Induction of 1,2-dicarbonyl compounds, intermediates in the formation of advanced glycation end-products, during heat-sterilization of glucose-based peritoneal dialysis fluids.
(17/814)
OBJECTIVE: To study the presence of 1,2-dicarbonyl compounds in peritoneal dialysis (PD) fluids, their concentration in effluents with increasing dwell time, and their role in the formation of advanced glycation end-products (AGEs). MEASUREMENTS: Dicarbonyl compounds in heat- and filter-sterilized PD fluids were quantified by reverse-phase high performance liquid chromatography (HPLC) after derivatization to dimethoxyquinoxaline derivatives. Kinetics of the in vitro formation of AGEs upon incubation of 1,2-dicarbonyl compounds or PD fluids with albumin, with or without aminoguanidine, were measured by AGE fluorescence (excitation/emission wavelengths of 350 nm/430 nm). PATIENTS: AGEs and dicarbonyl compounds were measured in effluents collected from standardized 4-hour dwells from 8 continuous cycling peritoneal dialysis patients. RESULTS: In PD fluids, 3-deoxyglucosone (3-DG) has been identified as the major dicarbonyl compound formed during the process of heat sterilization. The process also formed glyoxal (GO) and methylglyoxal (MGO), with the amount of 3-DG being approximately 25-60 times higher than GO and MGO. When incubated with albumin, the identified 1,2-dicarbonyl compounds rapidly formed AGEs. The formation of AGEs was more pronounced in conventional heat-sterilized PD fluids compared with filter-sterilized PD fluids, and was completely inhibited by aminoguanidine. In effluents, the concentration of MGO, GO, and 3-DG decreased with increasing dwell time, with a concomitant increase in AGE fluorescence. CONCLUSIONS: The dicarbonyl compounds 3-DG, MGO, and GO are potent promoters of AGE formation. The presence of these and possibly other dicarbonyl compounds formed during heat sterilization of glucose-based PD fluids is, to a large extent, responsible for the in vitroAGE formation by these fluids, as evidenced by the speed of AGE formation in PD fluids and the complete inhibition by aminoguanidine. Because 3-DG, MGO, and GO are rapidly cleared from PD fluids during dialysis, these compounds may contribute to the in vivo AGE formation in PD patients. (+info)
Effects of combined shear and thermal forces on destruction of Microbacterium lacticum.
(18/814)
A twin-screw extruder and a rotational rheometer were used to generate shear forces in concentrated gelatin inoculated with a heat-resistant isolate of a vegetative bacterial species, Microbacterium lacticum. Shear forces in the extruder were mainly controlled by varying the water feed rate. The water content of the extrudates changed between 19 and 45% (wet weight basis). Higher shear forces generated at low water contents and the calculated die wall shear stress correlated strongly with bacterial destruction. No surviving microorganisms could be detected at the highest wall shear stress of 409 kPa, giving log reduction of 5.3 (minimum detection level, 2 x 10(4) CFU/sample). The mean residence time of the microorganism in the extruder was 49 to 58 s, and the maximum temperature measured in the end of the die was 73 degrees C. The D(75 degrees C) of the microorganism in gelatin at 65% water content was 20 min. It is concluded that the physical forces generated in the reverse screw element and the extruder die rather than heat played a major part in cell destruction. In a rotational rheometer, after shearing of a mix of microorganisms with gelatin at 65% (wt/wt) moisture content for 4 min at a shear stress of 2.8 kPa and a temperature of 75 degrees C, the number of surviving microorganisms in the sheared sample was 5.2 x 10(6) CFU/g of sample compared with 1.4 x 10(8) CFU/g of sample in the nonsheared control. The relative effectiveness of physical forces in the killing of bacteria and destruction of starch granules is discussed. (+info)
Contamination of fluids from a hospital pharmacy.
(19/814)
An investigation into the cause of bacterial contamination of bottles of noninjectable water has been reported. A method of monitoring such bottles has also been described. The roles played by autoclave spray-cooling water and inadequate bottle seals in the contamination of fluids have been examined. Possible methods of reducing the risk of contamination are discussed and the design of an improved method of closure of sterile bottled fluids is stressed. Bacteriological examination is shown to be a more accurate index of the true rate of contamination than measurement of dye concentrations of bottle contents. (+info)
Sterilizable syringes: excessive risk or cost-effective option?
