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At least 343 records · Page 19Linked to original sources
PubMed2005

Residual formaldehyde on plastic materials and medical equipment following low-temperature steam and formaldehyde sterilization.

We measured the amount of residual formaldehyde on 16 plastic materials and five medical devices following low-temperature steam and formaldehyde (LTSF) sterilization, based on the European Standard EN14180. The amounts of formaldehyde residue on the plastic materials were compared with that on a filter paper of similar dimensions. The amount of residual formaldehyde on polyamide 6, polyurethane, natural rubber and polyacetal was higher (21.9, 15.2, 3.0 and 2.1 times, respectively) than that on the filter paper. The amount of formaldehyde recovered from a breathing circuit, anaesthesia circuit, oxygen tubing, airway tube and tweezers was 260, 240, 594, 56 and 0 microg, respectively, following LTSF sterilization. Our results emphasize the need to verify the main material composing the medical equipment before LTSF sterilization, as the amount of formaldehyde retrieved following sterilization varies according to the material used for construction.

Cross Infection↗
PubMed2001

Steam sterilisation of vesicular phospholipid gels.

Vesicular phospholipid gels (VPGs), highly concentrated phospholipid dispersions of semisolid consistency and vesicular morphology are under investigation as potential implantable depots for sustained release of drugs and as intermediates for subsequent dilution into 'conventional' liposome dispersions. It was investigated here if VPGs can be steam sterilised. VPGs prepared from 400 mg/g egg-phosphatidylcholine by high-pressure homogenisation retained their vesicular structure but showed a slight increase in vesicle size (freeze-fracture electron microscopy). However, autoclaving slowed down both, the in vitro release of the hydrophilic marker carboxyfluorescein and vesicles from VPGs. This was assumed to be due to bigger vesicle sizes and corresponding increase in packing density of the vesicular matrix. Upon dilution into a liposome dispersion both negative staining electron microscopy and dynamic laser light scattering analysis confirmed a distinct increase in liposome size, mainly due to fusion of small (20 nm) vesicles with unfavourable curvature. This was consistent with the observed increase in encapsulation efficiency of carboxyfluorescein. Phospholipid hydrolysis during autoclaving was negligible with lysophosphatidylcholine formation of less than 2% (thin layer chromatography). Despite significant change of their morphological and functional properties during autoclaving VPGs retained their main characteristics, such as vesicular structure, sustained release and dilutability to liposome dispersions, and are, therefore, considered as autoclavable.

Fluoresceins↗
PubMed1999

Effect of steam sterilization inside the turbine chambers of dental turbines.

OBJECTIVE: It has been demonstrated that contamination of the insides of high-speed dental turbines occurs and that bacteria as well as viruses may remain infectious when expelled from such turbines during subsequent use. Consequently, it has been widely recommended that a high-speed turbine be sterilized after each patient. The purpose of this study was to evaluate the effect of steam autoclaving on a high-speed dental turbine with a contaminated turbine chamber. STUDY DESIGN: Streptococcus salivarius and endospores of Bacillus stearothermophilus were used as test organisms to determine the effectiveness of 4 different small non-vacuum autoclaves and one vacuum autoclave. RESULTS: The study demonstrated different efficiencies among the small non-vacuum autoclaves, the best showing close to a 6 log reduction of the test organisms inside the turbine chamber. When cleaning and lubrication of the high-speed dental turbine was carried out before autoclaving, this level of reduction was observed for all the examined non-vacuum autoclaves. CONCLUSIONS: It is concluded that cleaning before sterilization is essential for safe use of high-speed dental turbines and that small non-vacuum autoclaves should be carefully evaluated before being used for the reprocessing of hollow instruments such as high-speed turbines.

Dental High-Speed Equipment↗
PubMedDate not supplied

Process considerations and economic evaluation of two-step steam pretreatment for production of fuel ethanol from softwood.

To increase the overall ethanol yield from softwood, the steam pretreatment stage can be carried out in two steps. The two-step pretreatment process was evaluated from a techno-economic standpoint and compared with the one-step pretreatment process. The production plants considered were designed to utilize spruce as raw material and have a capacity of 200,000 tons/year. The two-step process resulted in a higher ethanol yield and a lower requirement for enzymes. However, the two-step process is more capital-intensive and has a higher energy requirement. The estimated ethanol production cost was the same, 4.13 SEK/L (55.1 cent /L) for both alternatives. For the two-step process different energy-saving options were considered, such as a higher concentration of water-insoluble solids in the filter cake before the second step, and the possibility of excluding the pressure reduction between the steps. The most optimistic configuration, with 50% water-insoluble solids in the filter cake in the feed to the second pretreatment step, no pressure reduction between the pretreatment steps, and 77% overall ethanol yield (0.25 kg EtOH/kg dry wood), resulted in a production cost of 3.90 SEK/L (52.0 cent /L). This shows the potential for the two-step pretreatment process, which, however, remains to be verified in pilot trials.

