Biomedical subjects

C J Rabie

Publications and source records attributed to C J Rabie.

At least 19 recordsLinked to original sources

PubMed2004

Assessment of wood-inhabiting Basidiomycetes for biokraft pulping of softwood chips.

Wood-inhabiting Basidiomycetes have been screened for various applications in the pulp and paper industry and it is evident that different fungi need to be used to suit the specific requirements of each application. This study assessed the suitability of 278 strains of South African wood-decay fungi for the pre-treatment of softwood chips for kraft pulping. The influence of these fungi on kappa number, yield and strength properties of pulp was evaluated. A number of these strains were more efficient in reducing kappa number than the frequently used strains of Phanerochaete chrysosporium and Ceriporiopsis subvermispora. Six strains of Stereum hirsutum and a strain of an unidentified species were able to reduce the kappa number significantly without a significant influence on the pulp yield. Treatment of wood with two strains of S. hirsutum, one strain of Peniophora sp. and a strain of an unidentified species resulted in paper with improved strength properties.

Basidiomycota↗

PubMed1997

Enumeration of fungi in barley.

Estimation of fungal contamination of barley grain is important as certain fungi can proliferate during the malting process. The following factors which may affect the enumeration of fungi were evaluated: dilution versus direct plating, presoaked versus unsoaked grain, five culture media: potato dextrose agar (PDA), acidified Czapek-Dox agar (ACA), pentachloronitrobenzene agar; (PCNB) dichloran rose bengal chloramphenicol agar (DRBC) and malt salt agar; two disinfectants' ethanol/water (80:20 v/v) and sodium hypochlorite (3.5% w/v in H2O). Two barley samples, one having a high incidence of storage fungi and one with a high incidence of field fungi were used and most fungi were identified to species level. Results showed that direct plating was superior to dilution plating for assessing the mycoflora of barley. Unsoaked grain gave significantly higher counts than presoaked grain in the case of Alternaria alternata, Rhizopus oryzae, Epicoccum nigrum and Mucor spp. Presoaked grain resulted in higher counts of Penicillium spp. Chlorine disinfection resulted in significantly higher counts of Aspergillus flavus, Eurotium spp. and Penicillium spp. Ethanol disinfection resulted in higher counts of Mucor spp., Phoma sorghina, Rhizopus oryzae and Aspergillus restrictus. PDA and ACA, in general gave some what better results than DRBC for both field and storage fungi. PCNB consistently gave the highest Fusarium counts. More than thiry fungal genera were found in the two samples.

Agar↗

PubMed1991

Toxicity and moniliformin production by four recently described species of Fusarium and two uncertain taxa.

Four recently described species. Fusarium nygamai, F. dlamini, F. beomiforme and F. napiforme and two uncertain taxa, F. nygamai from millet in Africa and Fusarium species from rice with Bakanae disease, were tested for toxicity and moniliformin production. Cultures grown on autoclaved corn were fed to groups of four one-day-old ducklings for 14 days. Isolates that caused the death of 3 or 4 out of 4 ducklings were considered to be toxic and analyzed for moniliformin. All 15 isolates of F. dlamini tested were nontoxic. The other taxa contained some isolates that were toxic to ducklings and produced moniliformin in corn cultures. This is the first report of moniliformin production by F. beomiforme (200-890 micrograms/g), and F. napiforme (16-388 micrograms/g), and by F. nygamai not obtained from millet in Africa (15-874 micrograms/g). The highest production of moniliformin was obtained from the 19 isolates of F. nygamai from millet in Africa (4300-18,200 micrograms/g) and the 15 isolates from rice with Bakanae disease (2300-19,300 micrograms/g). The taxonomic position of these two uncertain taxa should be re-evaluated.

Animals↗

PubMed1991

Mycotoxic peripheral myelinopathy, myopathy, and hepatitis caused by Diplodia maydis in vervet monkeys.

During recent historical times many Africans changed their diet to one based on maize. The grain is regularly contaminated by fungi which are toxigenic to domestic animals and birds. After one of the fungi, Diplodia maydis, in pure culture on maize, was added to the food of omnivorous primates there was demyelination of nerves, atrophy, degeneration and necrosis of muscle, and hepatitis. These preliminary results are applicable to veterinary and laboratory animal sciences. They may also be medically significant since neuromuscular syndromes of unknown cause are prevalent among Africans. Nerve conduction velocities and organ weights are defined for vervet monkeys.

Animals↗

PubMed1991

Perinatal mortality in lambs of ewes exposed to cultures of Diplodia maydis (= Stenocarpella maydis) during gestation.

