Variable Growth Responses of Water Thyme (Hydrilla verticillata) to Whole-Cell Extracts of Cylindrospermopsis raciborskii

Static-renewal ecotoxicity trials monitored growth of Hydrilla verticillata in conjunction with exposure to Cylindrospermopsis raciborskii whole-cell extracts containing the cyanotoxin cylindrospermopsin (CYN). Maximum exposure concentrations were 400 μg L⁻¹ CYN over 14 days. The responses of Hydrilla to the treatments were variable according to the toxin concentrations and lengths of exposure. Plant deaths, chlorosis, and necrosis were not recorded from treated plants. However, Hydrilla experienced significant growth stimulation and redistribution of plant resources in conjunction with exposure to the whole-cell extracts. Root production was particularly impacted. The results of this study imply that root production could aid in reducing C. raciborskii cell concentrations and CYN toxicity. Results of chlorophyll analyses differed, indicating that CYN in whole-cell extracts might exert complex effects on photosynthesis. This is the first study to describe the responses of an aquatic macrophyte following exposure to C. raciborskii whole-cell extracts containing the cyanotoxin cylindrospermopsin.     

Physiological Stress of High NH<Stack><Subscript>4</Subscript><Superscript>+</Superscript></Stack> Concentration in Water Column on the Submersed Macrophyte <Emphasis Type="Italic">Vallisneria Natans</Emphasis> L.

The submersed macrophyte, Vallisneria natans L., was cultured in laboratory with NH₄⁺-enriched tap water (1 mg L⁻¹ NH₄-N) for 2 months and the stressful effects of high ammonium (NH₄⁺) concentrations in the water column on this species was evaluated. The plant growth was severely inhibited by the NH₄⁺ supplement in the water column. The plant carbon and nitrogen metabolisms were disturbed by the NH₄⁺ supplement as indicated by the accumulation of free amino acids and the depletion of soluble carbohydrates in the plant tissues. The results suggested that high NH₄⁺ concentrations in the water column may hamper the restoration of submersed vegetation in eutrophic lakes.     

Assessment of the contents of phytic acid and divalent cations in low phytic acid (lpa) mutants of rice and soybean

The objective of the study was to investigate the influence of mutational breeding on the contents of nutritionally relevant minerals in low phytic acid (lpa) mutants compared to their wild-types. Three lpa rice (Os-lpa-XQZ-1, Os-lpa-XS110-1, Os-lpa-XS110-2) and two lpa soybean mutants (Gm-lpa-TW75-1, Gm-lpa-ZC-2) were analyzed regarding their contents of phytic acid, lower inositol phosphates and the minerals calcium, iron and zinc. Additionally, cadmium was included into the spectrum of divalent cations analyzed. The phytic acid reduction in lpa rice was consistently more pronounced in Os-lpa-XS110-1 than in Os-lpa-XQZ-1 and Os-lpa-XS110-2. However, only for Os-lpa-XQZ-1, levels of calcium, iron and zinc were found to be consistently increased, whereas the cadmium level was shown to be predominantly decreased compared to the wild-type. Investigation of the two lpa soybean mutants, characterized by absence (Gm-lpa-TW75-1) and accumulation (Gm-lpa-ZC-2) of lower inositol phosphates, respectively, revealed no consistently decreased or increased contents of calcium, iron, zinc and cadmium. The data do not change the view that lpa mutations do not result in systematic increases or decreases of mineral contents in these crops. However, on the basis of the molar ratios of phytate/minerals in lpa rice and soybean mutants which are considered as predictive parameters, an improved bioavailability of minerals in the lpa materials can be expected.     

Stereoselective synthesis of (RP)-8-substituted-N⁶-acylated and N⁶-alkylated adenosine-3',5'-cyclic phosphorothioic acids as cAMP antagonists

N⁶-Monoalkylated, N⁶-dialkylated and N⁶-acylated (R_P)-adenosine 3′,5′-cyclic phosphorothioic acids have been prepared by stereoselective syntheses from cAMP for a study of protein kinase A antagonist activity. The antagonist activity of the parent primary 6-amino cAMP derivative was reduced after N-monoalkylation. No significant activity was detected in the N,N-dialkylated derivative. Mono N-acylation had little effect on the activity. Hydrogen bonding involving the 6-amino group in cAMPS seems necessary for activity.     

