The in vitro effect of antimicrobial photodynamic therapy with indocyanine green on Enterococcus faecalis: Influence of a washing vs non-washing procedure

IntroductionThe purpose of this study was to evaluate the in vitro effect of washing and non-washing of indocyanine green (ICG) as photosensitizer (PS) on bacterial count, biofilm formation, development and degradation of Enterococcus faecalis.MethodsThe anti-bacterial, anti-biofilm formation, anti-biofilm development and biofilm degradation of anti-microbial photodynamic therapy (aPDT) against E. faecalis was determined at concentrations of 3 to 2000 μg/mL of ICG, subject to 18 J/cm² dose of diode laser (808 nm) in washing and non-washing producers. Bacterial viability measurements and biofilm assays were evaluated by broth microdilution method and crystal violet assays, respectively.ResultsICG-mediated aPDT, using 25 to 2000 μg/mL and 50 to 2000 μg/mL showed significant reduction in E. faecalis growth when compared to the control in non-washing and washing producers, respectively (P < 0.05). Also, ICG-mediated aPDT showed a significantly inhibitory effect on biofilm formation of E. faecalis in concentration of 6 to 2000 μg/mL and 100 to 2000 μg/mL in non-washing and washing groups (P < 0.05). The biofilm development was inhibited by concentrations of 12 to 2000 μg/mL and 100 to 2000 μg/mL in non-washing and washing groups. The biofilm degradation increased from concentrations of 12 to 2000 μg/mL and 250 to 2000 μg/mL in non-washing and washing groups, respectively.ConclusionThis study shows that the application of ICG should be accompanied by laser irradiation without being washed out to achieve better result for bacterial count reduction and anti-biofilm effects.     

Effect of blending tricalcium phosphate on hydrolytic degradation of a block polyester containing poly(L-lactic acid) segment

The effect of blending tricalcium phosphate (TCP) on hydrolytic degradation of a new type of poly(L-lactic acid)/poly(ethylene;hexamethylene/ sebacate) block polyester (60 : 40 wt%) was studied. 100- and 250-μm film specimens blended with 0, 10, and 30 wt% TCP were immersed in phosphate buffered saline (pH 7.4) at 37°C for up to 80-104 weeks. At appropriate intervals, water absorption, dry and wet tensile strength, molecular weight, and thermal properties of the specimens were measured by weighing, tensile strength testing, size exclusion chromatography, and differential scanning calorimetry, respectively. Some samples were characterized by H NMR spectroscopy. Blending of TCP with the block polyester was effective in retarding degradation. The blended TCP was thought to retard degradation for the most part by neutralizing the lactic acid oligomers produced by hydrolysis of the poly(lactic acid) part during the initial stage of degradation.     

A new frontier in pharmacology: the endoplasmic reticulum as a regulated export pathway in health and disease

The endoplasmic reticulum (ER), the first secretory compartment of eukaryotic cells, co-ordinates the biogenesis and export of all membrane-bound and soluble cargo molecules to the cell surface. ER function is now recognised to have unprecedented links with signalling pathways regulating cell growth and differentiation and host physiology. Misfolding and aggregation of newly synthesised proteins in the ER or alterations in ER processing of cargo mediated by pathogens is responsible for a broad range of diseases including cystic fibrosis, emphysema and neuropathies such as Alzheimer’s disease. The central, integrative role of the ER in determining cell physiology in health and disease represents an untapped area for pharmacological intervention. This review focuses on the potential use of pharmacological agents to modulate cargo selection, folding and degradation in the ER with the goal of alleviating ER export disease. In addition, implementation of novel technologies that utilise normal ER function to store and release biologically active substances of therapeutic relevance are presented as a new frontier in drug delivery.     

