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Biomedical subjects

R Ouellette

Publications and source records attributed to R Ouellette.

17 recordsLinked to original sources
PubMed2001

Evaluation of subchronic toxicity of n-butyl acetate vapor.

The subchronic toxicity of n-butyl acetate (nBA), a common industrial solvent, was tested in rats in a 13-week inhalation study. Male and female Sprague-Dawley (SD) rats were exposed to concentrations of 0, 500, 1500 or 3000 ppm nBA for 6 h per day, 5 days per week for 13 consecutive weeks. Transient signs of sedation were observed only during exposure to the 1500 and 3000 ppm concentrations. Body weights for the 1500 and 3000 ppm groups were significantly reduced. Feed consumption values for the 1500 and 3000 ppm groups were significantly lower than the control group. Weights of the liver, kidneys and spleen were significantly lower for the 3000 ppm male group; testes and adrenal gland weights for the 1500 and 3000 ppm groups and the lung weight for the 3000 ppm male group were significantly higher than for the control group. Signs of irritation of the glandular stomach and necrosis in the non-glandular stomach were observed in 3000 ppm female rats. Degeneration of the olfactory epithelium along the dorsal medial meatus and ethmoturbinates of the nasal passages of some 1500 and all 3000 ppm rats was also seen. The severity was mild to moderate for the 3000 ppm group and minimal to mild for the 1500 ppm group. No effects were observed in the lungs of any group. The no-observed-effect level (NOEL) for this study is considered to be 500 ppm. The data presented here are relevant to the toxicity risk assessment of n-butanol due to the rapid hydrolysis of nBA in vivo.

Acetates↗
PubMed1999

Neurotoxicity evaluation of rats after subchronic inhalation exposure to isobutanol.

The subchronic neurotoxic effects of isobutanol were studied by exposing Sprague-Dawley rats to isobutanol vapor concentrations of 0, 250, 1000, and 2500 ppm for 6 hrs/day, 5 days/wk, for 3 months. A comprehensive set of neurotoxicity tests (functional observational battery, motor activity, perfusion fixation neuropathology, and schedule-controlled operant behavior) including an assessment of complex behavior dependent on learning and memory was conducted. In addition, full histopathology and blood chemistry evaluations were conducted in order to assess any potential functional/behavioral effects in the context of other possible systemic toxicities. There were no morphological or behavioral effects indicative of a specific, persistent or progressive effect of isobutanol on the nervous system at exposure concentrations up to 2500 ppm. A slight decrease in response to external stimuli was observed during exposures at all concentrations. These effects are likely transient effects of acute exposure to isobutanol.

Administration, Inhalation↗
PubMed1998

Evaluation of subchronic neurotoxicity of n-butyl acetate vapor.

n-Butyl acetate, a common industrial solvent, was selected by the US EPA as a chemical of concern for neurotoxicity as part of the Multisubstance Rule for the Testing of Neurotoxicity. The neurotoxic potential of n-butyl acetate was investigated in Sprague-Dawley rats using a functional observational battery, motor activity, neurohistopathology, and schedule-controlled operant behavior (SCOB) as indicators of neurotoxicity. Animals were exposed to concentrations of 0, 500, 1500, or 3000 ppm of n-butyl acetate for 6 hours per day for 65 exposures over 14 weeks. Functional observational battery and motor activity values for ad libitum-fed male and female rats were measured during Weeks -1, 4, 8, and 13. SCOB testing of food-restricted animals, using a multiple fixed ratio/fixed interval schedule, was conducted daily prior to each exposure to maintain the operant behavior; the data from Weeks -1, 4, 8, and 13 were evaluated for evidence of neurotoxicity. Transient signs of sedation and hypoactivity were observed only during exposure to the 1500 and 3000 ppm concentrations. The only signs of systemic toxicity were reduced body weights for the 3000 ppm ad libitum-fed groups and occasionally for the female 1500 ppm ad libitum-fed group. No evidence of neurotoxicity was seen during the functional observational battery examinations. Motor activity for the 3000 ppm male group was significantly (p < or = 0.05) higher than for the control group only during Week 4. No significant differences were observed among groups for Weeks 8 and 13. No significant differences in motor activity values were observed for female rats. No significant differences were seen in operant behavior at any test vapor concentration. Microscopic evaluations of sections from the brain, spinal cord (cervical and lumbar regions), dorsal and ventral spinal roots, dorsal root ganglia, sciatic nerve, and tibial nerve of animals in the control and 3000 ppm groups did not indicate any treatment-related effects. In conclusion, there was no evidence of cumulative neurotoxicity based on the functional observational battery, motor activity, neurohistopathology, and schedule-controlled operant behavior endpoints. The data presented here are relevant to the neurotoxicity risk assessment of n-butanol due to the rapid hydrolysis of n-butyl acetate in vivo.