Pleiotropic effects of the lpxM mutation in Yersinia pestis resulting in modification of the biosynthesis of major immunoreactive antigens

Deletion mutants in the lpxM gene in two Yersinia pestis strains, the live Russian vaccine strain EV NIIEG and a fully virulent strain, 231, synthesise a less toxic penta-acylated lipopolysaccharide (LPS). Analysis of these mutants revealed they possessed marked reductions in expression and immunoreactivity of numerous major proteins and carbohydrate antigens, including F1, Pla, Ymt, V antigen, LPS, and ECA. Moreover, both mutants demonstrated altered epitope specificities of the antigens as determined in immunodot-ELISAs and immunoblotting analyses using a panel of monoclonal antibodies. The strains also differed in their susceptibility to the diagnostic plague bacteriophage L-413C. These findings indicate that the effects of the lpxM mutation on reduced virulence and enhanced immunity of the Y. pestis EV ΔlpxM is also associated with these pleiotropic changes and not just to changes in the lipid A acylation.     

Sterilizing immunity against experimental Helicobacter pylori infection is challenge-strain dependent

The development of a murine model of Helicobacter pylori infection through serial in vivo passage of candidate strains has enabled a quantitative assessment of vaccine efficacy. In this study we compare infection with and protection against challenge from both CagA⁺ type I, and CagA⁻ type II in vivo adapted isolates. In vivo passage of a type II H. pylori isolate resulted in a highly infectious strain (X47-2AL), capable of reproducibly infecting mice to high density (10⁷ CFU/g of gastric tissue). Similarly adapted type I strains were found to colonize mice at a significantly lower level (10⁴–10⁵ CFU/g tissue). Mucosal immunization with recombinant urease (rUre) significantly protected animals against both types. Protection against X47-2AL was characterized by a ≥100-fold (or 2 log) reduction in bacterial density. However, the presence of a residual infection highlighted the inability to achieve sterilizing immunity against this strain. The level of protection appeared independent of challenge dose, and was stable for up to 6 months, all animals exhibiting a low-level residual infection that did not recrudesce with time. Similarly immunized mice challenged with isolates representing the residual infection were also protected, confirming that they did not represent a sub-population of H. pylori that could escape immunity. Immunization and challenge studies with type I adapted-isolates, demonstrated a similar 2–3 log reduction in the bacterial burden, but that in this instance resulted in sterilizing immunity. These results suggest varied specificity for the murine host by different Helicobacter strains that can influence the outcome of both infection and immunity.     

Re-assessment of the influence of polymorphisms of phase-II metabolic enzymes on renal cell cancer risk of trichloroethylene-exposed workers

Problem Individual differences in susceptibility to trichloroethylene-induced nephrocarcinogenicity may be conferred by genetic polymorphisms of glutathione S-transferases (GST), because enzymes of this group are pivotal for the metabolic activation of trichloroethylene. Because of a potential involvement of N-acetylation in the detoxication of reactive trichloroethylene metabolite(s) to N-acetyl-cysteine derivatives, polymorphisms of the NAT2 gene may also be relevant. Methods The primary collective used for a re-investigation of these questions was that of a hospital-based case-control study by Brüning et al. (Am J Ind Med 43:274–285, 2003) of 134 renal cell cancer cases (20 cases exposed to trichloroethylene) and 401 matched controls. Genetic polymorphisms of GSTT1, GSTM1, GSTP1 and NAT2 were studied. Additional control collectives of non-diseased persons were used for comparison of allele frequencies. Results No genetic influences on the development of renal cancer due to trichloroethylene were apparent, related to the deletion polymorphisms of GSTT1 and GSTM1, as well as to the NAT2 rapid/slow acetylator states. However, renal cell cancer cases displayed a somewhat higher proportion of the homozygous GSTP1 313A wild type (GSTP1*A), although this was not statistically significant (χ² test: P = 0.1071, when using only the original controls of Brüning et al. (2003); P = 0.0781 with inclusion of the additional controls). Conclusion The re-investigation does not confirm the working hypothesis of an influence of the deletion polymorphisms of the glutathione S-transferases GSTT1 and GSTM1 on renal cell cancer development due to high occupational exposures to trichloroethylene.     

