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M J Bass

Publications and source records attributed to M J Bass.

At least 19 recordsLinked to original sources
PubMed2005

Imaging photon-initiated reactions: a study of the Cl(2P(3/2))+CH4-->HCl+CH3 reaction.

The hydrogen or deuterium atom abstraction reactions between Cl((2)P(3/2)) and methane, or its deuterated analogues CD(4) and CH(2)D(2), have been studied at mean collision energies around 0.34 eV. The experiments were performed in a coexpansion of molecular chlorine and methane in helium, with the atomic Cl reactants generated by polarized laser photodissociation of Cl(2) at 308 nm. The Cl-atom reactants and the methyl radical products were detected using (2+1) resonantly enhanced multiphoton ionization, coupled with velocity-map ion imaging. Analysis of the ion images reveals that in single-beam experiments of this type, careful consideration must be given to the spread of reagent velocities and collision energies. Using the reactions of Cl with CH(4), CD(4), and CH(2)D(2), as examples, it is shown that the data can be fitted well if the reagent motion is correctly described, and the angular scattering distributions can be obtained with confidence. New evidence is also provided that the CD(3) radicals from the Cl+CD(4) reaction possess significant rotational alignment under the conditions of the present study. The results are compared with previous experimental and theoretical works, where these are available.

Journal Article↗
PubMed2004

The dynamics of the Cl+n-C4H10-->HCl (v',j') + C4H9 reaction at 0.32 eV.

Rotational state resolved center-of-mass angular scattering and kinetic energy release distributions have been determined for the HCl (v' = 0, j' = 0-6) products of the reaction of chlorine with n-butane using the photon-initiated reaction technique, coupled with velocity-map ion imaging. The angular and kinetic energy release distributions derived from the ion images are very similar to those obtained previously for the Cl plus ethane reaction. The angular distributions are found to shift from forward scattering to more isotropic scattering with increasing HCl rotational excitation. The kinetic energy release distributions indicate that around 30% of the available energy is channeled into internal excitation of the butyl radical products. The data analysis also suggests that H-atom abstraction takes place from both primary and secondary carbon atom sites, with the primary site producing rotationally cold, forward scattered HCl (v' = 0) products, and the secondary site yielding more isotropically scattered HCl (v' = 0) possessing higher rotational excitation. The mechanisms leading to these two product channels are discussed in the light of the present findings, and in comparison with studies of other Cl plus alkane reactions.

Journal Article↗
PubMed2004

Photodissociation and multiphoton dissociative ionization processes in CH(3)S(2)CH(3) at 193 nm studied using velocity-map imaging.

Dissociation and ionization processes in dimethyl disulfide, CH(3)S(2)CH(3), induced by one- or two-photon absorption of 193 nm light, have been studied using velocity-map ion imaging. The analysis of the ion images of the CH(3)S(2) (+), CH(3)S(+), S(2) (+), and S(+) fragments has allowed the characterization of the scattering dynamics of some of the main photolysis and dissociative-ionization processes. In particular, the experiments corroborate the formation of electronically excited SCH(3)((2)A(1)) products in the 193 nm photodissociation of dimethyl disulfide seen in earlier studies, and show that laser ionization provides a very sensitive method for their detection. The data have also allowed determination of the recoil energy and angular distributions of the CH(3)S(2) (+) and CH(3)S(+) products of the two-photon dissociative-ionization of the CH(3)S(2)CH(3) molecule. The measured distributions for these products are consistent with the formation of a transient parent ion which dissociates after a substantial intramolecular rearrangement, possibly yielding the most stable isomeric forms of the fragments, namely CH(2)S(2)H(+) and CH(2)SH(+).

Journal Article↗
PubMed1999

Evaluating the effectiveness of 2 educational interventions in family practice.