In vitro degradation of resin–dentin bonds with one-bottle self-etching adhesives

The purpose of this study was to evaluate the durability of one-bottle self-etching adhesive during long-term water-storage testing. Resin–dentin bonded specimens were prepared using four commercially available one-bottle self-etching adhesives. The specimens were sectioned perpendicular to the adhesive interface to produce beam-shaped specimens that were stored in water for 24 h (control group) and 100, 200, and 300 d (experimental groups). After each storage period, the beams were subjected to a microtensile bond test. After the bond test, fractured surfaces were examined using a scanning electron microscope. In addition, interfacial observations of the silver tracer were performed using the secondary and back-scatter modes of the scanning electron microscope. The bond strength of all tested adhesives decreased significantly after 100 or more days in water. The interfacial observations showed an oxygen-inhibition zone as electron lucent in the adhesive–composite border in control specimens, displaying silver impregnation with breakage after aging. The deterioration of the oxygen-inhibition zone in the adhesive–resin composite junction resulted in a decrease in bond strength after 100 d in water for one-bottle self-etching adhesives.     

Effect of propranolol on the activity of neutral,alkaline and acidic proteases in rat myocardium after aortic stenosis

Summary The aim of the study was to investigate the effect of propranolol upon the activity of proteases in rat myocardium subjected to aortic stenosis.In acute heart hypertrophy induced by aortic stenosis, the activity of all three proteases in the myocardium does not change significantly. Propranolol in the concentration of 10^–6 to 2×10^–4 M inhibited proteolytic activity dependent on neutral proteases.The degree of inhibition increased simultaneously with increasing concentrations of propranolol.Propranolol in a low concentration (10^–6–10^–5 M) also inhibited proteolytic activity dependent on alkalinc and acidic proteases, but in higher concentration (10^–4–2×10^–4 M) stimulated proteolytic activity of these enzymes 2–3 times.     

Absorption kinetics of subcutaneously injected insulin

Summary The absorption of subcutaneously injected insulin was examined by injecting semisynthetic [³H] insulin in anaesthetized pigs and subsequently analysing the tissue excised from the injection site. Contrary to previously accepted views, a significant proportion of insulin was degraded at the injection site. The disappearance of intact [³H] insulin from the injection site followed a monoexponential function with a half-time of 59 min.     

血必净注射液中洋川穹内酯I的降解动力学研究

[目的]研究洋川芎内酯I(Sen I)在血必净注射液及水溶液中,不同p H缓冲液、不同温度下降解的动力学规律,为血必净注射液及洋川芎内酯I的提取、贮藏及使用条件提供依据。[方法]建立高效液相色谱分析方法,考察不同p H(1~13)和温度(65、75、85、95℃)对Sen I稳定性的影响,利用速率方程、化学反应动力学模型及Arrhenius公式分析Sen I在不同条件下的降解规律并计算相关降解反应动力学参数。[结果]Sen I在碱性条件下降解较快,符合一级动力学规律,并随碱性增强,降解速度明显加快。温度对降解速度影响较大,温度升高,降解明显加快。经计算得,Sen I在水溶液和血必净注射液中降解活化能分别为177.94 k J/mol和194.86 k J/mol。[结论]在碱性和高温条件下,洋川芎内酯I更易降解。同样条件下,Sen I在血必净注射液中的稳定性都要高于其水溶液。     

Low subcutaneous degradation and slow absorption of insulin in insulin-dependent diabetic patients during continuous subcutaneous insulin infusion at basal rate

Summary As information on the absorption kinetics and local degradation of infused insulin is relevant to programming strategies for continuous subcutaneous insulin infusion, we examined the time relationship of systemic insulin appearance and quantitated subcutaneous degradation during a near-basal rate of continuous subcutaneous insulin infusion in five insulin-dependent diabetic patients. Plasma free insulin was monitored for 8 h during and 3 h after a subcutaneous (abdominal wall) infusion of neutral insulin at 2.4 U/h. An identical intravenous infusion (2–4 h) was given on a separate occasion. Plateau levels of free insulin were not significantly different during the subcutaneous (37±8 mU/l) and intravenous (40±7 mU/l) infusions. Fitting of the free insulin data to our two-pool model of the subcutaneous space gave a mean estimate of 9.2 units insulin (= 3.8 h infusion) for the subcutaneous depot after 8 h. Model estimates of systemic insulin appearance, as a percentage of subcutaneous infusion rate, were 59% and 93% after 4 and 8 h respectively, and 76% 2 h after cessation of infusion. In insulin-dependent diabetic patients subcutaneous degradation of infused insulin is negligible but local accumulation in the subcutaneous space is considerable. The delay in absorption has important clinical implications for interruption and resumption of continuous subcutaneous insulin infusion and also for programming of variable basal rates.