Search PubMed⌕ Search

Biomedical subjects

H Ham

Publications and source records attributed to H Ham.

At least 19 recordsLinked to original sources
PubMed1996

Effect of bone density evaluation on hormone replacement therapy prescription.

OBJECTIVES: This study evaluates whether Bone Mineral Density (BMD) results influence HRT prescription. METHODS: Successive charts of 29 postmenopausal women were summarised. For each chart, 3 'simulated cases' were created by modifying the BMD result (based on the Z-score) in order to have 4 groups with the same clinical story but a wide range of BMD values (Group I = Z-score > 0, Group II = Z-score between 0 and -1, Group III = Z-score between -1 and -2 and Group IV = Z-score < -2). The obtained cases were presented to 10 gynaecologists who were asked whether HRT should be prescribed. The gynaecologists were not aware of the above-mentioned manipulation. RESULTS: The overall treatment rate was 74.2%, ranging from 65% for women with the highest BMD (Group I), 73% for Group II, 79% for Group III and 80% for Group IV, i.e. women with the lowest BMD (Friedman analysis of variance; chi-square 17.2; P < 0.001). In approximately a third of the patients (11/29), there was agreement for initiation of therapy, regardless of the BMD. Most of these women presented other indications and no contra-indications for therapy. The prescription frequency of the 10 gynaecologists varied between 63% and 87%; Cochran Q Statistic 39.2; P < 0.0001). For some physicians, a trend to increase prescription was observed in relation to the BMD result, but a statistical difference could only be reached for one physician (P < 0.05). Furthermore, for some physicians no modification whatsoever could be observed. CONCLUSIONS: BMD appears to be a determinant factor for HRT prescription in only a limited proportion of the patients and a small number of the physicians. From an epidemiological point of view, BMD measurements may be useful in order to help deciding women to start HRT, especially those who are reluctant or to those who present relative contra-indications, provided that their physicians are aware of the usefulness of these investigations.

Adult↗
PubMed1996

Cyclical pamidronate infusions in postmenopausal osteoporosis.

OBJECTIVES: Until recently, two bisphosphonates, pamidronate (APD) and etidronate were available for clinical purposes. Contrary to etidronate, pamidronate was not extensively studied in osteoporosis. Therefore, we investigated the effect of cyclic intravenous APD treatment in postmenopausal osteoporosis. METHODS: Parameters of bone remodelling and lumbar spine bone mineral density (BMDL) were assessed in 36 postmenopausal women with osteoporosis (BMDL t-score < -2.5). They received five courses of APD. Intervals between courses were defined according to the fasting urinary calcium excretion (UCa/Cr, mg/mg creatinine) which was measured before each APD course and every 2 weeks after the first treatment. The patients were retreated when UCa/Cr had reached baseline levels. Serum biochemical parameters and urinary hydroxyproline (UOHPro/Cr, mg/mg) were measured before each APD. RESULTS: UCa/Cr decreased during 21-28 days after each course but UCa/Cr measured before APD infusion remained unchanged. UOHPro/Cr significantly fell after the third APD (P = 0.02). Serum calcium was however not modified. Parameters of bone remodelling decreased with time: bone-GLA protein (BGP) started to fall after the first APD (P = 0.0001) and continued to decrease until the fourth APD course, alkaline phosphatase (ALP) significantly decreased after the first APD (P = 0.005); intact PTH significantly increased at the fifth APD (P = 0.02). BMDL significantly increased after 1 year treatment: +2.9% of baseline value. CONCLUSIONS: Cyclical pamidronate treatment of postmenopausal osteoprosis appeared to be effective in reducing bone turnover assessed by BGP, ALP and OHPro/Cr. This effect is followed by an increase in vertebral BMD.

Adult↗
PubMed1995

Precision and accuracy of in vivo bone mineral measurement in rats using dual-energy X-ray absorptiometry.