BACKGROUND: Structured feedback of information can produce change in physician behaviour. The objective of this study was to assess the effectiveness of 2 educational interventions for improving the quality of care provided by family physicians in Ontario: the Practice Assessment Report (PAR) and the Continuing Medical Education Plan (CMEP) with a follow-up visit by a mentor. METHODS: The study was a randomized controlled trial. Physicians in the control group received only the PAR, whereas those in the experimental group received the PAR, CMEP and mentor interventions. The participants were 56 family physicians and general practitioners (27 in the PAR group and 29 in the CMEP group) in southern Ontario who agreed to participate in the interventions and provide data. A total of 2395 patients randomly sampled from the practices returned questionnaires and consented to have their medical records abstracted. The outcome measures were global scores in 4 areas--quality of care, charting, prevention and overall use of medications--and patient ratings of satisfaction with care and preventive practices. The measures were applied at the beginning (phase 1) and end (phase 2) of the study. RESULTS: The mean global scores at the end of the study for the PAR group were 70.1% for quality of care, 84.7% for prevention, 77.7% for charting and 82.2% for overall use of medications. The corresponding scores for the CMEP group were 68.3%, 82.1%, 76.4% and 83.2%. In the patient satisfaction component, the personal care scores at phase 2 were 93.6% for the PAR group and 94.6% for the CMEP group. Examples of the scores for prevention for the PAR group were 98.3% for children's current immunization, 96.6% for blood pressure measured within the previous 5 years, 79.4% for referral of women of the appropriate age for mammography within the previous 2 years, and 58.4% for discussion about alcohol use. The corresponding scores for the CMEP group were 95.8%, 97.6%, 77.6% and 64.6%. The changes in mean scores between phase 1 and phase 2 ranged from -1.9 to 2.3 points. There were no significant differences between the 2 groups in phase 1 or phase 2 scores or in change in scores. A total of 64.3% of the physicians rated the PAR as useful, 26.5% found the CMEP to be useful, and 41.0% considered the mentor strategy to be a useful form of continuing medical education. Although changes in practice related to the PAR, CMEP or mentor were reported by some physicians, they were not related to chart audit or patient scores. INTERPRETATION: Educational interventions based on quality-of-care assessments and directed to global improvements in quality of care did not result in improvements in the outcome measures. Educational interventions may have to be targeted to specific areas of the practice, with physicians being monitored and receiving ongoing feedback on their performance.

Education, Medical, Continuing↗
PubMed1999

Organ-selective homing defines engraftment kinetics of murine hematopoietic stem cells and is compromised by Ex vivo expansion.

Hematopoietic reconstitution of ablated recipients requires that intravenously (IV) transplanted stem and progenitor cells "home" to organs that support their proliferation and differentiation. To examine the possible relationship between homing properties and subsequent engraftment potential, murine bone marrow (BM) cells were labeled with fluorescent PKH26 dye and injected into lethally irradiated hosts. PKH26(+) cells homing to marrow or spleen were then isolated by fluorescence-activated cell sorting and assayed for in vitro colony-forming cells (CFCs). Progenitors accumulated rapidly in the spleen, but declined to only 6% of input numbers after 24 hours. Although egress from this organ was accompanied by a simultaneous accumulation of CFCs in the BM (plateauing at 6% to 8% of input after 3 hours), spleen cells remained enriched in donor CFCs compared with marrow during this time. To determine whether this differential homing of clonogenic cells to the marrow and spleen influenced their contribution to short-term or long-term hematopoiesis in vivo, PKH26(+) cells were sorted from each organ 3 hours after transplantation and injected into lethally irradiated Ly-5 congenic mice. Cells that had homed initially to the spleen regenerated circulating leukocytes (20% of normal counts) approximately 2 weeks faster than cells that had homed to the marrow, or PKH26-labeled cells that had not been selected by a prior homing step. Both primary (17 weeks) and secondary (10 weeks) recipients of "spleen-homed" cells also contained approximately 50% higher numbers of CFCs per femur than recipients of "BM-homed" cells. To examine whether progenitor homing was altered upon ex vivo expansion, highly enriched Sca-1(+)c-kit+Lin- cells were cultured for 9 days in serum-free medium containing interleukin (IL)-6, IL-11, granulocyte colony-stimulating factor, stem cell factor, flk-2/flt3 ligand, and thrombopoietin. Expanded cells were then stained with PKH26 and assayed as above. Strikingly, CFCs generated in vitro exhibited a 10-fold reduction in homing capacity compared with fresh progenitors. These studies demonstrate that clonogenic cells with differential homing properties contribute variably to early and late hematopoiesis in vivo. The dramatic decline in the homing capacity of progenitors generated in vitro underscores critical qualitative changes that may compromise their biologic function and potential clinical utility, despite their efficient numerical expansion.

Animals↗
PubMed1998

Procedures in ambulatory care. Which family physicians do what in southwestern Ontario?

