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Biomedical subjects

J A Webb

Publications and source records attributed to J A Webb.

At least 19 recordsLinked to original sources
PubMed1998

Computerised electrocardiology employing bi-group neural networks.

A configuration of bi-group neural networks (BGNN) is proposed combined with an evidential reasoning framework to interpret 12-lead electrocardiograms for three mutually exclusive classes. A number of pre-processing feature selection techniques were investigated prior to application of the input feature vector to each individual BGNN. The network outputs were discounted within a belief interval of 1 based on their performance on test data prior to combination. It was found that the application of the feature selection techniques enhanced the individual performance of the BGNN, and subsequently enhanced the overall performance. The proposed framework was compared with conventional classification techniques of multi-output neural networks and linear multiple regression. The framework attained a higher level of classification in comparison with the other methods; 70.4% compared with 66.7% for both multi-output neural and statistical techniques.

Diagnosis, Differential↗
PubMed1998

Age-related differences in mammography use and in breast cancer knowledge, attitudes, and behaviors.

BACKGROUND: This study examined age differences in breast cancer knowledge, attitudes, and early-detection behaviors in a multi-ethnic sample of economically disadvantaged women participating in a breast-cancer education outreach program. METHODS: Age differences in breast cancer knowledge, perceptions of risk of breast cancer, barriers to mammography, recommendations of mammography by health professionals, health promotion behaviors, and mammography use and intention were investigated. The subjects were 139 women aged 30 or older who were categorized in one of three age groups: 30 to 39, 40 to 49, and 50 years old or older. RESULTS: One fourth of the women between the ages of 30 and 39 reported both that they had had mammography in the past and that they intended to have it in the next year. Fifty percent of those in their forties reported mammography use at some time in the past, and 56% intended to obtain it in the coming year. Fifty percent of those 50 or older reported that they had had mammography in the past year. Women aged 40 or older were more likely than those in their thirties to report that their healthcare providers had encouraged them to get mammograms. No significant age differences were observed in breast cancer knowledge or perceptions of personal risk of breast cancer. CONCLUSION: The fact that the three age groups were similar in their perceptions of personal risk of breast cancer suggests that older women may not be accurately assessing their risk and thus may be obtaining screening mammography at less-than-optimal levels.

Adult↗
PubMed1997

The role of imaging in adult acute urinary tract infection.

Imaging is required in only a minority of patients with urinary tract infection. Some patients who present with severe loin pain are imaged because ureteric colic is suspected. If urinary tract infection does not respond normally to antibiotics, imaging is undertaken to check for evidence of renal obstruction or sepsis. Finally, after the acute infection has been treated, imaging is required in some patients to check for factors pre-disposing to renal damage or to relapsing or recurrent infection. This review discusses the appropriate choice of imaging technique to use in each clinical situation and summarises the expected findings.

Acute Disease↗
PubMed1997

Replication and extension of a risk profile for Amerasian youth.

The relationship between number of risk factors and symptoms of anxiety and depression was examined in a cohort of Vietnamese Amerasians, replicating a study done with a previous cohort. One hundred forty seven subjects awaiting U.S. placement completed the Hopkins Symptom Checklist, the Vietnamese Depression Scale, and a questionnaire which included items found to be risk factors for psychological distress among Amerasians. Number of risk factors was linearly related to symptoms of both depression and anxiety. Results are consistent with previous findings of the relationship between risk factors and symptoms of psychological distress. The profile may be helpful in anticipating which refugees may be at risk for future psychological distress, and thus be useful in preventively allocating scarce treatment resources.

Adolescent↗
PubMed1997

Comparative levels of psychological distress in a pre-migratory refugee population.

