The in vitro Iysozyme susceptibility of Candida albicans cultured in carbohydratesupplemented media

The in vitro lysozyme susceptibility of three oral isolates of Candida albicans cultured in carbohydrate-supplemented media was studied. Lysozyme was shown to have a dose- and time-dependent killing effect on C. albicans isolates. Fungieidal activity persisted to varying degrees when yeast isolates were cultured in a variety of carbohydrates (glucose, galascrose. sucrose, maltose. xylitol and laelose) before exposure to 20 μg/ml lysozyme. Sucrose and galactose grown yeasts exhibited increased resistance to iysozyne conipared with (in decreasing order) those grown in glucose, maltose, xylnol or laelose. Further, the C albicans isolates tested demonstrated strain variations in their susceptibility to lysozyme. These results suggesl that dietary carbohydrate may play a role in modulating the yeast cell populations in the oral —– by altering the fungal susceptibility to salivary lysozyme.     

Effects of delmopinol on antimicrobial peroxidase systems and lysozyme in vitro and in human whole saliva

Delmopinol is a new surface-active agent which can reduce plaque formation and gingivitis. This study was aimed to analyze whether delmopinol (0.0032–0.65 mM) interferes with the activity of two surface-active oral antimicrobial enzymes, salivary peroxidase and lysozyme. In addition to human whole saliva (pH 5.0 and 6.0), the experiments were done in 0.1 M phosphate buffer (pH 6.0) with purified laetoperoxidase (LPO) and myeloperoxidase (MPO). LPO and MPO were significantly inhibited in buffer by delmopinol concentrations >6.5 mM and 3.2 mM, respectively. No such inhibition was found for total peroxidase activity in mixed saliva. In vitro , delmopinol was found to desorb surface-bound peroxidases in an active form to the liquid phase. In further analyses, the possible effect of delmopinol on peroxidase-generated hypoihiocyanite (HOSCN/OSCN⁻) was studied in saliva and buffer. No effect was found in buffer, but salivary HOSCN/OSCN declined significantly with 6.5 mM delmopinol. This was obviously due to an enhanced decay of hypothiocyanite. rather than its reduced rate of formation. No deimopinol-related inhibition of lysozyine occurred in saliva or buffer. The results suggest that high concentration (6.4 mM – 0.2 %) of delmopinol may lower the concentrations of antimicrobial HOSCN/OSCN⁻ in saliva but has no effect on human lysozyme.     

液相中炭疽杆菌形貌的原子力显微镜观测

目的利用原子力显微镜液相模式观测炭疽杆菌形态,获得液相中炭疽杆菌芽胞和繁殖体对于溶菌酶的形态学抗性变化数据。方法应用原子力显微镜液相模式观察炭疽杆菌繁殖体及芽胞的超微结构,并对其主要指标进行测量比较。结果1×PBS溶液中的炭疽杆菌繁殖体,菌体杆状,竹节样排列,菌体间连接致密,长度为2,757.30±1227.086nm,宽度为1,710.90±226.10nm,Rq为15.447±3.418nm,Ra为13.239±2.733nm;炭疽杆菌芽胞椭圆形,多散在分布,表面平滑,长度为2,014.00±227.155nm,宽度为1,264.10±132.180nm,Rq为22.803±5.660nm,Ra为18.010±4.568nm。0.01 mg/mL溶菌酶溶液中的炭疽杆菌繁殖体形态不规则,表面凹凸起伏,边缘粗糙,有囊状突起,长度为2,836.00±1025.137nm,宽度为2,449.00±212.78nm,Rq为17.068±4.427nm,Ra为14.776±3.746nm;0.01 mg/mL溶菌酶溶液中的炭疽杆菌芽胞,形态规则,边缘平滑,未见凹凸起伏和囊状突起,而1 mg/mL溶菌酶溶液环境中的炭疽杆菌芽胞形态不规则,表面起伏,变化较大,其长度为2,155.00±202.663nm,宽度为1,344.00±162.631nm,Rq为24.849±3.427nm,Ra为20.869±2.550nm。结论通过原子力显微镜液相模式下的观察和测量,清楚地显示了溶液中炭疽杆菌的微观形貌及其变化,0.01 mg/mL的溶菌酶就能使炭疽杆菌繁殖体发生形态学变化,而炭疽杆菌芽胞形貌发生变化则需要1 mg/mL的高浓度溶菌酶的作用。