The aim of this study was to evaluate the precision and accuracy of dual-energy X-ray absorptiometry (DXA) for measuring bone mineral content at different sites of the skeleton in rats. In vitro the reproducibility error was very small (< 1%), but in vivo the intra-observer variability ranged from 0.9% to 6.0%. Several factors have been shown to affect in vivo reproducibility: the reproducibility was better when the results were expressed as bone mineral density (BMD) rather than bone mineral content (BMC), intra-observer variability was better than the inter-observer variability, and a higher error was observed for the tibia compared with that for vertebrae and femur. The accuracy of measurement at the femur and tibia was assessed by comparing the values with ash weight and with biochemically determined calcium content. The correlation coefficients (R) between the in vitro BMC and the dry weight or the calcium content were higher than 0.99 for both the femur and the tibia. SEE ranged between 0.0 g (ash weight) and 2.0 mg (Ca content). Using in vitro BMC, ash weight could be estimated with an accuracy error close to 0 and calcium content with an error ranging between 0.82% and 6.80%. The R values obtained between the in vivo and in vitro BMC were 0.98 and 0.97 respectively for femur and tibia, with SEE of 0.04 and 0.02 g respectively. In conclusion, the in vivo precision of the technique was found to be too low. To be of practical use it is important in the design of experimentation to try to reduce the measurement error.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1995

Clinical significance of heterogeneity of vertebral mineral density.

Important variations in Z-score per vertebra, which is a common expression of bone mineral density (BMD), are sometimes observed. The present study evaluates the clinical significance of this heterogeneity. Normal and osteoporotic subjects were defined by using strict criteria. For every scan, the minimal Z-score (the vertebra with the lowest Z-score) and the delta Z (highest Z-score--lowest Z-score) was calculated. Of the investigated subjects, 30% presented a delta Z > or = 1. No significant correlation could be found between delta Z and age, BMD, height and weight. There was no difference in delta Z between scans of good, average or poor quality. Osteoporotic subjects had significantly lowered BMD values, whether evaluated through Z-scores for the L2-L4 site (P < 0.001; t = 3.71) or by minimal Z-score (P < 0.001; t = 3.97). Reproducibility calculated for the L2-L4 site on phantoms as well as on patients was excellent (C.V. < 1%). When reproducibility was calculated on each vertebra in vitro or in vivo, an increase in variability was observed. These data show that marked heterogeneity in BMD per vertebra is not infrequent. In some subjects low BMD may be measured at certain vertebrae but not at the total site. Our data suggest that in those cases the lowest BMD should be considered. In follow-up studies however, the BMD should be calculated on the L2-L4 segment, since a loss of precision is observed when only one vertebra is measured.

Absorptiometry, Photon↗
PubMed1994

360 degrees or 180 degrees for bone SPECT of the spine?

Acquisitions of 360 degrees are usually performed for bone single photon emission computed tomography (SPECT). However, the spine is a peripheral and median structure, it therefore seemed interesting to compare the 360 degrees and the posterior 180 degrees SPECT images. In a phantom study and in 25 adult patients, the 360 degrees SPECT images were compared with the posterior 180 degrees images obtained during the same acquisition: the posterior 180 degrees images are at least equivalent to the 360 degrees images. With a reduction in the examination time, SPECT could become easier to perform, especially in patients suffering from back pain.

Adult↗
PubMed1993

Decrease of bone mineral density during estrogen substitution therapy.

A decrease in bone mineral density (BMD) in patients treated with hormone replacement therapy (HRT) is sometimes observed in clinical practice. In order to assess the frequency and the characteristics of these cases, we reviewed the data of 102 women treated with HRT for more than 2 years, and who had undergone at least 3 lumbar BMD measurements during that period. For each patient, a linear function was fitted to the BMD data in relation to time. The slope was calculated. There was an overall gain in BMD during treatment, mean (+/- S.E.M.) values of slope 0.007 g/cm2/year (+/- 0.002). Fifty-three patients had a slope higher than 0.005, 28 a slope close to 0 (between 0.005 and -0.005) and 21 a slope lower than -0.005. By dividing the patients in tertiles of slopes (tertile I: slope < 0; tertile II: 0 < slope < 0.011; tertile III: slope > 0.011), significant differences were observed between the three groups of slope for the initial BMD (P < 0.001), hydroxyproline/creatinine ratio (P < 0.01), weight, DHEAS and alkaline phosphatase (P < 0.05). Only 1 of the 15 patients with a low bone mass (lower than mean +/- 1 S.D.) had a negative slope, while 9 of the 16 with a high-bone mass (higher than mean +/- 1 S.D.), had a negative slope. Under HRT, about 21% of postmenopausal women have a slight decrease in BMD as assessed by DPA. Because of the DPA coefficient of variation, however, the exact number of bone losers cannot be determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1993

