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Biomedical subjects

C Bohm

Publications and source records attributed to C Bohm.

At least 19 recordsLinked to original sources
PubMed2001

Cardiac risk factors and the use of cardioprotective medications in patients with chronic renal insufficiency.

Cardiovascular disease (CVD) is a major cause of morbidity and mortality among patients with chronic renal insufficiency (CRI). beta-Adrenergic blockers, acetylsalicylic acid (ASA), angiotensin-converting enzyme (ACE) inhibitors, and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) all reduce CVD mortality, but little is known about the extent to which these medications are used in patients with CRI. This study, a prospective cross-sectional study of consecutive patients seen by nephrologists in four Canadian centers for follow-up of progressive CRI in 1999, was performed to investigate the prevalence of coronary risk factors and use of cardioprotective medications among patients with CRI. Patients had creatinine clearances of 75 mL/min or less but were not on dialysis therapy. Three hundred four consecutive patients meeting the inclusion criteria were enrolled. Mean age was 60.8 +/- 15.7 years, mean creatinine clearance was 30.3 +/- 18 mL/min, and the case mix of kidney diseases was similar to that in the Canadian Organ Replacement Registry data. One hundred seventeen of 304 patients (38.5%) had a history of previous CVD, and the prevalence of CVD was greater in patients with more severe CRI. Two hundred forty-three patients (79.9%) had a history of hypertension, 132 patients (43.4%) had hyperlipidemia, 114 patients (37.5%) had diabetes mellitus, and 71 patients (27.3%) were smokers. Thirty-five percent of the patients with CVD had blood pressures greater than 140/90 mm Hg; 103 patients (33.9%) were administered beta-blockers; 196 patients (64.5%), ACE inhibitors or angiotensin-receptor blockers; 83 patients (27.3%), ASA; and 56 patients (18.4%), statins. Patients with diabetes were not more likely than those without diabetes to be prescribed cardioprotective medications. CVD is common in the predialysis population, and its prevalence increases with more severe kidney failure. Despite this, the use of cardioprotective medications is relatively low, and many patients had suboptimal blood pressure control. Given the high burden of disease in these patients, beta-blockers and ACE inhibitors should be used to control hypertension and/or for cardioprotection, and the increased use of ASA and statins should be considered.

Adult↗
PubMed2000

Career and parenting satisfaction among medical students, residents and physician teachers at a Canadian medical school.

BACKGROUND: Studies of career and parenting satisfaction have focused separately on medical students, residents and practising physicians. The objective of this study was to compare satisfaction across a spectrum of stages of medical career. METHODS: A survey of incoming medical students, current medical students, residents and physician teachers at the University of Saskatchewan was conducted in the spring of 1997. Response rates were 77% (43/56), 81% (177/218), 65% (134/206) and 39% (215/554) respectively. Factors assessed in the stepwise regression analysis were the effect of sex, parenting and level of training on the likelihood of recommending parenting to medical students or residents, and on parenting dissatisfaction, job dissatisfaction, career dissatisfaction and the importance of flexibility within the college program to accommodate family obligations. RESULTS: More male than female physician teachers had partners (92% v. 81%, p < 0.01) and were parents (94% v. 72%, p < 0.01). Female physician teachers spent equal hours per week at work compared with their male counterparts (mean 52 and 58 hours respectively) and more than double the weekly time on family and household work (36 v. 14 hours, p < 0.01). Physician teachers were the most likely respondents to recommend parenting to residents and their peers. Residents were the most dissatisfied with their parenting time. At all career stages women were less likely than men to recommend parenting, were more dissatisfied with the amount of time spent as parents and were more likely to regard flexibility within the college program as beneficial. There were no sex-related differences in job dissatisfaction and career dissatisfaction. However, married women were more dissatisfied with their jobs than were married men. Job dissatisfaction was greatest among medical students, and career dissatisfaction was greatest among residents. INTERPRETATION: The optimal timing of parenthood appears to be upon completion of medical training. Women were less likely to recommend parenting, less satisfied with the time available for parenting and more likely to value flexibility within the college program to accommodate family needs. These differences did not translate into women experiencing more job or career dissatisfaction.

Adult↗
PubMed2000

The influence of gender and specialty on reporting of abusive and discriminatory behaviour by medical students, residents and physician teachers.

