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Biomedical subjects

H van Doorne

Publications and source records attributed to H van Doorne.

11 recordsLinked to original sources
PubMed2000

The lactoperoxidase system: the influence of iodide and the chemical and antimicrobial stability over the period of about 18 months.

The lactoperoxidase (LP) system is a natural antimicrobial system, the use of which has been suggested as a preservative in foods and pharmaceuticals. The effect of adding iodide to the LP system, the chemical stability and the change in antimicrobial effectiveness during storage was studied. Addition of iodide with thiocyanate increased the fungicidal and bactericidal effect against Candida albicans, Escherichia coli and Staphylococcus aureus. Pseudomonas aeruginosa showed the same inhibition in the LP system with iodide and without iodide. Storage of the LP system in completely filled airtight containers for 18 months caused a 35% loss of the initial thiocyanate concentration. The antimicrobial activity of this LP system was strong enough to kill inocula of 106 cfu ml-1 of the four test organisms within 2 h of contact time. During storage of the air-containing LP system, the concentration of thiocyanate was reduced below detection limit within 7 d, the concentrations of hypothiocyanite and hypoiodite within 350 d. After 516 d the antimicrobial activity of air-containing LP system was strong enough to kill inocula of 106 cfu ml-1 Ps. aeruginosa within 2 h, Staph. aureus within 4 h and Candida albicans and E. coli within 1 week of contact time.

Anti-Bacterial Agents↗
PubMed1994

The preservation of some oral liquid preparations. The replacement of chloroform by other preservatives.

Chloroform should be considered as an obsolete preservative for pharmaceutical preparations, because of its toxicological implications and its physical instability. The effectiveness of possible alternatives for chloroform in three oral liquid pharmaceutical preparations was investigated, using a microbiological challenge test. Magnesium trisilicate mixture (British Pharmacopoeia) can be adequately preserved with methylparaben (2 g/l). Only insignificant amounts of methylparaben were absorbed by the solids present in the magnesium trisilicate mixture. Ferrous sulfate mixture (British Pharmacopoeia) can be preserved with a mixture of methylparaben (1.8 g/l) and propylparaben (0.2 g/l). Sorbic acid (1 g/l) is a suitable preservative for promethazine hydrochloride syrup.

Administration, Oral↗
PubMed1994

Influence of background air on microbial contamination during simulated i.v.-admixture preparation.

The effect of the cleanliness of environmental air on the microbial contamination of a simulated i.v.-admixture during its preparation by aseptic transfer was studied under three conditions: (i) in a laminar air flow (LAF) bench situated in a class 1000 clean room, (ii) in an LAF bench in a microbiology laboratory and (iii) on a bench in an ordinary laboratory. Three thousand bottles were manually filled with 10 ml of a nutrient broth under each of the three conditions. The liquid was transferred by means of a syringe and a needle that pierced through the rubber closures of the bottles. The numbers of contaminated bottles under those three conditions were 1, 1 and 2, respectively. Background contamination had no demonstrable effect on the incidence of contamination, provided that preparation of the simulated i.v.-admixture solution was performed by skilled personnel in an LAF cabinet and air contact is avoided.

Air Pollution, Indoor↗
PubMed1984

Microbial contamination of a vitamin A formulation, prepared in local pharmacies, and its preservation against yeasts and moulds.

The microbial contamination of 44 samples of a vitamin A preparation in sucrose syrup was investigated. The contaminants were almost exclusively yeasts and moulds. Microbiological and physicochemical studies showed that sorbic acid was the preservative of choice for this formulation. The results are discussed with respect to the preservation of non-sterile pharmaceuticals.

Drug Contamination↗
PubMed1981

Liquid modification of Baird-Parker's medium for selective enrichment of Staphylococcus aureus.

A liquid modification of Baird-Parker's medium is suggested for the detection of low (less than 20/g) numbers of Staphylococcus aureus. Model experiments showed that the medium had an acceptable level of selectivity and that it was non-inhibitory to injured cells. Practical evaluation demonstrated the advantage of selective enrichment procedures over both non-selective enrichment technique and direct plating methods.

Bacteriological Techniques↗
PubMedDate not supplied

Saponin, an inhibitory agent of carbon dioxide production by white cells: its use in the microbiologic examination of blood components in an automated bacterial culture system.

BACKGROUND: Blood components with a white cell count > 100 x 10(9) per L may cause false-positive results when the BacT/Alert system is used for the microbiologic examination. The effects of different concentrations of saponin on bacterial growth and on carbon dioxide production by blood fractions with a high white cell count, in particular peripheral blood progenitor cells and buffy coats, were investigated. STUDY DESIGN AND METHODS: The effect of saponin on carbon dioxide production was studied by adding different fractions of white cell-rich material (buffy coat or leukapheresis material) to BacT/Alert culture bottles with or without saponin and incubating these bottles. Five bacterial strains were used to inoculate the culture bottles at four levels ranging from about 1 colony-forming unit per mL to about 10(3) colony-forming units per mL. Aerobic and anaerobic bottles with and without saponin were used. RESULTS: It was demonstrated that the addition of 0.5 percent saponin to BacT/Alert culture bottles effectively inhibited carbon dioxide production, without affecting bacterial growth. CONCLUSION: Saponin at a concentration of 0.5 percent is a valuable additive to BacT/Alert culture media because it prevents false-positive results in the examination of white cell-rich blood components.

Bacteriological Techniques↗
PubMedDate not supplied

Sorption of bacterial endotoxin and retention of bacteria by positively charged membrane filters.

Positively charged membrane filters (Pall, Posidyne) were studied for their ability to retain both bacterial endotoxins and bacteria. Filters (0.2 microns pore size) were challenged with high (up to 5* 10(5) EU) levels of bacterial endotoxin. When the endotoxin was dispersed in water, a more than 10,000 fold reduction of the endotoxin was obtained, whereas the reduction was only a factor 20 when Ringer's solution was used to disperse the endotoxin. Retention of bacteria was dependent on the type of organism, the pore size of the filter and the suspending liquid. Although filters with pore sizes > 0.2 microns were not suitable to be used as a final filter in an aseptic production process, a very reduction in the number of bacteria could be obtained. Possible applications for these filters in the production of sterile pharmaceuticals are discussed.

Adsorption↗