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Biomedical subjects

R W Norman

Publications and source records attributed to R W Norman.

At least 19 recordsLinked to original sources
PubMed2001

Metabolic evaluation of stone disease patients: a practical approach.

The high success rates of extracorporeal shockwave lithotripsy and endourological techniques, together with their ease of use, in the treatment of urinary stones often overshadow the importance of the metabolic component of stone disease. It is my opinion that the prevention of further stones complements management of the acute episode. This review summarizes a variety of approaches to the measurement and manipulation of individual risk factors in recurrent urinary stone disease.

Humans↗
PubMed2001

Biomechanical and psychosocial risk factors for low back pain at work.

OBJECTIVES: This study determined whether the physical and psychosocial demands of work are associated with low back pain. METHODS: A case-control approach was used. Case subjects (n = 137) reported a new episode of low back pain to their employer, a large automobile manufacturing complex. Control subjects were randomly selected from the study base as cases accrued (n = 179) or were matched to cases by exact job (n = 65). Individual, clinical, and psychosocial variables were assessed by interview. Physical demands were assessed with direct workplace measurements of subjects at their usual jobs. The analysis used multiple logistic regression adjusted for individual characteristics. RESULTS: Self-reported risk factors included a physically demanding job, a poor workplace social environment, inconsistency between job and education level, better job satisfaction, and better coworker support. Low job control showed a borderline association. Physical-measure risk factors included peak lumbar shear force, peak load handled, and cumulative lumbar disc compression. Low body mass index and prior low back pain compensation claims were the only significant individual characteristics. CONCLUSIONS: This study identified specific physical and psychosocial demands of work as independent risk factors for low back pain.

Adult↗
PubMed2001

Optimal prevention and management of proximal ureteral stent migration and remigration.

PURPOSE: We evaluated issues associated with proximal ureteral stent migration and remigration, including causes and management, and the predictability of ureteral length. MATERIALS AND METHODS: All proximal ureteral stent migrations that occurred from January 1997 to March 2000 were reviewed. Characteristics and treatment of the 33 patients with proximal ureteral stent migration were compared with those of 66 randomly selected controls who did not have stent migration. We also analyzed a subgroup of 6 cases of remigration. RESULTS: Of the ureteral stents 2% migrated proximally. Mean height was greater in patients with versus without a migrated stent (p = 0.028). The stent-to-ureter length ratio was lower in the migrated than in the nonmigrated group (p <0.0001). Patient height and side of migration were significant predictors of ureteral length (R2 = 0.3511, p <0.0001 and 0.0007, respectively). Of the patients who required continued ureteral stenting migrated stent management included placement of a longer stent in 9 (group 1) and a stent of equal length in 4 (group 2), and repositioning of the original stent in 4 (group 3). There was no remigration in group 1. However, migration recurred in 2 patients in group 2 (50%) and in all 4 in group 3 (100%). CONCLUSIONS: Proximal migration occurs when a stent is too short for the ureter. We recommend that ureteral length should be measured directly from an x-ray to select the optimal stent length. If it is necessary to continue stenting a ureter after migration has been detected, a longer stent should be placed.

Female↗
PubMed2000

Serum phosphate in stone formers: what does a low serum phosphate level mean?

PURPOSE: Metabolic evaluation is indicated in stone formers to identify and subsequently modify risk factors for nephrolithiasis. Some believe that serum phosphate may be an important indicator of nephrolithiasis risk. We determined whether serum phosphate is an independent risk factor for recurrent calcium stone formation and whether it may be used as an early marker for occult disease, such as hyperparathyroidism. MATERIALS AND METHODS: The charts of all patients with regular long-term stone clinic followup were reviewed. Initial serum phosphate levels were compared with stone recurrence, complications due to stones, initial visit urinary laboratory values and the medical diagnoses made during followup. Unpaired 2-sample t tests, and correlation and logistic regression analyses were performed with statistical significance at p <0.05. RESULTS: Data were available on 51 men and 25 women 22 to 74 years old (mean age 52). Of the patients 50 were recurrent and 26 were single stone formers. Serum phosphate levels were lower in women than in men. No consistent associations existed between initial or future serum phosphate levels and stone recurrence, complications from stones, urinary values or other medical diagnoses made during followup. CONCLUSIONS: Serum phosphate does not appear to be an independent risk factor for urinary tract stone recurrence or complications, or a reliable early predictor of occult disease.

Adult↗
PubMed2000

Effects of dietary fat on the urinary risk factors of calcium stone disease.