OBJECTIVE: This study compares levels of psychological distress in a pre-migratory sample of Vietnamese Amerasians with those in a like-aged, non-migratory sample of Vietnamese living in Ho Chi Minh City, Vietnam. METHOD: Subjects were assessed using two measures developed and validated for Vietnamese clinical populations in the United States: the Hopkins Symptom Checklist-25 and the Vietnamese Depression Scale. RESULTS: Amerasians had significantly higher symptom levels on the depression scale of the Hopkins Symptom Checklist-25, but not on the other measures utilised. CONCLUSIONS: Amerasians' higher levels of depressive symptoms are probably a result of their traumatic lives in Vietnam, but may also reflect acute situational factors or selection bias.

Acculturation↗
PubMed1997

A prospective study of psychological distress related to refugee camp experience.

OBJECTIVE: Previous reports have suggested a direct relationship between refugee camp experience and levels of psychological distress among refugees. Specifically, it has been postulated that refugee camps with harsh conditions and low levels of social support foster high levels of psychological distress. The present study was designed to assess the relationship between camp conditions and social support within a refugee camp and refugees' levels of psychological distress. Unlike previous reports, which were based on retrospective data, the present study evaluated psychological distress among a group of Vietnamese refugees both prior to departure from Vietnam and during their refugee camp experience. METHOD: A group of 101 Vietnamese Amerasians was assessed at a transit centre in Vietnam and subsequently at a refugee camp in the Philippines. Assessment instruments were the Hopkins Symptom Checklist-25 and a Camp Comparison Questionnaire. RESULTS: There were significant decreases in symptom levels of anxiety and depression between the transit centre in Vietnam and the refugee camp in the Philippines. However, these changes were not related to changes in refugee camp conditions or social support within the camp. CONCLUSIONS: Contrary to previous reports, levels of psychological distress among this group of Vietnamese refugees were not related to either refugee camp conditions or levels of social support within the camp.

Adolescent↗
PubMed1996

The prevalence of psychiatric disorders among Vietnamese Amerasians: a pilot study.

A pilot study of the prevalence rate of DSM-III psychiatric disorders among Vietnamese Amerasians prior to migration from Vietnam found current prevalence of such disorders to be lower than previously reported among Vietnamese refugees in the United States and Australia. Methodological and cultural factors contributing to the lower than expected prevalence rate are discussed, and implications for clinical assessments and future research are noted.

Adolescent↗
PubMed1996

Demographic, psychosocial, and objective risk factors related to perceived risk of skin cancer.

BACKGROUND AND METHODS: The present study examined the ways in which demographic, psychosocial, and objective risk factors were related to perceived risk of skin cancer among 384 hospital employees who participated in a screening program. It was hypothesized that pyschosocial risk factors would account for a significant portion of the variance in risk perception beyond that accounted for by the other risk factors. RESULTS: The risk factors accounted for approximately 44% of the variance in risk perception. Psychosocial risk factors accounted for a statistically significant portion of the variance in risk perception beyond that accounted for by other risk factors. Worry, family history of skin cancer, and race/ethnicity were most strongly related to perceived risk. CONCLUSIONS: Results are discussed in terms of the need for educational programs that emphasize the relationship between level of risk and skin cancer and provide specific information regarding steps that can be taken to prevent skin cancer.

Adult↗
PubMed1996

Premigratory expectations and postmigratory mental health symptoms in Vietnamese Amerasians.

OBJECTIVE: To determine the relationship between premigratory expectations for one's future life in the United States and postmigratory symptoms of anxiety and depression in a group of Vietnamese Amerasians. METHOD: A cohort of 161 Vietnamese Amerasian migrants was assessed prior to departure from Vietnam using the Hopkins Symptom Checklist-25 (HSCL-25), the Vietnamese Depression Scale, and an Expectations Questionnaire. After migration to the United States, subjects were reassessed using the HSCL-25 and the Vietnamese Depression Scale. RESULTS: Premigratory expectations for support from the Vietnamese community in the United States were associated with significantly higher scores on the HSCL-25 Depression scale. Of subjects reassessed in the United States, 20% scored in the clinical range for depression. CONCLUSIONS: Like-ethnic community support is critically important in preventing depressive symptoms among Vietnamese Amerasian migrants. Clinicians working with Amerasians should target those with unrealistically high expectations for preventive intervention and should approach Vietnamese community leaders to mobilize support for recently arrived Amerasians.

