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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
PubMed1992

Diet and calcium stones.

OBJECTIVE: To review the current literature on the dietary modification of urinary risk factors as a means of reducing the likelihood of recurrent stone formation and to develop practical dietary recommendations that might be useful to this end. DATA SOURCES: MEDLINE was searched for English-language articles published from 1983 to 1990. Additional references were selected from the bibliographies of identified articles. STUDY SELECTION: Nonrandomized trials and retrospective reviews were included because of a paucity of randomized controlled trials. DATA SYNTHESIS: Information on the dietary intake of calcium, oxalate, protein, sodium and fibre and on alcohol and fluid intake was used to develop practical guidelines on dietary modification. CONCLUSION: Dietary modification plays an important role in the reduction of urinary risk factors in patients with calcium stone disease of the urinary tract. As an initial form of prevention attention should be directed toward moderating the intake of calcium, oxalate, protein, sodium and alcohol and increasing the intake of fibre and water. Future research should include an assessment of the long-term reduction of dietary and urinary risk factors and the rates of recurrence of calcium stones.

Alcohol Drinking↗
PubMed1992

111Indium-oxine-labeled leukocytes and 67gallium-citrate as indicators of renal injury following extracorporeal shock wave lithotripsy.

To document the extent and persistence of traumatic inflammation after extracorporeal shock wave lithotripsy (ESWL), 15 patients were randomly chosen to have either 67gallium (67Ga)-citrate or 111indium (111In)-oxine scans within 24 to 48 hours of ESWL. Positive scans were repeated at 8 to 12 weeks. Nine patients had renal calculi, and 6 had ureteral calculi and acted as controls. Of the patients with renal calculi 6 were scanned with 67Ga-citrate and 3 with 111In-oxine. Four of the former and 2 of the latter scans showed evidence of renal injury. Followup scans were normal. There was no correlation between power index (number of shocks times accelerating voltage) and scan results. Half of the control subjects were scanned with 67Ga-citrate and the remainder with 111In-oxine and all scans were negative. 67Ga-citrate and 111In-oxine scans can show evidence of renal injury immediately after ESWL but abnormal scans 2 to 3 months later would be suggestive of a different inflammatory process.

Adult↗
PubMed1991

Cytogenetic abnormalities associated with renal cell carcinoma.

Cytogenetic analysis was performed on 23 renal cell carcinomas (21 sporadic and 2 associated with von Hippel-Lindau's disease). Clonal chromosomal abnormalities were found in 19 of 21 of the sporadic tumors. The most frequent abnormalities were a loss or rearrangement of material in 3p (11 of 21 cases) or an extra chromosome 7 (7 of 21 cases). Correlation between specific chromosomal abnormalities and clinical presentation was absent with the exception of trisomy 7 and -Y, which occurred only in patients more than 60 years old. An increasing number of cytogenetic abnormalities were associated with a greater likelihood of renal vein and/or capsule involvement. Both patients with von Hippel-Lindau's disease had tumors with a normal karyotype.

Adult↗
PubMed1991

Trunk muscle and lumbar ligament contributions to dynamic lifts with varying degrees of trunk flexion.

This study was done to assess the interplay between muscular and ligamentous sources of extensor moment during dynamic lifting with various loads and flexion angles of the trunk segment for 15 subjects lifting a total of 150 loads. Ligament forces predicted from an anatomically detailed biomechanical model did not generally contribute more than 60 Nm for most of the lifts because the lumbar spine was only flexed to a moderate and constant degree for each load condition. In contrast, additional moment demands associated with increases in hand load were supported by muscle. Although the compression forces on the L4-5 intervertebral disc were fairly insensitive to the interplay between the recruitment of muscle and ligament, the shear force was significantly higher with a greater degree of lumbar flexion. The risk of injury may be influenced more by the degree of lumbar flexion than the choice of stoop or squat technique.