Acetates↗
PubMed1995

Regional anesthesia: is it safer?

This article provides an overview of the current status of general anesthesia and regional anesthesia techniques including complications occurring after using these techniques. The advantages, disadvantages, mortality, and morbidity are described for these two techniques.

Anesthesia, Conduction↗
PubMed1991

Panic attacks in the community. Social morbidity and health care utilization.

This article focuses on social morbidity and health care utilization in persons with panic attacks not meeting full diagnostic criteria for panic disorder. The findings are based on data from a random sample of over 18,000 adults drawn from five US communities. Panic attacks not meeting full criteria for panic disorder have a relatively high lifetime prevalence (3.6% of the adult population). Persons with panic attacks had impairment in perceived physical and emotional health, and in occupational and financial functioning, increased use of health care facilities, emergency departments, and psychoactive drugs. Persons with panic attacks were intermediate in severity between those with panic disorder and those with other psychiatric disorders. The findings could not be explained by comorbidity with other psychiatric disorders. We conclude that panic attacks have clinical significance and are associated with substantial morbidity.

Adolescent↗
PubMed1990

Table-sag errors in CT treatment planning.

It is common practice to utilize CT scans in place of patient contours for computerized treatment planning. Our experience, in particular with pelvic patients, is that setting up the patient for a CT scan using landmarks from a radiation therapy simulator does not always produce accurate field margins. In general, the treatment field center as produced by the CT scan is superior to the center as defined by the simulator film. We have determined this problem to be caused by simulator table sag as compared to the CT. We offer suggestions to correct the problem.

Humans↗
PubMed1990

Panic disorder and cardiovascular/cerebrovascular problems: results from a community survey.

Follow-up studies of psychiatric patients with panic disorder have shown an abnormally high mortality rate in men due to cardiovascular and cerebrovascular events. The authors report that in the New Haven portion of the Epidemiologic Catchment Area program the risk for stroke in persons with lifetime diagnoses of panic disorder was over twice that in persons with other psychiatric disorders or no psychiatric disorder. After adjustments for demographic differences between groups, the risk was even higher. While the results should be interpreted cautiously because of the small sample and absence of medical examinations, these findings are consistent with clinical studies showing an association between panic disorder and cardiovascular/cerebrovascular events.

Adolescent↗
PubMed1990

Mainstreaming and postsecondary educational and employment status of a rubella cohort.

The postsecondary education and work status of 46 rubella deaf young adults was described and evaluated as an outcome of ethnicity, socioeconomic status, preschool attendance, early parent involvement, and degree of prior mainstreaming. With regard to postsecondary education attendance, 24 had two or more years, 11 had one year or less, and 11 had none. At time of interview, 19 were still attending school, 22 were working and five were neither working nor attending an educational program. Ethnic minority young adults were underrepresented in the group with two or more years of postsecondary education, and overrepresented in the group neither working nor in school at time of interview. Prior mainstreaming was a determinant of postsecondary education attendance over and above the effects of demographic and background characteristics. Implications of these findings are discussed.

Adult↗
PubMed1989

Suicidal ideation and suicide attempts in panic disorder and attacks.