OBJECTIVE: To determine how often family physicians perform 12 ambulatory care procedures and factors associated with procedure performance. DESIGN: Mailed, self-administered survey. The survey was conducted according to the Dillman Total Design method. SETTING: Family physicians' offices in London, Ont, and in surrounding communities. PARTICIPANTS: A total of 395 family physicians practising within the London area were mailed surveys, 237 in London and 158 outside London. Response rates were 80.6% and 75.9%, respectively. Nonresponders did not differ significantly from responders in sex but included more solo practitioners. MAIN OUTCOME MEASURES: Performance of ambulatory care procedures, sex, and practice characteristics of participant family physicians. RESULTS: For all responders, activities significantly associated with procedure performance were delivering babies, managing psychological problems, working emergency, and teaching. Mean total procedure scores ranged from 6.55 for managing psychological problems to 7.68 for working emergency. Sex-specific analysis showed that practice location and years in practice were significant factors for female but not for male family physicians. Mean total procedure scores for female physicians were 7.06 (outside London) and 4.74 (in London). CONCLUSIONS: Factors associated with procedure performance for family physicians in and around London included delivering babies, working in emergency, managing psychological problems, and teaching. Practice location was a significant factor for only female family physicians; those practising outside London performed procedures more than their urban counterparts and at similar rates to male physicians.

Ambulatory Care↗
PubMed1998

Changing face of family practice.

OBJECTIVE: To identify trends in family practice in London, Ont, between 1974 and 1994. DESIGN: Interview survey of all London family physicians in 1974. Questionnaire surveys in 1984 and 1994. SETTING: City of London, Ont. PARTICIPANTS: One hundred twenty-eight family physicians and general practitioners practising in London in 1974, 180 in 1984, and 237 in 1994. RESULTS: The percentage of female practitioners, practitioners with no in-hospital patients, and practitioners making no home visits in an average week increased significantly. The percentage of solo practitioners and family physicians practising obstetrics decreased significantly. Changes were found in the numbers of patients seen, in weekend coverage, in evening, and Wednesday afternoon office hours, and in level of satisfaction with practice. CONCLUSION: Fewer physicians cared for in-hospital patients, made home visits, practised solo, and delivered babies in 1994 than in 1974. Substantially more women were practising family medicine in 1994 than in 1974. The trend away from in-hospital care, with no corresponding increase in home care, raises questions about how urban family physicians can maintain certain clinical skills.

Family Practice↗
PubMed1996

Willingness to follow breast cancer. Survey of family physicians.

OBJECTIVE: To identify the experience and willingness of family physicians to accept follow-up care of patients treated for stage I breast cancer. DESIGN: Mailed questionnaire. PARTICIPANTS: One hundred eighty-nine family physicians in southwestern Ontario with oversampling of female physicians and physicians practising more than 20 km from a cancer clinic. MAIN OUTCOME MEASURE: Willingness to follow breast cancer patients and time after treatment family physicians would be willing to begin follow-up care. RESULTS: We had an 81.5% response rate. Of the 154 respondents, 53% had been involved previously in the 5-year, follow-up care of a patient with breast cancer and 77.1% believed it appropriate for family physicians to assume responsibility for follow-up care in all or most cases. If asked by a patient, the family, or an oncologist to provide follow-up care, 90.1% of family physicians reported they would accept this responsibility. Willingness to follow breast cancer patients was not associated with sex, years in practice, proximity to a cancer clinic, or certification status but was associated with having previously provided such care (P = .043). Of those willing to care for these patients, almost 90% would prefer to start within 1 year of treatment. CONCLUSION: Although only half the respondents had experience in providing follow-up care to breast cancer patients, most were willing to take on this role, especially if asked.

Aftercare↗
PubMed1995

Factors associated with location of death (home or hospital) of patients referred to a palliative care team.

OBJECTIVE: To identify factors associated with the location of death (home or hospital) of patients referred to a palliative care home support team. DESIGN: Retrospective case-control chart review. SETTING: Palliative care inpatient unit with a home support team in a large chronic care hospital. SUBJECTS: All 75 patients receiving services from the home support team who died at home between June 1988 and January 1990 and 75 randomly selected patients receiving the same services who died in hospital. OUTCOME MEASURES: Place of death (home or hospital). RESULTS: Of the 267 patients referred to the palliative care home support team during the study period 75 (28.1%) died at home. Factors significantly associated with dying at home were the patient's preference for dying at home recorded at the time of the initial assessment (p < 0.001), a family member other than the spouse involved in the patient's care (p = 0.021) and the use of private shift nursing (p < 0.001). The patients who died in hospital were more likely than the other patients to have had no home visits from the palliative care team after the initial assessment (p = 0.04). The patient's preference for dying at home was not met if the caregiver could not cope or if symptoms were uncontrolled. The patient's preference for dying in hospital was not met if his or her condition deteriorated rapidly or if the patient died suddenly. CONCLUSIONS: Patients' preference as to place of death, level of caregiver support and entitlement to private shift nursing were significantly associated with patients' dying at home. The determination of these factors should be part of every palliative care assessment. Patients and their families should be informed about available home support services.

