlicker at the above address     

昆布多糖硫酸酯对H2O2诱导乳鼠心肌细胞损伤的保护作用Δ

目的研究昆布多糖硫酸酯(LAPS)对过氧化氢(H2O2)诱导乳鼠心肌细胞氧化损伤的保护作用。方法分次消化法分离原代培养的乳鼠心肌细胞,建立H2O2诱导心肌细胞损伤模型;四甲基偶氮唑盐(MTT)法检测不同浓度LAPS对心肌细胞的保护作用;试剂盒检测LAPS对细胞乳酸脱氢酶(LDH)、肌酸磷酸激酶(CK)、丙二醛(MDA)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)及谷胱甘肽过氧化物酶(GSH-Px)含量的影响;利用荧光探针二氯二氢荧光素-乙酰乙酸酯(DCFH-DA)检测细胞内活性氧(ROS)含量。结果100μmol/L的H2O2能明显造成心肌细胞损伤,LAPS能改善H2O2所造成的心肌细胞损伤;LAPS能够明显降低的过氧化损伤心肌细胞外液中LDH和CK含量、明显降低过氧化损伤心肌细胞内MDA和活性氧(ROS)的含量、明显提高过氧化损伤心肌细胞内SOD、GSH-Px和CAT的活力。结论 LAPS对心肌细胞的过氧化损伤有保护作用,与其降低或阻断脂质过氧化反应,降低细胞内ROS含量,进而阻断因ROS对细胞造成的损害,及时修复受损细胞有着密切关系。     

Activation of phospholipase D involved in both injury and survival in A549 alveolar epithelial cells exposed to H2O2

To determine the role of the phospholipase D (PLD) pathway in injury and survival of alveolar epithelial cells, A549 cells were exposed to H₂O₂ (500 μM) which resulted in time-dependent injury and bi-phasic increase of PLD activity at 5 min and at 3 h, respectively. n-Butanol (0.5%) inhibited PLD activation, attenuated cell injury at 5 min of H₂O₂ exposure, but enhanced injury at 3 h of exposure. This activation was inhibited by treatment with catalase (500 units/ml). Exogenous phosphatidic acid mimicked the effects of PLD activation, and diphenyliodonium (NADPH oxidase inhibitor) reversed the decline in cell viability induced by H₂O₂ exposure. Propranolol (phosphatidic acid phospholydrolase inhibitor) and quinacrine (phospholipase A2 inhibitor) had weak effects on H₂O₂-induced PLD activation but reversed H₂O₂-induced injury. We speculate that PLD activation at the initiation of H₂O₂ exposure predominantly results in NAPDH oxidase activation, which mediates A549 cell injury, but turns to mediating cell survival as the H₂O₂ attack continues, which might be mainly due to the accumulation of intracellular phosphatidic acid.