During 1987 when cob rot was rife, perinatal losses were reported in flocks and herds that had been exposed to diplodiosis. The affected lambs or calves were either stillborn or died soon after birth. Dosing trials at the Onderstepoort Veterinary Research Institute involving 82 ewes revealed that 66% of the offspring of dams exposed to cultures of Diplodia maydis (= Stenocarpella maydis) in the second trimester of pregnancy and 87% of lambs of ewes exposed in the third trimester were born dead or died soon afterwards. A status spongiosus similar to that of the field cases was present in the white matter of the brains of all the affected lambs. The lambs of ewes that had shown nervous signs and those of ewes that had not shown such signs were equally affected. The experiments also clearly demonstrated that foetuses were much more susceptible to diplodiosis than the adults, e.g. in the third trimester 87% of the lambs were affected compared to only 44% of the dams. No perinatal mortalities were recorded in the group exposed to the culture in the first trimester. Ewes developed significant resistance to intoxication after initial exposure to the culture and both the length of gestation and birth mass of the affected lambs were less than those of their untreated counterparts.

Animal Feed↗

PubMed1987

Toxicity of Diplodia maydis to broilers, ducklings, and laying chicken hens.

The toxicity of corn culture material of Diplodia maydis to ducklings, chicken broilers, and laying hens was investigated. Screening trials in ducklings using a 50% dietary concentration of D. maydis culture material showed that thirteen out of sixteen isolates obtained from different corn samples from South Africa as well as ones from the US and Argentina were highly toxigenic. Culture material of two isolates added as 20, 10, and 5% of the diet also proved to be toxic in ducklings. Incorporation of D. maydis culture material of two different South African isolates at 5%, 2% and 1% dietary concentrations in broilers resulted in significantly poorer weight gains. These isolates, both capable of inducing diplodiosis in ruminants and both acutely toxic in ducklings, nevertheless differed significantly in their toxigenic effect in broilers. Feeding of 5% culture material to laying hens for 7 days resulted in a drastic (43%) drop in egg production. Even at a .5% dietary level, egg production as well as egg weights of laying hens were significantly reduced. These results show that the regular and widespread occurrence of D. maydis in South African corn may be of economic importance in the poultry industry.

Animal Nutritional Physiological Phenomena↗

PubMed1986

T-2 toxin production by Fusarium acuminatum isolated from oats and barley.

Oats grain from South Africa was frequently found to be infested by toxic strains of Fusarium acuminatum, as was one barley sample. All 11 toxic strains tested produced T-2 toxin (0.8 to 2,600 mg/kg), and 6 of 11 strains produced diacetoxyscirpenol (0.6 to 8.4 mg/kg). This is the first record of T-2 toxin-producing Fusarium isolates from Africa and of the production of large amounts of T-2 toxin at relatively high (25 degrees C) temperatures.

Animals↗

PubMed1985

Toxicity of Diplodia maydis in farm and laboratory animals.

The acute toxicity of maize culture material of eight strains of Diplodia maydis in ducklings, as well as the ability of five of these strains to induce typical diplodiosis (a neuromuscular disease) in cattle and sheep was shown. Typical diplodiosis was induced in 17 sheep and 11 cattle. Two of the five toxic strains were isolated from maize involved in diploidiosis outbreaks, the others from commercial maize. Strains inducing diplodiosis could be isolated from commercial maize from the USA, Argentina and South Africa. There was no correlation between the toxicity of D. maydis strains in ducklings and their ability to induce diplodiosis in cattle and sheep. Some isolates were acutely toxic to ducklings and rats but were unable to induce diplodiosis in either cattle or sheep. Others, equally toxic to ducklings and rats, induced diplodiosis in cattle and sheep at low dose levels. Two doses, each of 5 g/kg, of maize culture material of isolates from the USA, Argentina and South Africa induced diplodiosis in sheep. Culture material incubated for less than 8 wk could not induce diplodiosis in cattle. Acute toxicity in ducklings and rats also increased with longer incubation periods. Cultures of non-sporulating and profusely sporulating strains were equally toxic to ducklings. Heat treatment of culture material for 48 days at 45 degrees C failed to reduce toxicity in ducklings.

Animal Feed↗

PubMed1985

Induction of diplodiosis, a neuromycotoxicosis, in domestic ruminants with cultures of indigenous and exotic isolates of Diplodia maydis.

