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Biomedical subjects

G Beauchamp

Publications and source records attributed to G Beauchamp.

At least 19 recordsLinked to original sources
PubMed2001

Spatial variation in mercury concentrations in wild mink and river Otter carcasses from the James bay territory, Québec, Canada.

Mercury concentrations were analyzed in different organs/tissues of wild minks (Mustela vison) and river otters (Lutra canadensis) trapped during two seasons in the James Bay territory (49 degrees N to 55 degrees N, Québec, Canada). In 1993-94, mean total Hg concentration (microg/g, wet weight) in 39 wild mink and 12 river otter carcasses was greatest in fur/hair samples (30.1 and 20.7 microg/g, respectively) and least in brain samples (0.96 and 0.8 microg/g, respectively) with liver, kidney, and muscle samples showing intermediate values. Pooling data from the 1993-94 and 1994-95 trapping seasons revealed mean (SD) liver total Hg concentrations of 3.71 microg/g (3.91) in 316 wild mink carcasses and 4.05 microg/g (3.41) in 153 river otter carcasses. Log liver total Hg concentration increased with age in wild mink but not in river otter. Log liver total Hg concentration in each species was greatest in areas with moraine deposits and least in areas with rich clay deposits, but the effect of soil deposits could be confounded by uneven deposition of anthropogenic Hg. Controlling for type of soil deposits, log liver total Hg concentration decreased with increasing distance from local industrial centers in each species but varied little with changes in distance from hydroelectric reservoirs. In a subsample of carcasses from the moraine sector, log liver total Hg concentration was higher in wild mink than in river otter. Spatial variation in log liver total Hg concentration in relation to soil deposit type and proximity to industrial centers suggests that the two wild furbearer species could be useful indicators of environmental contamination.

Animals↗
PubMed2001

Characterization of the inflammatory infiltrate in canine chronic hepatitis.

Canine chronic hepatitis (CCH) is a progressive inflammatory disease of unknown etiology. To characterize the inflammatory infiltrate, 16 dogs with CCH were selected and classified into three groups based on the stage of fibrosis, as evaluated with Masson's trichrome stain. The inflammatory infiltrate in each liver section was immunohistochemically characterized and evaluated using CD3, lysozyme, lamba and kappa light chain, and alpha-smooth muscle actin antibodies. Numerous breeds were affected, and middle-aged females predominated in this select group. Necroinflammatory activity progressively increased and then waned as the hepatitis progressed to cirrhosis. CD3+ lymphocytes were the most numerous lymphoid cells in dogs with CCH. Degenerate hepatocytes were occasionally surrounded by CD3+ lymphocytes. Necrosis was positively correlated with the number of CD3+ lymphocytes. The lamba and kappa light chain-positive cell infiltrate was variable but generally mild. A positive correlation between the lambda and kappa light chain-positive cells and the portal alpha-smooth muscle actin was found. The number of alpha-smooth muscle actin-positive cells (myofibroblasts) in portal triads and fibrous septa was positively correlated with the stage of fibrosis. In contrast, no correlation was found between the number of lysozyme-positive cells (Kupffer cells) and the stage of fibrosis. These results further support the idea of an immune-mediated process in CCH and suggest that periductular myofibroblasts play an important role in canine liver fibrogenesis.

Actins↗
PubMed2001

Open antireflux repairs for simple reflux esophagitis: short- and long-term results.

This analysis of the results of open antireflux surgery clearly shows a benefit for antireflux surgery in most patients who have severe esophagitis with or without hiatal hernia. The authors of this article have found many variations in the methodology used to evaluate these results. Aside from these problems, however, the authors also have noticed the remarkably serious and honest work performed by most surgeons in trying to report the truth with the methodologies available to them. The principles of antireflux surgery can be found among the different studies that are reviewed in this article. These principles include: 1. The necessity of closing the crura; 2. The importance of repositioning the distal esophagus into the abdominal cavity; 3. The necessity of increasing the LES pressure by using the musculature of the fundus; 4. The preference for using a short and floppy fundoplication to avoid side effects; and 5. The need for long-term follow-up in evaluating results.

Esophagitis, Peptic↗
PubMed2001

The reproducibility of ophthalmic utility values.

PURPOSE: Utility values have been used in the ophthalmic literature to measure the quality of life associated with a health state. By convention, a utility value of 1.0 is associated with perfect health, and a value of 0.0 is associated with death. Construct validity of utility values has been demonstrated, particularly in regard to decreasing utility values as the vision decreases in the better seeing eye, but long-term test-retest reliability has not been demonstrated. The purpose of this study was to demonstrate the test-retest reliability of ophthalmic utility values. METHODS: One hundred fifteen patients with ophthalmic diseases and stable visual acuity underwent time trade-off utility analysis with retesting at various intervals ranging from 1 month to 2 years. The results were analyzed using the Wilcoxon signed rank test. The study was designed to have an 50% power, using a two-sided alpha of 5%, to be able to detect a 10% difference between the test and retest groups. RESULTS: The mean time from testing to retesting was 0.87 years, with a median time of 1.0 year and range of 1 month to 2 years. The mean utility value in the test group was 0.766 (SD = .21; 95% CI, 0.730-0.802), while the mean utility value in the retest group was 0.763 (SD = .22; 95% CI, 0.724-0.802). The difference between the means of the test-retest groups was not significant (P = .99). The intraclass correlation between the initial and follow-up utility scores was .5246 (P < .00005). CONCLUSIONS: Ophthalmic utility values appear to have good test-retest reliability over prolonged periods of time. This information is important because it gives researchers increased confidence in the validity of basic tools for ophthalmic cost-effective (cost-utility) analyses.