Adult↗
PubMed1991

Differential effect of 5 alpha-reductase inhibition and castration on androgen-regulated gene expression in rat prostate.

Castration reduces prostate size and causes intraprostatic testosterone (T) and dihydrotestosterone (DHT) to fall to very low levels. 5 alpha-Reductase inhibition also reduces prostate size, but results in a marked increase in intraprostatic T levels. To compare the effects of 5 alpha-reductase inhibition and castration on prostate physiology, male Sprague-Dawley rats were left intact, castrated, or given the selective 5 alpha-reductase inhibitor finasteride for up to 9 days. To be sure that finasteride itself did not directly affect gene expression, an additional group of rats was castrated and given finasteride for 4 days. The prostates were weighed, intraprostatic RNA, DNA, and androgen levels were measured, and mRNAs for two androgen-regulated genes, prostate steroid-binding protein (PSBP; an androgen-induced gene) and testosterone-repressed prostate message (TRPM-2), were quantitated by Northern and slot blot analyses. Finasteride caused a 95% reduction in intraprostatic DHT levels and a 10-fold increase in intraprostatic T levels. Finasteride, as expected, caused a pronounced decrease in prostate weight (45% on day 4). DNA content fell correspondingly (48% on day 4). Intraprostatic DNA (micrograms of DNA per gland) on day 4 was 328 +/- 53 in control rats, 171 +/- 10 in finasteride-treated rats (P less than 0.001 compared to controls), 115 +/- 2 in castrated rats (P less than 0.05 compared to finasteride), and 107 +/- 43 in finasteride-treated plus castrated rats (P = NS compared to castration alone). There were no significant differences in DNA levels among the groups when expressed per mg prostate tissue, indicating that mean prostate cell size was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

5-alpha Reductase Inhibitors↗
PubMed1991

Lumbar spine loads during the lifting of extremely heavy weights.

The reaction moments at the knee, hip, and L4/L5 joints, and the compressive and shearing forces on L4/L5 are documented in powerlifters competing in a national powerlifting championship. Analyses were made of 13 female and 44 male competitors. The joint moments and forces were estimated from a linked segment model (WATBAK) that incorporated functional low back extensor musculature with a moment arm of 6 cm and a line action that was oriented 5 degrees posteriorly to the L4/L5 compression axis. This oblique orientation of the extensor muscles reduced the anterior shearing load on the vertebral motion unit. Average compressive loads on L4/L5 were estimated up to 17,192 N while the highest average L4/L5 and hip moments were 988 and 1047 N.m, respectively. The sumo deadlift style resulted in a 10% reduction in the joint moment and 8% reduction in the load shear force at the L4/L5 level when compared with the conventional lifting style. Formulation of linear regression equations to predict the load lifted using reaction joint moments yielded substantial unexplained variability, though significant relationships were found. This analysis suggested that there is large variability in the pattern of loading joints among national class powerlifters.

Biomechanical Phenomena↗
PubMed1990

Dietary restriction of sodium as a means of reducing urinary cystine.

We assessed 5 patients with recurrent cystine urolithiasis before and after implementation of a low sodium diet. This diet led to a significant decrease in the 24-hour urinary excretion of sodium and cystine. Dietary restriction of sodium should be an important component of the therapeutic strategy of patients with cystinuria.

Adult↗
PubMed1990

The effect of an abdominal belt on trunk muscle activity and intra-abdominal pressure during squat lifts.

