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Biomedical subjects

Robert Harrison

Publications and source records attributed to Robert Harrison.

At least 19 recordsLinked to original sources
PubMed2006

The proportion of self-reported asthma associated with work in three States: California, Massachusetts, and Michigan, 2001.

OBJECTIVES: To assess the proportion of adult asthma at the state level that may be related to work. DESIGN: Work-related asthma questions were added to the 2001 Behavioral Risk Factor Surveillance System (BRFSS) questionnaire in California, Massachusetts, and Michigan. RESULTS: Findings indicate 7.4-9.7% of those with current asthma reported that their asthma may be work related. These results estimate that approximately 137,000 adults in California, 39,000 in Massachusetts, and 63,000 in Michigan have asthma that may be work related. CONCLUSIONS: These findings are unique in providing population-based estimates at the state level that illustrate that a substantial portion of adult asthma morbidity is due to exposures in the work environment.

Adolescent↗
PubMed2006

Rule generation for protein secondary structure prediction with support vector machines and decision tree.

Support vector machines (SVMs) have shown strong generalization ability in a number of application areas, including protein structure prediction. However, the poor comprehensibility hinders the success of the SVM for protein structure prediction. The explanation of how a decision made is important for accepting the machine learning technology, especially for applications such as bioinformatics. The reasonable interpretation is not only useful to guide the "wet experiments," but also the extracted rules are helpful to integrate computational intelligence with symbolic AI systems for advanced deduction. On the other hand, a decision tree has good comprehensibility. In this paper, a novel approach to rule generation for protein secondary structure prediction by integrating merits of both the SVM and decision tree is presented. This approach combines the SVM with decision tree into a new algorithm called SVM_ DT, which proceeds in three steps. This algorithm first trains an SVM. Then, a new training set is generated through careful selection from the output of the SVM. Finally, the obtained training set is used to train a decision tree learning system and to extract the corresponding rule sets. The results of the experiments of protein secondary structure prediction on RS126 data set show that the comprehensibility of SVM_DT is much better than that of the SVM. Moreover, the generalization ability of SVM_DT is better than that of C4.5 decision trees and is similar to that of the SVM. Hence, SVM_DT can be used not only for prediction, but also for guiding biological experiments.

Algorithms↗
PubMed2006

Patients' perceptions of joint teleconsultations: a qualitative evaluation.

OBJECTIVE: To determine patient perceptions of joint teleconsultations (JTC), with particular reference to reasons underlying, and factors contributing to, patient satisfaction and dissatisfaction with this mode of health delivery. BACKGROUND: Telemedicine has been welcomed as one way of improving health-care delivery, by improving patient access to secondary care and specialist services hence widening patient choice, particularly for patients outside major conurbations. However, a recent systematic review found currently available data on patient satisfaction with telemedicine to be methodologically flawed. Qualitative evaluations offer the opportunity to elucidate the details of patient satisfaction with this mode of health-care delivery. DESIGN: Qualitative study using semi-structured interviews. SETTING AND PARTICIPANTS: Purposive sample of 28 participants of a major randomized controlled trial (Virtual Outreach study) of JTC conducted in one urban and one rural area in Britain. INTERVENTION: Joint teleconferenced consultations with the patient, patient's general practitioner (GP), and a hospital specialist. The patient and GP were sited in the local practice, while the hospital specialist was in the hospital outpatient department, and the two parties were connected by an ISDN2 link and video-conferencing software. MAIN OUTCOME MEASURES: Patient experiences of JTC, with particular reference to reasons underlying, and factors contributing to, overall satisfaction or dissatisfaction. RESULTS: Two major themes were identified: customer care and doctor-patient interaction. Patients appreciated the customer care aspects of JTC, particularly the enhanced convenience, reduced costs and improved punctuality associated with JTC. However, there were divergent views about the doctor-patient interactions with some patients expressing a sense of alienation arising from the use of technology, and problems with doctor-patient communication. CONCLUSIONS: These data add significantly to the existing literature on patient satisfaction with telemedicine, by elucidating the factors underlying overall satisfaction scores and hence have implications for future service delivery and implementation of telemedicine.

England↗
PubMed2006

A qualitative study of the educational potential of joint teleconsultations at the primary-secondary care interface.

