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Biomedical subjects

N Humphries

Publications and source records attributed to N Humphries.

5 recordsLinked to original sources
PubMed2004

Angle-dependence and reproducibility of dual-beam vector doppler ultrasound in the common carotid arteries of normal volunteers.

Dual-beam vector Doppler has the potential to improve peak systolic blood velocity measurement accuracy by automatically correcting for the beam-flow Doppler angle. Using a modified linear-array system with a split receive aperture, we have assessed the angle-dependence over Doppler angles of 40 degrees -70 degrees and the reproducibility of the dual-beam blood maximum velocity estimate measured in the common carotid arteries (CCA) 1 to 2 cm prior to the bifurcation of 9 presumed-healthy volunteers. The velocity magnitude estimate was reduced by approximately 7.9% as the angle between the transmit beam and the vessel axis was increased from 40 degrees to 70 degrees. With repeat measurements made, on average, approximately 6 weeks apart, the 95% velocity magnitude limits of agreement were as follows: Intraobserver -41.3 to +45.2 cm/s; interobserver -29.6 to +46.8 cm/s. There was an 8.6 cm/s interobserver bias in velocity magnitude. We conclude that the dual-beam vector Doppler system can measure blood velocity within its scan plane with low dependence on angle and with similar reproducibility to that of single-beam systems.

Adult↗
PubMed2001

Identifying bone mass and muscular changes.

The aim of this investigation was to examine the impact of a six-month high intensity strength-training program on lumbar bone mineral density (BMD), trunk and lower limb strength in a population of Australian women aged 50 years and over. A subject pool of 44 women were recruited and randomly allocated into either strength training (n = 19) or active control (n = 25) groups. All subjects trained twice weekly in either a 50 minute supervised strength training session that progressed from 60% one repetition maximum (1RM) to 90% 1RM or a 50 minute group walk session. Measurements included a lumbar (L2-L4) BMD scan: peak isokinetic trunk strength and a dynamic 1RM squat as a measure of lower body strength. No significant group differences in lumbar BMD were evident at the completion of training. However, a significant (p < 0.05) within group change was apparent for the active control group as lumbar BMD decreased 1.7% below baseline testing. A significant (p < 0.05) group difference was evident with the strength trained group increasing peak isokinetic trunk strength (19.3%) and 1RM squat strength (34.4%) above that of the active controls. It was concluded that strength training provides an effective means for increasing trunk and lower limb strength in women over 50 years. The impact of strength training on lumbar BMD was not conclusive in the present study.

Absorptiometry, Photon↗
PubMed2000

Effect of exercise intensity on bone density, strength, and calcium turnover in older women.

PURPOSE: This study examined the effects of 24 wk of high intensity strength training or low intensity walking on lumbar bone mineral density (BMD), muscular strength, and calcium turnover in Australian women either taking hormone replacement therapy (HRT) or not taking HRT. METHODS: A subject pool of 64 women between 45-65 yr and randomly allocated into weights (N = 21), walking (N = 20), weightsHRT (N = 14), and walkingHRT (N = 9) groups completed this study. All subjects trained twice weekly in either a 50-min walking or weight-training program (60-90% IRM). Measurements included maximal isometric knee strength, IRM bench press, IRM squat, isokinetic back strength, lumbar (L2-L4) BMD, serum osteocalcin, and urinary deoxypyridinoline crosslinks (Dpd). RESULTS: No significant group differences in BMD were evident at the completion of training. However, a significant (P < 0.05) within group change was apparent for the walking group since BMD decreased 1.3% below baseline testing. Osteocalcin levels increased significantly (P < 0.05) in the walking (22%) group. Maximal bench press and squat strength improved significantly (P < 0.05) in the weights (25.8% and 37.7%) and weightsHRT (25.4% and 35.7%) groups. The weights group also increased significantly (P < 0.05) in isokinetic back strength (22.2%). CONCLUSION: It was concluded that short-term high intensity resistance training provides an effective means for increasing muscular strength in women between 45 and 65 yr. The training effects on lumbar BMD were not apparent in the present study.

Aged↗
PubMed1999

Reasons for outpatient referrals from generalists to specialists.

OBJECTIVE: To determine the relative importance of medical and nonmedical factors influencing generalists' decisions to refer, and of the factors that might avert unnecessary referrals. DESIGN: Prospective survey of all referrals from generalists to subspecialists over a 5-month period. SETTING: University hospital outpatient clinics. PARTICIPANTS: Fifty-seven staff physicians in general internal medicine, family medicine, dermatology, orthopedics, gastroenterology, and rheumatology. MEASUREMENTS AND MAIN RESULTS: For each referral, the generalist rated a number of medical and nonmedical reasons for referral, as well as factors that may have helped avert the referral; the specialist seeing the patient then rated the appropriateness, timeliness, and complexity of the referral. Both physicians rated the potential avoidability of the referral by telephone consultation. Generalists were influenced by a combination of both medical and nonmedical reasons for 76% of the referrals, by only medical reasons in 20%, and by only nonmedical reasons in 3%. In 33% of all referrals, generalists felt that training in simple procedures or communication with a generalist or specialist colleague would have allowed them to avoid referral. Specialists felt that the vast majority of referrals were timely (as opposed to premature or delayed) and of average complexity. Although specialists rated most referrals as appropriate, 30% were rated as possibly appropriate or inappropriate. Generalists and specialists failed to agree on the avoidability of 34% of referrals. CONCLUSIONS: Generalists made most referrals for a combination of medical and nonmedical reasons, and many referrals were considered avoidable. Increasing procedural training for generalists and enhancing informal channels of communication between generalists and subspecialists might result in more appropriate referrals at lower cost.

Ambulatory Care↗