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Frontiers in Public Health 2022Nanomaterials are suspected of causing health problems, as published studies on nanotoxicology indicate. On the other hand, some of these materials, such as... (Review)
Review
BACKGROUND
Nanomaterials are suspected of causing health problems, as published studies on nanotoxicology indicate. On the other hand, some of these materials, such as nanostructured pyrogenic and precipitated synthetic amorphous silica (SAS) and silica gel, have been used for decades without safety concerns in industrial, commercial, and consumer applications. However, in addition to many and studies that have failed to demonstrate the intrinsic toxicity of SAS, articles periodically emerge, in which biological effects of concern have been described. Even though most of these studies do not meet high-quality standards and do not always use equivalent test materials or standardized test systems, the results often trigger substance re-evaluation. To put the results into perspective, an extensive literature study was carried out and an example of amorphous silica will be used to try to unravel the reliability from the unreliable results.
METHODS
A systematic search of studies on nanotoxicological effects has been performed covering the years 2013 to 2018. The identified studies have been evaluated for their quality regarding material and method details, and the data have been curated and put into a data collection. This review deals only with investigations on amorphous silica.
RESULTS
Of 18,162 publications 1,217 have been selected with direct reference to experiments with synthetically produced amorphous silica materials. The assessment of these studies based on defined criteria leads to a further reduction to 316 studies, which have been included in this systematic review. Screening for quality with well-defined quantitative criteria following the GUIDE nano concept reveals only 27.3% has acceptable quality. Overall, the and data showed low or no toxicity of amorphous silica. The data shown do not support the hypothesis of dependency of biological effects on the primary particle size of the tested materials.
CONCLUSION
This review demonstrates the relatively low quality of most studies published on nanotoxicological issues in the case of amorphous silica. Moreover, mechanistic studies are often passed off or considered toxicological studies. In general, standardized methods or the Organization for Economic Cooperation and Development (OECD) guidelines are rarely used for toxicological experiments. As a result, the significance of the published data is usually weak and must be reevaluated carefully before using them for regulatory purposes.
Topics: Nanostructures; Particle Size; Reproducibility of Results; Silicon Dioxide
PubMed: 35784253
DOI: 10.3389/fpubh.2022.902893 -
Pharmacology Research & Perspectives Aug 2020Severe hyperthermia from classical or exertional heatstroke, or from drug ingestion or other noninfective pyrogens, is associated with a high mortality and morbidity. A...
Severe hyperthermia from classical or exertional heatstroke, or from drug ingestion or other noninfective pyrogens, is associated with a high mortality and morbidity. A systemic pro-inflammatory response occurs during heatstroke, characterized by elevated cytokines with endotoxemia from elevated lipopolysaccharide (LPS) levels. Corticosteroids reduce LPS and cytokine levels, suggesting that they may improve outcome. A systematic review searching Embase, MEDLINE, and PubMed from the earliest date available until September 2019 was conducted, according to the PRISMA guidelines, with five papers identified. In four studies, systemic steroids administered before or at the onset of heat stress improved mortality or reduced organ dysfunction. Survival time was greatest when steroid administration preceded heat stress. In one study, a nonsignificant increase in mortality was seen. A dose response was observed, with higher doses extending survival time. Animal studies suggest that steroids improve mortality and/or organ dysfunction after an episode of heat stress or extreme hyperthermia.
Topics: Animals; Cytokines; Dose-Response Relationship, Drug; Glucocorticoids; Heat Stroke; Humans; Hyperthermia; Lipopolysaccharides; Randomized Controlled Trials as Topic; Severity of Illness Index
PubMed: 32666709
DOI: 10.1002/prp2.626 -
Biomedical Instrumentation & Technology 2023The effect of sterilization on bacterial endotoxin is receiving greater attention within the medical device industry. Contributing factors to this increased attention...
The effect of sterilization on bacterial endotoxin is receiving greater attention within the medical device industry. Contributing factors to this increased attention include the growing popularity of transferring devices among sterilization modalities and the focus on aspects of microbiological quality other than sterilization. This systematic review examined the effects of sterilization on bacterial endotoxin, with attention drawn to industry standards and regulations to elucidate whether such documents are aligned with published data. In summary, numerous experiments have shown a reduction in pyrogenicity and/or limulus amebocyte lysate reactivity of endotoxin following sterilization, whereas a number of publications and industry standards have claimed (without data or references) that sterilization does not inactivate endotoxin. The results of this review would be useful for device manufacturers when selecting a sterilization modality or deciding whether to test for endotoxin pre- vs poststerilization, as well as for standards developers and regulators in aligning standards and regulations with peer-reviewed data.
Topics: Ethylene Oxide; Electrons; Steam; Endotoxins; Sterilization
PubMed: 37624937
DOI: 10.2345/0899-8205-57.3.98 -
Frontiers in Pharmacology 2012Fifty years after the elucidation of lipopolysaccharides (LPS, endotoxin) as the principal structure of Gram-negative bacteria activating the human immune system, its...
Fifty years after the elucidation of lipopolysaccharides (LPS, endotoxin) as the principal structure of Gram-negative bacteria activating the human immune system, its Gram-positive counterpart is still under debate. Pyrogen tests based on the human monocyte activation have been validated for LPS detection as an alternative to the rabbit test and, increasingly, the limulus amebocyte lysate test. For full replacement, international validations with non-endotoxin pyrogens are in preparation. Following evidence-based medicine approaches, a systematic review of existing evidence as to the structural nature of the Gram-positive pyrogen was undertaken. For the three major constituents suggested, i.e., peptidoglycan, lipoteichoic acids (LTA), and bacterial lipoproteins (LP), the questions to be answered and a search strategy for relevant literature was developed, starting in MedLine. The evaluation was based on the Koch-Dale criteria for a mediator of an effect. A total of 380 articles for peptidoglycan, 391 for LP, and 285 for LTA were retrieved of which 12, 8, and 24, respectively, fulfilled inclusion criteria. The compiled data suggest that for peptidoglycan two Koch-Dale criteria are fulfilled, four for LTA, and two for bacterial LP. In conclusion, based on the best currently available evidence, LTA is the only substance that fulfills all criteria. LTA has been isolated from a large number of bacteria, results in cytokine release patterns inducible also with synthetic LTA. Reduction in bacterial cytokine induction with an inhibitor for LTA was shown. However, this systematic review cannot exclude the possibility that other stimulatory compounds complement or substitute for LTA in being the counterpart to LPS in some Gram-positive bacteria.
PubMed: 22529809
DOI: 10.3389/fphar.2012.00056