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Biomedical subjects

S Charbonneau

Publications and source records attributed to S Charbonneau.

At least 19 recordsLinked to original sources
PubMed2003

Dietary fibers reduce the urinary excretion of 1-hydroxypyrene following intravenous administration of pyrene.

During biological monitoring of exposure to a chemical, a possible source of interindividual variability in the measurement of a urinary metabolite that undergoes enterohepatic cycling is the presence of dietary fiber in the gastrointestinal tract. This study examined the effect of diets containing either the insoluble fiber Alphacel (nonnutritive bulk cellulose) or the soluble pectin (from citrus fruit, MW 20,000-40,000). Five groups of male Sprague-Dawley rats received one of the following diets: poor (5% w/w) or rich (15% w/w) in Alphacel, poor (5% w/w) or rich (15% w/w) in pectin, or no fiber (NF). Five micromol/kg of pyrene was administered by iv injection immediately after feeding the animals with their respective diet, and urine and feces collections started for the determination of 1-hydroxypyrene (1-OHP), a metabolite of pyrene. The type of fiber had no influence on the results. The rats receiving diets both poor and rich in fiber excreted less 1-OHP (18 +/- 8 and 15 +/- 7 pmol per g of rat, respectively) in the 24-h urine samples than the NF group (28 +/- 6 pmol/g). There was a nonstatistically significant trend towards increased fecal and total (urinary + fecal) 1-OHP excretion with increasing amount of fiber in the diet. An in vitro experiment showed an inverse correlation (r(2) = 0.98) between the amount of Alphacel in suspension in a 1-OHP aqueous solution and the recovery of 1-OHP from the soluble fraction. The reduction in urinary output of the metabolite due to fiber reaching approximately 40% may contribute to its interindividual variability observed in occupational and environmental studies.

Adsorption↗
PubMed2003

Perception and production of facial and prosodic emotions by chronic CVA patients.

Variable etiology, limited testing of emotions and inclusion of patients in acute and chronic phases have made it difficult to specify the extent of right hemisphere involvement in the processing of emotional material. In addition, there is an absence of data concerning CVA patients' long-term abilities to process emotional information. Two groups of subjects with unilateral brain damage (15 RBD, 17 LBD), matched for chronicity (minimum 12 months post-CVA), etiology (ischemic CVA), duration of hospitalization and other variables, and an appropriate control group participated in two experiments to address these concerns. In the first experiment, subjects were given a series of tasks (discrimination, identification, imitation, production on request) to assess their processing of facial expressions of the six universal emotions [P. Ekman, W. Friesen, Unmasking the face, Prentice-Hall, Englewood Cliffs, 1975]. The results showed that three emotions (surprise, happiness, fear) discriminate between RBD and LBD patients and controls, with RBD subjects performing worse than the other groups on the identification task only. Using tasks of the same nature, the second experiment investigated the processing of emotional prosody. The results showed that three emotions (fear, sadness, anger) discriminate between RBD and LBD patients and controls, with RBD subjects again performing worse than the others on the discrimination, imitation and production on request tasks. LBD subjects performed as well as normal controls on almost all tasks. The RBD subjects were the only ones who showed relatively consistent impairment in the processing of both facial and prosodic emotional information. Taken together, these data strongly suggest that the right hemisphere is preferentially involved in processing emotional information in the chronic phase of brain damage.

Acoustic Stimulation↗
PubMed2001

The gene encoding the major viral structural protein stimulates recombination in polyomavirus DNA.

RmI is a chimeric DNA molecule consisting of a polyoma genome in which a partly duplicated VP1-coding region brackets an insert of murine DNA (Ins); when transfected into mouse cells, RmI recombines intramolecularly to yield infectious, unit-length, polyoma DNA. We report here that RmI encodes a polypeptide of 337 amino acids (designated VmP1) which includes the N-terminal 328 amino acids of VP1 and 9 amino acids specified by Ins. Mutating the VmP1-coding sequence strongly reduces the ability of RmI to yield polyoma DNA. In contrast, mutating the portion of the VP1-coding sequence which is not part of the VmP1-coding sequence has little or no impact on the ability of RmI to yield polyoma DNA, even though it renders such DNA noninfectious. Thus, release of polyoma DNA from RmI involves a function of VP1 distinct from that ensuring virus assembly and propagation; since VP1 can arise only after recombination has occurred, VmP1, but not VP1, could carry such a function. We suggest that VmP1 acts in concert with VP2, which we have already reported to stimulate recombination in RmI.

Amino Acid Sequence↗
PubMed2000

Involvement of minor structural proteins in recombination of polyoma virus DNA.

We have previously observed that a polyoma-mouse chimeric DNA molecule (RmI) in which the murine DNA insert is flanked by directly repeated viral sequences is effectively converted into unit-length polyoma DNA upon transfection of permissive mouse cells. This intramolecular recombination event appears to be dependent on VmP1, a protein encoded by RmI which includes the 328 N-terminal amino acids of polyoma VP1, and nine amino acids of murine origin carrying the C-terminus of the protein. We report here that introducing mutations into the VP2/VP3 coding sequence reduces the ability of RmI to generate polyoma DNA, even though the same mutations seem to exert little or no effect on the ability of polyoma DNA to either replicate or accumulate inside transfected cells. A mutation affecting VP2 alone being as effective as one that affects both VP2 and VP3, VP2 appears to be playing a critical role in recombination.

Animals↗
PubMed1996

Red-Emitting Semiconductor Quantum Dot Lasers

Visible-stimulated emission in a semiconductor quantum dot (QD) laser structure has been demonstrated. Red-emitting, self-assembled QDs of highly strained InAlAs have been grown by molecular beam epitaxy on a GaAs substrate. Carriers injected electrically from the doped regions of a separate confinement heterostructure thermalized efficiently into the zero-dimensional QD states, and stimulated emission at approximately 707 nanometers was observed at 77 kelvin with a threshold current of 175 milliamperes for a 60-micrometer by 400-micrometer broad area laser. An external efficiency of approximately 8.5 percent at low temperature and a peak power greater than 200 milliwatts demonstrate the good size distribution and high gain in these high-quality QDs.

Journal Article↗
PubMed1991

Presence of fecal material in diapers as a potential source of error in estimations of postmortem interval using arthropod development rates.

Second instar larvae of the fly Chrysomya megacephala (Diptera, Calliphoridae) were recovered from the diapers of a 16-month-old child abandoned by her mother on Oahu, Hawaii. The development of these larvae indicated a minimum period of 23.5 h of exposure prior to discovery of the child. Larvae of this species of fly are not normally associated with living tissues in Hawaii, but rather with feces and remains during the early stages of decomposition. Had the child in this case died and data not been provided detailing the site of infestation, the postmortem interval estimated would have been significantly longer than was actually the case, because of the development of the larvae inside the diapers of the living child. The need for caution in cases involving deaths of infants, the elderly, and individuals not capable of caring for themselves is stressed.

Animals↗