OBJECTIVES: To assess the association between dietary fat and various urinary risk factors of calcium stone disease in a group of calcium stoneformers attending an outpatient stone clinic. METHODS: Mean daily fat intake from self-recorded 4-day dietary food records and mean 24-hour urinary risk factors from two separate collections were evaluated in 476 patients selected randomly from an adult population attending an outpatient stone clinic for the first time. RESULTS: Mean daily total fat intake for men and women was significantly different at 105.6 and 78.1 g, respectively. Examination of the relationship between total fat intake and 24-hour urinary volume, pH, and excretions of magnesium, citrate, oxalate, calcium, and uric acid revealed no significant regressions in men and only a weak association between fat intake and urinary uric acid in women. CONCLUSIONS: Dietary fat does not have a significant effect on the urinary risk factors of calcium stone disease.

Adolescent↗
PubMed2000

The dietary habits of idiopathic calcium stone-formers and normal control subjects.

OBJECTIVES: To examine the relationship between 12 macro- and micro-nutrients and the risk of recurrent calcium stone formation by comparing the diets of a large outpatient clinic-based group of patients who had formed calcium-based urinary tract calculi with that of a population-based control group matched for age, gender and body mass index. PATIENTS, SUBJECTS AND METHODS: The dietary intake of 500 patients (cases) randomly selected from the adult population attending an outpatient renal-stone clinic and being evaluated and/or treated for biochemically or radiologically diagnosed calcium-based upper urinary tract calculi were compared with those of 500 control subjects selected to match for age, sex and body mass index from a stratified probability sample of 2212 adults (not institutionalized) living in the same geographical area. RESULTS: Comparing the mean nutritional intakes showed a statistically higher consumption of energy, carbohydrates, sodium, fibre, vitamin C, fat and folic acid among cases than in controls. The intake of calcium, alcohol and vitamin A was significantly higher among the controls. There were no significant differences in the intake of protein, niacin or iron. The results of these comparisons varied when the groups were stratified by sex, age and body mass index. CONCLUSIONS: Dietary risk factors for calcium-based urinary tract calculi are many and complex, and a detailed consideration of sex, age and body mass index is important in interpreting such data. While it is difficult to draw firm conclusions about causes and effects of individual nutrients from the available data, this study indicates a possibly more important role for dietary fat in stone formation than has been previously recognized. This relationship needs to be further explored in relation to urinary risk factors, as it may be possible to advise patients to reduce dietary fat as a prophylactic measure for stone formation. As dietary fat has been associated with cardiovascular diseases and possibly cancer, an overall recommendation to these patients for a low dietary fat intake may be easier to follow.

Adult↗
PubMed2000

Prostate cancer in a hypogonadal male receiving androgen supplementation.

Although androgen supplementation is clearly indicated in most hypogonadal males, it is also gaining popularity in the health management of the aging male without clearly low testosterone levels as the concept of male menopause becomes more accepted and recognized. The benefits include improved energy, sexual function and bone strength. A potential downside of exogenous androgen is the provocation of an underlying prostate cancer, which now represents the most common type of cancer and the second most common cause of cancer death among men in Canada. This problem is illustrated in our case of prostate cancer in a hypogonadal male on androgen supplementation. We recommend that serum PSA and digital rectal examination (DRE) be performed prior to the initiation of and regularly throughout the course of androgen supplementation. Changes in either should be investigated appropriately and termination of androgen supplementation should be considered an important component of management of prostate cancer in these patients.

Adenocarcinoma↗
PubMed2000

Primary extranodal lymphoma of the scrotum.

Primary extranodal lymphomatous involvement of the skin or genitourinary tract is rare. We report a case of primary scrotal diffuse large cell non-Hodgkin's lymphoma in a 78 year-old male.

Aged↗
PubMed1999

Impact of a shared decision-making program on patients with benign prostatic hyperplasia.

OBJECTIVES: To determine patient views about the Shared Decision-Making Program (SDP), an interactive videodisk program designed to inform patients with benign prostatic hyperplasia (BPH) about their condition and treatment options and to determine its impact on perceived knowledge and treatment preference. METHODS: Six hundred seventy-eight patients with symptomatic BPH from eight Canadian centers viewed the SDP. Before and after viewing the video, patients answered questionnaires designed to assess treatment preference, knowledge gained, and satisfaction with this educational format. A 1-year follow-up survey was also conducted. RESULTS: Most patients showed a high desire for information and high satisfaction with the SDP; this satisfaction persisted at 1 year. Patients' self-reported knowledge increased significantly (P <0.0001). However, the SDP did not alter initial treatment preferences among those with already formed preferences, although it aided almost half of those initially undecided in forming a preference. Viewing the SDP also appeared to enhance the physician-patient relationship. CONCLUSIONS: Patients saw the SDP as an effective method for teaching patients about BPH and the risks and benefits of various treatments, clarifying particular areas about which many patients appear to have a desire for more information than is often provided. Patients were enthusiastic about the educational value of the program, and their active participation in the decision-making process may actually enhance the physician-patient relationship. Contrary to other studies, we found no significant alterations in treatment preferences. Problems relating to the cost and timely updating of the software need to be addressed for these kinds of programs to realize their full potential.