Adult↗
PubMed1995

Who provides follow-up care for patients with early breast cancer?

OBJECTIVE: To assess how often family physicians are involved in posttreatment care of their stage I breast cancer patients and to identify factors associated with family physicians providing follow-up care. DESIGN: A retrospective cohort study with a 5-year follow up by chart review. PARTICIPANTS: All cases of breast cancer seen at the London Regional Cancer Centre between 1982 and 1987 were reviewed to identify 183 stage I cancer patients alive at 5 years. MAIN OUTCOME MEASURES: Whether a physician (other than an oncologist) was involved in the follow-up care of patients, and whether the physician was a family physician or a surgeon. RESULTS: Follow-up care during the 5-year postoperative period was provided in most cases by oncologists alone (66.7%); family physicians and surgeons were involved in 17.5% and 15.8% of cases, respectively. Surgeons became involved in follow-up care much earlier (12 months) than family physicians did (23 months) (P = 0.01) and were more likely to provide care for patients who received radiation treatment (P = 0.04) and for patients who lived in London (P = 0.004). Most malignant breast lesions (77.5%) were discovered by patients themselves (P = 0.0001). CONCLUSIONS: Currently, family physicians are infrequently involved in follow-up care of their patients with early breast cancer.

Adult↗
PubMed1994

Evaluation of a palliative care service: problems and pitfalls.

OBJECTIVE: To evaluate a palliative care home support team based on an inpatient unit. DESIGN: Randomised controlled trial with waiting list. Patients in the study group received the service immediately, those in the control group received it after one month. Main comparison point was at one month. SETTING: A city of 300,000 people with a publicly funded home care service and about 200 general practitioners, most of whom provide home care. MAIN OUTCOME MEASURES: Pain and nausea levels were measured at entry to trial and at one month, as were quality of life for patients and care givers' health. RESULTS: Because of early deaths, problems with recruitment, and a low compliance rate for completion of questionnaires, the required sample size was not attained. CONCLUSION: In designing evaluations of palliative care services, investigators should be prepared to deal with the following issues: attrition due to early death, opposition to randomisation by patients and referral sources, ethical problems raised by randomisation of dying patients, the appropriate timing of comparison points, and difficulties of collecting data from sick or exhausted patients and care givers. Investigators may choose to evaluate a service from various perspectives using different methods: controlled trials, qualitative studies, surveys, and audits. Randomised trials may prove to be impracticable for evaluation of palliative care.

Canada↗
PubMed1993

Errors in death certificate completion in a teaching hospital.

A retrospective chart review was conducted to determine the types and frequency of errors, other than those of diagnostic accuracy, made in recording information on death certificates and to assess factors that might affect those rates. The sample (n = 426) consisted of 50% of all deaths in a London, Ontario teaching hospital over one year. For each certificate reviewed, 6 questions were asked based on W.H.O. guidelines: 1) Was there an acceptable cause of death? 2) If mechanisms of death were recorded, were they adequately explained by an underlying cause of death? 3) Were there any sequencing errors? 4) Were there 2 competing causes of death listed? 5) Was there recorded any time interval between onset of the condition and death? 6) Was there any other inappropriate information recorded? The death certificates were filled out in an acceptable fashion 68.1% of the time. Comparing the 6 major departments in the hospital, there was significant difference in the error rates of the different departments (p = .0035). Error rates were not significantly better for certificates that had been signed by a coroner nor in those that had an autopsy performed. The majority of the death certificates (89.4%) were completed by house staff. More attention has to be devoted to raising physicians' awareness of the types of errors made in completing death certificates. Recurring educational sessions and feedback, if provided in teaching hospitals, could be helpful to increase the accuracy of these important documents.

Autopsy↗
PubMed1992

Risk language preferred by mothers in considering a hypothetical new vaccine for their children.