Bioreactors↗
PubMed2002

Singlet oxygen mediated degradation of lignin--isolation of oxidation products from steam-exploded lignin from pine.

Lignin obtained from steam explosion of pine was fully characterized. Elemental analysis, GPC, and ultraviolet and 1H and 13C NMR spectra revealed that the obtained lignin contains both guaiacyl and syringyl units. Lignin was dissolved in acetonitrile-ethanol and treated with visible light in the presence of both oxygen and Rose Bengal for different irradiation times. Column chromatography of the residue showed the presence of six compounds: trans-sinapyl alcohol, 4-hydroxy-3,5-dimethoxybenzaldehyde, 4-hydroxy-3,5-dimethoxyphenylacetone, 4-hydroxy-3-methoxybenzaldehyde, cis-sinapyl alcohol, and sinapyl aldehyde. The total amount of fine chemicals increases with the irradiation time. However, it increases rapidly during the first eight hours, but increases slowly after this period. The most important compounds obtained were sinapyl alcohol and 4-hydroxy-3,5-dimethoxybenzaldehyde, but sinapyl alcohol was obtained in the highest amounts after eight hours' irradiation, while the highest amounts of 4-hydroxy-3,5-dimethoxybenzaldehyde were obtained after irradiation for 4 h. After 48 h irradiation comparable amounts of sinapyl aldehyde were obtained. We obtained only compounds derived from the syringyl units in lignin in agreement with the hypothesis that the guaiacyl units are more easily oxidised.

Lignin↗
PubMed1989

[Atmocausis vaporization. Most severe internal burns following intrauterine use of steam].

The article gives a brief historical review of the now obsolete method of atmocausis and reports on two cases of very deep internal burns after direct intrauterine application of superheated steam; one of the patients died as a result of this procedure. In the thirties this method was used especially to arrest intrauterine perimenopausal bleeding, but has since been abandoned.

Adult↗
PubMed1990

Resistance of scrapie infectivity to steam autoclaving after formaldehyde fixation and limited survival after ashing at 360 degrees C: practical and theoretical implications.

Scrapie-infected hamster brains and their extracted amyloid fibrils were subjected to formaldehyde and steam autoclaving, alone or in combination. Treatment with formaldehyde before autoclaving stabilized infectivity, whereas treatment after autoclaving was either inactive or further reduced infectivity. In additional experiments on specimens (not treated with formaldehyde) that were subjected to dry heat, a small amount of infectivity still survived a 1-h exposure to temperatures as high as 360 degrees C. These results are consistent with the operation of a comparatively primitive molecular mechanism for the initiation of scrapie agent replication (perhaps an inorganic crystal nucleation step) and the subsequent participation of an organic macromolecule (scrapie amyloid protein) that is susceptible to intramolecular cross-stabilization by formaldehyde.

Animals↗
PubMed2006

Larkinella insperata gen. nov., sp. nov., a bacterium of the phylum 'Bacteroidetes' isolated from water of a steam generator.

A Gram-negative bacterium, designated strain LMG 22510T, was isolated from water of a pharmaceutical company steam generator. The cells had a ring-like and horseshoe-shaped morphology and possessed gliding motility. Phylogenetic analysis of the 16S rRNA gene sequence showed that the strain was a member of the Flexibacter group within the phylum 'Bacteroidetes'; its nearest neighbour was Spirosoma linguale (88.8 % sequence similarity). DNA base content, fatty acid composition and biochemical characteristics were determined. Genotypic and phenotypic data indicated that strain LMG 22510T could not be assigned to any recognized genus; therefore, a novel genus and species is proposed, Larkinella insperata gen. nov., sp. nov., with LMG 22510T (= NCIMB 14103T) as the type strain.

Base Composition↗
PubMed1995

Biological indicators for low temperature steam and formaldehyde sterilization: the effect of defined media on sporulation, growth index and formaldehyde resistance of spores of Bacillus stearothermophilus strains.

Preliminary screening was carried out on spores of 29 strains of Bacillus stearothermophilus to determine their potential as biological indicator organisms for low temperature steam and formaldehyde sterilization. Each strain was sporulated on four chemically defined media. Fourteen strains produced satisfactory sporulation on one or more of the media but there was considerable variation in the extent of sporulation. The growth index of the spores, which was dependent on both the strain of organism and the sporulation medium, ranged from 1% to 90%. The spores were appraised on the basis of their resistance to inactivation by 0.5% w/v formaldehyde in aqueous solution at 70 degrees C. The survivor curves obtained could be characterized into five types on the basis of the shape of the curve. Only five strains of Bacillus stearothermophilus produced spores with the characteristics of high resistance, linear semi-logarithmic survivor curve and high growth index that would be required of a potential biological indicator organism.

Culture Media↗
PubMed1988

Outcome of sterilization by steam autoclaves in Danish dental offices.