INTRODUCTION: The perception of whether a given behaviour is abusive differs between students and teachers. We speculated that attitudes towards reporting abusive and discriminatory behaviour may vary by specialty as well as by gender. METHODS: We report a cross-sectional survey of incoming medical students, medical students, residents, and teaching faculty at one Canadian medical school. The discrimination and abuse questions were in the following domains: (i) psychological abuse, (ii) sexual abuse, (iii) physical abuse, (iv) gender discrimination, (v) racial discrimination, (vi) disability discrimination, (vii) derogatory remarks regarding homosexuality. The frequency of self-reported witnessed or experienced abusive and discriminatory behaviour was compared by gender, specialty choice and stage of training. RESULTS: The response rates varied by respondent group: 44/56 (79%) of incoming medical students, 177/218 (81%) of medical students, 134/206 (65%) of residents and 215/554 (38%) of physician teachers. The frequency of these behaviours was perceived to be low by both male and female respondents. Abusive and discriminatory behaviour by physician teachers was noted more frequently by residents (P < 0.001) and physician teachers themselves (P < 0.001) compared with incoming medical students. As well, in general, women noted more abusive and discriminatory behaviour by all teachers, compared with men (P < 0. 003). Each response to the abuse/discrimination questions was also modelled as the independent variable using stepwise multiple regression. The area of specialization (surgical versus non-surgical) altered the reporting of abusive and discriminatory behaviour by women. CONCLUSION: We conclude that female surgical residents and medical students undergo a process of acclimatization to the patriarchal surgical culture. As female surgeons become physician teachers they revert to a culture more similar to that of their female non-surgical colleagues. Although a process of deidealization occurs in medical training, these attitudes are not necessarily retained throughout the practising lifetime of physicians as they regain autonomy and more personal control.

Adult↗
PubMed1999

Surveying physicians to determine the minimal important difference: implications for sample-size calculation.

The minimal important difference (MID) is the smallest benefit of treatment that would result in clinicians recommending it to their patients. The MID is necessary to calculate sample size for randomized clinical trials, but its chosen value is often arbitrary. This study set out to determine the practicability of surveying physicians to elicit the MID for clinical trial sample-size calculation. Using a mail survey, we elicited the MID of different physician specialties (family medicine, internal medicine, vascular surgery) for using propranolol to slow abdominal aortic aneurysm (AAA) growth assuming that propranolol was efficacious in this condition. We used different outcome measures (growth rate or proportion of patients requiring surgery) and different methods of data presentation for the proportion of patients requiring surgery (absolute risk reduction or number needed to treat). The MID varied significantly by physician specialty, experience with AAA and propranolol, and the method used to elicit the MID. Consequently, sample-size calculations using these various MIDs varied from 116 to 3015. Future attempts to elicit the MID need to consider carefully who is surveyed, how data are presented, and how opinions are elicited.

Adrenergic beta-Antagonists↗
PubMed1997

Fate of recurrent acute interstitial cellular rejection in an HLA identical kidney transplant recipient: impact of donor microchimerism.

We and others have shown that the incidence of acute interstitial rejection in HLA identical and non-identical kidney transplantation is similar. Chronic vascular rejection is, however, rare in full matched recipients. In light of the known correlation between previous acute cellular and chronic vascular rejections, lack of chronic rejection in full matched kidney allografts suggest that the immunological basis of acute and chronic rejections are different and/or only high-grade acute cellular rejection leads to chronic vascular rejection. Herein, we present the case of an HLA identical kidney transplant from a male donor to a female recipient who, because of poor compliance, had frequent acute interstitial cellular rejection culminating into chronic interstitial fibrosis with no evidence of vasculopathy or glomerulopathy characteristic of chronic vascular rejection. Donor cells, as examined by the presence of the Y chromosome DNA, were present in the peripheral blood during the most recent acute rejection but not thereafter. These findings support the notion that acute interstitial cellular rejection can lead to interstitial fibrosis but not chronic vasculopathy/glomerulopathy, and that microchimerism did not confer protection against acute cellular rejection.

Adult↗
PubMed1995

CBA--an atlas-based software tool used to facilitate the interpretation of neuroimaging data.

CBA, a software tool used to improve quantification and evaluation of neuroimaging data has been developed. It uses a detailed 3-dimensional brain atlas that can be adapted to fit the brain of an individual patient represented by a series of displayed images. Anatomical information from the atlas can then be introduced into the images. If the patient has been imaged in different modalities, adaptation of the atlas to the different images will provide the transformation that brings the images into registration. CBA can thus be used as a tool for fusing multimodality information from the same patient. Furthermore, by applying the inverse atlas transformation, images from a patient can be transformed to conform to the anatomy of the atlas brain. This anatomical standardization, where the atlas brain itself serves as the anatomy standard, brings data from different individuals into a compatible form providing possibilities to perform individual-group and group-by-group comparisons between patients and normal controls.

