Trichosporon beigelii infection in an immunocompromised host.

A case of Trichosporon beigelii infection in a patient with non-Hodgkins lymphoma that illustrates some of the associated diagnostic and chemotherapeutic problems, is described. Despite prolonged isolation of the yeast from blood cultures, the patient recovered from the infection after treatment with amphotericin B and flucytosine. Presenting features, diagnosis and monitoring of antifungal therapy in renal failure are discussed.

The toxicity of phomopsin for sheep.

Pure phomopsin was administered to young Merino x Border Leicester wethers by single subcutaneous (SC) and by single and multiple intraruminal (IR) injection. The toxicity after IR injection was influenced by the size of individual doses and the time over which the total dose was given. At high levels of ingestion the toxicity of phomopsin may be limited by absorption rates; with low daily doses the capacity to repair liver damage may be sufficient to prevent cumulative effects. By SC injection a single dose of 10 micrograms/kg approximated the LD50. By IR injection the overall clinical, biochemical and histological responses closest to these of this SC dose resulted from a single dose of 1,000 micrograms/kg. The same total dose administered at daily rates of 50 or 200 micrograms/kg was more toxic and killed all sheep. A single dose of 500 micrograms/kg caused significant liver damage, but no deaths. Single doses of 125 and 250 micrograms/kg and repeated daily doses of 12.5 micrograms/kg over 16 weeks caused no detectable tissue damage. Inappetence was the most sensitive indicator of phomopsin toxicity. About 10% of the sheep differed substantially from the rest of the flock in their susceptibility to phomopsin poisoning.

The localization of a Mason-Pfizer monkey virus-related antigen in jaagsiekte tumour tissue and cell lines.

Mason-Pfizer monkey virus-related antigen was detected in 3 out of 5 jaagsiekte lungs examined using a direct immunoperoxidase staining technique with anti-MPMV p27 serum. Most of the antigen was localized in the alveolar lumina of the lesions. The reaction was further characterised on immune blots and found to involve a protein with a molecular mass of 29 000 daltons (JSRV p29). JSRV p29 antigen was also detected in 2 jaagsiekte cell lines.

A scanning and transmission electron microscopy study of jaagsiekte lesions.

A scanning electron microscopy (SEM) and transmission electron microscopy (TEM) study was made of lesions from acute, experimentally induced cases of jaagsiekte. In the SEM study tumour cells were easily identified by the abundant microvilli on their peripheral surface. The SEM study gave further insight into the development of lesions and the spatial relationship of cells involved in jaagsiekte. TEM revealed that the tumour cells were in a state of rapid protein synthesis and had many characteristics in common with other malignant cells.

The morphology and morphogenesis of jaagsiekte retrovirus (JSRV).

Jaagsiekte retrovirus ( JSRV ) was recently shown to be the aetiological agent of jaasiekte (ovine pulmonary adenomatosis). The morphogenesis of JSRV was studied in jaagsiekte tumour tissue. Intracytoplasmic particles, often associated with centrioles, were found in tumour cells. JSRV budded from tumour cells with a complete core which appeared to mature during the budding process. Extracellular particles were found in the alveolar lumen. Immature extracellular particles were rare. Mature extracellular JSRV was membrane-bound and had a slightly eccentric nucleoid with an electron-dense perinucleoidal space. In negatively stained preparations of JSRV the envelope was covered with spikes. JSRV is morphologically distinct from all known retroviruses.

Isolation and preliminary characterization of the jaagsiekte retrovirus (JSRV).

Jaagsiekte, or ovine pulmonary adenomatosis, is caused by a recently discovered retrovirus. The virus cannot be cultivated in vitro at present, but a procedure is described for the isolation and purification of small amounts in the form of immune complexes with IgA from affected lungs. The virion was shown to possess a 70S RNA genome which can be transcribed by an endogenous reverse transcriptase. Nine size from 94 000 to 25 000 daltons, were found in purified preparations. Using neutralization of the viral reverse transcriptase and an enzyme immunoassay as criteria, no serological relationship could be demonstrated to representatives of type B, C and C oncoviruses, or to bovine leukemia virus, maedi-visna virus of sheep or caprine arthritis-encephalitis virus.

Inhibition of glycosylation by corynetoxin, the causative agent of annual ryegrass toxicity: a comparison with tunicamycin.

The biological activities of corynetoxins, the causative agents of annual ryegrass toxicity, were compared with those of the closely related tunicamycins and found to be essentially identical. Both showed similar antibiotic activity against Newcastle disease virus and a range of gram-positive bacteria. In preparations of rat liver rough microsomes they also strongly inhibited the uridine diphospho-N-acetylglucosamine (UDP-GlcNAc):dolichol-P N-acetylglucosamine-1-phosphate (GlcNAc-1-P) transferase, an enzyme essential for N-glycosylation of glycoproteins. Pretreatment of rats with corynetoxins resulted in dose- and time-related reduction in the level of activity of this transferase in liver microsomal preparations. The implications of this reduction are discussed with reference to annual ryegrass toxicity, the only field disease known to be caused by tunicamycin-related compounds. Both corynetoxin and tunicamycin produced similar neurological effects and increased vascular permeability in nursling rats and they showed similar LD50-values of 137 and 132 micrograms/kg, respectively, in the nursling rats.