浙江省舟山市269例海岛渔民病毒性肝炎型别分析

为探讨海岛渔民病毒性肝炎的病毒种类及其与临床的关系，对269例海岛渔民肝炎患者的型别进行了分析。研究对象为浙江省舟山市人民医院2001年1月至2004年12月住院的269例渔民病毒性肝炎患者，均为男性，年龄18～65岁，平均32．5岁。诊断标准根据2000年9月中华医学会传染病与寄生虫病学分会、肝病学分会联合修订的病毒性肝炎防治方案。患者人院后常规进行甲、乙、丙、丁、戊、庚型肝炎血清标志物检测，采用酶联免疫吸附法，HCV—RNA，HBV—DNA（采用PCR）。     

Virulence factors and O groups of Escherichia coli isolates from patients with acute pyelonephritis, cystitis and asymptomatic bacteriuria

The relationship between the presence of bacterial virulence factors and the severity of urinary tract infection (UTI) was analized in this study. The production of -hemolysin (Hly), the expression of P-fimbriae and the mannose-resistant hemagglutination (MRHA) type IVa (associated with the presence of P-fimbriae), were all detected more frequently in Escherichia coli strains from acute pyelonephritis than in strains isolated from cystitis and asymptomatic bacteriuria. In contrast, the production of cytotoxic necrotizing factor type 1 (CNF1) and the expression of MRHA types III and IVb were distributed uniformly between strains causing different clinical categories of UTI. Thus 88% of the E. coli strains from acute pyelonephritis showed some of the virulence factors investigated in this study, whereas only 60% (p < 0.01) and 56% (p < 0.01) repectively of the strains isolated from cystitis and asymptomatic bacteriuria possessed virulence factors. There were no significant differences in the prevalence of virulence properties between strains isolated from patients with or without complicating factors. Only 16% (p < 0.001) of the fecal isolates from healthy individuals showed virulence factors. The virulence factors were concentrated in strains belonging to 10 (O1, O2, O4, O6, O7, O14, O18, O22, O75 and 083) of the 12 serogroups most frequently detected in uropathogenic E.coli strains. The majority of uropathogenic O4, O6, O14, O22, O75 and O83 E.coli strains were Hly⁺CNF1⁺ and expressed P-fimbriae or MRHA type III, whereas the strains of serogroup O18 were Hly⁺CNFI^– and P-fimbriated. Among O1 and O7 strains we found Hly^– CNF1^–strains that expressed P-fimbriae. Among O2 strains we found Hly⁺CNF1⁺ strains that expressed P-fimbriae or MRHA type III and other Hly^–CNF1^–strains that possessed P-fimbriae. We conclude that E.coli strains isolated from pyelonephritis show virulence factors more frequently than those from cystitis and asymptomatic bacteriuria, and that strains that cause urinary tract infections in Spain belong to the same serogroups as uropathogenic E.coli isolated in other areas of the world. Our results support the special pathogenicity theory and suggest that many cases of serious urogenital disease may be caused by a limited number of P-fimbriated E.coli strains that usually produce -hemolysin.     

Structure-activity relationship studies of CNS agents. Part 29. N-Methylpiperazino-substituted derivatives of quinazoline, phthalazine and quinoline as novel α1, 5-HT1A and 5-HT2A receptor ligands

New N-methylpiperazino-substituted quinazolines 8 and 9, phthalazine 13, and quinoline 19 have been synthesized. The receptor binding profiles (α₁, 5-HT_1A, 5-HT_2A) of these compounds and their analogs (7–22) have been determined. It has been demonstrated that orientation of a local dipole moment of the heteroaromatic ring system affects both the α₁ and 5-HT_2A affinity of the investigated class of ligands. Distortion of the coplanar unfused heteroaromatic ring system results in a decreased 5-HT_2A affinity. 4-(4-Methylpiperazino)-2-(2-thienyl)quinoline 18 is the most active and selective α₁ ligand (K_i = 4.9 nM) with a much lower affinity for 5-HT_1A (K_i = 3420 nM) and 5-HT_2A (K_i = 211 nM) receptors.     

