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Biomedical subjects

J G Truscott

Publications and source records attributed to J G Truscott.

At least 19 recordsLinked to original sources
PubMed2000

Osteoporosis and osteopenia in adults and adolescents with cystic fibrosis: prevalence and associated factors.

BACKGROUND: Patients with cystic fibrosis (CF) have many risk factors for reduced bone mineral density (BMD). The aim of this study was to determine the prevalence of osteoporosis and osteopenia in a large cross section of patients and to identify risk factors. METHODS: All patients attending the regional centre were invited to participate in the study. Bone mineral density was measured at the lumbar spine, femoral neck, and for total body with a Lunar DPX-L densitometer. Multiple indices of disease severity were investigated, and liver and thyroid function, blood calcium, phosphate, 25-OH vitamin D, follicle stimulating and luteinising hormone, oestradiol, and testosterone levels were measured. Patients completed a four day prospective dietary diary. Exercise was assessed by a seven day activity recall questionnaire. Sexual development and treatment histories were obtained. The relationship between all these variables and BMD measurements was analysed. RESULTS: Sixty six percent of 114 patients assessed had osteopenia or osteoporosis. The Shwachman-Kulczycki (SK) clinical score (higher score = less severe disease) correlated significantly with BMD at the lumbar spine and femoral neck, and with total body BMD (p<0.001). There was a predicted increase of 0.0032 g/cm(2) in lumbar spine BMD for every unit increase in the SK score. Oral steroid use was significantly associated with reduced BMD at the lumbar spine (p = 0.017) and femoral neck (p = 0.027). CONCLUSIONS: Osteopenia and osteoporosis are common findings in a heterogeneous population of adults with CF. Patients at most risk are those with severe disease and those who have used corticosteroids.

Adolescent↗
PubMed1999

Limited ileal resection in infancy: the long-term consequences.

BACKGROUND/PURPOSE: The longer-term sequelae of short bowel syndrome in infancy are reasonably well documented, but little is known about the long-term nutritional and metabolic effects of limited (less than 50 cm) ileal resection. This makes it difficult to formulate a rational follow-up policy in such children. METHODS: All children who underwent limited ileal resection for either necrotizing enterocolitis (NEC) or intussusception at our institution between 1984 and 1992 were invited to attend a detailed clinical, anthropometric, hematologic, and biochemical assessment, together with a biliary and renal ultrasound scan and measurement of bone mineral density. RESULTS: Twenty-four children (NEC, 17; intussusception, 7) of median age 7.4 years (range, 5.5 to 13.7 years) agreed to participate. Nine previously had undergone an isolated ileal resection, and 15 also had had variable lengths of colon removed. The length of resected ileum ranged from 3 to 44 cm, with a median of 10 cm. Seven control subjects in whom neonatal NEC developed but recovered without surgery were also evaluated. Median height, weight, and body mass index after ileal resection were between the 25th and 50th percentiles; no child was stunted or wasted. After ileal resection, one boy was found to have asymptomatic vitamin B12 deficiency, and three children had low plasma concentrations of vitamin A. Hematologic and biochemical parameters were otherwise normal apart from a few marginally low trace element levels in both subjects and controls. No renal calculi were detected, and bone mineral density measurements were normal in all except one child. Four children had cholelithiasis, all of whom had previously undergone limited ileal resection for NEC (two isolated, two ileocolic). Thus, the prevalence of cholelithasis after limited ileal resection for NEC was 24% at a median age of 7.0 years. CONCLUSIONS: Growth and nutritional status are well preserved after limited ileal resection in infancy. Limited ileal resection for NEC is associated with a subsequent high prevalence of cholelithiasis and a risk of vitamin B12 deficiency. These findings are important when planning strategies for long-term follow-up.

Bone Density↗
PubMed1998

An evaluation of the reproducibility and responsiveness of four 'state-of-the-art' ultrasonic heel bone measurement systems using phantoms.

This paper evaluates four modern ultrasonic heel bone scanners: the Osteometer DTU-one, Hologic Sahara, CUBA Clinical and Lunar Achilles+. Six phantoms, ranging in porosity from 50% to 83%, were used to evaluate the range of values of broadband ultrasonic attenuation (BUA), speed of sound (SOS) and Stiffness/quantitative ultrasound index (where available) from each machine. Differences in inter-system variability between the lowest and highest porosity phantoms up to a factor of 3.8 were demonstrated. The reproducibility of each system was measured using a single phantom and gave values of 0.03-0.15% for SOS, 0.39-1.6% for BUA and 0.73-1.11% for Stiffness. This contrasted with values of range normalized standard deviation (CX) of 0.2-1.19% for SOS, 0.71-1.86% for BUA and 0.83-1.12% for Stiffness when the output range of the measurement is taken into account. Measures of all quantities differed between machines and care should be taken when expressing and comparing results from different systems.

