Biomedical subjects

R Beaudry

Publications and source records attributed to R Beaudry.

18 recordsLinked to original sources

PubMed2004

Ethylene modulates development and toxin biosynthesis in aspergillus possibly via an ethylene sensor-mediated signaling pathway.

Ethylene, a biologically active natural compound, inhibited aflatoxin accumulation by Aspergillus parasiticus on a solid growth medium in a dose-dependent manner at concentrations of 0.1 to 150 ppm. The activity of the nor-1 promoter (an early aflatoxin gene) was reduced to nondetectable levels by similar quantities of ethylene, suggesting that the inhibitory effect on toxin synthesis occurred, at least in part, at the level of transcription. The inhibitory effect of ethylene on aflatoxin accumulation was also observed when A. parasiticus was grown on raw peanuts. Under similar growth conditions and doses, ethylene strongly inhibited development of asci and ascospores in Aspergillus nidulans, with no detectable effect on Hülle cell formation, conidiation, or sterigmatocystin accumulation. During early growth, A. parasiticus and A. nidulans produced ethylene with approximately twofold higher quantities measured in continuous light than in the dark. 1-Methylcyclopropene (an inhibitor of ethylene receptors in plants), light, CO2, temperature, and growth medium composition altered the effect of ethylene on A. nidulans and A. parasiticus. These observations are consistent with the existence of an ethylene sensor molecule that mediates the function of an ethylene-responsive signaling pathway(s) in Aspergillus.

Aflatoxins↗

PubMed1999

Effect of superficial scald suppression by diphenylamine application on volatile evolution by stored Cortland apple fruit.

Cortland apple fruit (Malus x domestica Borkh.) stored for 120-140 days in air at 0 degrees C were warmed to 22 degrees C and held for 8 days. A portion of the fruit was dipped in a solution of diphenylamine (DPA) at harvest to prevent scald development. Scald occurred only in those fruit not treated with DPA, and its development was accelerated after transfer to 22 degrees C. Ester production from apple fruit tended to increase from day 0 to day 6 of poststorage holding and declined thereafter in both treatments. However, ester production in scald-developing fruit was reduced by approximately 50%. The reduction in volatile production remained relatively constant during the rapid development of scald symptoms. Furthermore, the reduction in volatile production appeared to be independent of respiration and ethylene production. Production of esters derived from hexanol was most reduced in fruit developing scald, with hexyl 2-methylbutanoate production being reduced approximately 15-fold. Interestingly, the production of methyl butanoate was detected only in scalding fruit. alpha-Farnesene production in fruit developing scald was reduced 43% compared with DPA-treated fruit. In contrast, the primary volatile oxidation product of alpha-farnesene, 6-methyl-5-hepten-2-one (MHO), was present only in fruit developing scald. The data suggest that inhibition of ester production may occur as a result of the physiological changes associated with susceptibility to, rather than expression of, scald symptoms.

Diphenylamine↗

PubMed1999

Relationship between ethylene response manipulation and volatile production in Jonagold variety apples.

The ripening of Jonagored Jonagold apple fruit (Malus x domestica Borkh.) during development was manipulated with preharvest applications of ReTain or a combination of ReTain plus Ethrel. The fruits, harvested preclimacteric at approximately the same stages of maturity, were stored in refrigerated air (RA) for 45 days or in controlled atmosphere (CA) for 180 days at 0 degrees C. Volatile evolution, ethylene production, and respiration of stored fruit were studied during poststorage holding at 22 degrees C. ReTain reduced volatile production by 19%, but application of Ethrel to ReTain-treated fruit increased production to control levels. The inhibition of volatile production by ReTain appears to be independent of respiration but may be related to the ethylene-producing capacity of the fruit. Although ReTain reduced flavor-related volatile esters, it did not affect levels of the compound responsible for the typical spicy flavor in Jonagored Jonagold fruit, 4-methoxy-2-propenylbenzene. The CA-stored fruit had a much reduced production of volatile compounds compared to RA-stored fruit, with more discernible effects in ReTain-treated fruit. Ethrel application to ReTain-treated fruit improved the volatile production intermediate between the ReTain alone and control in CA-stored fruit. The data collectively suggest that ReTain may have some promise for better scheduling of harvest of apples with no appreciable loss in RA-stored fruit quality. Reduction in production of alpha-farnesene by ReTain may also reduce the potential for scald development in CA-stored fruit.

Chromatography, Gas↗

PubMed1995

Doping effects on the magnetic phase diagram of the spin-Peierls system CuGe1-xSixO3.

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Journal Article↗

PubMed1992

Idiopathic ulcerative proctitis may be the initial manifestation of Crohn's disease.

Of 213 patients with proctitis of all etiologies seen between 1977 and 1987, we studied an original cohort of 96 patients with idiopathic ulcerative proctitis (mean follow-up of 62 months). The diagnosis was made according to strict inclusion criteria, and all cases with any initial feature suggestive of Crohn's disease were excluded. Follow-up showed that 13 patients (13.6%) eventually progressed to Crohn's disease, usually within the first 3 years of the initial diagnosis of idiopathic ulcerative proctitis. Their clinical, endoscopic and histological features at initial presentation were indistinguishable from those in whom the diagnosis remained that of idiopathic ulcerative proctitis. In nine of 13 of these patients (70.0%), the clinical course was characterized by a more protracted course and a poorer response to standard treatment. Such features were not found in those in whom the diagnosis of idiopathic ulcerative proctitis was maintained. Clinicians should be aware that Crohn's disease may present initially as apparent idiopathic ulcerative proctitis.

Adolescent↗

PubMed1980

Meningo-ependymitis in Whipple's disease.

Six years after apparent complete recovery from intestinal Whipple's disease, a 56 year old man developed insidious progressive somnolence and gait ataxia. Studies showed hydrocephalus with obstruction of the aqueduct and CSF leukocytosis and elevated protein. Arachnoid biopsy during craniotomy revealed chronic inflammatory infiltration with PAS-positive macrophages. The patient died 5 years later despite two courses of antibiotic therapy. This is the first report of histologically confirmed cerebral Whipple's disease during life. Whipple's disease is a systemic infectious disorder. Cerebral involvement even in neurologically asymptomatic patients should be sought with periodic CSF cytologic studies and a search for hydrocephalus. The possibility of cerebral Whipple's disease should be considered in the presence of unexplained hydrocephalus and/or chronic inflammatory changes in the spinal fluid, especially in those with past or active intestinal disease.

Arachnoid↗

PubMed1980