Biomedical subjects

Edward C Tidswell

Publications and source records attributed to Edward C Tidswell.

3 recordsLinked to original sources

PubMed1996

Ether-bond scission in the biodegradation of alcohol ethoxylate nonionic surfactants by Pseudomonas sp. strain SC25A.

Pseudomonas sp. strain SC25A, previously isolated for its ability to grow on alcohol ethoxylates (PEG dodecyl ethers) as sole source of carbon and energy, was shown to be capable of growth on the dodecyl ethers of mono-, di, tri- and octaethylene glycols. Comparative growth yields for this series of alcohol ethoxylate nonionic surfactants indicated that, whereas all of the carbon of monoethylene glycol dodecyl ether (MEGDE) was assimilable, only the alkyl chains were assimilated from the higher ethoxamers. These results are interpreted in terms of a primary biodegradation mechanism in which the scission of the dodecyl-ether bond is the first step. In the case of MEGDE this step separates the dodecyl chain from a C2 fragment, both of which are readily assimilable; for the higher ethoxamers, the assimilable dodecyl chain is accompanied by an ether-containing PEG derivative which would require further rounds of either scission before assimilation. Whole cells and cell extracts converted [1-14C]MEGDE initially and very rapidly to radiolabelled dodecanol. Disappearance of [14C]dodecaol was accompanied by production of [14C]dodecanal. [14C]Dodecanoic acid was present at relatively low concentrations throughout the incubation periods. [14C]Dodecan-1, 12-dioic acid was produced in significant quantities (up to 25% radiolabel), and the onset of its production coincided with the peak concentration of dodecanal, the disappearance of which mirrored the appearance of the dioic acid. Under anaerobic conditions in the presence of cell extracts, dodecanol (55% of radiolabel) and dodecanal (22%) accumulated rapidly from MEGDE, but there was little subsequent conversion to mono- or dicarboxylic acids. These results are interpreted in terms of a pathway initiated by dodecyl-ether cleavage to produce dodecanol, which is subsequently oxidized to dodecanal and dodecanoic acid. The formation of dodecan-1, 12-dioic acid, probably from dodecanal, may represent a means of harbouring carbon under non-growing conditions.

Biodegradation, Environmental↗

PubMedDate not supplied

Bacterial adhesion: considerations within a risk-based approach to cleaning validation.

Pharmaceutical manufacturing processes are vulnerable to varying degrees of microbial challenge (hazard) quantifiable as microbial ingress, and microbial retention risks affecting raw materials and inputs to the final product. Control over these risks is exacted by both purposefully designed and incidental (or fortuitous) properties of the manufacturing processes. Within the manufacturing environment, equipment cleaning and hold processes are uniquely prone to microbial challenge yet paradoxically demonstrate the greatest potential for mitigation of these risks. Cognition of those components and contributing factors associated with microbial challenge are necessary to facilitate scientifically sound risk assessments. In the context of equipment cleaning and hold processes, risk assessments are necessary to identify and contrive conditions, which are truly worst case for the validation of the control of microbial challenge. A number of components contribute to the risk of microbial retention, yet the phenomenon of microbial adhesion to surfaces remains one of the most ubiquitous and perplexing. The dual purpose of this review is to primarily précis and provide in a single reference those multi-factorial features and variables contributing to bacterial adhesion, and secondly to provide a guide for interpretation of those considerations for integration into a risk-based approach to cleaning validation.

Bacterial Adhesion↗

PubMedDate not supplied

Quantitative risk modeling in aseptic manufacture.

Expedient risk assessment of aseptic manufacturing processes offers unique opportunities for improved and sustained assurance of product quality. Contemporary risk assessments applied to aseptic manufacturing processes, however, are commonly handicapped by assumptions and subjectivity, leading to inexactitude. Quantitative risk modeling augmented with Monte Carlo simulations represents a novel, innovative, and more efficient means of risk assessment. This technique relies upon fewer assumptions and removes subjectivity to more swiftly generate an improved, more realistic, quantitative estimate of risk. The fundamental steps and requirements for an assessment of the risk of bioburden ingress into aseptically manufactured products are described. A case study exemplifies how quantitative risk modeling and Monte Carlo simulations achieve a more rapid and improved determination of the risk of bioburden ingress during the aseptic filling of a parenteral product. Although application of quantitative risk modeling is described here purely for the purpose of process improvement, the technique has far wider relevance in the assisted disposition of batches, cleanroom management, and the utilization of real-time data from rapid microbial monitoring technologies.

Algorithms↗