Animals↗
PubMed1994

Use of a computerized brain atlas in magnetoencephalographic activation studies.

A pilot study was carried out to test the feasibility of an adjustable computerized brain atlas, adapted to the individual anatomy for localizing current dipoles by means of magnetoencephalography (MEG). The atlas can be adapted to individual computed tomography (CT) or magnetic resonance (MR) images. Position information is transferred between these imaging methods and MEG using a stereotactic technique. For this purpose, a special non-magnetic helmet was designed to be used together with the ordinary head fixation system. It seems likely that the proposed combination of the brain atlas with MEG, CT and MRI methods will become a powerful tool in exploring different brain functions.

Anatomy, Artistic↗
PubMed1992

The role of anatomic information in quantifying functional neuroimaging data.

When using modern neuroimaging tools, such as CT, PET, SPECT, MRI and MEG, in brain research and brain diagnostics, there is a common need for including external anatomical information into the interpretation and analysis of data. This information may be used to aid the interpretation of structures in images from low resolution imaging tools. With high resolution tools it can help to identify resolved structures. It can also facilitate the merging of data from different modalities, or from different individuals. The anatomical information is often given as regions of interests (ROIs), which may be manually created from an anatomy rich image or automatically created from a standard template collection or from an atlas data base. Automatic methods will lead to a substantial reduction in bias and in size of the systematic errors. Functional ROIs can correspondingly be derived from functional images (usually PET or SPECT). Different aspects of these processes are discussed in the report.

Brain↗
PubMed1991

Specification and selection of regions of interest (ROIs) in a computerized brain atlas.

The computerized individually adjustable brain atlas (CBA) has been further developed. The atlas was primarily designed for anatomical localization and quantitative evaluation of data in positron emission tomography (PET), but may also be employed for other neuroimaging modalities, such as transmission computed tomography (CT) and magnetic resonance imaging (MRI). The atlas is based on anatomical information obtained from digitized cryosectioned brains. Using spatially standardized and then averaged MRI images, we demonstrate the high localization accuracy and precision of the brain atlas. This is a prerequisite for obtaining accuracy when using the atlas in the localization and the quantitative evaluation of PET data. The specification and the selection of region of interests (ROIs) by the CBA are presented and discussed.

Brain↗
PubMed1990

Accuracy and precision of the computerized brain atlas programme for localization and quantification in positron emission tomography.

The computerized brain atlas programme (CBA) provides a powerful tool for the anatomical analysis of functional images obtained with positron emission tomography (PET). With a repertoire of simple transformations, the data base of the CBA is first adapted to the anatomy of the subject's brain represented as a set of magnetic resonance (MR) or computed tomography (CT) images. After this, it is possible to spatially standardize (reformat) any set of tomographic images related to the subject, PET images, as well as CT and MR images, by applying the inverse atlas transformations. From these reformatted images, statistical images, such as average images and associated error images corresponding to different groups of subjects, may be produced. In all these images, anatomical structures can be localized using the atlas data base and the functional values can be evaluated quantitatively. The purpose of this study was to determine the spatial and quantitative accuracy and precision of the calculated regional mean values. Therefore, the CBA was applied to regional CBF (rCBF) measurements with [11C]fluoromethane and PET on 26 healthy male volunteers during rest and during three different physiological stimulation tasks. First, the spatial accuracy and precision of the reformation process were determined by measuring the spread of defined anatomical structures in the reformatted MR images of the subjects. Second, the mean global CBF and the mean rCBF in the average PET images were compared with the global CBF and rCBF in the original PET images. Our results demonstrate that the reformation process accurately transformed the individual brains of the subjects into the standard brain anatomy of the CBA. The precision of the reformation process had an SD of approximately 1 mm for the lateral dislocation of midline structures and approximately 2-3 mm for the dislocation of the inner and outer brain surfaces. The quantitative rCBF values of the original PET images were accurately represented in the reformatted PET images. Moreover, this study shows that the application of the CBA improves the analysis of functional PET images: (a) The average PET images had a low background noise [0.4 ml/100 g/min +/- 0.7 (SD)] compared to the mean rCBF changes specifically induced by physiological stimulation. (b) The reformatted PET images had a voxel volume of 10.9 mm3. Owing to this high sampling resolution, it was possible to differentiate the mean rCBF changes in adjacent activated fields such as the left motor hand area from the sensory hand area and the left premotor cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1990

Functional anatomy of storage, recall, and recognition of a visual pattern in man.