(20/814)
In recent years, many poorer countries have chosen to use disposable instead of sterilizable syringes. Unfortunately, the infrastructure and management systems that are vital if disposables are to be used safely do not exist. WHO estimates that up to 30% of injections administered are unsafe. The traditional sterilizable syringe had many disadvantages, some of which have been minimized through better design and the use of modern materials; others have been overcome because staff are able to demonstrate that they have performed safely. For example, the time-steam saturation-temperature (TST) indicator has enabled staff to demonstrate that a sterilizing cycle has been successfully completed. Health facility staff must be able to sterilize equipment, and the sterilizable syringe remains the least costly means of administering an injection. Data from countries that have acceptable systems for processing clinical waste indicate that safe and environmentally acceptable disposal, destruction and final containment cost nearly as much as the original cost of a disposable syringe. By careful supervision of staff behaviour and good management, some countries have demonstrated that they are able to administer safe injections with sterilizable syringes at a price they can afford. (+info)
Autoclaves and their dangers and safety in laboratories.
(21/814)
Using a laboratory downward displacement vertical autoclave with the help of thermocouples recorded on a 12 point multichannel strip recorder, the risk of failing to sterilize laboratory discard buckets has been demonstrated. The use of proper temperature and time controls can prevent this risk. A load in a bucket with perforated sides is more easily sterilized than in a solid bucket. Wire baskets, where appropriate, facilitate the sterilizing practice. The addition of water to a bucket does not reduce the time of heating up. It is desirable that sealed bottles of media should not be sterilized in simple downward displacement autoclaves, but if used, strict monitoring of temperatures and times is essential both in the heating up stage and especially in the cooling stage. The temperatures in bottles are slow to rise and very slow to fall. Bottles at high temperature 80-105 degrees C. or over have a high internal pressure which can allow the bottles to explode when subjected to thermal shock if removed too early. It is suggested that all laboratory autoclaves should have a load temperature simulator or similar device to control the temperature of the load during the cycle automatically. For the sterilization of fluid media, it is suggested that, in addition to a simulator there should be accelerated cooling to reduce damage to the media and, what is more important, to rapidly bring down the temperature and thus the internal pressure in the bottles to a safe level. The opening of the sterilizer door or lid should be automatically controlled by the load temperature simulator. (+info)
The effect of autoclave resterilisation on polyester vascular grafts.
(22/814)
OBJECTIVES: polyester grafts are expensive, single-use items. Some manufacturers of uncoated, woven grafts include instructions for autoclave resterilisation to be performed at the surgeon's own request. Others warn against such manipulation. Theoretically, the glass transition point of polyester at 70-80 degrees C and the possible acceleration of hydrolysis suggest that autoclave resterilisation at 135 degrees C might be a problem. MATERIALS AND METHODS: a DeBakey Soft Woven Dacron Vascular Prosthesis (Bard) and a Woven Double Velour Dacron Graft (Meadox) were autoclave-resterilised 0 to 20 times, having been weighed before and after sterilisation. Tactile testing was performed. Mechanical properties were examined by probe puncture and single-filament testing, the surface was examined by scanning electron microscopy and the degree of hydrolysis by infra-red spectroscopy. RESULTS: tactile testing revealed a change of feeling with increasing cycles of resterilisation. Investigation of weight, textile strength, single-filament strength, electron microscopy of the surface and infra-red spectroscopy showed no change of the material. CONCLUSIONS: changes felt are presumably a surface phenomenon, not measurably affecting strength or chemistry of material after autoclave resterilisation. We therefore feel that it is safe to use once-autoclave-resterilised surplus uncoated polyester grafts, provided that sterility is guaranteed. (+info)
Preclinical evaluation of prototype products.
(23/814)
Preclinical evaluation of medical devices (prototype products) offers the opportunity to investigate and study the intended use of device materials. Preclinical evaluation programs are designed to determine the efficacy, safety, and biocompatibility of biomaterials, prostheses, and medical devices. The purpose of safety testing is to determine if a material presents potential harm to the human; it evaluates the interaction of the material with the in vivo environment and determines the effect of the host on the implant. Preclinical evaluation is the determination of the ability of the prototype product to perform with appropriate host response in a specific application, considered from the perspective of human clinical use. Therefore, preclinical data should include materials science and engineering, biology, biochemistry, medicine, host reactions and their evaluation, the testing of biomaterials, and the degradation of materials in a biological environment. (+info)
Strategies for safe injections.
(24/814)
In 1998, faced with growing international concern, WHO set out an approach for achieving injection safety that encompassed all elements from patients' expectations and doctors' prescribing habits to waste disposal. This article follows that lead and describes the implications of the approach for two injection technologies: sterilizable and disposable. It argues that focusing on any single technology diverts attention from the more fundamental need for health services to develop their own comprehensive strategies for safe injections. National health authorities will only be able to ensure that injections are administered safely if they take an approach that encompasses the whole system, and choose injection technologies that fit their circumstances. (+info)