Plasmodium vivax recombinant vaccine candidate AMA-1 plays an important role in adaptive immune response eliciting differentiation of dendritic cells

The Apical Membrane Antigen-1 (AMA-1) is a well-characterized and functionally important merozoite protein and is currently considered a major candidate antigen for a malaria vaccine. Previously, we showed that AMA-1 has an influence on cellular immune responses of malaria-naïve subjects, resulting in an alternative activation of monocyte-derived dendritic cells and induction of a pro-inflammatory response by stimulated PBMCs. Although there is evidence, from human and animal malaria model systems that cell-mediated immunity may contribute to both protection and pathogenesis, the knowledge on cellular immune responses in vivax malaria and the factors that may regulate this immunity are poorly understood. In the current work, we describe the maturation of monocyte-derived dendritic cells of P. vivax naturally infected individuals and the effect of P. vivax vaccine candidate Pv-AMA-1 on the immune responses of the same donors. We show that malaria-infected subjects present modulation of DC maturation, demonstrated by a significant decrease in expression of antigen-presenting molecules (CD1a, HLA-ABC and HLA-DR), accessory molecules (CD40, CD80 and CD86) and FcγRI (CD64) receptor (P ≤ 0.05). Furthermore, Pv-AMA-1 elicits an upregulation of CD1a and HLA-DR molecules on the surface of monocyte-derived dendritic cells (P = 0.0356 and P = 0.0196, respectively), and it is presented by AMA-1-stimulated DCs. A significant pro-inflammatory response elicited by Pv-AMA-1-pulsed PBMCs is also demonstrated, as determined by significant production of TNF-α, IL-12p40 and IFN-γ (P ≤ 0.05). Our results suggest that Pv-AMA-1 may partially revert DC down-modulation observed in infected subjects, and exert an important role in the initiation of pro-inflammatory immunity that might contribute substantially to protection.     

Efficacy of phytol-derived diterpenoid immunoadjuvants over alum in shaping the murine host's immune response to Staphylococcus aureus

The ubiquitous gram-positive bacterium Staphylococcus aureus occupies a unique niche in humans for its ability to survive both as a commensal and a life-threatening pathogen. Its complex relationship with the host and its ability to engender a throng of virulence factors, have hindered the development of a successful vaccine against it. The use of immunoadjuvants to enhance host immunity and prevent the shift from commensalism to pathogenicity is a rational approach for containing infection. The objective of this study was to understand the mechanisms by which alum and two phytol-derived immunoadjuvants, phytanol (PHIS-01) ¹ and phytanyl chloride (PCl) ² shape the interaction between S. aureus and its murine host. We studied the effects of the phytol derivatives, relative to alum, on the induction of inflammatory cytokines and chemokines, recruitment of CD11b⁺ cells, generation of specific anti-S. aureus antibodies and in vitro clearance of S. aureus. Our results showed that both PHIS-01 and PCl were stronger inducers of protective cytokines IL-17 and IL-1β than alum, and far exceeded alum in enhancing anti-S. aureus antibody response. However, both alum and the phytol derivatives (particularly PCl) promoted efficient recruitment of CD11b⁺ cells. Furthermore, PHIS-01, alum and to a lesser extent, PCl were able to up-regulate the expression of key inflammation-related genes that were highly down-regulated by S. aureus alone. In vitro killing assays showed that both PHIS-01 and PCl were far more potent than alum in promoting S. aureus clearance; this indicated their efficiency in shaping an effective anti-S. aureus immune microenvironment. In summary, our study provides evidence for the better effectiveness of phytol-derived immunoadjuvants over alum in enhancing anti-S. aureus immunity.     