Panic disorder, which is found in about 1.5 percent of the population at some time in their lives, includes recurrent episodes of sudden, unpredictable, intense fear accompanied by symptoms such as palpitations, chest pain, and faintness. Panic attacks, which do not meet these diagnostic criteria fully, are two to three times more prevalent. Since panic symptoms can mimic those of other medical disorders, patients with these symptoms use medical services frequently. To determine the risk of suicidal ideation and suicide attempts in panic disorder and attacks, we studied a random sample of 18,011 adults drawn from five U.S. communities. Subjects who had panic disorder, as compared with other psychiatric disorders, had more suicidal ideation and suicide attempts, with an adjusted odds ratio for suicide attempts of 2.62 (95 percent confidence interval, 1.83 to 3.74). The odds ratio was 17.99 (95 percent confidence interval, 12.18 to 26.58) when the group with panic disorder was compared with subjects who had no psychiatric disorder. Twenty percent of the subjects with panic disorder and 12 percent of those with panic attacks had made suicide attempts. These results could not be explained by the coexistence of major depression or of alcohol or drug abuse. We conclude that panic disorder and attacks are associated with an increased risk of suicidal ideation and suicide attempts. Physicians working in general medical settings and emergency departments should be alert to this problem.

Adolescent↗
PubMed1989

Quality of life in panic disorder.

Data from the Epidemiologic Catchment Area study showed that a lifetime Diagnostic Interview Schedule/DSM-III diagnosis of panic disorder was associated with pervasive social and health consequences similar to or greater than those associated with major depression. These consequences included subjective feelings of poor physical and emotional health, alcohol and other drug abuse, increased likelihood of suicide attempts, impaired social and marital functioning, financial dependency, and increased use of psychoactive medications, health services, and the hospital emergency department for emotional problems. Comorbidity of panic disorder with major depression, agoraphobia, and alcohol or other drug abuse did not explain these findings. The social and health consequences of panic disorder (quality of life) should be considered, as risks and benefits of currently available acute and maintenance treatments are evaluated. Clinical trials of panic disorder, whether of drugs or behavioral treatment, should include quality of life assessments as outcome measures. Long-term prospective studies based on clinical samples of patients with panic disorder are indicated to relate the illness more precisely to social morbidity.

Adolescent↗
PubMed1989

Machine specific equivalent squares for two commonly employed blocked treatment fields.

In an attempt to find the most suitable method for determining the equivalent square for two commonly employed blocked field arrangements, a comparison of measured outputs was made for four different treatment machines. The machines varied by manufacturer, design, and energy. The fields in question were a midline-blocked field and a half-blocked field. The data obtained was used to streamline calculations made by technologists for the original treatment setting. It was further used to enhance the accuracy of computer-generated verification of the original setting. The authors recommend that each institution employing such fields consider obtaining similar data for their own treatment machines.

Humans↗
PubMed1989

Physical work capacity of older women and men living in rural communities of eastern Ontario, Canada.

The physical work capacity of a population of older men and women living in rural municipalities of Eastern Ontario, Canada, was similar to the one observed on a group of Swedes living in the urban district of Uppsala. The physical work capacity test determined at 150 heart frequency per minute (PWC-150) in older men and women did not appear to be heart rate/age-related. There appeared to be no relationship between physical stature and heart rate response to physical exercise in the men and women tested.

Aged↗
PubMed1987

Recipient's mood, relationship type, and helping.

We conducted two studies to examine how a potential helper is affected by having a communal orientation toward a relationship with a potential recipient and by the potential recipient's sadness. We hypothesized that (a) having a communal orientation would increase helping and that (b) people high in communal orientation, but not others, would respond to a potential recipient's sadness by increasing helping. These hypotheses were tested in two studies. In Study 1, individual differences in communal orientation toward relationships were measured by using a new communal orientation scale reported for the first time in this article. In Study 2, manipulations were used to lead subjects to desire either a communal or an exchange relationship with another person. In both studies, subjects were exposed to a sad person or to a person in a neutral mood whom they were given a chance to help. As hypothesized, in both studies communally oriented subjects helped the other significantly more than did others. Also as hypothesized, in both studies communally oriented subjects but not others, increased helping in response to the other person's sadness although this effect reached statistical significance only in the second study.

Adult↗
PubMed1986

Legal aspects of urgent dental care.

It is safe to conclude that the practitioner may be held liable if he or she fails to recognize an emergency or if he or she concludes that an emergency exists when the circumstances do not warrant such a conclusion.

Dental Care↗