Adult↗
PubMed2000

The effect of prior residence and pair bond on scrounging choices in flocks of zebra finches, Taenopygia guttata.

In groups, animals can use the producer tactic to locate food patches and the scrounger tactic to join the food discoveries of other companions. At equilibrium, models predict a mixture of the two tactics with equal payoffs. Several factors may constrain the use of tactics and lead to biases in scrounging choices. I explored the effect of prior residence and pair bond as potential constraints on scrounging choices in flocks of zebra finches (Taenopygia guttata). Experimental flocks contained two birds already established in an aviary (prior residents) and two birds recently released in the aviary for the first time (new residents). All birds were previously trained to find food on a foraging grid. In the aviary, new residents followed prior residents from perches to the grid and relied heavily on prior residents to locate food patches. Low initial success by new residents probably favoured heavy reliance on the scrounger tactic. New residents that formed pair bonds with prior residents foraged closer to their mates and scrounged selectively from their mates in some cases. Prior residence, and pair bond to a lesser extent, influenced scrounging choices in zebra finches and could lead to deviation from the expected use of foraging tactics.

Journal Article↗
PubMed2000

Learning rules for social foragers: implications for the producer-scrounger game and ideal free distribution theory.

In population games, the optimal behaviour of a forager depends partly on courses of action selected by other individuals in the population. How individuals learn to allocate effort in foraging games involving frequency-dependent payoffs has been little examined. The performance of three different learning rules was investigated in several types of habitats in each of two population games. Learning rules allow individuals to weigh information about the past and the present and to choose among alternative patterns of behaviour. In the producer-scrounger game, foragers use producer to locate food patches and scrounger to exploit the food discoveries of others. In the ideal free distribution game, foragers that experience feeding interference from companions distribute themselves among heterogeneous food patches. In simulations of each population game, the use of different learning rules induced large variation in foraging behaviour, thus providing a tool to assess the relevance of each learning rule in experimental systems. Rare mutants using alternative learning rules often successfully invaded populations of foragers using other rules indicating that some learning rules are not stable when pitted against each other. Learning rules often closely approximated optimal behaviour in each population game suggesting that stimulus-response learning of contingencies created by foraging companions could be sufficient to perform at near-optimal level in two population games.

Animals↗
PubMed1999

Food exploitation: searching for the optimal joining policy.

Commonly invoked foraging advantages of group membership include increased mean food intake rates and/or reduced variance in foraging success. These foraging advantages rely on the occurrence of 'joining': feeding from food discovered or captured by others. Joining occurs in most social species but the assumptions underlying its analysis have been clarified only recently, giving rise to two classes of model: information-sharing and producer-scrounger models. Recent experimental evidence suggests that joining in ground-feeding birds might be best analysed as a producer-scrounger game, with some intriguing consequences for the spatial distribution of foragers and patch exploitation.

Journal Article↗
PubMed1998

Lung cancer in women compared with men: stage, treatment, and survival.

BACKGROUND: In cardiac disease there appears to be a difference in the treatment of men and women, and thus an advantage in survival in men. This study aimed to determine whether these differences exist in lung cancer. METHODS: We undertook a retrospective cohort study in a university hospital. The study population consisted of 104 consecutive women and 104 consecutive men with newly diagnosed lung cancer between March 1988 and June 1990. The following information was collected: sex, age, presenting symptoms, investigations, histology, stage, treatment, and survival. RESULTS: The location of the tumor, presenting symptoms, investigations, and stages were similar in men and women. There was a difference in the distribution of the various histologic types of lung cancer: Small cell lung cancer was more frequent in women (25% versus 11.5% in men) and squamous cell carcinoma more frequent in men (38% in women versus 51% in men). The overall survival was similar among the two sexes, but there was a survival advantage in women when adjusted for stage. CONCLUSIONS: There was a higher incidence of small cell carcinoma in women and squamous cell carcinoma in men. There was evidence of a difference in the survival rate of lung cancer in favor of women according to stage.

Bias↗
PubMed1998

General surgeons and clinical ethics: a survey.

