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H van de Voorde

Publications and source records attributed to H van de Voorde.

At least 37 records · Page 2Linked to original sources
PubMed1982

Determination of the time of death by fungal growth.

A woman was found in her bedroom, which had been kept at a constant temperature of 12 degrees C, several weeks after she had been murdered. The establishment of the time of death was attempted by examination of fungal development on two parts of her body. Agar slopes were inoculated with the fungal growth present on an eyelid and on the inguinal skin. After 1 day at 20 degrees C, the cultures were incubated at 11-12 degrees C. The cultures were then observed daily until growth was comparable to that on the tissues that had been frozen. By these means it could be established that the victim died at least 18 days before her body was discovered. This, in fact, turned out to be the case. Hyphomycetes growth on a corpse may be helpful in determining the time of death when the event happened 10-20 days earlier, provided that the average surrounding temperature is known.

Eyelids↗
PubMed1982

Sensitivity of aflatoxin b1 to ionizing radiation.

Aflatoxin B1 in a 5-micrograms/ml water solution was sensitive to ionizing radiation. Inactivation was assayed by the Ames microsome mutagenicity test and confirmed by thin-layer chromatography. Destruction of aflatoxin B1 had already begun at 2.5 kilograms (kGy; 1 kGy = 0.1 Mrad), but a dose exceeding 10 kGy was necessary for total destruction.

Aflatoxin B1↗
PubMed1979

A collaborative study on a new quantitative suspension test, the in vitro test, for the evaluation of the bactericidal activity of chemical disinfectants.

In a collaborative study on a new quantitative suspension test for the evaluation of the bactericidal activity of chemical disinfectants, three laboratories performed the in vitro test on a phenol and an aldehyde standard in the critical use dilutions using Staphylococcus aureus and Pseudomonas aeruginosa as test organisms. The most striking finding was that the means of the germidical effect of one laboratory were significant lower than those of both others. Nevertheless the dispersion of the results did not differ among the laboratories. The differences could not be attributed to the subculture technique followed, nor to the daily inconstancy of the bacterial suspension resistance. The only feature that could explain the difference was the assessment of the microbiological work in itself. It should be stated, however, that the variance of the germicidal-effect values were rather low for this kind of microbiological work, so that differences between laboratories were significant even if the absolute values differed less than 1 unit.

Aldehydes↗
PubMed1979

Course of antibiotic sensitivities in Escherichia coli and Staphylococcus aureus from animals.

In order to establish the evolution of resistance against the common antibiotics from the beginning of their use up to the present time, the sensitivity of Escherichia coli isolated from the cecum of wild boars was determined. The MIC's of E. coli from these animals in a zoological garden was examined for comparison. The samples from the wild boars were collected in five forests in the Belgian Ardennes. The MIC's obtained (Table 1) are comparable to the mean values given in the early literature concerning strains of human origin (Table 7). E. coli from wild boars in a zoological garden has less sensitivity than from domesticated animals. However, the MIC's of staphylococci from fecal matter of the animals in captivity were not markedly enhanced except for streptomycin (Table 3). It was striking to find that staphylococci were absent in all the fecal samples from the wild boars living in their natural environment. The specific habitat of staphylococci is in man. Wild boars are the ancestors of domestic pigs. The MIC's of E. coli from the latter were determined for evaluation of altered resistance. All isolated strains were fairly resistant to the six substances tested (Table 2). Chloramphenicol was still the most active antibiotic. Staphylococci from some domestic animals (pigs, cattle, chicken) were sensitive to all the substances tested except the aminoglucosides and ampicillin (Table 3). E. coli from pigs bred on large farms in Spain (Toledo and Badajoz Provinces) were also highly resistant (Table 4) to five compounds and sensitive to cephalotin, polymyxin B, furoxone, and Carbadox. The samples obtained from family farms also contained unsensitive strains (Avila Province). These animals had never been given antibacterial feed additives as was confirmed by examination of feed samples (Table 6). Staphylococci when present in the Spanish samples can be considered to be antibiotic sensitive with the same exceptions as in the Belgian samples and also unsensitive to chloramphenicol. The use of antibiotics in animal feed was very common in Spain as was shown by feed analysis (Table 6). The risk of transferable resistance by plasmids between animal species must not be very high. In some cases where resistance formation could be mediated by R-factors, sensitive E. coli or staphylococci were isolated. Resistance was not generalized among animals from the same farm or in adjacent sties. No explanation for this discrepancy was found.

Animal Feed↗
PubMed1977

Factors affecting pyrogen testing in rabbits.