We conducted an evaluation of joint teleconsultations involving specialists, general practitioners (GPs) and their patients. Semistructured interviews (n = 39) and focus groups (2 groups with specialists; 6 groups with GPs) were used to collect data to explore participants' views on the educational aspect of joint teleconsultations, and to seek examples of learning that had taken place. The results showed that the teleconsultation was a complex situation in which some learning took place for the generalists, but overall participants were disappointed. Three themes emerged that could enhance the educational potential in future: generalists' reasons for referral as an influence on perceived learning; lack of clarity among clinicians regarding their role and conduct; and the presence of patients as an inhibitor in doctor-doctor interactions.

Attitude of Health Personnel↗
PubMed2006

A qualitative study of communication during joint teleconsultations at the primary-secondary care interface.

It has been suggested that joint teleconsultations can improve communication at the primary-secondary care interface. We examined data from a qualitative analysis of social interactions in teleconsultations between specialists and general practitioners. The primary interaction was between specialists and patients. The general practitioners mostly adopted a 'back seat role', listening and observing, but not becoming actively involved. Teleconsultations create a number of interactional difficulties, which are likely to impede implementation and sustainability.

Attitude of Health Personnel↗
PubMed2005

A conserved motif in transmembrane helix 1 of diphtheria toxin mediates catalytic domain delivery to the cytosol.

A 10-aa motif in transmembrane helix 1 of diphtheria toxin that is conserved in anthrax edema factor, anthrax lethal factor, and botulinum neurotoxin serotypes A, C, and D was identified by blast, clustal w, and meme computational analysis. Using the diphtheria toxin-related fusion protein toxin DAB(389)IL-2, we demonstrate that introduction of the L221E mutation into a highly conserved residue within this motif results in a nontoxic catalytic domain translocation deficient phenotype. To further probe the function of this motif in the process by which the catalytic domain is delivered from the lumen of early endosomes to the cytosol, we constructed a gene encoding a portion of diphtheria toxin transmembrane helix 1, T1, which carries the motif and is expressed from a CMV promoter. We then isolated stable transfectants of Hut102/6TG cells that express the T1 peptide, Hut102/6TG-T1. In contrast to the parental cell line, Hut102/6TG-T1 cells are ca. 10(4)-fold more resistant to the fusion protein toxin. This resistance is completely reversed by coexpression of small interfering RNA directed against the gene encoding the T1 peptide in Hut102/6TG-T1 cells. We further demonstrate by GST-DT140-271 pull-down experiments in the presence and absence of synthetic T1 peptides the specific binding of coatomer protein complex subunit beta to this region of the diphtheria toxin transmembrane domain.

Amino Acid Sequence↗
PubMed2005

Simulated microgravity produces attenuated baroreflex-mediated pressor, chronotropic, and inotropic responses in mice.

Whether myocardial contractile impairment contributes to orthostatic intolerance (OI) is controversial. Accordingly, we used transient bilateral carotid occlusion (TBCO) to compare the in vivo pressor, chronotropic, and inotropic responses (parts 1 and 2) to open-loop selective carotid baroreceptor unloading in anesthetized mice. In part 3, in vitro myocyte responses to isoproterenol in mice exposed to hindlimb unweighting (HLU) for approximately 2 wk were determined. Heart rate (HR) and mean arterial pressure (MAP) responses to TBCO were measured. In control mice, TBCO increased HR (15 +/- 2 beats/min, P < 0.05) and MAP (17 +/- 2 mmHg, P < 0.05). These responses were markedly potentiated in denervated control (DC) mice, in which the aortic depressor nerve and sympathetic trunk were sectioned before measurement. Baroreflex responses to TBCO were eliminated by blockade with hexamethonium bromide (10 microg/kg). In HLU (denervated) mice, HR and MAP responses were reduced approximately 70% compared with DC mice. In part 2, myocardial contractile responses to TBCO were measured with a left ventricular micromanometer-conductance catheter. TBCO in DC mice increased the slope of the end-systolic pressure-volume relation (end-systolic elastance) by 86 +/- 13%. This inotropic response was attenuated (14 +/- 10%, P < 0.005) after HLU. In part 3, contractile responses to isoproterenol were impaired in myocytes isolated from HLU mice. In conclusion, selective carotid baroreceptor unloading stimulates HR, blood pressure, and myocardial contractility, and HLU attenuates each response. These findings have important implications for the management of OI in astronauts, the elderly, and individuals subjected to prolonged bed rest.

