Search PubMed⌕ Search

Biomedical subjects

D J Butler

Publications and source records attributed to D J Butler.

18 recordsLinked to original sources
PubMed2005

Shift in absorbed dose for megavoltage photons when changing to TRS-398 in Australia.

Australian primary standards of air kerma and absorbed dose are realized in 60Co gamma rays. To calibrate the megavoltage photon beams from linear accelerators, radiotherapy centres have their ionization chamber calibrated in a 60Co beam and then use a protocol to transfer this calibration to the higher energy. The radiotherapy community is in the process of changing from the ACPSEM Protocol (Second Edition 1998) based on an air kerma calibration to the IAEA's TRS-398 Code of Practice, based on an absorbed dose to water calibration. To evaluate the shift in absorbed dose resulting from the new protocol, the absorbed dose should be determined using both protocols and compared. We present a formula for this shift which can be used to check the result. To use this formula the centre needs to measure a displacement correction and know the ratio of the air kerma to absorbed dose to water calibration factors at 60Co. We calculate the change they should expect by using the average ratio of the air kerma and absorbed dose to water calibration factors for NE2571 and NE2561 chambers, based on Australian standards, and by estimating the displacement correction from published depth dose data. We find the absorbed dose in a megavoltage photon beam to increase by between 0.1 and 0.6% for NE2571 chambers and between 0.7 and 1.1% for NE2561 chambers, for beams up to 35 MV. The dose measured using TRS-398 is always higher.

Australia↗
PubMed2000

Photometric observations of a polychromatic laser guide star.

We report the photometric observation of a polychromatic laser guide star (PLGS) using the AVLIS laser at the Lawrence Livermore National Laboratory (LLNL). The process aims at providing a measurement of the tilt of the incoming wave front at a telescope induced by atmospheric turbulence. It relies on the two-photon coherent excitation of the 4D5/2 energy level of sodium atoms in the mesosphere. We used two laser beams at 589 and 569 nm, with a maximum total average output power of approximately 350 W. For the purpose of photometric calibration, a natural star was observed simultaneously through the same instrument as the PLGS at the focus of the LLNL 50-cm telescope. Photometric measurements of the 330-nm return flux confirm our previous theoretical studies that the PLGS process should allow us at a later stage to correct for the tilt at wavelengths as short as approximately 1 microm at good astronomical sites. They show also that, at saturation of two-photon coherent absorption in the mesosphere, the backscattered flux increases by a factor of approximately 2 when the pulse repetition rate decreases by a factor of 3 at constant average power. This unexpected behavior is briefly discussed.

Journal Article↗
PubMed2000

Conference formats in family practice residencies.

BACKGROUND: This study was intended to establish national baseline data of the current structure of conferences at family practice residencies and to determine if there are differences in conference formats among types of residencies. METHODS: An author-developed survey was mailed to 331 programs stratified by type and randomly selected. Statistical analysis included chi-square tests and non-parametric tests. RESULTS: The response rate was 84%. The average time devoted to lectures was 4.5 hours a week, with the noon hour the most common time. Most speakers were from within the program, and community-based family physicians were rarely present. Structural changes were frequent. CONCLUSIONS: Results indicate that a variety of formats are implemented for meeting Residency Review Committee requirements in the structure of family practice residencies' conferences. Program settings do influence how conferences are structured. More research is needed on this neglected area of formal resident education.

Chi-Square Distribution↗
PubMed1999

Post-traumatic stress reactions following motor vehicle accidents.

Despite improvements in road conditions, vehicle safety and driver education, over 3 million persons are injured in motor vehicle accidents each year. Many of these persons develop post-traumatic stress symptoms that can become chronic. Patients with post-traumatic stress disorder experience disabling memories and anxiety related to the traumatic event. Early identification of these patients is critical to allow for intervention and prevent greater impairment and restriction. The family physician is in an ideal position to identify, treat or refer patients with traumatic responses to traffic accidents. The physician's awareness of patient characteristics and pre-accident functioning allows him or her to critically evaluate symptoms that may begin to interfere with the resumption of daily activities.

Accidents, Traffic↗
PubMed1998

Predicting resident confidence to lead family meetings.