Bone mineral density measured by dual photon and dual energy X-ray absorptiometry: a problem of accuracy.

Dual photon absorptiometers (DPA) are currently being replaced by dual energy X-ray absorptiometers (DXA) for measurements of bone mineral density (BMD). In order to evaluate how to use the previously obtained BMD results by DPA (BMDo) in the follow-up of patients, the following study was performed. Ninety-five women who had had BMDo during the last 12 months were selected. L2-L4 BMD was measured twice on the same day using both DPA (BMDp) and by DXA (BMDx). BMDp was highly correlated to BMDx (R = 0.95; P < 0.001) but a wide variation of the ratio BMDp:BMDx was observed which ranged between 0.65 and 1.09 (mean 0.90, S.D. 0.05). There was no significant relationship between the ratio BDMp:BMDx and age or height but there was a significant relationship between this ratio and the weight of the patient (R = 0.31; P < 0.001). The results also indicated that the correlation between DXA and DPA was lower than that observed between the two DPA measurements (R = 0.98; P < 0.001) which, moreover, were not performed on the same day. These observations contrast with the relatively high precision of both instruments and have to be attributed to relative inaccuracy of one or probably both techniques.

Absorptiometry, Photon↗
PubMed1992

Time related bias in longitudinal studies using dual photon absorptiometry.

Examining the bone mineral density (BMD's) slope of patients regularly followed in our department, we observed recently that the group of patients who had their last BMD during the last 6 months of 1989, had a different slope than patients who had their last BMD during the following 6 months. In order to investigate if a small time-related bias of measurement, unsuspected by the former quality control investigations, could exist, we performed the following analyses. A regression equation between BMD and time was calculated and a slope was obtained for 95 women who had been followed for at least 3 yr and had had at least 3 BMD measurements during that time. The women were divided in 3 groups according to when the last BMD measurement had been performed (July-December 1989, January-June 1990 or July-December 1990). The slopes of the 3 groups of patients were compared. For each value of BMD of every patient, a predicted BMD (BMDp) was calculated using the regression equation and the relative difference (RD) between BMDp and BMD was calculated and analysed in relation to time. There was a significant difference (p < 0.05) between the slopes of patients in relation to the time when the last BMD had been measured. Significant fluctuations (p < 0.001) in RD were observed in relation to time. These RD variations suggested the existence of a time-related error. The presence of this error is also substantiated by the fact that a parallelism existed between the curve of the RD variations and the curve of the mean values of BMD of all patients referred to our department, calculated per period of 4 months. Although the fluctuation of the latter curve was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1992

Detection of bilateral and symmetrical anomalies in technetium-99m-HMPAO brain SPECT studies.

The detection of bilateral and symmetrical regional cerebral blood flow (rCBF) abnormalities requires knowledge of the antero-posterior rCBF distribution in normal subjects of all age groups. These data are very difficult to obtain in children for ethical reasons and in older subjects because of the necessity of recruiting a large number of healthy volunteers from each age group. Therefore, to obtain normal values of antero-posterior rCBF distribution, we have retrospectively selected a group of patients with a low probability of having cerebral lesions, whose 99mTc-HMPAO brain SPECT studies were analyzed semiquantitatively. Cerebellum/mean cerebral cortex index when compared to young adults was higher in the neonatal period, slightly lower between 2 mo and 15 yr, and more or less identical after 15 yr. Cortico/occipital indexes exhibit considerable changes during the first year of life due to important differences in maturation timing of cerebral cortical areas. After 1 yr, all cerebral cortical areas approximately displayed a parallel evolution. A slight increase in fronto/occipital and temporo/occipital indexes was, however, still observed during childhood, while in elderly subjects there was a trend towards a decrease in all cortico/occipital indexes (particularly in prefrontal and motor areas). Changes that occurred after 1 yr were, however, usually smaller than interindividual variation. Despite the large range of "normal" values, the antero-posterior analysis could be useful in various neurologic disorders, because it allows detection of symmetrical rCBF anomalies undiagnosed by the right-left analysis.