Adolescent↗
PubMed1996

Do fifth graders' attitudes and intentions toward alcohol use predict seventh-grade use?

OBJECTIVE: To examine the relationship among children's perceptions of peer and parental attitudes toward alcohol use, fifth graders' attitudes toward alcohol use and intentions to use alcohol in junior high school, and alcohol use of these same children as seventh graders. METHODS: Subjects completed questionnaires as fifth graders that assessed their perception of parents' and peers' attitudes toward alcohol use, children's attitudes toward alcohol use, and intentions to use alcohol in junior high school. They completed a survey in the seventh grade that assessed alcohol use. RESULTS: Path analyses indicated that perceived peer and parental attitudes were directly related to children's fifth-grade attitudes toward alcohol use. Attitudes, in tum, were related to fifth-grade intentions, which were related to seventh-grade alcohol use. Peer and parental attitudes, and children's attitudes as fifth graders, were not directly related to later alcohol use. CONCLUSIONS: Peer and parental attitudes toward alcohol use among fifth graders exert an indirect, rather than direct, influence on later alcohol use. Similarly, attitudes of fifth graders influence later alcohol use through their influence on intentions to use alcohol. Prevention programs should be targeted toward younger children prior to initiation of alcohol use and should address both peer and parental influences on attitudes and intentions to use alcohol.

Adolescent↗
PubMed1996

A comparative study of Vietnamese Amerasians, their non-Amerasian siblings, and unrelated, like-aged Vietnamese immigrants.

OBJECTIVE: The authors compared the personal histories, levels of psychological distress, and adaptation to American life of Vietnamese Amerasians (N=140), their non-Amerasian siblings (N=71), and a group of unrelated, like-aged Vietnamese immigrants (N=118). METHOD: Subjects completed two self-administered symptom checklists and provided demographic and personal history data. RESULTS: Vietnamese Amerasians differed significantly from the other two groups on measures of alcohol use, number of hospitalizations, years of education, childhood trauma, perceived effects of trauma, and score on the Vietnamese Depression Scale. The Amerasians did not, however, differ on measures of social support or in their success at adapting to life in the United States. CONCLUSIONS: Despite multiple disadvantages, Vietnamese Amerasians appear to be adapting to life in the United States as well as other like-aged Vietnamese immigrants.

Acculturation↗
PubMed1996

Sonographic abnormalities of the thyroid gland following radiotherapy in survivors of childhood Hodgkin's disease.

The aims of this study were as follows. (1) To demonstrate the spectrum, frequency and changes on follow-up of sonographic abnormalities in the thyroid gland of survivors of Hodgkin's disease who had received radiotherapy to the neck in childhood. (2) To compare the sonographic findings with clinical examination and radionuclide imaging. (3) To investigate the association between the presence or absence of focal sonographic abnormalities with age at radiotherapy, the interval from radiotherapy, the presence of a raised thyroid stimulating hormone (TSH) and the length of time the TSH had been raised. 46 patients were scanned prospectively and rescanned at 6-18 months. The mean age at first sonography was 22.7 years, the median age at radiotherapy was 12.5 years, and the median interval post-radiation was 10.3 years. Sonographic abnormalities were seen in all 46 patients. 45 had diffuse atrophy and 30 had focal sonographic abnormalities. 18 patients developed new focal sonographic abnormalities on follow-up. Focal sonographic abnormalities were more commonly associated with longer duration of a raised TSH. Two patients had thyroid carcinoma. Sonographic abnormalities of the thyroid are common in patients following neck radiotherapy in childhood. Focal abnormalities are usually associated with a longer duration of raised TSH.

Adolescent↗
PubMed1995

Contractile responses and structure of small bronchi isolated from rats after 20 months' exposure to ozone.