Animals↗
PubMed2005

Work-related asthma among health care workers: surveillance data from California, Massachusetts, Michigan, and New Jersey, 1993-1997.

BACKGROUND: Asthma morbidity has increased, posing a public health burden. Work-related asthma (WRA) accounts for a significant proportion of adult asthma that causes serious personal and economic consequences. METHODS: Cases were identified using physician reports and hospital discharge data, as part of four state-based surveillance systems. We used structured interviews to confirm cases and identify occupations and exposures associated with WRA. RESULTS: Health care workers (HCWs) accounted for 16% (n = 305) of the 1,879 confirmed WRA cases, but only 8% of the states' workforce. Cases primarily were employed in hospitals and were nurses. The most commonly reported exposures were cleaning products, latex, and poor air quality. CONCLUSIONS: Health care workers are at risk for work-related asthma. Health care providers need to recognize this risk of WRA, as early diagnosis will decrease the morbidity associated with WRA. Careful product purchasing and facility maintenance by health care institutions will decrease the risk.

Adult↗
PubMed2005

Costs and survival of patients with colorectal cancer in a health maintenance organization and a preferred provider organization.

BACKGROUND: Colorectal cancer is relatively frequent among adults of working age, yet few studies have examined treatment, outcomes, and costs for people under 65 years of age with this disease. OBJECTIVE: The objective of this study was to compare the initial treatments, survival, cancer-related medical costs, and overall medical costs for working-aged persons with colorectal cancer in 2 large health insurance plans in Washington State, one a preferred provider organization (PPO) and the other a group model health maintenance organization (HMO). STUDY POPULATION: This study consisted of patients, aged 20-64 years, diagnosed with colorectal cancer in both health plans from 1996 to 1998. For each cancer case, up to 5 control subjects, matched on age and sex, were selected for the analysis. METHODS: We calculated unadjusted, attributable, and overall medical costs using the Kaplan-Meier sample average estimator. We calculated relative mortality rates using Cox regression. We used propensity scores to adjust overall costs and survival for potential confounding factors. RESULTS: Two hundred ten persons in the PPO and 136 persons in the HMO, aged 20-64 years, were diagnosed with cancer over the observation period and included in this study. Patients in the PPO were more likely to have local excision of their tumor (16% compared with 11%) and were less likely to receive chemotherapy (48% compared with 60%). The overall medical costs for the cancer cases were $46,000 in the HMO and $46,400 in the PPO (95% confidence interval for the difference: -$19,300 to 20,100). The cancer-attributable medical costs over 2 years were $40,400 in the HMO and $44,300 in the PPO (95% confidence interval for the difference: -$17,400 to 25,200). Survival was similar in the 2 health plans: the hazard ratio was 0.89 for those enrolled in the PPO (95% confidence interval: 0.50 to 1.59). Adjustment for potential confounding factors altered the results little. CONCLUSIONS: There were differences in the initial treatment of the patients in each health plan, but costs and survival were not significantly different between the 2 plans.

Adult↗
PubMed2005

Improved K-means clustering algorithm for exploring local protein sequence motifs representing common structural property.

Information about local protein sequence motifs is very important to the analysis of biologically significant conserved regions of protein sequences. These conserved regions can potentially determine the diverse conformation and activities of proteins. In this work, recurring sequence motifs of proteins are explored with an improved K-means clustering algorithm on a new dataset. The structural similarity of these recurring sequence clusters to produce sequence motifs is studied in order to evaluate the relationship between sequence motifs and their structures. To the best of our knowledge, the dataset used by our research is the most updated dataset among similar studies for sequence motifs. A new greedy initialization method for the K-means algorithm is proposed to improve traditional K-means clustering techniques. The new initialization method tries to choose suitable initial points, which are well separated and have the potential to form high-quality clusters. Our experiments indicate that the improved K-means algorithm satisfactorily increases the percentage of sequence segments belonging to clusters with high structural similarity. Careful comparison of sequence motifs obtained by the improved and traditional algorithms also suggests that the improved K-means clustering algorithm may discover some relatively weak and subtle sequence motifs, which are undetectable by the traditional K-means algorithms. Many biochemical tests reported in the literature show that these sequence motifs are biologically meaningful. Experimental results also indicate that the improved K-means algorithm generates more detailed sequence motifs representing common structures than previous research. Furthermore, these motifs are universally conserved sequence patterns across protein families, overcoming some weak points of other popular sequence motifs. The satisfactory result of the experiment suggests that this new K-means algorithm may be applied to other areas of bioinformatics research in order to explore the underlying relationships between data samples more effectively.