Bone and Bones↗
PubMed1998

Broadband ultrasound attenuation in the os calcis and its dependence on the receiver aperture size.

The broadband ultrasonic attenuation (BUA) was measured in 10 os calces on the same site with two transducer separations and five different receiving apertures built from perspex. The results displayed relative differences greater than 40%. However, a clear trend (increasing or decreasing BUA) with smaller aperture size or transducer separation was not observed and hence the differences do not seem to be predictable. The cause for this may be the influence of four factors--averaging, phase cancellation, diffraction and scattering--which are interactive and frequency dependent. This means that values measured with different equipment and experimental set-up are not directly comparable and hence the introduction of measurement standards seems to be necessary.

Calcaneus↗
PubMed1998

Comparison of in-vivo body composition using two Lunar dual-energy X-ray absorptiometers.

OBJECTIVE: To compare in-vivo composition analysis between two dual energy X-ray absorptiometers, a DPX and a DPX/L, from the same manufacturer (LUNAR), pre(Study A) and post(Study B) hardware changes on both absorptiometers. DESIGN: Comparison of (1) quality assurance (QA) data: air-counts low (38 keV), air-counts high (70 keV), air-counts ratio, percent spillover, R-delrin; and (2) total body compartments: total body tissue (TBTISS), total body fat (TBF), percent total body fat (%TBF), total body lean (TBLEAN), total body bone mineral content (TBBMC) and total body bone mineral density (TBBMD), between the two absorptiometers. SETTING: Centre for Bone and Body Composition Research, University of Leeds. SUBJECTS: Study A, 14 normal subjects and Study B, a different cohort of 19 normal subjects, were scanned on both machines on the same day. RESULTS: In Study A, large significant differences were observed in the QA parameters between the two machines. The DPX, air-counts low and air-counts high, being 25% and 22% lower than the DPX/L. The Bland Altman method of analysis indicated that the DPX was significantly higher for TBTISS (0.3 kg), %TBF (2%) and TBF ( 1.4 kg) and correspondingly lower for TBLEAN (-1.0 kg). No significant difference was observed in TBBMC. After the hardware changes (Study B) a marked reduction in the differences in QA air-counts was observed. The DPX air-counts low was now 1% higher and air-counts high 8% lower than the DPX/L. The DPX had now only small significant negative differences for %TBF (-0.6%) and TBF (-0.4 kg) and a small significant positive difference for TBLEAN (0.4 kg), compared to the DPX/L. TBBMC difference although slightly increased, was still non-significant. CONCLUSIONS: The closer agreement observed in the QA parameters after the hardware changes was associated with a reduction in the mean differences, 95%CI of the mean differences and limits of agreement of the comparison of body composition analysis from the Lunar machines using the Bland-Altman method. The study indicates that the QA limits set for bone mineral analysis may require more stringent limits for body composition.

Absorptiometry, Photon↗
PubMed1997

Reference data for ultrasonic bone measurement: variation with age in 2087 Caucasian women aged 16-93 years.

Data from the measurement of broadband ultrasonic attenuation (BUA) and speed of sound (SOS), using the Lunar Achilles ultrasonic densitometer, were collected for Caucasian women from five centres in the United Kingdom (Leeds, London, Nottingham, Lincoln and Sheffield). After correcting for machine variability at each site, the data were combined into a central reference database comprising 2087 women aged 16-93 years. The data are presented in 5-year bands and show a mean fall of 0.36% per year for BUA and 0.08% per year for SOS in the 60 years following the attainment of peak bone mass. This fall in BUA compares with that observed using dual energy X-ray absorptiometry studies of the lumbar spine and femoral neck of 0.32% per year and 0.44% per year, respectively, for the age range 25-65 years.

Adolescent↗
PubMed1997

A suggested methodology for the construction of national bone densitometry reference ranges: 1372 Caucasian women from four UK sites.