Aged↗
PubMed1999

Assessment of an EMG-based method for continuous estimates of low back compression during asymmetrical occupational tasks.

Variables, such as peak and accumulated moments and spine compression forces, have been shown to be risk factors for occupational low back pain. Estimates of these forces during prolonged, dynamic, asymmetric tasks using biomechanical models is complex and time-consuming. A simple technique for continuous measurement of these variables over a prolonged period is needed to measure the distribution of spinal loading during both sagittal plane lifts and complex asymmetrical jobs. The aim of this study was to determine whether a linear normalization of erector spinae EMG to spine compression force, called compression normalized EMG (CNEMG), could be used to estimate spinal loading for simulations of asymmetrical occupational tasks. The estimates of spine compression force obtained using the normalized EMG are presented in the form of an amplitude probability distribution function and are compared with estimates of a three-dimensional biomechanical model. The per cent time a worker spends above particular levels of spinal loading of interest, such as the NIOSH action limit for compression, are displayed. Five males performed simulated occupational tasks. The exposure time at a specific level of spine compression force for a combination of three tasks, estimated by CNEMG, was, on average, within 6.5% of the time calculated by the biomechanical model. However, if the task combination was dominated by an axial twisting moment, then the difference was, on average, 13.4%. The difference in magnitude of spine compression at a specific probability was, on average, 14.9% and when axial trunk twist dominated, 30.7%. It is concluded that CNEMG can estimate probability at a specific level of spine compression force when the task combination is characterized by a predominant extensor moment in the sagittal plane. Estimates of spine compression at a specific probability, and estimates obtained during task combinations dominated by an axial twisting moment, are poor.

Adult↗
PubMed1999

Comparison of four peak spinal loading exposure measurement methods and their association with low-back pain.

OBJECTIVES: This paper examines the performance of 4 different methods of estimating peak spinal loading and their relationship with the reporting of low-back pain. METHODS: The data used for this comparison was a subset of subjects from a case-referent study of low-back-pain reporting in the automotive industry, in which 130 random referents and 105 cases (or job-matched proxies) were studied. The peak load on the lumbar spine was determined using a biomechanical model with model inputs coming from a detailed self-report questionnaire, a task-based check list, a video digitization method, and a posture and load sampling technique. RESULTS: The methods were directly comparable through a common metric of newtons or newton meters of spinal loading in compression, shear, or moment modes. All the methods showed significant and substantial associations with low-back pain in all modes (odds ratios 1.6-2.3). The intraclass correlation coefficients (ICC) showed strong similarities between the checklist and video digitized techniques (ICC 0.84-0.91), moderate similarities between these techniques and the work sampling method (ICC 0.49-0.52), and poor correlations (ICC 0.16-0.40) between the self-report questionnaire and the observer recorded measures. CONCLUSIONS: While all the methods detected significant odds ratios, they cannot all be used interchangeably for risk assessment at the individual level. Peak spinal compression, moment, and shear are important risk factors for low-back pain reporting, no matter which measurement method is used. Questionnaires can be used for large-scale studies. At the individual level a task-based checklist provides biomechanical model inputs at lower cost and equal performance compared with the criterion video digitization system.

Biomechanical Phenomena↗
PubMed1998

"Mirror pain" as an unusual presentation of renal colic.

Although most patients suffering from pain related to upper urinary tract stones feel the discomfort on the same side as the stone, rarely it is perceived on the opposite side. We sought to identify the prevalence of this clinical scenario and to review possible explanations. The charts and x-rays of all patients with unilateral, symptomatic, radiologically identifiable upper urinary tract stones, seen at an outpatient clinic between June 1993 and August 1996, were reviewed retrospectively in terms of the side of the discomfort in comparison to the side of the stone. Three of 631 patients presented with contralateral or "mirror pain" secondary to a renal or ureteric calculus. In each case the symptoms resolved completely following successful extracorporeal shock wave lithotripsy or spontaneous passage of the stone.

