甘草提取物对四种牙周常见致病菌的抑菌作用

目的 体外评价甘草提取物对牙龈卟啉单胞菌、中间普氏菌、具核梭杆菌和伴放线放线杆菌四种牙周常见致病菌的抑制效果。方法 以牙龈卟啉单胞菌、中间普氏菌、具核梭杆菌和伴放线放线杆菌四种牙周常见致病菌作为供试菌,采用液体稀释法,考察甘草提取物对这四种细菌的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）;并采用不同浓度的甘草提取物溶液,绘制甘草提取物对四种牙周致病菌的时间‒杀菌曲线。结果 甘草提取物对牙龈卟啉单胞菌、中间普氏菌、具核梭杆菌和伴放线放线杆菌的MIC值分别为1.50、1.50、0.75和1.50 mg/mL,MBC值分别为6、3、3和3 mg/mL。当甘草提取物达到对四种细菌的MBC值时,对于牙龈卟啉单胞菌、中间普氏菌、伴放线放线杆菌可在2 h后可达到杀菌效果,对于具核梭杆菌可在4 h后达到杀菌效果。结论 甘草提取物对以上四种牙周常见致病菌具有良好的抑菌及杀菌作用。     

Effect of Weak Acid Hypochlorous Solution on Selected Viruses and Bacteria of Laboratory Rodents

Weak acid hypochlorous solution (WAHS) is known to have efficacy for inactivatingpathogens and to be relatively safe with respect to the live body. Based on theseadvantages, many animal facilities have recently been introducing WAHS for daily cleaningof animal houses. In this study, we determined the effect of WAHS in inactivating specificpathogens of laboratory rodents and pathogens of opportunistic infection. WAHS with anactual chloride concentration of 60 ppm and a pH value of 6.0 was generated usingpurpose-built equipment. One volume of mouse hepatitis virus (MHV), Sendai virus,lymphocytic choriomeningitis virus, Bordetella bronchiseptica,Pasteurella pneumotropica, Corynebacterium kutscheri,Staphylococcus aureus, and Pseudomonas aeruginosa wasmixed with 9 or 99 volumes of WAHS (×10 and ×100 reaction) for various periods (0.5, 1,and 5 min) at 25°C. After incubation, the remaining infectious viruses and live bacteriawere determined by plaque assay or culture. In the ×100 reaction mixture, infectiousviruses and live bacteria could not be detected for any of the pathogens examined evenwith the 0.5-min incubation. However, the effects for MHV, B.bronchiseptica, and P. aeruginosa were variable in the ×10reaction mixture with the 0.5- and 1-min incubations. Sufficient effects were obtained byelongation of the reaction time to 5 min. In the case of MHV, reducing organic substancesin the virus stock resulted in the WAHS being completely effective. WAHS is recommendedfor daily cleaning in animal facilities but should be used properly in order to obtain asufficient effect, which includes such things as using a large enough volume to reduceeffects of organic substances.     

Antagonism of Aeromonas hydrophila by propolis and its effect on the performance of Nile tilapia, Oreochromis niloticus

Propolis, a resinous substance collected by Apis mellifera bees from various plant sources and mixed with secreted beeswax, is a multifunctional material used by bees in the construction, maintenance, and protection of their hives. The collected propolis sample, from High Egypt, was dark-green with olive-odor. The minimal inhibition concentration (MIC) of propolis-ethanolic-extract, against Aeromonas hydrophila, was 80 μg Propolis-ethanolic-extract and crude propolis (1%) were added to artificial basal diet with (30% crude protein) to evaluate their efficacy on the fish growth-performance, immunostimulation and resistance to A. hydrophila. Two hundred and twenty-five Oreochromis niloticus (8 ± 0.45 g/fish) were divided into three equal treatments (T) of triplet replicates. The fish of T₁ were fed on basal diet (control). The fish of T₂ were given the basal diet, containing propolis-ethanolic-extract. The fish of T₃ were given the basal diet containing crude propolis for 28 day. The fish were intraperitoneally challenged by A. hydrophila (0.2 × 10⁷ cells ml⁻¹) at the end of the feeding period and kept for 15 more days.The best growth rate and feed conversion ratio were obtained with T_2. The increase in the average daily gain, specific growth rate and feed efficiency ratio were highly significances in T₂ followed by T₃ when compared with the control group. The HCT-level and monocyte-counts were increased (T₂). No significant change, in the large lymphocytic-count was found among the three treatments (28–27–28%), while the neutrophil-count was significantly decreased (7%) with T₂ and increased (13.11%) with the control. A significant increase in serum lysozyme and serum bactericidal activities was found with T₂. The RLP against A. hydrophila was high with T₂ and T₃.The propolis-ethanolic-extract enhanced the growth, immunity and resistance of O. niloticus against A. hydrophila more than the crude propolis.     

Studies on the in vivo cellular reactions of insects: Fate of pathogenic and non-pathogenic bacteria in Galleria mellonella nodules

The fate of radioactively-labelled bacteria within nodules of Galleria mellonella was examined over time and the percentage relative viabilities of a pathogen, B. cereus, and a non-pathogen, E. coli K12, were compared. Although large numbers of both species were killed within the nodules during the first six hours, B. cereus eventually overcame the insect's defence mechanisms and multiplied some 200-fold in the haemolymph, inducing a secondary bacteraemia and larval death. In contrast, E. coli remained entrapped in the cell aggregates and failed to kill their hosts. The nature and implication of an active killing mechanism within the nodules is discussed.     