Adolescent↗
PubMed1991

Technetium 99m mercaptoacetyltriglycine gamma camera clearance calculations: methodological problems.

Major sources of errors in the gamma-camera methods for the calculation of renal clearance are the accuracy of background correction for obtaining the true renal time-activity curve and the validity of the externally recorded pre-cordial activity as an estimate of the plasmatic time-activity curve. With technetium 99m mercaptoacetyltriglycine (99mTc-MAG3), because of its high protein plasma binding, one could expect minimal extravascular diffusion and hence a more accurate externally detected plasmatic curve. The high extraction rate should reduce the influence of the background, but, on the other hand, the effect of hepatobiliary excretion on the calculation of renal clearance might be significant. Our results suggest that the hepatobiliary excretion of 99mTc-MAG3 does not influence the gamma-camera renal clearance determination, even in patients with low renal function. However, the pre-cordial curve does not reflect accurately the plasmatic disappearance curve; its calibration with a single plasma sample taken at the 20th min is responsible for significant errors, probably because of an unfavourable ratio between the intravascular and extravascular activities at the 20th min.

Adult↗
PubMed1991

Choice of parameter for expressing bone mineralization.

In this cross-sectional study, the relative importance of anthropometric factors and that of biological parameters on bone mineralization were evaluated and their practical implications inferred on the choice of the parameter to be used for the estimation of bone mineralization. A close relationship between anthropometric factors and bone mineral content (BMC) was observed and this relationship was shown to be independent of age. Furthermore, by regression analyses, anthropometric parameters appeared to explain a large part of the variance in BMC and preceded the hormonal parameters in the stepwise analysis of this model. Using bone mineral density (BMD) data, however, we observed a weaker relationship between anthropometric factors and bone mineralization and a relatively stronger relationship between steroid hormones and bone mineralization than those observed using the BMC data. Furthermore, by multiple regression analysis the hormonal factors preceded the anthropometric parameters in the stepwise analysis of the model. As strong epidemiological and clinical evidence exists on the relationship between steroid hormones and bone loss, these results constitute a supplementary argument for the use of BMD for the estimation of bone mineralization.

Adult↗
PubMed1991

Oesophageal involvement in rheumatoid arthritis patients: a study with oesophageal radionuclide transit using 81Krm.

Rheumatoid arthritis (RA) is an inflammatory disease affecting mainly the joints. In addition, signs of systemic disease are likely to be present although they are not always clinically evident. Oesophageal motility dysfunction, present in 75% of progressive systemic sclerosis patients, was also reported in various other connective tissue diseases. The present study involved 32 rheumatic patients devoid of any gastrointestinal complaints or diseases: 16 RA, nine Raynaud's syndrome and seven mild osteoarthritis as controls. Oesophageal transit was assessed by using 81Krm radionuclide scan, a sensitive and non-invasive technique. Diffusing lung capacity for carbon monoxide (DLCO) was performed as evidence of subclinical systemic involvement. Abnormal oesophageal transit was observed in 5/16 RA (31%). Two of them were subsequently discarded due to the presence of asymptomatic goiter and asymptomatic gastrointestinal reflux leaving 3/14 RA for analysis. They all had extra-articular features (EAF) (pericarditis, nodules) and two of them had diminished DLCO. Two with Raynaud's syndrome had abnormal oesophageal transit but none of the controls had abnormal oesophageal transit. Upper gastrointestinal dysfunction after exclusion of symptomatic patients appears thus to be not very frequent in RA, even when a sensitive technique is used. Radionuclide transit scanning of the oesophagus is not a more useful method than others in detecting early EAF in RA.