Impact of Elevated CO<Subscript>2</Subscript> and O<Subscript>3</Subscript> Concentrations on Biogenic Volatile Organic Compounds Emissions from <Emphasis Type="Italic">Ginkgo biloba</Emphasis>

In natural environment with ambient air, ginkgo trees emitted volatile organic compounds 0.18 μg g⁻¹ h⁻¹ in July, and 0.92 μg g⁻¹ h⁻¹ in September. Isoprene and limonene were the most abundant detected compounds. In September, α-pinene accounted for 22.5% of the total. Elevated CO₂ concentration in OTCs increased isoprene emission significantly in July (p < 0.05) and September (p < 0.05), while the total monoterpenes emission was enhanced in July and decreased in September by elevated CO₂. Exposed to elevated O₃ increased the isoprene and monoterpenes emissions in July and September, and the total volatile organic compounds emission rates were 0.48 μg g⁻¹ h⁻¹ (in July) and 2.24 μg g⁻¹ h⁻¹ (in September), respectively. The combination of elevated CO₂ and O₃ did not have any effect on biogenic volatile organic compounds emissions, except increases of isoprene and Δ3-carene in September. Foundation item: The National Natural Science Foundation of China (No. 90411019).     

Effects of transgenic corn and Cry1Ab protein on the nematode, Caenorhabditis elegans

The effects of the insecticidal Cry1Ab protein from Bacillus thuringiensis (Bt) on the nematode, Caenorhabditis elegans, were studied with soil from experimental fields cultivated with transgenic Bt corn (MON810) and with trypsinized Cry1Ab protein expressed in Escherichia coli. The content of Cry1Ab protein was above the detection limit of an ELISA test in only half of the soil samples obtained from transgenic plots, ranging from 0.19 to 1.31 ng g⁻¹ dry weight. In a laboratory bioassay, C. elegans was exposed to rhizosphere and bulk soil from fields with isogenic or transgenic corn or to solutions of Cry1Ab protein (0, 24, 41, 63, 118, and 200 mg l⁻¹) over a period of 96 h, with growth and reproduction serving as the test parameters. Nematode reproduction and growth were significantly reduced in rhizosphere and bulk soil of Bt corn compared with soil from isogenic corn and were significantly correlated with concentrations of the Cry1Ab protein in the soil samples. Moreover, the toxicity of pure Cry1Ab protein to the reproduction and growth of C. elegans was concentration-dependent. As significant inhibition occurred at relatively high concentrations of the Cry1Ab protein (41 mg l⁻¹), the effects of the soil samples from Bt corn could not be assigned directly to the toxicity of the Cry1Ab protein. The results demonstrate that bioassays with the nematode, C. elegans, provide a promising tool for monitoring the potential effects of Bt toxins in aqueous medium and soils.     

Effects of Japan Sea Proper Water on the growth ofLegionella pneumophila, Escherichia coli, andStaphylococcus aureus

Objective To assess whetherLegionella pneumophila serogroup 1 and serogroup 6,Escherichia coli, andStaphylococcus aureus can survive in Japan Sea Proper Water (JSPW). Methods The inhibitory effects of JSPW, surface seawater (SSW), phosphate buffer solution with 3.5% NaCl of pH 7.0 (3.5% NaCIPBS), and the 10²- and 10⁴-fold dilute solutions with purified water or phosphate buffer solution of pH 7.0, and purified water were investigated. Survival cells were counted immediately after the water and the bacteria were mixed, and at 1,3,5, and 7 days after incubation at 37°C. If the number of surviving cells was decreased more than 2 log units compared with the starting value, we judged the medium to have had an inhibitory effect on the growth of the bacteria. Results The survival cells of the bacteria in JSPW had decreased more than 2 log units compared with the starting value at 1 day after incubation. After 1 day of incubation, the cells ofLegionella pneumophila serogroup 6 andStaphylococcus aureus were found to have decreased more than 2 log units in purified water (PW) used as a control. Furthermore,Legionella pneumophila serogroup 1 in the 10²-fold dilute solution of JSPW was only 1.04 log units lower than the starting value at 7 days after incubation. In the 10²- and 10⁴-fold dilute solutions of JSPW,Escherichia coli survived for 7 days after incubation. These results were almost similar to the results in SSW and 3.5% NaCIPBS. Conclusions The present findings demonstrate thatLegionella pneumophila serogroup 1 andEscherichia coli cannot survive in undiluted JSPW for over a day at 37°C, suggesting the inhibitory effects may be due to the sodium chloride contained in JSPW.     