Short-term exposure to high concentrations of ozone has been shown to increase airway responsiveness in normal humans and in all laboratory animal species studied to date. While our knowledge concerning the pulmonary effects of single exposures to ozone has increased rapidly over recent years, the effects of repeated exposures are less understood. The goal of the present study was to determine whether airway responsiveness is increased after near-lifetime exposure to ozone. Airway segments representing approximately eighth generation airways were isolated from Fischer 344 rats of both genders that had been exposed for 6 hr per day, 5 days per week for 20 months to 0, 0.12, 0.5, or 1.0 parts per million (ppm) ozone. Circumferential tension development was measured in isolated airways in response to bethanechol, acetylcholine, and electrical field stimulation. Responsiveness of the airways to the contractile stimuli was described by the effective dose or frequency that elicited half-maximum contraction (ED50) and the maximum response. Since ozone exposure is associated with remodeling of peripheral airways, smooth muscle area was determined and tension responses were normalized to the area measurements. Before normalization of tension data to smooth muscle area, neither the ED50 nor maximum response of small bronchi to the contractile stimuli was altered after chronic ozone exposure. Smooth muscle area was greater in airways isolated from animals that had been exposed to 0.5 ppm ozone. After accounting for smooth muscle area, maximum responses of the small bronchi isolated from male rats were significantly reduced after 0.12 and 0.5 ppm ozone. Although not significant statistically, a similar trend was observed in airways isolated from female rats. These results suggest that the increase in airway responsiveness associated with acute ozone exposure does not persist during near-lifetime exposure. Although the mechanism responsible for the adaptation to the effects of O3 on airway responsiveness is unknown, the results indicate that smooth muscle cell function was compromised by the chronic exposure. The mechanism(s) responsible for mediating this effect and the relevance of these results to humans remains to be determined.

Adaptation, Physiological↗
PubMed1995

A pilot study of abuse among Vietnamese Amerasians.

This report describes a pilot study of the prevalence of physical and sexual abuse, and current levels of psychological distress correlated with a history of abuse, in a group of Vietnamese Amerasians bound for the United States. A sample of Vietnamese Amerasians, part of a larger cohort originally selected in Vietnam, was assessed in the Philippines. Subjects completed a self-administered questionnaire regarding a history of physical and/or sexual abuse and three other self-administered questionnaires: the Hopkins Symptom Checklist-25, the Vietnamese Depression Scale, and the Youth Self Report. A history of physical and/or sexual abuse was reported by 22% of male and 18% of female Amerasians. Abused male Amerasians reported significantly higher levels of psychological distress than nonabused male Amerasians, while abused and nonabused female Amerasians did not differ in their levels of psychological distress.

Adolescent↗
PubMed1995

Unaccompanied status as a risk factor in Vietnamese Amerasians.

This study prospectively evaluates the relationship between unaccompanied status and levels of psychological distress in a group of Vietnamese Amerasians both prior to, and during, migration. Its objective was to determine whether unaccompanied migrant status functions as an independent post-departure risk factor for psychological distress, or if unaccompanied migrants are already at increased risk for, and have higher levels of, psychological distress prior to departure and the acquisition of unaccompanied status. Seventy-five Vietnamese Amerasian youth were evaluated at two points during their migration utilizing Felsman's Personal Information Form, the Hopkins Symptom Checklist-25, and the Youth Self-Report. The first assessment was conducted prior to migration at the Amerasian Transit Center in Vietnam, and the second during migration at the Philippine Refugee Processing Center. Unaccompanied Amerasians were found to have significantly higher risk levels for, and significantly more symptoms of, psychological distress prior to migration than accompanied Amerasians. During migration the difference in levels of psychological distress between accompanied and unaccompanied Amerasians increased beyond that attributable to predeparture risk levels alone. This significant differential increase in levels of psychological distress among unaccompanied Amerasians is attributable to unaccompanied status. Unaccompanied migrant status thus appears to function both as an independent postdeparture risk factor for psychological distress and also as a marker for increased levels of risk and psychological distress prior to migration.

Adolescent↗