Two Oxazolyl Compounds and a Monosubstituted α-Pyrone as Free-radical Scavengers Isolated from a Fungus

In the course of our screening for free radical scavengers, (1′E)-erythro-4-(3′,4′-dihydroxypentenyl)oxazole (1) (1′E,4′S)-4-(3′-oxo-4′-hydroxypentenyl)oxazole (2) and 6-pentyl-α-pyrone (3) were isolated from an unidentified fungal metabolite. These compounds, especially novel oxazolyl compound 2, inhibited the bactericidal effect of the Fenton reagent toward Bacillus subtilis. They and their acetylated compounds (diAc-1 and Ac-2) also showed inhibitory activity against linoleate autoxidation. Furthermore, 1–3 inhibited oxidative enzymes (soybean lipoxygenase and mushroom tyrosinase).

To investigate the radical scavenging mechanism of 3, two oxidized products (4 and 5) were isolated from the reaction mixture of 3 and the Fenton reagent. Compounds 4 and 5 seemed to be derived from 3 by scavenging the hydroxyl radical.     

人类杀菌肽基因cDNA片段的克隆

采用RT－PCR方法,从慢性粒细胞白血病患者的外周血白细胞中扩增得到长度约为1.5kb的有类杀菌肽cDNA进一步得到长度约为600bp的该多肽的氨基端部分cDNA扩增产物,将上述两种长度的扩增产物分别克隆至pUCm-T载体中,为进一步开展该重组抗菌肽的表达和活性研究奠定了基础。     

中华蟾蜍足垫部位对植物血凝素的反应及其组织学和血液学变化

为探究中华蟾蜍(Bufogargarizans)对植物血凝素(PHA-P)反应的最适浓度及足垫部位皮肤组织学和血液学的变化,比较了在足垫部位注射1.0、2.5和5.0g/L植物血凝素条件下的PHA-P反应,以及最适注射浓度条件下PHA-P反应高峰值时足垫部位皮肤组织和循环血中各型白细胞的百分比,血液中血清杀菌能力的变化。结果表明,中华蟾蜍对PHA-P的反应无性别差异(P 0.05),最适注射浓度为2.5 g/L,注射后12 h达反应峰值;注射PHA-P或生理盐水的左足与注射生理盐水或不注射任何物质的右足皮肤组织相比,各型白细胞的百分比均无显著差异(P0.05),但循环血中淋巴细胞的百分比升高(P 0.05),嗜酸性粒细胞的百分比下降(P 0.05),血清杀菌能力无明显变化(P 0.05)。2.5 g/L的注射浓度适用于中华蟾蜍,反应高峰值与足垫部位皮肤组织中各型白细胞的动态无关,但循环血中淋巴细胞被激活、嗜酸性粒细胞功能弱化,这可能是导致中华蟾蜍PHA-P反应的主要原因。     

Tolerance ofStaphylococcus epidermidis grown from indwelling vascular catheters to antimicrobial agents

During a prospective study of indwelling vascular catheter-related infections, 134 isolates ofStaphylococcus epidermidis were grown from 700 catheter tips.In vitro antimicrobial susceptibility testing of these isolates to oxacillin, vancomycin and ofloxacin was performed using the standard broth microdilution technique. These results were compared to those for the same organisms grown in biofilm before the addition of antimicrobial agents. In 96-well flat bottom microtiter plates, 10⁴–10⁵ colony forming units ofS. epidermidis in 0.1 ml broth were grown for 18 h at 37°C, at which time a biofilm was observed for all isolates. Different concentrations of antimicrobial agents (0.1 ml) were then added to the plates. The plates were incubated for 18 h at 37°C. Since MICs could not be estimated in these plates, all the wells were subcultured after mixing the biofilm with the broth. Minimum bactericidal concentrations (MBCs) were defined as 99.9% reduction in colony forming units. For organisms grown in suspension, 100% of the isolates were susceptible to vancomycin, 81% to ofloxacin and 40% to oxacillin. MBCs of susceptible isolates were within four-fold differences for vancomycin (53%), oxacillin (50%), and ofloxacin (51%). When grown as a biofilm, 78%, 93% and 71% of isolates had MBCs of 2048 g ml^–1 of oxacillin, vancomycin and ofloxacin respectively. These data demonstrate the reduced bactericidal activity of antimicrobial agents againstS. epidermidis in a biofilm and a simple method for its detection in the microbiology laboratory.     

Novel synthesis scheme and in vitro antimicrobial evaluation of a panel of (E)-2-aryl-1-cyano-1-nitroethenes

Drug resistance has become a major concern in the field of infection management, therefore searching for new antibacterial agents is getting more challenging. Our study presents an optimized and eco-friendly synthesis scheme for a panel of nitroalkenes bearing various functional groups in the aromatic moiety and bromine or cyano substituents in 1 position of nitrovinyl moiety. The presence of nitrolefine group outside the ring minimalizes genotoxic properties while conjugation of aryl group with nitrovinyl moiety increases stability of the compounds. Then our research focused on evaluation of biological properties of such obtained (E)-2-aryl-1-cyano-1-nitroethenes. As they exhibit strong bacteriostatic and bactericidal activities against reference bacteria and yeast species with no detectable cytotoxicity towards cultured human HepG2 and HaCaT cells, they could be promising candidates for the replacement of traditional nitrofurane-containing antibacterial drugs. Nevertheless, validation of the obtained data in an in vivo model and additional safety studies on mutagenicity are still required.