Diplodiosis, a neuromycotoxicosis, principally of cattle, which is characterized by ataxia, paresis and paralysis, was induced in 13 cattle, 16 sheep and 3 goats, by dosing them with Diplodia maydis [= D. zeae (Schw.) Lév.] cultured on sterilized maize seeds. The results of these experiments confirmed the findings of earlier workers that diplodiosis is a mycotoxicosis caused by D. maydis. The intoxication was induced with cultures of South African isolates of D. maydis obtained from local maize, one of which was associated with a suspected field outbreak, and with cultures of isolates from maize imported from the United States of America and Argentina. Other findings emerging from the experiments were, inter alia, that cultures incubated for less than 8 weeks were seemingly non-toxic, that there was little individual variation in response of cattle to cultures of the different toxic isolates or batches of the isolates, that apparent relapses of clinical signs can occur several weeks after dosing had ceased and that a small percentage of animals can show permanent locomotory disturbance. Light microscopical examination revealed no lesions in acutely affected animals, but an extensive laminar subcortical status spongiosis was evident in the cerebrum and cerebellum of a sheep that had been long paralysed and a steer that had permanent locomotory disturbance.

Animals↗

PubMed1984

Toxicity of rhizonin A, isolated from Rhizopus microsporus, in laboratory animals.

Maize culture material of 25 isolates of the genera Rhizopus and Mucor caused deaths in day-old unsexed Pekin ducklings when fed as a 50% (w/w) mixture with duckling feed. Nine of these isolates were tested for toxicity in young inbred male BD IX rats, which were fed a mixture of 50% (w/w) culture material and rat feed. Only one isolate of Rhizopus microsporus was clearly toxic, causing 100% mortality in rats within 10 days. Growth in rats was reduced by adding culture material of this isolate to the feed in concentrations of 2.5, 5, 10 or 20% (w/w). The same isolate of R. microsporus was used to produce the mycotoxin rhizonin A. Pure rhizonin A was dissolved in dimethylsulphoxide and given to young male partially inbred albino rats by gavage in single doses of 70, 96, 131 or 180 mg/kg. The lowest dose exceeded the LD100. Evaluated by light microscopy, lesions in livers and kidneys were similar in rats fed culture material and in those intubated with rhizonin A. Hepatocytes showed changes ranging from degeneration to necrosis, the liver-tissue architecture was changed by disassociation of liver cell cords and there was periportal bile-duct proliferation. Renal tubular epithelium showed changes ranging from degeneration to necrosis.

Animals↗

PubMed1982

Moniliformin production and toxicity of different Fusarium species from Southern Africa.

Four new moniliformin-producing species of Fusarium were found, viz., F. acuminatum, F. concolor, F. equiseti, and F. semitectum. Isolates of F. acuminatum and F. concolor produced large amounts of moniliformin (3.4 and 9.5 g/kg, respectively), whereas isolates of the other three species yielded less than 30 mg/kg. The production of moniliformin by isolates of F. oxysporum and F. avenaceum from southern Africa is described. All 14 toxic isolates of F. oxysporum produced moniliformin. Most isolates of F. fusarioides and all six isolates of Fusarium moniliforme va. subglutinans tested produced moniliformin, as did 28 of 36 toxic isolates of F. moniliforme. A number of F. moniliforme isolates produced greater than 10 g/kg, and one isolate yielded 33.7 g/kg in corn after incubation for 5 weeks at 25 degrees C. Moniliformin production in the field in corn ears was shown by inoculating plants with known moniliformin-producing isolates of three Fusarium species. Yields of up to 645 mg/kg were recorded. Isolates of F. acuminatum, F. equiseti, F. fusarioides, and F. moniliforme were found that were highly toxic to ducklings but which did not produce moniliformin.

Animals↗

PubMed1981

Inhibitory effect of molybdenum and vanadium salts on aflatoxin B1 synthesis by Aspergillus flavus.

The effects of the elements zinc, manganese, iron, copper, molybdenum, and vanadium, added in various salt forms, on mycelial weights and aflatoxin B1 accumulation in the mycelium of Aspergillus flavus were investigated in liquid shake cultures. Ammonium heptamolybdate, when added to a complete medium at concentrations of 50-100 mg/L, appreciably reduced aflatoxin B1 accumulation without affecting growth of the fungus. Sodium molybdate and sodium monovanadate also reduced aflatoxin B1 yields without affecting mycelial growth but to a lesser extent. The addition of zinc sulphate stimulated aflatoxin B1 production in all media used. The influence of the other trace elements on aflatoxin production depended on the level of trace elements present in the basal medium. In general, manganese chloride had a stimulatory effect, whereas copper sulphate depressed yields. Mycelial levels of aflatoxin had peaked and then declined before mycelial dry weights had reached maximum. High yields of aflatoxin B1 were obtained in media having a final pH as low as pH 2.8.