This paper presents a simple methodology for combining bone densitometry data from different sites in the UK, having instruments from the same manufacturer (LUNAR Radiation). Additive normalization factors were used on all data prior to inclusion in a reference database which ultimately included data on 1372 Caucasian women, aged 20-70 years, of whom 749 were post-menopausal. Reference data for spine (L2-L4) and femoral neck bone mineral density are given in tabular form as 3 year moving averages for: (1) all women; (2) perimenopausal women grouped by menopausal status; and (3) post-menopausal women with respect to years since menopause. These data may be used to construct Z-score. T-score or percentile reporting ranges and may be adopted as the core for a UK reference range.

Adult↗
PubMed1996

Ultrasonic measurement: an evaluation of three heel bone scanners compared with a bench-top system.

Three commercial ultrasound bone scanners designed for os calcis measurements (Lunar Achilles, C.U.B.A. "Research" and UBA 575) were compared using the Leeds Ultrasonic Bone Phantoms. The porosity of the phantoms ranged from 50% to 83% with velocities between 1490 and 1621 m s-1 and broadband ultrasound attenuation (BUA) values in the range 46-115 dB MHz-1. The three devices tested were able to discriminate porosity differences of at least 3%, although the values obtained for the propagation parameters varied widely. Velocity differences of up to 38 m s-1 and BUA variations of up to 33 dB MHz-1 were found, although a relationship was identified between the velocity and BUA measurements. In some cases, the variation can be attributed to differences in the measurement technique adopted, although there also seem to be detailed differences in the definition of the parameters themselves. The variation between different devices from the same manufacturer (Lunar) was also studied. Measurements taken from five devices showed variation in velocity values of up to 25 m s-1 (SD 10.8 m s-1) and in BUA values of up to 11 dB MHz-1 (SD 4.3 dB MHz-1). We conclude that the variation both between manufacturers and between nominally identical machines may be of clinical significance. Both users and manufacturers need to consider urgently the introduction of quality standards and consensus definition of terms and techniques. The fact that all machines studied have been superseded commercially does not invalidate these conclusions, since many of the devices tested remain in clinical use and there is no evidence of fundamental change in manufacturers' procedures.

Heel↗
PubMed1996

DXA scanning.

The steady improvement in densitometric technique is reviewed in this paper culminating in the newest generation of DXA scanners. The suitability of the lumbar spine, femur and hand as sites for the densitometric measurement of bone loss in rheumatoid disease is assessed. The recent improvement in hand scanning technique using DXA has led to improved clinical utility in the detection of juxta-articular bone loss. The enhanced resolution offered by the newest, solid state detector DXA scanners, and their ability to detect bone loss where no systemic features are evident, makes it possible that DXA scanning of the hand will be a useful modality for the monitoring of early rheumatoid disease.

Absorptiometry, Photon↗
PubMed1996

A portable system for measuring bone mineral density in the pre-term neonatal forearm.

Current systems used to measure bone mineral content (BMC) in the neonate have the major drawback that the child must be well enough to be moved to the scanner. Consequently, low birth weight pre-term neonates, a group at particular risk of mineral compromise, cannot be measured. This paper describes a portable neonatal bone mineral device capable of measuring bone mineral in the incubator. It uses a radiation sensitive, charge coupled device (CCD) to acquire a bone mineral image enabling bone mineral to be measured at various sites. It measures bone mineral density (BMD) with a precision of 5.5 mg cm-2 in vivo, reduced to 7.5 mg cm-2 when repositioning between scans is taken into account. The procedure takes under 5 min with an image acquisition time of 30 s and an absorbed radiation dose to skin of 6 microSv. Calibration has been undertaken with aluminium foils of differing thickness to confirm the linearity of the system throughout the intended measurement range. A regression line fitted to the data demonstrated linearity and correlation between BMD and aluminium thickness with r = 0.99 (p < 0.0001). Preliminary measurements on pre-term neonates show values of BMD ranging from 43 to 115 mg cm-2 in babies aged 23-41 weeks post-conception. These figures are within the linear range of the system.

Absorptiometry, Photon↗
PubMed1996

Spatial distribution of femoral bone mineral in dual energy X-ray absorptiometry images: a possible technique to improve discrimination between normal and osteoporotic patients.