The aims of this study were to evaluate the performance of autoclaves and the use of biologic indicators for sterilization control, and to look for predictor variables for improperly functioning autoclaves in Danish dental offices. The study population comprised 314 Danish dental offices (participation rate 94%); 177 from the public Child Dental Service (CDS) and 137 from private practice. A minor questionnaire and five biologic indicators (Attest Biological Indicator for Steam Sterilization, 3M) were sent to the participants. CDS offices were found more inclined to use biologic indicators than PP offices (P less than 0.00001). Among CDS autoclaves 2.3% (95% confidence limit: 0.9-5.7%) failed to sterilize compared to 7.3% (95% confidence limit: 4.0-12.9) of the PP autoclaves. This difference is not statistically significant, but the confidence intervals indicate a possible true difference in favor of a better outcome in the CDS offices. Looking at the whole sample no other predictor variable for inadequate sterilization could be determined as differences were statistically insignificant with regard to years of professional experience, age and brand of autoclave, and use of biological control. Recommendations from an official body stating the approved types of sterilization control in dental offices would be of value.

Denmark↗
PubMed1996

The effect of steam sterilization on the properties of set dental gypsum models.

The aim of this study was to investigate the viability of autoclave sterilization of set dental gypsum models. The effects of autoclaving on the strength, surface hardness and dimensions of specimens of plaster, stone and diestone were investigated. In addition, sodium succinate was used to minimize any changes produced by autoclaving. It has been shown that dental gypsum casts can be successfully steam sterilized. The results showed that for fully-dried gypsum products, autoclaving at 132 degrees C for 5 minutes rendered the casts unacceptable for use. Autoclaving at 121 degrees C for 16 minutes had less effect although casts were still not satisfactory, with the main problems being excessive expansion for plaster and significant strength and surface hardness loss for stone and diestone. The effect of three additional treatment procedures was examined and the least degradation was observed when the casts were soaked in 1 per cent sodium succinate solution and dried prior to autoclaving, then soaked in water immediately after. Using this procedure the average change in properties for plaster, stone and diestone respectively were: loss of strength 36, 21 and 28 per cent, loss of surface hardness 34, 21 and 33 per cent, and linear expansion 0.05, 0.09 and 0.13 per cent. Further refinement may improve the procedure.

Calcium Sulfate↗
PubMedDate not supplied

Monitoring steam sterilization practices in primary care settings.

Steam sterilization is a common method for processing reusable instruments in ambulatory care settings. Ensuring that sterilization practices are consistent with accepted standards is a quality-of-care parameter as well as an infection control issue. Factors that must be considered in improving performance in this important area are: operator training and continued competency, selection of chemical and biological media and methods, work flow controls, documentation methods and standards, written policies and procedures to support practices, and ongoing monitoring of the system and practices with feedback to responsible persons.

Ambulatory Care↗
PubMed1961

Factors concerned in the efficient steam sterilization of surgical dressings.

Some of the factors affecting the efficient steam sterilization of dressings have been examined. A jacketed sterilizer will process a load more quickly than a sterilizer without a jacket. The level of fore-vacuum is critical and must reach an absolute pressure of 20 mm. Hg (29.2 in.Hg vacuum) or less. This will overcome all conditions of overpacking studied. The level of after-vacuum should be 100 mm. Hg absolute or less, preferably near 50 mm. Hg absolute. Overpacking cannot be defined in terms of weight of a fabric per unit volume of container but occurs when a load is compressed in its container.

Bandages↗
PubMed1968

Residual formaldehyde after low-temperature steam and formaldehyde sterilization.

The levels of formaldehyde remaining in various articles have been estimated immediately after a low-temperature steam and formaldehyde sterilizing process and after various periods of aeration. These levels have been compared with the levels of ethylene oxide remaining after exposure to an ethylene oxide sterilizing process. In rubber and polythene and a plastic, formaldehyde levels are low and slowly fall even further. Ethylene oxide levels are relatively much higher even after seven days' aeration. It is not considered that the residual levels of formaldehyde in rubber, polythene, and a plastic should constitute a danger. Residual levels of formaldehyde in fabrics and paper are higher but this may be of value by giving a self-disinfecting action on storage.

Air↗
PubMed1973

Testing a steam-formaldehyde sterilizer for gas penetration efficiency.

A test piece is described for monitoring the performance of low-temperature steam-with-formaldehyde sterilizers. Comparative tests have shown it to be more difficult to penetrate than an arterial catheter when exposed to the same sterilizing conditions. It is permanent and simple to use and maintain. The growth or non-growth of bacterial spores, in the convenient form of spore strips, is used to indicate the efficacy of sterilization.

Atmospheric Pressure↗
PubMed1978

Sterilisation in the laboratory autoclave using direct air displacement by steam.

A device using a steam injection funnel is described by means of which air can be driven quickly and surely from an autoclave load. It is simple and inexpensive, necessitates no changes in the working routine of a microbiology laboratory, and does not interfere with the operation of the autoclave in its normal mode.

Laboratories↗