BACKGROUND AND OBJECTIVES: Family physicians frequently encounter patients' family members in family meetings regarding health care. Although residents are expected to learn how to interview families, no quantitative studies have examined variables associated with building residents' confidence in their ability to lead family meetings. The current study sought to clarify the relationship between a number of training, participant, and situational components and resident confidence. METHODS: All family practice residents (n = 90) in a five-residency program system were sent a survey that examined their experience in and perceived competence to conduct family meetings. Responses were analyzed with a hierarchical regression analysis and an ex post facto univariate analysis. RESULTS: Residents with higher perceived confidence in their ability to run a family meeting were male, had specific training for leading family meetings, had participated in and initiated more family meetings, perceived stronger family physician faculty support, and had more family systems training than lower-confidence residents. CONCLUSIONS: The results highlight the experiential, curricular, and environmental variables that are associated with building resident confidence to lead family meetings. Residents may benefit from early exposure to the skills needed for family meetings and from reinforcement of these skills through observations of skilled practitioners, the expectation that they will initiate meetings, and the opportunity to debrief meetings with supportive faculty. Family meeting curricula should include conflict management skills and incorporate input from other specialists and hospital personnel who meet with families.

Data Collection↗
PubMed1995

Family practice residents' learning needs and beliefs about office-based psychological counseling.

BACKGROUND AND OBJECTIVES: Teaching office-based psychological counseling is an essential component of family practice training. Most counseling training has been adapted from other disciplines without adequately identifying residents' learning needs, attitudes, and beliefs about counseling. This study was designed to 1) assess family practice residents' perceived learning needs for counseling, and 2) elicit and clarify their attitudes and beliefs about counseling. METHODS: Three consecutive groups of residents anonymously recorded their questions about psychological counseling. These questions were presented to the residents in focus groups for elaboration and clarification of underlying attitudes and beliefs. A consensus panel then categorized the learning needs and identified residents' attitudes and beliefs. RESULTS: Eighty-six distinct learning need questions were identified. These items clustered into four categories: skill development, problem/patient selection, practice management, and role confusion. Focus group findings identified four major themes: the need for limits and boundaries, limited understanding of change and the therapeutic process, doubts about personal readiness, and difficulty with the integration of mind and body. CONCLUSION: These findings parallel the concerns of physicians in practice and reinforce the need to identify resident concerns about office-based counseling. Failure to identify and respond to learner concerns may limit the effectiveness of teaching efforts in this curricular area.

Attitude of Health Personnel↗
PubMed1993

Men sexually abused in childhood. Sequelae and implications for the family physician.

Although the majority of childhood sexual abuse victims are women, male children are also at risk for sexual assault and consequent long-term effects including major psychiatric disorders, substance abuse, sexual dysfunction, and somatization syndromes. Male patients sexually abused in childhood or adolescence may present to the primary-care physician with specific interpersonal or developmental crises or with persistent depression, anxiety, or somatic complaints. The physician can serve a therapeutic role by validating the patient's experience and can provide the patient with information on the prevalence and consequences of male sexual abuse. Assessment of the impact of sexual abuse will rely on the sensitive and systematic evaluation of critical variables related to the abuse. More severely traumatized patients will require assessment for suicide potential and referral for mental health services.

Adolescent↗
PubMed1993

Functions of an adult sickle cell group: education, task orientation, and support.

Although psychosocial concerns of patients with sickle cell disease have been described, these descriptions are based primarily on experience with adolescents and children. In addition, there is an absence of reports on sickle cell groups specifically designed for adult patients. This article reports on the development of an adult sickle cell support group and provides a description of the psychosocial factors most prevalent in patients' lives. Major adjustment difficulties for group members included increasing anxiety about death, the disruption of their social support network, disability, dependence on pain medication, and conflicts with health care providers. This community-based support group enhanced participants' knowledge about sickle cell disease, improved the physician-patient relationship, and helped resolve psychosocial adjustment problems.

Adaptation, Psychological↗
PubMed1991

Physician impairment: physicians' exposure, attitudes, and beliefs.

Concern about physician impairment has resulted in increased efforts to educate physicians about its nature and scope. This study reports the results of a survey of how family physicians obtain information about impairment, which sources they value, and how exposure to impairment relates to their attitudes and beliefs. A significant association was found between involvement in group-oriented programs and recognition of risk factors unique to the profession. Important differences were found between physicians who acknowledged the role of personal vulnerability in impairment and those who attributed causality to external sources. Results also revealed that this sample of physicians was almost equally divided on whether impairment should be defined exclusively by professional conduct.

