Radiation sterilization of enzyme hybrids with biodegradable polymers

Ionizing radiations, which have already been utilized for the sterilization of medical supplies as well as gas fumigation, should be the final candidate to decontaminate “hybrid” biomaterials containing bio-active materials including enzymes because irradiation induces neither heat nor substances affecting the quality of the materials and our health. In order to check the feasibility of ⁶⁰Co-gamma rays on these materials, we selected commercial proteases including papain and bromelain hybridized with commercial activated chitosan beads and demonstrated that these enzyme-hybrids suspended in water showed the significant radiation durability of more than twice as much as free enzyme solution at 25-kGy irradiation. Enhanced thermal and storage stability of the enzyme hybrids were not affected by the same dose level of irradiation, either, indicating that commercial irradiation sterilization method is applicable to enzyme hybrids without modification.     

Field evaluations of the VDmax approach for substantiation of a 25 kGy sterilization dose and its application to other preselected doses

The International and European standards for radiation sterilization require evidence of the effectiveness of a minimum sterilization dose of 25 kGy but do not provide detailed guidance on how this evidence can be generated. An approach, designated VD_max, has recently been described and computer evaluated to provide safe and unambiguous substantiation of a 25 kGy sterilization dose. The approach has been further developed into a practical method, which has been subjected to field evaluations at three manufacturing facilities which produce different types of medical devices. The three facilities each used a different overall evaluation strategy: Facility A used VD_max for quarterly dose audits; Facility B compared VD_max and Method 1 in side-by-side parallel experiments; and Facility C, a new facility at start-up, used VD_max for initial substantiation of 25 kGy and subsequent quarterly dose audits. A common element at all three facilities was the use of 10 product units for irradiation in the verification dose experiment.

The field evaluations of the VD_max method were successful at all three facilities; they included many different types of medical devices/product families with a wide range of average bioburden and sample item portion values used in the verification dose experiments. Overall, around 500 verification dose experiments were performed and no failures were observed. In the side-by-side parallel experiments, the outcomes of the VD_max experiments were consistent with the outcomes observed with Method 1.

The VD_max approach has been extended to sterilization doses >25 and <25 kGy; verification doses have been derived for sterilization doses of 15, 20, 30, and 35 kGy. Widespread application of the VD_max method for doses other than 25 kGy must await controlled field evaluations and the development of appropriate specifications/standards.     

Novel oxygen sensitive complexes for optical oxygen sensing

Novel optical sensing films for oxygen based on highly luminescent iridium (III) and ruthenium (II) complexes have been developed. These demonstrate excellent long-term photostability (several months) when incorporated into polystyrene membranes. The influence of different plasticizers on the specific luminescence quantum yield, the Stern-Volmer constant, the reversibility and the response time were evaluated. Additionally the sensing films can be sterilized by chemical cleaning and gamma-ray irradiation.     

Radiosterilization of sulfonamides: I: determination of the effects of gamma irradiation on solid sulfonamides

Three antibiotics sulfafurazole (SFZ), sulfamethoxazole (SMZ) and sulfacetamide sodium (SSA-Na) belonging to sulfonamides were irradiated and changes in physico-chemical properties, pH, melting points, UV, IR, NMR, TLC, GC-MS, ESR characteristics, antimicrobial activities of active components were studied at normal and accelerated stability test conditions. Two radiolytic intermediates for both SFZ and SMZ and four radiolytic intermediates for SSA-Na were found in the irradiated solid samples after the GC-MS analysis. The results obtained under normal and accelerated stability test conditions were observed to be consistent with the unirradiated values.     

等离子体羽中氧原子的光谱强度分布

大气压等离子体羽放电产生的低温等离子体由于不需要真空装置,可以对复杂材料进行三维处理等,在工业上具有广泛的应用前景。本工作利用等离子体针放电装置在大气压空气中产生了稳定的等离子体羽。通过光谱测量,发现等离子体羽发射谱中存在777.5和844.6nm的氧原子谱线。这表明在大气压空气放电中产生了具有高化学活性的氧原子。通过光谱学方法研究了氧原子谱线强度的空间分布,发现靠近电极处氧原子谱线强度远大于其他位置。为了对这一现象进行解释,利用光电倍增管对等离子体羽的发光信号进行了空间分辨测量,发现靠近电极处发光信号宽度远大于其他位置的发光信号宽度。这些结果对大气压空气等离子体羽在杀菌消毒等领域的应用具有重要意义。     