OBJECTIVES: To determine the type of risk language preferred by mothers considering the use of hypothetical new vaccine for their children and to compare their choice with what their physicians perceived they would prefer. DESIGN: Mail survey. SETTING: Thirteen family practices in southwestern Ontario. PARTICIPANTS: Women with at least one child between the ages of 6 months and 5 years and their physicians. MAIN OUTCOME MEASURES: Preferred risk language and physicians' predictions about patient preference. RESULTS: Of the 226 women sent the questionnaire 208 (92%) responded. Of the 192 who indicated their risk language preference 118 (61%) chose a numeric statement. Of the 11 physicians who answered the question 8 (73%) predicted that their parents would prefer non-numeric statements. Although the women in the study were more likely to be married, were better educated and had higher family incomes than women of the same age in the Ontario population, risk language preference was not found to be related to any of those demographic characteristics. CONCLUSION: Physicians must be prepared to outline the risks associated with vaccination in both quantitative and qualitative terms.

Adult↗
PubMed1992

Determinants of maternal tolerance of vaccine-related risks.

In a time when informed consent requires knowledge of the risks and benefits of medical care and technology to be communicated to the public, perceptions of benefits and risks of these techniques and procedures take on special importance. The purpose of the present study was to examine the determinants of maternal tolerance of vaccine-related side-effects in their children. A questionnaire was sent to 226 mothers of young children in southwestern Ontario seeking their opinion of the benefits and risks of selected medical procedures. It asked them to identify the risk of serious reactions they would tolerate for a new vaccine with benefits similar to that of pertussis vaccine. The response rate to the questionnaire was 92%. This group of young, well-educated mothers had high regard for some of the most common procedures and treatments used in family practice. The less common and more invasive procedures (heart surgery, brain surgery) were viewed as carrying almost as much risk as benefit. Abortion was perceived as involving more risk than benefit. Levels of acceptable risk with respect to a hypothetical new childhood vaccine were determined. A risk level of 1 in 1 million was the most popular level of acceptable risk, chosen by 25% of the respondents. The next most frequently chosen risk level was 1 in 100,000, chosen by 22%. Tolerance of possible vaccine side-effects did not differ with maternal age, education or prior experience with adverse vaccine or drug reactions. A summary net benefit score was derived for four technologies commonly used in family practice (antibiotics, vaccinations, birth control pills and X-rays).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Assessing functional status in family practice.

Family physicians need functional assessment skills to care effectively for elderly patients. Self-assessment instruments, such as the COOP charts, offer promise. Educators must give priority to functional assessment and develop specific materials for residency training.

Activities of Daily Living↗
PubMed1991

Ambulatory blood pressure monitoring and the primary care physician.

The primary care physician welcomes technology that will reduce overlabelling and overtreatment of hypertension. Three concerns with respect to ambulatory blood pressure monitoring are: the clear identification of those patients who will benefit from monitoring; the potential for labelling patients prematurely as having technical abnormalities (i.e., 'hypervariability'), which may have little clinical significance; and the inaccessibility of ambulatory monitoring. To determine patient acceptance of ambulatory monitoring, a follow-up survey of 37 patients who used the Spacelab 5200 device was conducted. Twenty-four percent said they would not be agreeable to further monitoring. While newer devices may be less disruptive, the point is made that it is important to include patient assessments in the evaluation of these devices. A comparison is undertaken between ambulatory monitors and the more accessible self-monitoring devices which involve the patient to a greater degree in his/her own care.

Blood Pressure Determination↗
PubMed1989

Quality of care in family practice: does residency training make a difference?

As the proportion of physicians who enter residency training in family practice steadily increases, so does the need to evaluate the impact of their training and postgraduate education on the quality of care in their practices. We audited the practices of 120 randomly selected family physicians in Ontario, who were separated into four groups: nonmembers of the College of Family Physicians of Canada (CFPC), members of the CFPC with no certification in family medicine, certificated members without residency training in family medicine and certificated members with residency training in family medicine. The practices were assessed according to predetermined criteria for charting, procedures in periodic health examination, quality of medical care and use of indicator drugs. Generally the scores were significantly higher for CFPC members with residency training in family medicine than for those in the other groups, nonmembers having the lowest scores. Patient questionnaires indicated no difference in satisfaction with specific aspects of care between the four groups. Self-selection into residency training and CFPC membership may account for some of the results; nevertheless, the findings support the contention that residency training in family medicine should be mandatory for family physicians.

Adult↗