Expression of pertussis toxin subunit S4 as an intracytoplasmic protein in Bacillus subtilis

The expression and secretion of pertussis toxin subunits S1 to S5 in Bacillus subtilis by the aid of a bacillar signal sequence has been reported. While secretion of subunit S1 was high, that of others was low. Ways have now been explored to improve the yield, using S4 as an example. The addition of a protease inhibitor was found to increase the amount of S4 in the culture supernatant, but the final amount was still much below that of S1. However, intracellular expression of S4 gave a high yield (500 mg I⁻¹) and the aggregated protein could easily be isolated in a few simple steps.     

The Effect of some Selected Pesticides on the Growth and Reproduction of Fresh Water <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>, <Emphasis Type="Italic">Chrysicthys nigrodigitatus</Emphasis> and <Emphasis Type="Italic">Clarias gariepinus</Emphasis>

Studies were carried out to determine the toxicity of some selected pesticides on fresh water fish in a tropical environment. The uptake of the pesticides lindane, pentachlorophenol (PCP), and propoxur, which are frequently used on farms, and in industries as well as by loggers and timber men on wood were studied in concrete ponds at the University of Cape Coast, in Ghana. The fish used for the study were Oreochromis niloticus, Clarias gariepinus, and Chrysicthys nigrodigitatus. They were obtained from cultured ponds in the Cape Coast and Mankessim districts in the Central Region and Weija Dam, in the Greater Accra region of Ghana. Single high lethal concentration (SD) or acute treatment and cumulative/chronic (or multiple minor) lethal concentration (CD) treatment were employed in administering the pesticides to the fish via water. Gas chromatograph electron capture detector analysis was done on the dead fish to see the extent of ingestion. The LC₅₀ values obtained for lindane on the three fish samples were as follows: Chrysicthys – 0.38 mg L⁻¹; Oreochromis – 0.42 mg L⁻¹, and Clarias – 1.2 mg L⁻¹. Mortalities occurred in fish within 3–5 days of application. For the PCP on Chrysicthys, Oreochromis, and Clarias species the LC₅₀ values were 0.42, 0.32 and 0.64 mg L⁻¹, respectively, for over a 2- to 3-day period. For a three-time influx period of propoxur the LC₅₀ for Chrysicthys, Oreochromis, and Clarias, were 22.0, 30.40, and 45.04 (all in mg L⁻¹), respectively. The results obtained indicated that the pesticides had adverse effects on the general growth and reproduction of fish as shown by gonadosomatic indices.     

