Validation of methods
Philip A. Geis in Cosmetic Microbiology, 2006
The most expedient way to validate a sterilizing cycle in a microbiology laboratory is the use of a biological indicator (BI).3 We have not discussed sterilizers other than autoclaves, but BIs are useful for all sterilizer cycle validation methods including steam, dry heat, and ethylene oxide. For more extensive discussion of various other sterilizing devices, refer to Gardner and Peel.4 Biological indicators come in a variety of forms, including inoculated products with sterilant-resistant spores, spore paper strips, and disks and commercially available self-contained BI systems. The BIs should be placed in each corner of a load and in the center of an autoclave. The BIs are then incubated after exposure to the autoclave to see whether sterilization was effective.
Biomarkers of Toxicant Susceptibility
Anthony P. DeCaprio in Toxicologic Biomarkers, 2006
Methods for evaluating exposure and/or biological effects to genotoxic compounds are listed in Table 2. Biological indicators (biomarkers) of genotoxic risk are subdivided into indicators of internal dose, biologically effective dose, and early biological effects. According to this classification, it is possible to identify a biological indicator at every step of the pathway of a genotoxic substance within the organism, from absorption to nucleophilic attack, damage fixation, and excretion. In biological monitoring, a distinction must be made between indicators of exposure and of effect. The former (concentration of the substance or its metabolites in biological fluids; mutagenicity of excreted substances; attack by metabolites on hemoglobin and DNA) aim at highlighting the absorption of the compound in question and, if possible, at measuring its internal dose and biologically effective dose. The latter [chromosome aberrations (CA), sister chromatid exchanges (SCE), micronuclei (MN), hypoxanthine-guanine phosphoribosyl transferase (HPRT) mutants, simple cell gel electrophoresis (also called COMET assay), etc.] measure alterations in important genetic targets (i.e., chromosomes, chromatids, gene sequences, etc.). The link between the measured parameter and the development of tumors is very probably closer in the case of indicators of effect. In particular, elevated CA levels have clearly been associated with higher incidence of cancer (8).
Dermal Hypersensitivity: Immunologic Principles and Current Methods of Assessment
David W. Hobson in Dermal and Ocular Toxicology, 2020
Biological Monitoring — Because the immune response has the exceptional qualities of sensitivity and specificity, it can be manipulated as a biological indicator of exposure to a variety of chemicals, including allergens. The utility of an immune response to detect exposure to contact sensitizers and aeroallergens was demonstrated in BALB/c mice.212 Dose-dependent changes were observed in immune responses which could serve as an indicator of recent exposure to a specific allergenic chemical. The responses were highly specific (few false-positives) due to specific immunologic recognition of a chemical allergen moiety.213 In addition, specific serum antibodies can serve as qualitative indicators of prior exposures to a chemical. Such allergenic chemicals usually elicit an immunologic response against their form as a hapten, which is recognized by the circulating immunoglobulin during subsequent exposures in a sensitized host.119
Design and evaluation of in situ gel eye drops containing nanoparticles of Gemifloxacin Mesylate
Published in Drug Delivery, 2023
Vishwa J. Kalaria, S. Saisivam, Anas Alshishani, Jameel S. Aljariri Alhesan, Sumit Chakraborty, Mohamed Rahamathulla
The optimized formulation B3 in situ gel formulation containing Gemifloxacin Mesylate Nanoparticles was sterilized in an autoclave. During the sterilization process, a sterile filter paper strip impregnated with spores of Bacillus stearothermophilus as a biological indicator packed in an aluminum foil was also subjected to autoclave sterilization along with optimized formulation . The Biological indicator was transferred aseptically into petriplate containing nutrient agar medium and incubated at 37° C for 24 hrs. The Petriplate did not show any growth of Bacillus stearothermophilus. This proves that autoclave sterilization is proper. Apart from this, the sterilize optimized formulation was also subjected to test for sterility as per Indian Pharmacopeia (2018). The formulation passed the test for sterility proving that there is no microbial contamination.
Cluster analysis of lymphocyte subset from peripheral blood in newly diagnosed idiopathic aplastic anaemia patients
Published in Annals of Medicine, 2022
Wei Yu, Qianqian Wang, Meili Ge, Xue Shi
IAA is a special autoimmune disease attacked by autoreactive lymphocytes on haematopoietic precursors, leading to progressive aggravation of pancytopenia. Patients often manifest with anaemia, haemorrhage and severe infection. IAA is also a heterogeneous disease, characterised by a great difference in terms of disease severity and treatment outcome. Therefore, seeking a biological indicator that can distinguish patients with similar clinical patterns is of great importance to instruct treatment options and improve long-term survival of IAA patients. In this study, we identified four distinct subgroups of newly diagnosed IAA patients based on lymphocyte subset clustering analysis, and each subgroup shared immunological similarity of lymphocyte subset. We also investigated the clinical differences among the four subgroups.
An oxidation resistant pediocin PA-1 derivative and penocin A display effective anti-Listeria activity in a model human gut environment
Published in Gut Microbes, 2022
Taís M. Kuniyoshi, Paula M. O’Connor, Elaine Lawton, Dinesh Thapa, Beatriz Mesa-Pereira, Sara Abulu, Colin Hill, R. Paul Ross, Ricardo P. S. Oliveira, Paul D. Cotter
Distal colon model assays were approved by the Clinical Research Ethics Committee of the Cork Teaching Hospitals (protocol no. APC 104). Human fecal inoculum was prepared as previously described by O´Donnell et al.42 Briefly, each standardized fecal inoculum consisted of eight healthy donors who had not taken an antibiotic for 6 months prior to donating a fecal sample and did not harbor any significant acute or chronic illness. Ex vivo fermentation was carried out in bench top bioreactors micro-Matrix (Applikon Biotechnology, Heertjeslaan, DE, NE) according to the protocol described by O´Donnell et al.42 for each well: 400 µL of slurry, 6.5 log CFU/mL of L. monocytogenes 10403S, 2.6 µM of purified pediocin PA-1, pediocin M31L or penocin A were inoculated in fecal media46 up to a final volume of 5 mL. A well containing the bioindicator strain alone (no bacteriocin) was used as a control. Each treatment was performed in two independent assays. Samples were collected during the fermentation at time 0 (T0h), 5 (T5h) and 24 hours (T24h) and were serially diluted in maximum recovery diluent (MRD) (Oxoid Ltd., Basingstoke, HA, UK) and plated on Listeria Chromogenic Media supplemented with Polymyxin and Ceftazidime (Cruinn Diagnostics Ltd., Dublin, DU, IRE) at 30 °C for 48 h.
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