Adult↗
PubMed1990

The use of isoelectric focusing to identify rhinoceros keratins.

Keratins represent the principal structural proteins of hair. They are also found in horn, nail, claw, hoof, and feather. Hair and nail samples from human and canine sources and hair samples from mule deer, white tail deer, cat, moose, elk, antelope, caribou, raccoon, and goat were studied. Parrot and goose feathers were also analyzed. Keratins are polymorphic, and species differences are known to exist. Proteinaceous extracts of deer and antelope antlers and bovine and rhinoceros horn were prepared by solubilizing 10 mg of horn sample in 200 microL of a solution containing 12M urea, 74mM Trizma base, and 78mM dithiothreitol (DTT). Extraction took place over a 48-h period. A 25-microL aliquot of extract was removed and incubated with 5 microL of 0.1 M DTT for 10 min at 25 degrees C. Keratins were then separated by isoelectric focusing (IEF) on 5.2% polyacrylamide gels for 3 h and visualized using silver staining. At least 20 bands could be observed for each species studied. However, band patterns differed in the position of each band, in the number of bands, and in band coloration resulting from the silver staining process. Horn from two species of rhinoceros was examined. For both specimens, most bands occurred in the pH range of 4 to 5. Although similar patterns for both species were observed, they differed sufficiently to differentiate one from the other. As might be expected, the closer two species are related phylogenetically, the greater the similarity in the IEF pattern produced from their solubilized keratin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Field stimulation responses of rat urinary bladder detrusor smooth-muscle. Dependence upon slow calcium channel activity determined by K+ depolarization and calcium antagonists.

Field stimulation responses of rat urinary bladder detrusor smooth muscle were unaffected by atropine, phentolamine, propranolol, caffeine and theophylline. After caffeine or theophylline treatment, previously quiescent detrusor preparations developed pronounced spontaneous contractile activity. Both natural spontaneous contractile activity and field stimulation responses were eliminated in Ca-free EGTA media. After washout, both kinds of activity returned but over quite different time scales. At moderate levels of K+-induced depolarization which inactivate fast Ca-channels, field stimulation responses persisted and additively superimposed upon the K+-induced tension, suggesting that field stimulation-induced depolarization had activated slow voltage-dependent Ca-channels. Almost 61% of detrusor muscle preparations examined showed some spontaneous contractile activity. Such preparations were more sensitive to K+-induced depolarization than quiescent preparations and K+-depolarization greatly accelerated the spontaneous activity of these muscle strips. The slow Ca-channel blockers nifedipine and verapamil eliminated field stimulation responses in the 10(-6)-10(-5) M range, but octylonium bromide was far less effective even at 10(-4) M. The inorganic Ca-channel blocker Mn2+ inhibited field stimulation responses at 0.5-1.0 mM but La3+ was surprisingly far less effective than Mn2+ in this concentration range, requiring a 1 mM level to achieve a 50% inhibition of response. It is concluded that field stimulation induced a depolarization of rat urinary bladder detrusor muscle which activates slow voltage-dependent Ca-channels. Field stimulation responses and natural spontaneous activity appear to strongly depend upon a sustained Ca influx through these channels for the sustained release of intracellular calcium and the maintenance of contractile force.

Animals↗
PubMed1972

Malignant granuloma.

Explore the source record for details and available documents.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Amputation: preoperative psychological preparation.

More than 90 percent of all amputations are now due to the complications of chronic disease. Because most amputations can be anticipated, the preoperative period allows the opportunity for psychological preparation of the patient. This article highlights the important contribution family physicians can make before patients undergo amputation. Common patient reactions before and after amputation are reviewed, and an illustrative case is described. Our experience and review of the literature suggest that psychological intervention during the preoperative period is associated with a less complicated postoperative adjustment and grieving experience. The family physician can promote patient adjustment by providing accurate information, eliciting unspoken fears, and encouraging the involvement of the patient's family. By emphasizing the patient's enduring characteristics and his or her past coping ability, we believe that family physicians can lessen the psychological distress of amputation and facilitate adaptation.

Adaptation, Psychological↗