Algorithms↗
PubMed2004

Improved protein secondary structure prediction using support vector machine with a new encoding scheme and an advanced tertiary classifier.

Prediction of protein secondary structures is an important problem in bioinformatics and has many applications. The recent trend of secondary structure prediction studies is mostly based on the neural network or the support vector machine (SVM). The SVM method is a comparatively new learning system which has mostly been used in pattern recognition problems. In this study, SVM is used as a machine learning tool for the prediction of secondary structure and several encoding schemes, including orthogonal matrix, hydrophobicity matrix, BLOSUM62 substitution matrix, and combined matrix of these, are applied and optimized to improve the prediction accuracy. Also, the optimal window length for six SVM binary classifiers is established by testing different window sizes and our new encoding scheme is tested based on this optimal window size via sevenfold cross validation tests. The results show 2% increase in the accuracy of the binary classifiers when compared with the instances in which the classical orthogonal matrix is used. Finally, to combine the results of the six SVM binary classifiers, a new tertiary classifier which combines the results of one-versus-one binary classifiers is introduced and the performance is compared with those of existing tertiary classifiers. According to the results, the Q3 prediction accuracy of new tertiary classifier reaches 78.8% and this is better than the best result reported in the literature.

Algorithms↗
PubMed2004

Processes of care for individuals with work related asthma: treatment characteristics and impact of asthma on work.

The prevalence of asthma among working adults continues to rise each year. The California Department of Health Services conducts surveillance of work related asthma (WRA) to classify each work related exposure using Doctor's First Reports of Occupational Illness and Injury (DFRs). Using a cross-sectional, descriptive, comparative design, additional interviews were conducted and medical records were reviewed to explore workers' and providers' perceptions of follow up care. Two cohorts were compared: workers with WRA who belonged to a large, single HMO (n = 79) and workers with WRA who underwent follow up outside this HMO (n = 76). The interview asked about providers seen, tests ordered, and the impact of asthma on work. The HMO clients were significantly more likely than the non-HMO clients to see occupational medicine specialists (p = .004) and have pulmonary function testing (p = .049) during initial treatment. Twenty-four percent of clients currently working reported missed workdays caused by asthma in the past 6 months. The findings indicate management of WRA varies by health care system in California.

Absenteeism↗
PubMed2004

Garment workers in California: health outcomes of the Asian Immigrant Women Workers Clinic.

In this cross sectional descriptive study, the demographics, risk factors, and health outcomes of a volunteer, symptomatic sample of monolingual Cantonese garment workers in the Oakland, California Chinatown area are documented. Methods included a questionnaire and clinical examination and treatment at the Asian Immigrant Women Workers Clinic, a free clinic providing culturally focused occupational health consultation and treatment for painful musculoskeletal disorders. Because garment work involves highly repetitious, sustained awkward postures, focused education on stretching and ergonomics also was provided. Results from the first 100 clients revealed a highly symptomatic sample, with an average age of 48.7 years. Sixty-six percent rated their health status as fair or poor. Sixteen percent of the sample had nerve entrapments, and 99% had a diagnosed strain or sprain of the spine or upper extremities. This population did not file workers' compensation claims because of a lack of knowledge and a fear of reprisal. This study documented the barriers to seeking care for this low wage, immigrant population.

Adult↗
PubMed2003

Understanding the normalization of telemedicine services through qualitative evaluation.