Aflatoxin B1↗

PubMed1979

Toxic aspergilli from pistachio nuts.

Pistachio nut samples taken during various stages of development from orchards in Iran, showed that contamination with fungi occurred mainly during the later stages of nut development. Members of the genera Aspergillus and Penicillium occurred most frequently. Of the Aspergilli, the species A. niger, A. flavus and A. fischeri var. spinosus occurred most frequently, followed by A. terreus, A. tamarii and A. nidulans. Twenty-two isolates comprising 13 species were tested for toxicity to ducklings. Isolates of known toxic fungi included A. flavus, A. niger, A. parasiticus, A. ochraceus, A. versicolor, A. nidulans and A. terreus. The toxicity of A. fischeri var. spinosus is reported. Chemical analysis showed that all isolates of A. flavus and A. parasiticus produced aflatoxin B1, the isolates of A. versicolor and A. nidulans produced sterigmatocystin while the toxic isolate of A. ochraceus did not produce ochratoxins.

Aflatoxins↗

PubMed1977

New species of Aspergillus producing sterigmatocystin.

A number of species belonging to the genus Aspergillus were evaluated for their toxicity to ducklings and the ability to produce sterigmatocystin. Three new species capable of producing sterigmatocystin were found, namely, Aspergillus aurantio-brunneus, Aspergillus quadrilineatus, and Aspergillus ustus. All three were toxic to ducklings. The production of sterigmatocystin by Aspergillus rugulosus was confirmed, and the toxicity of Aspergillus stellatus and Aspergillus multicolor is described.

Aflatoxins↗

PubMed1977

Toxicity of Diplodia maydis to laboratory animals.

Ten strains of Diplodia maydis isolated from commercial corn samples and grown on whole yellow corn at 25 degrees C for 6 weeks were toxic to ducklings and rats. The degree of toxicity depended on the incubation period and temperature. Minimum incubation periods of 3 to 4 weeks and 6 weeks were necessary to cause mortality in ducklings and rats, respectively. Cultures incubated at 31 and 25 degrees C were much more toxic than those kept at 16 and 20 degrees C. Heat treatments at 80 to 90 degrees C destroyed most of the toxicity of moldy meal. Mild lesions of a similar histopathological nature were found in subclinically and lethally poisoned rats. These included toxic myocarditis, enteritis, focal renal tubular necrosis, degeneration and peripheral necrosis of the islets of Langerhans, and a generalized venous congestion.

Animal Feed↗

PubMed1976

Production of sterigmatocystin by Aspergillus versicolor and Bipolaris sorokiniana on semisynthetic liquid and solid media.

Higher yields of sterigmatocystin were obtained with Aspergillus versicolor than with Bipolaris sorokiniana both in liquid and on solid media. The optimum temperature for sterigmatocystin production by A. versicolor was 27 to 29 degrees C and 23 degrees C for B. sorokiniana. In liquid shake cultures, production of sterigmatocystin by B. sorokiniana was negligible, whereas maximal production by A. versicolor was 210 mg/liter. On solid substrates, the highest yields (8 g/kg) were obtained with A. versicolor on still cultures of whole corn supplemented with Soytone.

Aspergillus↗

PubMed1975

Onyalai--the possible involvement of a mycotoxin produced by Phoma sorghina in the aetiology.

A number of species of fungi were isolated from millet (Pennisetum typhoides Staph and Hubb) and grain sorghum (Sorghum vulgare Pers) obtained from the households of patients suffering from onyalai. Several proved to be toxic to rats and chickens, including Phoma sorghina (Sacc.) which was the predominating fungus. Cultures of P. sorghina grown on maize and wheat were added to standard rations at concentrations of 5-30%. When fed to day-old New Hampshire chickens, the majority died within 4 days, exhibiting traces of blood on the beak and the cloaca. Rats given 10% or more of the mouldered material in the diet developed thrombocytopenia after 14 days which was followed by haematuria, epistaxis, melaena, and death. Pathological, including histological examination, revealed extensive damage to the fascular system which resulted in widespread haemorrhages.

Animals↗

PubMed1975

Production of sterigmatocystin.

A procedure for the isolation of pure sterigmatocystin is described. It involves cultivation of an appropriate fungus on sterile maize, and extraction and column chromatographic purification of the crude extract. With this method sterigmatocystin may be obtained at a fraction of its commercial cost. Aspergillus versicolor seemed to be the best producer (5-12 g/kg) in 250 ml Erlenmeyer flasks. The yield dropped markedly with increasing flask size.

Aspergillus↗