With the purpose of mapping the anatomical structures participating in memory of visual patterns, we measured regional cerebral blood flow (rCBF) as an indicator of synaptic metabolism in eleven volunteers during four conditions: rest, visual learning of colored geometrical patterns, recall with the eyes closed, and recognition of the patterns. Learning changed rCBF in the primary visual cortex, visual association areas, temporal pole, anterior hippocampus, dorsal thalamus, caudate nucleus, putamen, and the anterior cingulate cortex. Recall and recognition changed rCBF in other limbic, thalamic, and striatal sectors. Only the highest order parieto-occipital visual areas were activated during recall. These areas were assumed to be the storage sites. It was inferred that the limbic and striatal circuits participating in learning were replaced by other limbic and thalamic circuits to recall and recognize the learned patterns.

Adult↗
PubMed1990

Motor learning in man: a positron emission tomographic study.

We measured regional cerebral blood flow (rCBF) with positron emission tomography to study changes in anatomical structures during the course of learning a complicated finger sequence of voluntary movements. Motor learning was accompanied by rCBF increases in the cerebellum, decreases in all limbic and paralimbic structures, and striatal decreases which changed to striatal increases as the motor skill was learned. Simultaneously, activations of initially contributing non-motor parts of the cerebral cortex vanished. Both cerebellar circuits and striatal circuits appear important for the storage of motor skills in the brain.

Adult↗
PubMed1989

A computerized adjustable brain atlas.

A computerized brain atlas, adjustable to the patients anatomy, has been developed. It is primarily intended for use in positron emission tomography, but may also be employed in other fields utilizing neuro imaging, such as stereotactic surgery, transmission computerized tomography (CT) and magnetic resonance imaging (MRI). The atlas is based on anatomical information obtained from a digitized cryosectioned brain. It can be adjusted to fit a wide range of images from individual brains with normal anatomy. The corresponding transformation is chosen so that the modified atlas agrees with a set of CT or NMR images of the patient. The computerized atlas can be used to improve the quantification and evaluation of PET data by: Aiding and improving the selection of regions of interests. Facilitating comparisons of functional image data from different individuals or groups of individuals. Facilitating the comparison of different examinations of the same patient, thus reducing the need of reproducible fixation systems. Providing external a priori anatomical information to be used in the image reconstruction. Improving the attenuation and scatter corrections. Aiding in selecting a suitable patient orientation during the PET study. By applying the inverse atlas transformation to PET data set it is possible to relate the PET information to the anatomy of the reference atlas. Thus reformatted PET data from different patients can be averaged, and averages from different categories of patients can be compared. This procedure will facilitate the identification of statistically significant differences in the PET information from different groups of patients.

Brain↗
PubMed1989

Scatter fraction: measurement and correction.

The concept of scatter in Positron Emission Tomography is reviewed regarding origin and influence on data. Different ways to measure and correct for scatter are discussed.

Scattering, Radiation↗
PubMed1986

Applications of a computerized adjustable brain atlas in positron emission tomography.

A computerized brain atlas, adjustable to the patient's anatomy, has been developed. It is primarily intended for use in positron emission tomography (PET), but may also be employed in other fields utilizing neuro-imaging, such as stereotactic surgery. The atlas is based on anatomic information obtained from digitized cryosectioned cadaver brains. It can be adjusted to fit a wide range of individual brains with reasonable accuracy. The corresponding transformation is chosen so that the modified atlas agrees with a set of CT or MR images of the patient. The computerized atlas can be used to facilitate and improve the quantification and evaluation of PET data by: enabling the merging and comparison of results from different individuals or groups of individuals; serving as a vehicle in the comparison of different examinations of the same patient, thus reducing the need of reproducible fixation systems; supplying external information to be used in the image reconstruction, such as proper three-dimensional regions of interest; improving the attenuation and scatter corrections; helping to select suitable patient orientation during the PET study. By applying the inverse atlas transformation to the PET data volume it is possible to relate the PET information to the anatomy of the reference atlas. Reformatted PET data from different patients can thus be averaged, and averages from different categories of patients can be compared. The method will facilitate the identification of statistically significant differences in the PET information from different groups of patients.

Brain↗