上海市1962-2011年霍乱弧菌表型特征及分子分型研究

目的 分析1962-2011年上海市霍乱弧菌的表型及分子分型特征.方法 采用WHO推荐的改良K-B纸片法,对222株霍乱弧菌进行11种抗菌药物(头孢曲松、强力霉素、诺氟沙星、环丙沙星、复方新诺明、丁胺卡那霉素、四环素、氯霉素、萘啶酸、氨苄西林、庆大霉素)敏感试验.以PCR检测霍乱毒素基因(ctxA)、小带联结毒素基因(zot)、辅助霍乱肠毒素基因(ace)、溶血素基因(hlyA)、毒素协调菌毛基因(tcpA)、外膜蛋白基因(ompU)和调控蛋白基因(toxR).采用脉冲场凝胶电泳(PFGE)方法对菌株进行分子分型,用BioNumerics软件分析电泳图谱.结果 222株霍乱弧菌经药物敏感试验分析显示,1962-1996年的菌株对多种药物敏感,2005-2011年的菌株对多种药物耐药.O139群耐药率明显高于O1群,O139群产毒株的耐药率比非产毒株高.毒力基因分析显示,1962-1996年霍乱患者来源菌株多为O1群产毒株,2005-2011年患者来源菌株多为O139群产毒株,水体来源菌株未检出ctxA基因,O1群水产来源菌株以hlyA⁺ toxR⁺ ompU⁺为主,占25.6％(11/43),O139群水产来源菌株以hlyA⁺ toxR⁺ompU⁺ctxA ⁺ace ⁺zot⁺ tcpA⁺为主,占76.1％(16/21).PFGE分析将222株菌分为121个PFGE型,O139群分为3个聚类,O1群分为5个聚类.结论 上海市霍乱弧菌随着时间推移表型及分子特征均发生了很大变化,耐药情况加重.     

三种表面活性剂对表皮葡萄球菌生物膜渗透性及成膜关键基因agr表达的影响

目的 通过探究三种类型表面活性剂（十二烷基羟丙基磺基甜菜碱、十二烷基苯磺酸钠、溴化十六烷基吡啶）分别对表皮葡萄球菌（Se）生物膜渗透性及成膜关键基因——附属基因调节子（agr）表达的影响,为临床利用表面活性剂控制由Se生物膜引起的相关感染提供依据。 方法 建立Se生物膜渗透模型,检测经表面活性剂处理后对生物膜渗透性的影响;选择在不同时间段,观察三种表面活性剂对悬浮状态下产膜Se的agr转录水平的影响,从分子水平评估表面活性剂对产膜Se黏附及毒力等可能的作用。 结果 三种类型表面活性剂在最低抑菌浓度（MIC）分别为2、1、1/2浓度时,均明显影响Se生物膜的渗透性（P < 0.001）,增强药物对生物膜的渗透作用。与阴性对照组比较,十二烷基羟丙基磺基甜菜碱在0.5、4、12 h时间段,对agr表达有显著上调作用（P < 0.001）;十二烷基苯磺酸钠在0.5、4、24 h时间段,对agr表达有显著下调作用（P < 0.001）,在12 h时间段对agr表达有显著上调作用（P < 0.001）;溴化十六烷基吡啶在0.5 h时间段对agr表达有显著上调作用（P < 0.01）,在12、24 h时间段,对agr表达有显著下调作用（P < 0.001）。 结论 三种不同类型的表面活性剂对Se生物膜渗透作用均有较强的影响,在不同时间段对agr表达有显著调节作用,因而可能在Se生物膜的形成、防止感染的扩散并导致细菌毒力减弱等方面发挥作用。     

Differential Involvement of Dopamine D1 And D2 Receptors and Inhibition by Dopamine of Hypothalamic VMN Neurons in Early Postnatally Overfed Juvenile Rats

Dopamine is among the neurotransmitters involved in central regulation of food intake and body weight control. To study possible changes in neuronal responses to dopamine, single unit activity of the ventromedial hypothalamic nucleus (VMN) was recorded in brain slices of normal and obese rats. The latter had developed overweight throughout juvenile life (p < 0.05) by early postnatal over-nourishment due to a reduction of litter size from 3rd to 21st day of life (small litters, SL). With effective concentrations of about 100–500 nM/1 dopamine inhibited significantly more VMN neurons in obese than normal rats (Chi-square p < 0.05). While D² receptors in the VMN are reported to mediate inhibition of food intake, the responses to dopamine were blocked by D₂ receptor antagonists in significantly fewer neurons of SL than normal rats (p < 0.05). Furthermore, including results of action of D₁receptor agonists we found that significantly more neurons in SL than NL rats seem to express D₁ receptors. Thus, increased suppression by dopamine of firing of VMN neurons that signal satiety with a rise in the discharge rate, and changed expression or activity of dopamine receptors might contribute to increased feeding behavior in juvenile rats hyperphagic and overweight due to early postnatal overfeeding.