A response of rabbits to toxins causing fever and originating from microorganisms may be related to different factors. In this respect the race and the age of the animals were examined as variables. Three rabbit strains of local origin were used: New Zealand White, White of Dendermonde and Holland race. As pyrogen preparations sterile surface water and preparations of E. coli strains were used. A bacterial count, as for ordinary drinking water examination, was carried out in order to evaluate the presence of bacteria to pyrogenicity. An attempt was made to remove the pyrogens by absorption on charcoal and by filtration through asbestos filters. A decrease of pyrogenicity was obtained but the fever toxins did not completely disappear with the simple procedure. The stability of the toxins found in surface waters was examined over a short range of preservation. Only a slow decrease in pyrogenic activity was seen. Pyrogens of E. coli were prepared in vitro, but used unpurified. A slight difference in the strains was observed, but all E. coli's were pyrogenic.

Age Factors↗
PubMed1976

Differences in destruction of cysts of pathogenic and nonpathogenic Naegleria and Acanthamoeba by chlorine.

The destructive action of chlorine on the pathogenic Naegleria fowleri and Acanthamoeba culbertsoni, the nonpathogenic N. gruberi, and an avirulent Acanthamoeba isolate was investigated. N fowleri is somewhat more sensitive to chlorine than N. gruberi, whereas the two Acanthamoeba strains are very resistant. This study yields information needed for the destruction of amoebic cysts in drinking water and swimming pools. It also gives some explanation for the occurence of Acanthamoeba strains in these waters.

Cell Wall↗
PubMed1976

Sensitivity of environmental microorganisms to antimicrobial agents.

The sensitivity of different microorganisms, considered as typical representatives of the microflora of soil and water, was established to evaluate the influence of the nonmedical use of antimicrobial agents on bacterial ecology. Only seven strains, six chemoorganotrophs and one chemolithotroph, could be considered as relatively sensitive to the 21 antimicrobial compounds tested. The other 29 microorganisms may be regarded as resistant to most antimicrobial agents. Streptomyces were sensitive to high concentrations of active substances. Broad-spectrum antibiotics showed an effect on environmental bacteria similar to that on human pathogens. Cephalothin stimulated the growth of a Chlorella sp. From these experiments, it appears that spilled antimicrobial agents have little chance of causing an alteration in the microbial ecology.

Anti-Bacterial Agents↗
PubMed1975

[Air pollution due to the burning of thermoplastics II (author's transl)].

Following on from the first publication, (12) concerning the burning of plastics, another 13 chemical pure polymers were burnt in an electric oven to determine the level of solid and gaseous air pollution caused by their stackgases. All 13 polymers are highly combustible but require different burning temperatures (300-900 degrees C) in order to be burnt completely (i.e. without ashrest). With the exception of PMMA and PTFE, all plastics leave a very heavy tar- and soot deposit after burning. At the other end of the scale, burning at low temperature (300 degrees C) gives rise to high concentrations of alipathic aldehyds. The pH of the exhaust-gases, dissolved in water, is neutral to strong acid (PTFE), and will cause a severe corrosion. The nitrogen-containing polymers pollute by forming cyanides, nitrogenoxides and ammonia. PTFE gives off high concentrations of fluorid into the air. PMMA decomposes in its monomer methylmethacrylate and forms large amounts of aliphatic aldehyds. ABS and SBR cause a styrene pollution.

Air Pollutants↗
PubMed1975

[The meaning of the results of four national disinfectant testing techniques (author's transl)].

The bactericidal activity of three disinfectant standards has been determined by four national methods (the qualitative suspension test of the German Society for Hygiene and Microbiology DGHM, the quantitative suspension test of the Dutch Committee on Phytopharmacy, the use-dilution method of the A.O.A.C. and the Kelsey and Sykes' test) in order to compare these four testing techniques. In previous publications the results of these experiments and the degree of standardisation of the four methods have been tested. The purpose of the present study is to evaluate to what extent the results obtained by the four testing techniques do correspond. The bactericidal activity can be expressed as a germicidal effect. In theory (Tab. 1) the values of germicidal effect can be similar for the four testing techniques. In practice (Tab. 2 and 3) it has been found that with the suspension technique of the DGHM systematically higher values are obtained than in the other tests. These can not be compared to each other, because the medication times differ. Although the values of the germicidal effect obtained are widely different, it can happen that the minimum effective concentration determined by the four methods be identical as each of these methods applies different criteria. The authors have therefore calculated the minimum effective concentration which is required for the disinfectant standard by the four disinfectant testing techniques (Tab. 4). Even here, no correspondence has been found between the four methods. The lethal concentration of the disinfectant standards determined by the use-dilution method of the A.O.A.C. is thus 2 to 16 times those required by the Dutch suspension test. The difference in effective concentrations, however, is not constant and is not related to the type of disinfectant or the test organism. In consequence, there is no way of establishing a comparison between the results of the four methods with a view to setting up a conversion table. Each disinfectant testing technique has its own characteristics.

Disinfectants↗