The measurement of bone mineral density (BMD) using dual energy X-ray absorptiometry (DXA) provides an indicator of subsequent risk of hip fracture, but because of the significant overlap of measurements obtained from osteoporotic and control groups its predictive power is limited. The radiographic technique of Singh grading for the assessment of femoral osteoporosis utilizes information about the distribution of trabecular bundles, but the morphological information available in the DXA image has not previously been analysed. In this study of DXA images from 64 individuals (32 controls and 32 classified as osteoporotic) a subjective grading technique analogous to Singh grading is proposed, and quantitative measurements are made of image features corresponding to two of the categories. Discrimination was assessed using receiver operating characteristic (ROC) curves: the best discrimination was by spinal BMD (Az = 0.85 +/- 0.05) a performance equalled by one of the new parameters; the subjective grading method (Az = 0.79 +/- 0.07) performed as well as measurements of BMD in the femur. These results suggest that although the alternative measures do not improve on the discrimination possible using spinal BMD, morphological information from the hip itself may in the future have a place in the assessment of bone quality.

Absorptiometry, Photon↗
PubMed1993

Bone mineralisation, body fat and anthropometric measurement in mothers delivering preterm.

Twenty mothers of preterm babies who had survived to 1 year old, were matched for age and parity of the mother and time of birth of the baby, with 20 mothers delivering fullterm. Bone mineral, body composition and anthropometric measurements were obtained for each mother and analysed using paired t-tests. The only significant difference (P < 0.01) between the groups was a lower fat-free mass in the preterm mothers calculated from skinfold thickness measurements.

Adipose Tissue↗
PubMed1993

Variation in lumbar spine and femoral neck bone mineral measured by dual energy X-ray absorption: a study of 329 normal women.

Reference ranges used in dual energy X-ray absorptiometry (DXA) have previously used piecewise linear fits to the whole data set for spine or femur bone mineral density (BMD) as a function of age. In a study of 329 Caucasian normal women we present a refinement to the normal range by fitting straight lines between quinquennial mean values of BMD for each site measured (lumbar spine, femoral neck and Ward's triangle). From the age of 40 years onwards the premenopausal women demonstrated minimal loss of BMD whereas postmenopausal women showed a rapid loss amounting to 27% in the lumbar spine, 27% in the femoral neck and 38% in the Ward's triangle region in the age range under examination. Comparison of quinquennial means for pre and postmenopausal women in age bands 45-49 years and 50-54 years shows that at these ages postmenopausal BMD is significantly lower than premenopausal BMD (P < 0.05). This finding suggests that separate normal ranges should be used for pre and postmenopausal women. As reduction in the production of oestrogen is a major factor in postmenopausal bone loss and oestrogen function is related to years since menopause (YSM), a more logical way of displaying postmenopausal normal BMD ranges would be in terms of YSM rather than chronological age. Such data are given in this paper.

Absorptiometry, Photon↗
PubMed1992

Bone ultrasonic attenuation in women: reproducibility, normal variation and comparison with photon absorptiometry.

The reproducibility of two methods of measuring broadband ultrasonic attenuation (BUA) in the calcaneus have been studied. An improvement in reproducibility in vivo from 9.6% to 2.8% between old and new techniques has been observed. Measurements of the calcaneus using BUA were correlated with measurements of bone mineral density measured by dual energy x-ray absorptiometry in the lumbar spine, femur and total body and bone mineral content in the distal and proximal forearm measured by single photon absorptiometry. For the older BUA technique the correlation coefficients ranged between r = 0.27 and r = 0.34. For the newer BUA technique the correlation coefficients ranged between r = 0.49 and r = 0.62 and were all significant (P less than 0.001).

Absorptiometry, Photon↗
PubMed1990

Spontaneous resolution of bone mineral depletion in preterm infants.

Fifteen preterm infants and 17 born at full term whose gestational ages ranged from 25 to 34 weeks and 38 to 42 weeks, respectively, were examined initially at postconceptional ages ranging from 38 to 44 weeks and subsequently at 46 to 71 weeks. Each examination included measurement of bone mineral content of the mid-forearm by single photon absorptiometry. For the preterm group, the mean (SD) value of bone mineral content at the first examination was 109.0 (27.6) mg/cm and was significantly lower than the corresponding value of 194.4 (19.6) mg/cm for the whole full term group. The mean subsequent rate of mineral accretion in the preterm group was 8.70 (4.60) mg/cm/week, the mean individual duration of observation being 9.7 weeks. Rate of mineral accretion for the full term group was independent of the duration of observation and averaged 1.60 (2.20) mg/cm/week. The difference between mean values of rate of mineral accretion in the preterm and full term groups was highly significant. Our results show that there is a phase of rapid mineral accretion starting at 40 weeks' postconception in preterm infants that substantially reduces the perinatal mineralisation deficit.

Absorptiometry, Photon↗