Irradiation effects on hydrases for biomedical applications

To apply an irradiation technique to sterilize “Hybrid” biomedical materials including enzymes, we selected papain, a well-characterized plant endopeptidase as a model to examine durability of enzyme activity under the practical irradiation condition in which limited data were available for irradiation inactivation of enzymes. Dry powder and frozen aqueous solution of papain showed significant durability against ⁶⁰Co-gamma irradiation suggesting that, the commercial irradiation sterilizing method is applicable without modification. Although irradiation of unfrozen aqueous papain solution showed an unusual change of the enzymatic activity with the increasing doses, and was totally inactivated at 15 kGy, we managed to keep the residual activity more than 50% of initial activity after 30-kGy irradiation, taking such optimum conditions as increasing enzyme concentration from 10 to 100 mg/ml and purging with N₂ gas to suppress the formation of free radicals.     

Sterilization of health care products by 5 MeV bremsstrahlung (X ray)

Radiation sensitivities of . pumilus and spores were examined to bremsstrahlung of 5 MeV EB and Cobalt -60 γ rays in order to confirm the effects of radiation and dose rate. Biological indicators (SPORTROL, NAmSA, USA) were irradiated with the X ray in the dose rate range of 4.7–47kGy/h. D-value of spores was 1.4–1.5 kGy, and that of was 1.1–1.3 kGy. The D-values of and have very small dose rate dependences to X ray, and the D-values are similar to those of γ ray. Dose distribution by X-ray and γ irradiation was measured for cartons containing 32 unit dialyzers. The D_max./D_min. of the X-ray irradiation (1.2) was smaller than that of γ ray (1.3).     

Blood Coagulation and Living Tissue Sterilization by Floating-Electrode Dielectric Barrier Discharge in Air

Thermal plasma discharges have been widely used in the past for treatment of living human and animal tissue. However, extensive thermal damage and tissue desiccation occurs due to extreme temperatures. Some solutions have been offered where the temperature is lowered by short current pulses, addition of noble gases, or significant decrease in the size of treatment electrodes. We propose a method of direct treatment of living tissue that occurs at room temperature and pressure without visible or microscopic tissue damage. The presented Floating-Electrode Dielectric Barrier Discharge plasma is proven electrically safe to human subjects and our results show no gross (visual) or histological (microscopic) damage to skin samples in minutes, complete tissue sterilization from skin flora in seconds, and blood clot formation in seconds of electric plasma treatment. We also observe significant hastening of blood clot formation via electric plasma induced catalysis of “natural” processes occurring in human blood. A model describing these processes is offered.An erratum to this article can be found at     

Sterilization of Bacillus spores by converted X rays

Relative sensitivities of endospores of Bacillus pumilus E601, B. subtilis IAM1069, B. megaterium S31 and B. brevis S5 to gamma rays, converted X rays (bremsstrahlung) and electron beams were examined in order to estimate the conditions in which converted X rays kill Bacillus spores. The radiation sensitivities to gamma rays and electron beams of each strain dried on glass fiber filter without additives were found to be almost equivalent, and D values were obtained as follows: 1.5–1.6 kGy for B. pumilus, 1.4–1.5 kGy for B. subtilis, 1.9–2.0 kGy for B. megaterium and 1.6–2.0 kGy for B. brevis. The radiation sensitivities of endospores of each strain to electron beams were slightly lower than those to gamma rays in the dry condition with additives of 2% peptone + 1 % glycerin on glass fiber filters. The increase of radiation resistance in the presence of additives was also observed with X rays, and it was on an intermediate level between those with gamma rays and electron beams. In the dry condition using cellulose filter paper, only the radiation resistances of B. megaterium and B. brevis in the presence of additives B. megaterium and B. brevis in the presence of additives were increased.     

消毒供应中心(室)的风险管理

为探讨消毒供应中心（室）的风险管理，提高防范意识，减少风险事件的发生等，分析了消毒供应中心的风险因素，提出了风险防范措施，包括：合理的建筑布局，配置必要的设备，规范工作流程，完善工作制度，制订质量标准等。结果表明，规范化的管理是降低消毒供应室医院感染风险的有效保证。