OBJECTIVE: Qualitative studies can help us understand the "successes" and "failures" of telemedicine to normalize within clinical service provision. This report presents the development of a robust conceptual model of normalization processes in the implementation and development of telemedicine services. DESIGN: Retrospective and cumulative analysis of longitudinal qualitative data from three studies was undertaken between 1997 and 2002. Observation and semistructured interviews produced a substantial body of data relating to approximately 582 discrete data collection episodes. Data were analyzed separately in each of three studies. Cumulative analysis was conducted by constant comparison. RESULTS: (1) Implementation of telemedicine services depends on a positive link with a (local or national) policy level sponsor. (2) Adoption of telemedicine systems in service depends on successful structural integration so that development of organizational structures takes place. (3) Translation of telemedicine technologies into clinical practice depends on the enrollment of cohesive, cooperative groups. (4) Stabilization of telemedicine systems in practice depends on integration at the level of professional knowledge and practice, where clinicians are able to accommodate telemedicine through the development of new procedures and protocols. CONCLUSION: A rationalized linear diffusion model of "telehealthcare" is inadequate in assessing the potential for normalization, and the political, organizational, and "ownership" problems that govern the process of development, implementation, and normalization need to be accounted for. This report presents a model for assessing the potential for successful implementation of telehealthcare services. This model defines the requirements for the successful normalization of telemedicine systems in clinical practice.

Diffusion of Innovation↗
PubMed2003

Hormone replacement therapy in relation to survival in women diagnosed with colon cancer.

INTRODUCTION: Colorectal cancer is the second leading cause of cancer death among US men and women. A number of studies report that hormone replacement therapy (HRT) reduces the risk of colorectal cancer, but fewer studies have examined the relation between HRT use and survival after diagnosis and none examined this relation by anatomic location of the primary colon tumor. METHODS: Data from a cohort of 699 women 50-79 years of age diagnosed with colon cancer between 1980 and 1998 in a large Health Maintenance Organization based in Seattle, Washington were analyzed to examine the relation between HRT use prior to diagnosis and survival. Use of HRT was ascertained from a computerized pharmacy database. RESULTS: HRT use was associated with a 41% reduction in risk of death after adjustment for age, stage, and diagnosis year (p= 0.037). The association between HRT use and colon cancer survival was strongest among women with cancer in the distal colon (hazard rate ratio 0.33, 95% confidence interval, 95% CI: 0.13-0.83), while little or no association between HRT use and survival was observed among women with proximal tumors (HRR 0.78, 95% CI: 0.42-1.44). CONCLUSIONS: These findings suggest that HRT use is associated with improved survival from colon cancer. Future observational and laboratory studies should shed light on how hormones may be related to reduced incidence and improved prognosis.

Aged↗
PubMed2003

Cancer-attributable costs of diagnosis and care for persons with screen-detected versus symptom-detected colorectal cancer.

BACKGROUND & AIMS: Colorectal cancer screening is effective and cost-effective, but little data from health plan settings are available inform decision-makers regarding direct economic implications of colorectal cancer screening programs. The purpose of this study was to compare the prediagnosis evaluation and first-year treatment costs of persons diagnosed with colorectal cancer, stratified by whether the cancer was detected by screening using fecal occult blood testing or evaluation of symptoms. METHODS: This retrospective study analyzed persons diagnosed with colorectal cancer from 1993 to 1999 in Group Health Cooperative, a large health maintenance organization in Washington state. Total health care costs during 3 months before and 12 months following diagnosis were compared for screen-detected versus symptom-detected individuals. RESULTS: During this time, 206 cancers were detected by screening and 717 by symptoms. In the 3 months before diagnosis, total costs were 7346 US dollars for persons with screen-detected versus 10,042 US dollars for those with symptom-detected cancer (P < 0.01). Stratified by stage, diagnosis costs were significantly lower for persons with stage B cancer (7282 US dollars vs. 11,682 US dollars ; P < 0.01) and nonsignificantly lower for other stages. A total of 53% of screen-detected cases were Dukes' stage A or in situ at diagnosis versus 30% of symptom-detected cases (P < 0.01). Overall costs were lower for the screen-detected group in the 12 months following diagnosis (22,369 US dollars vs. 29,471 US dollars; P < 0.01). CONCLUSIONS: Colorectal cancer screening can substantially reduce prediagnosis evaluation costs. These savings are of interest to health plans and should be factored into cost-effectiveness evaluations of screening programs.

Aged↗