The purpose of this study was to determine whether abdominal belts such as those prescribed to industrial workers reduced trunk muscle activity and/or increased intra-abdominal pressure (IAP). In this study, six subjects lifted loads (72.7 to 90.9 kg) both with and without wearing a weightlifter belt. In addition, further trial conditions required that subjects lifted both with the breath held or continuously expiring on lifting effort. Dynamic hand loads were recorded together with intra-abdominal pressure (IAP) and abdominal, intercostal and low back EMG. Every subject demonstrated an increase in IAP when wearing the belt during both breathing conditions: 99 mmHg with no belt; 120 mmHg wearing belt (p less than 0.0001). However, it was also found that significant increases in IAP occurred (p less than 0.017) when the breath was held versus exhaling with or without the belt. One would expect that if the belt relieved either the direct compressive load on the spine or assisted IAP to produce an extensor moment then this would be reflected in diminished extensor muscle activity. Erector spinae activity tended to be lower with the breath held suggesting a reduced load on the lumbar spine although wearing a belt did not augment this reduction. In the case studies with subjects wearing an ergogenic corset designed for use by industrial manual materials handlers, perceptions of improved trunk stability were reported. However, the muscle activity and IAP results of this study during short duration lifting tasks make it difficult to justify the prescription of abdominal belts to workers.

Abdominal Muscles↗
PubMed1990

Factors influencing the effectiveness of extracorporeal shock-wave lithotripsy of biliary duct calculi.

The authors examined the effectiveness of extracorporeal shock-wave lithotripsy on patients who had bile-duct stones. Thirty-eight patients were treated with an unmodified HM-3 Dornier lithotripter; 35 (92%) patients either passed the stone fragments spontaneously or had them reduced to a size which allowed removal by percutaneous or endoscopic techniques. As stone size increased so did the number of shocks required for satisfactory fragmentation, the number of treatments and the rate of post-treatment manipulation. The number of stones was not as important a variable as the authors expected. Pre-treatment sphincterotomy was not always necessary and was of no benefit in terms of spontaneous passage of fragments. Complications were minor. Extracorporeal shock-wave lithotripsy of stones throughout the biliary tree is a safe, effective and invaluable adjunct in the management of bile-duct stones.

Adult↗
PubMed1990

The optimum spine.

Explore the source record for details and available documents.

Biomechanical Phenomena↗
PubMed1989

Retroperitoneal air, extracorporeal shock wave lithotripsy and epidural anesthesia.

During a 13-month period, 1,344 patients underwent extracorporeal shock wave lithotripsy. Plain x-rays done routinely 24 hours after lithotripsy to assess stone fragmentation revealed evidence of retroperitoneal air in 6 patients. All 6 patients had epidural anesthesia induced by loss of resistance to air in a syringe to identify the epidural space. It was believed likely that this was the cause of the air and 2 types of distribution were identified: 1 showed tracking of air along spinal nerves and 1 along tissue planes. This hypothesis eventually was confirmed by 2 patients in whom the air was identified after epidural anesthesia but before extracorporeal shock wave lithotripsy. Retroperitoneal air is found in a small number of patients undergoing epidural anesthesia and extracorporeal shock wave lithotripsy, and physicians treating these patients in the early postoperative period should be aware of this possible radiological finding and appreciate its benign nature.

Adult↗
PubMed1988

Mechanical measures during maximal velocity knee extension exercise and their relation to fibre composition of the human vastus lateralis muscle.

A method for measuring the maximal velocity of knee extension exercise is described using a very light lever arm. Instrumentation of the lever arm with a potentiometer and accelerometer also allows for the measurement of peak acceleration, time to peak acceleration, the average rate of development of acceleration (jerk) and peak torque. With this apparatus and surface electromyography, electromechanical delay (EMD) was also determined. This apparatus was tested using 17 female and 10 male subjects, and the measures obtained were related to the percentage of fast twitch fibres (% FT) and the relative area of fast twitch fibres (% FTA) in the vastus lateralis determined from duplicate muscle biopsy samples. Peak velocity of unloaded knee extension averaged 12.1 +/- 1.2 and 12.2 +/- 1.7 rad.s-1 for females and males, respectively, and were not significantly different. As well, peak acceleration, time to peak acceleration jerk and EMD values were not significantly different between the female and male subjects, but the mean peak torque for the female subjects (73.5 +/- 14.7 N.m) was significantly lower than that for the males (98.4 +/- 31.5 N.m). Peak acceleration was significantly correlated with %FT (r = 0.40, P = 0.04) for the total subject population. None of the other measures was significantly related to either %FT or %FTA for the male and female subjects or the combined population of subjects.