OBJECTIVE: To determine the preoccupation of general surgeons concerning ethics. DESIGN: A survey by questionnaire. PARTICIPANTS: One thousand members of the Canadian Association of General Surgeons were surveyed through a questionnaire, which inquired about the influence of ethics in their clinical practices. The questionnaire contained 12 questions. There was no recall for those who did not respond. MAIN OUTCOME MEASURES: Responses to questions concerning the sex of the respondents, location of practice, number of years in practice, the presence of hospital support, surgeons' interest in ethical issues, use of autonomy, beneficence, nonmaleficence and justice in solving ethical dilemmas and level of education in clinical ethics. RESULTS: Men made up 95% of the respondents; 64% of respondents had been in practice more than 16 years; 58% came from a community or regional hospital; only 10% had no interest in clinical ethics; only 3% stated that they experienced no ethical problems in their practices; and 52% had no formal education in ethics. CONCLUSIONS: There was general sensitivity for clinical ethics but an evident lack of formal education and of the presence of ethics committees and ethics consultants in many hospitals.

Attitude of Health Personnel↗
PubMed1997

Atypical antidepressants inhibit depolarization-induced calcium uptake in rat hippocampus synaptosomes.

The effect of the atypical antidepressants mianserin, iprindole, and fluoxetine on synaptosomal calcium uptake was tested under conditions where a selective action on voltage-dependent calcium channels can be documented. Synaptosomes from rat hippocampus were incubated with 45calcium either in choline-rich medium or in depolarizing (60 mM K+) choline-rich medium, and drug effects on calcium uptake in these two conditions, as well as on the net depolarization-induced calcium uptake, were studied in the range of concentrations 0.6-200 microM. A concentration-dependent marked inhibition of uptake in depolarizing choline medium was observed for the three antidepressants, whereas only a minor degree of inhibition of uptake in resting choline medium was present at the highest drug concentration; as a result, the concentration-effect relationships exhibited a strong concentration-dependent inhibition of net depolarization-induced calcium uptake. The IC50 values, calculated by interpolation of the last three or four points of the concentration-effect relationships, were 27, 39, and 68 microM for fluoxetine, iprindole, and mianserin, respectively. Significant degrees of calcium channel inhibition are not expected at brain concentrations of mianserin and iprindole that are likely to be encountered during clinical use; however, the fluoxetine concentration-effect relationship established in the present study, coupled with the published ratio of 20:1 for brain:plasma concentrations of fluoxetine-norfluoxetine in humans, suggests that brain calcium channel function could be appreciably reduced in some patients treated with this atypical antidepressant.

Animals↗
PubMed1997

Bowel preparation with polyethylene glycol electrolyte lavage solution is potentially hazardous in patients with carcinoma of the cardia: a case report.

Polyethylene glycol (PEG) electrolyte solution can induce potentially fatal complications when used as a lavage in preoperative bowel preparation. A 60-year-old man with carcinoma of the esophagogastric junction had a Mallory-Weiss tear after bowel preparation with PEG. He was successfully resuscitated, first with balanced salt solution then by transfusion. The literature on the subject is reviewed and recommendations are made, which include consideration of alternative methods of bowel preparation (e.g., sodium phosphate solution) in patients with esophageal obstruction.

Adenocarcinoma↗
PubMed1996

Effects of sweet taste stimulation on growth and sucking in preterm infants.

OBJECTIVE: To evaluate the effect of sweet taste stimulation in augmenting the reported growth-enhancing effects of nonnutritive sucking in preterm infants who are gavage-fed. DESIGN: Random assignment of preterm infants to receive stimulation by one of three methods during each feeding until totally orally fed. SETTING: Hospital intensive-care and infant transitional units. PATIENTS: Eligibility criteria included body weight greater than or equal to 1,250 g, gestational age younger than 34 weeks, growth parameters appropriate for gestational age, tolerating at least 100 kcals/kg/day by gavage feeding with evidence of weight gain, and no clinical evidence of health complications. Data are presented for 42 infants who completed 14 days of treatment. INTERVENTIONS: Exposure to a sweet pacifier, a latex pacifier, or maternal heartbeat sounds during gavage feedings. MAIN OUTCOME MEASURES: Growth, time to total oral feeding, and sucking responses. RESULTS: No significant differences in sucking measures were noted among treatment groups. Differences in progression time to total oral feedings and weight gain favored the sweet-pacifier group but were not statistically significant. CONCLUSIONS: Oral stimulation of gavage-fed, preterm infants during a 2-week hospitalization was not sufficient to elicit a significant improvement in growth efficiency, progression to total oral feedings, or sucking maturation. Additional studies may show a beneficial effect of chemosensory stimulation in preterm infants.

Child Development↗
PubMed1996

Acute ascites with blunt cardiac rupture.

A unique case of acute ascites following blunt cardiac rupture is reported. A 32-year-old woman was admitted to another hospital and transferred to the authors' institution in cardiopulmonary shock with a very distended abdomen 2.5 h after a motor vehicle accident. Laparotomy was immediately performed and revealed 4 to 5 L of crystal clear fluid and a severe liver congestion. Cardiac tamponade was suspected and confirmed through a transdiaphragmatic pericardial window. Sternotomy was performed and a single right atrial appendage laceration identified, which was successfully repaired. The literature regarding blunt traumatic cardiac rupture is briefly reviewed, and the possible pathophysiology of ascites in a blunt traumatic cardiac rupture is discussed.

Accidents, Traffic↗