Biosynthesis of radiolabeled phomopsin by Phomopsis leptostromiformis.

[14C]phomopsin and [36Cl]phomopsin were synthesized by Phomopsis leptostromiformis in liquid cultures containing various labeled compounds. [U-14C]isoleucine, [U-14C]phenylalanine, and [U-14C]proline were the best precursors in terms of labeling efficiency, whereas [36Cl]hydrochloride was much less efficient. When each of the four precursors was used, a large proportion of recovered label was associated with phomopsin. The specific activities of phomopsin produced with labeled isoleucine, phenylalanine, proline, and hydrochloride were 150, 120, 90, and 17 muCi/mmol, respectively. 14C label from acetate, malate, propionate, sucrose, or tryptophan was neither specifically nor efficiently incorporated into phomopsin.

Lupinosis: response of sheep to different doses of phomopsin.

Phomopsin, the mycotoxin produced by Phomopsis leptostromiformis, was found to have a very high toxicity for sheep. When administered as a single, subcutaneous injection over the dose range 1 X 25 to 98 microgram/kg body weight, all sheep given 37 X 5 microgram/kg or more died. Some, though not all, died following lower doses, the minimum lethal dose being 10 microgram/kg. The time course of hepatic response over 21 days after phomopsin administration was followed by plasma biochemical analyses including those for some enzymes (glutamate dehydrogenase, gamma-glutamyl transpeptidase, aspartate aminotransferase and alkaline phosphatase), total bilirubin and the determination of bromosulphophthalein clearance rates. Hepatobiliary impairment was apparent after all dosages of 2.5 microgram/kg and above while 1.25 microgram/kg approximated the 'no effect' level.

Isolation of a group of glycolipid toxins from seedheads of annual ryegrass Lolium rigidum Gaud.) infected by Corynebacterium rathayi.

A group of highly toxic compounds was isolated from galled seedheads of annual ryegrass (Lolium rigidum Gaud.) containing Corynebacterium rathayi. Purified extracts were resolved by reverse-phase high-performance liquid chromatography into eight main fractions which have been partially characterised and shown to be toxic to nursling rats. A mixture of the toxins also produced clinical signs and brain lesions in lambs consistent with annual ryegrass toxicity. The name 'corynetoxin' is tentatively proposed for the series, individual members being designated according to their order of elution from the high performance liquid chromatography column as corynetoxins 1 to 8. The two main fractions are corynetoxins 3 and 4 of which the former has been crystallised. They appear to be of glycolipid character, 3-hydroxyheptadecanoic acid and a C6 amino sugar being identified among the hydrolysis products of corynetoxin 3, and heptadec-2-enoic acid and a C6 amino sugar from corynetoxin 4.

Production of tremorgenic toxins by Penicillium janthinellum Biourge: a possible aetiological factor in ryegrass staggers.

Topsoil, herbage and faeces collected during an outbreak of ryegrass staggers in sheep were examined for tremorgenic penicillia. No such fungi were recovered from the plant material, but they were found among the predominant fungi in the soil and faecal samples. The commonest species of Penicillium, and almost the only tremorgenic species encountered, was Penicillium janthinellum Biourge. When fed to sheep, the mycelium of this fungus evoked a number of the clinical signs seen in field cases of ryegrass staggers. Two tremorgenic toxins were isolated from the mycelial felts and available evidence indicates that they are verruculogen and fumitremorgin A. P. janthinellum also produced these tremorgens when cultured in moist, autoclaved soil, but not in unheated soil. The results obtained from this study are in accord with the hypothesis that ryegrass staggers is caused by tremorgenic mycotoxins.

Phomopsin A production by Phomopsis leptostromiformis in liquid media.

Phomopsis leptostromiformis WA1515 produced 75 to 150 mg of phomopsin A per liter in stationary cultures in a Czapek-Dox medium supplemented with 5 to 10 g of yeast extract per liter. pH and temperature optima were approximately 6.0 and 25 degrees C, respectively. A commercial tryptic digest of casein was a satisfactory alternative to the yeast extract, but poor growth and very little phomopsin were obtained when the yeast was replaced by vitamin-free Casamino Acids or a mixture of 18 amino acids. Approximately 95% of the phomopsin A produced was found in the cutlure liquid. No phomopsin was detected in shaken cultures. No phomopsin B was found in any culture. Methods are described for recovery and estimation of phomopsin A from culture liquids.

Isolation of toxic metabolites of Phomopsis leptostromiformis responsible for lupinosis.

Two metabolites of P. leptostromiformis (phomopsins A and B) have been isolated as a crystalline mixture from a culture of the fungus on lupin seed. The mixture has been shown to be capable of inducing lupinosis in sheep and in young rats. Key steps in the isolation were the transfer of the phomopsins from crude aqueous solution to tetrahydrofuran and chromatography on macroreticular polystyrene resin. The bioassays used in monitoring fractions were based on inhibition of cell cultures and the mitosis-arresting effect of the metabolites on liver cells in vivo.