Biomechanical Phenomena↗
PubMed1988

Measurement of the trunk musculature of active males using CT scan radiography: implications for force and moment generating capacity about the L4/L5 joint.

The purpose of this study was to add to the growing database of cross-sectional areas and moment arm lengths of trunk musculature using the methods of computerized tomographic scanning. An attempt was also made to estimate muscle force and moment generating capacity under various reported values of muscle force per unit cross-sectional area. The data were obtained on 13 active men 40.5 +/- 11.9 years of age, 173.8 +/- 5.9 cm tall and 89.1 +/- 11.7 kg body mass. Transverse CT scans were taken at the level of the L4/L5 disc with the subjects supine. Muscle cross-sectional areas were measured from 35 mm slides of the scans using a planimeter and moment arm length in the transverse plane were taken from the centroid of the L4/L5 disc to the centroid of the muscle section. Prior to estimating force and moment generating capacity, areas were corrected, where necessary, for fibre pennation angle to produce a physiological cross-sectional area. The physiological cross-sectional areas (cm2) for one side of the body were (mean +/- S.D.): sacrospinalis (SS) 15.9 +/- 2.5; multifidus (Mu) 4.2 +/- 0.7; psoas (Ps) 17.6 +/- 4.0; rectus abdominis (RA) 7.9 +/- 2.5; external oblique (EO) 9.4 +/- 2.7; internal oblique (IO) 8.1 +/- 2.3; transverse abdominus (TA) 2.9 +/- 1.3. The anterior posterior moment arm lengths were: erector mass (SS and Mu combined) 5.90 +/- 0.52; Ps 0.58 +/- 0.40; R.A. 10.28 +/- 2.07; E.O. (anterior portion) 5.94 +/- 1.39; E.O. (posterior portion) 2.08 +/- 1.39; I.O. (anterior portion) 6.92 +/- 1.63; I.O. (posterior portion) 3.85 +/- 1.54. The corresponding lateral moment arm lengths were: 3.26 +/- 0.36; 4.88 +/- 0.36; 4.35 +/- 1.31; 12.86 +/- 1.93; 13.95 +/- 1.16; 10.77 +/- 2.02; 12.52 +/- 1.26. The maximum force per unit cross-section that human muscles are capable of generating is not well defined. However, assuming an intermediate value of 50 N cm-2 of physiological cross-section, the erector musculature observed at the L4/L5 level should be capable of generating an extensor moment of about 118 N.m. At a muscle stress of 30 or 90 N cm-2, values also reported on human muscle, the moment would be 71 and 213 Nm, respectively. It must be remembered, however, that muscles not observable at the L4/L5 level can create moments around that center of rotation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1988

Potential of lumbodorsal fascia forces to generate back extension moments during squat lifts.

The lumbodorsal fascia (LDF) has been implicated in numerous biomechanical interpretations of low back mechanics as a tissue that provides support to the lumbar spine during demanding load bearing. One hypothesis is that oblique abdominal muscle forces contribute to trunk extensor moment by transforming lateral abdominal tension into longitudinal tension via the LDF. However, a review of the anatomical literature supports the hypothesis that extensor forces in the LDF result from tension within the latissimus dorsi muscle. The purpose of our work was to evaluate the potential of the LDF to generate trunk extensor moment using two mathematical models: one that activated the LDF with the abdominals and another that activated the LDF with the latissimus dorsi. Efforts were made to represent the anatomy as accurately as possible. The results from three subjects performing six squat lifts each, suggested that the potential of the LDF to contribute significant extensor moment has been overestimated. In fact, the issue of whether the LDF is activated by the abdominals or the latissimus dorsi is irrelevant because neither strategy appeared able to generate sizable extensor moments in the type of lift studied.

Adult↗