Adult↗
PubMed1998

Renal cell carcinoma metastatic to the contralateral ureter.

The ureter is an uncommon location for cancer metastases, the majority of which are due to nonurologic cancers such as stomach and breast.(1) Renal cell carcinoma (RCC) metastatic to the ureter has been reported infrequently. We report a case of metachronous metastatic RCC to the contralateral ureter.

Journal Article↗
PubMed1996

Disability resulting from occupational low back pain. Part I: What do we know about primary prevention? A review of the scientific evidence on prevention before disability begins.

This is the first of two papers that systematically review available scientific evidence on the causes of disability from occupational low back pain, and the effectiveness of interventions to prevent it-before disability begins (primary prevention-Part I) and after its onset (secondary prevention-Part II). This first paper reviews the risk factors for the onset of pain and associated disability followed by a critical summary of intervention studies attempting to achieve prevention and to evaluate the results.

Disability Evaluation↗
PubMed1996

Disability resulting from occupational low back pain. Part II: What do we know about secondary prevention? A review of the scientific evidence on prevention after disability begins.

This is the second of two papers that systematically review available scientific evidence on the causes of disability from occupational low back pain, and the effectiveness of interventions to prevent it after its onset (secondary prevention). This paper reviews the national history of how back pain and the risk factors for its extension into chronic disability, followed by a critical summary of intervention studies attempting to reduce the duration of this disability, and to evaluate the results.

Disability Evaluation↗
PubMed1996

Mechanically corrected EMG for the continuous estimation of erector spinae muscle loading during repetitive lifting.

Few studies have been carried out on the changes in biomechanical loading on low-back tissues during prolonged lifting. The purpose of this paper was to develop a model for continuously estimating erector spinae muscle loads during repetitive lifting and lowering tasks. The model was based on spine kinematics and bilateral lumbar and thoracic erector spinae electromyogram (EMG) signals and was developed with the data from eight male subjects. Each subject performed a series of isometric contractions to develop extensor moments about the low back. Maximum voluntary contractions (MVCs) were used to normalize all recorded EMG and moment time-histories. Ramp contractions were used to determine the non-linear relationship between extensor moments and EMG amplitudes. In addition, the most appropriate low-pass filter cut-off frequencies were calculated for matching the rectified EMG signals with the moment patterns. The mean low-pass cut-off frequency was 2.7 (0.4) Hz. The accuracy of the non-linear EMG-based estimates of isometric extensor moment were tested with data from a series of six rapid contractions by each subject. The mean error over the duration of these contractions was 9.2 (2.6)% MVC. During prolonged lifting sessions of 20 min and of 2 h, a model was used to calculate changes in muscle length based on monitored spine kinematics. EMG signals were first processed according to the parameters determined from the isometric contractions and then further processed to account for the effects of instantaneous muscle length and velocity. Simple EMG estimates were found to underestimate peak loading by 9.1 (4.0) and 25.7 (11.6)% MVC for eccentric and concentric phases of lifting respectively, when compared to load estimates based on the mechanically corrected EMG. To date, the model has been used to analyze over 5300 lifts.

Adult↗
PubMed1996

A simple polynomial that predicts low-back compression during complex 3-D tasks.

While most existing models that predict loads on the low back for occupational risk analysis are restricted to assessing moments in the sagittal plan, a few have the ability to determine spine compression from three-dimensional (3-D) loading. The objective of this work was to find a method to estimate low-back compression forces during 3-D loading tasks from a model that contains as much biological content validity as the authors could incorporate, such as the effects of muscle co-contraction, but was simple enough to be implemented into a model appropriate for industrial use. The problem that had to be solved was how to represent the anatomical reality that a given muscle force vector contributes simultaneously to all three moments, flexion or extension, lateral bend and axial twist. Simply summing the compression components of independent equivalent muscles in each plane unrealistically assumes that muscles are uncoupled (i.e. each one works independently to support only one moment). In this study, loads in the various tissues of the low back that resulted from the simultaneous generation of moments about the three orthopaedic axes during 3-D tasks were estimated by an anatomically detailed 90 muscle model. A four-dimensional regression equation was developed to predict low-back compression from the three moments generated about the three axes (R2 = 0.94). Comparison of compression estimates from an uncoupled model showed that accounting for muscle coupling reduces compression by 22% on average. The predictive equation is presented to simplify analysis of complex 3-D industrial tasks for those who would like to incorporate it into their own models that produce moments of force in three plans of the L4/L5 level of the lumbar spine.

Adult↗