Adult↗
PubMed1990

Age, steroids and bone mineral content.

The possible existence of correlations between bone mineral content (BMC), age and serum levels of steroid hormones was investigated. It was found that dehydroepiandrosterone sulphate (DHEA-S), oestradiol (E2) and delta-4-androstenedione (A) were correlated with BMC, whereas oestrone (E1) and testosterone (T) were not. Partial correlations after adjustment for age were significant (P less than 0.05) only between E2 and DHEA-S and BMC at the L2-L4 lumbar site (BMC-1) and between DHEA-S (P less than 0.01) and BMC at the midradius site (BMC-r). Stepwise multiple regression analysis showed that, apart from age, E2 was the only factor to fit (P less than 0.05) into the mathematical model with BMC-1 as the dependent variable, while DHEA-S was the only factor to fit (P less than 0.01) with BMC-r as the dependent variable. These data suggest that different hormonal influences are related to BMC at different sites, namely E2 to lumbar trabecular bone (L2-L4) and DHEA-S to cortical bone (midradius).

Adult↗
PubMed1990

Cerebral palsy: initial experience with Tc-99m HMPAO SPECT of the brain.

The outlook for children with cerebral palsy is determined by the severity of motor problems and the presence of associated disabilities, in which early detection remains a medical challenge. The authors studied 13 children (aged 13 months to 12 years) with cerebral palsy by means of single photon emission computed tomography (SPECT) of the brain with technetium-99m hexamethylpropyleneamineoxime (HMPAO). In all children with hemiplegia, SPECT demonstrated hypoperfusion in the hemisphere contralateral to the motor deficit. SPECT demonstrated normal findings in patients with mild diplegia; bilateral hypoperfusion in the superior motor cortex in patients with moderate di- or tetraplegia; and bilateral reduction of perfusion in the superior motor, inferior motor, prefrontal, and parietal cortices in patients with severe di- or tetraplegia. Results suggest that Tc-99m HMPAO SPECT of the brain is a valuable complementary tool for thorough neurologic assessment in cerebral palsy.

Brain↗
PubMed1989

Prediction of pulmonary arterial pressure in chronic obstructive pulmonary disease by radionuclide ventriculography.

Pulmonary arterial hypertension represents an important parameter for the assessment of the severity of chronic bronchitis. The measurement of the pulmonary arterial pressure, however, requires invasive techniques of limited routine use because of costs and associated risks. The aim of this study is to evaluate whether the 81mKr right ventricular ejection fraction and parameters derived from equilibrium 99mTc red blood cells' right ventricular curve allow a better estimation of PAP than the 99mTc RVEF. In 41 patients with severe chronic bronchitis, the linear correlation between PAP and 99mTc RVEF was -0.61 (p less than 0.001). None of the parameters derived from the right ventricular curve was better correlated to PAP than the 99mTc RVEF. In 16 other chronic bronchitis patients, the 81mKr RVEF correlated moderately to PAP. In conclusion, the alternative isotopic methods proposed in this work do not provide a reliable estimation of pulmonary arterial pressure in patients with chronic bronchitis.

Blood Pressure↗
PubMed1989

[Anthropometric factors in the prevention of osteoporosis].

Osteoporosis, an important health problem, essentially concerns postmenopausal women since women have a lower peak bone mass than men when they reach adulthood and since the menopause is associated with an accelerated bone loss. We retrospectively analysed the bone measurements of 318 women, age less than 50. The bone mineral contents and densities of the mid- and distal radius (BMC m-rad, BMD m-rad, BMC d-rad, BMD d-rad) and of the lumbar L2-L4 vertebra (BMC L2-L4, BMD L2-L4) were measured using single and dual photon absorptiometer, respectively. The relations between age, height, weight, body mass index and the bone measurements were studied using multiple regression analyses. The anthropometric factors were accepted as first factors in the equations. R2 were respectively 17%, 17%, 28% for BMC m-rad, BMC d-rad, BMC L2-L4 and 7%, 5%, 8% for BMD m-rad, BMD d-rad, BMD L2-L4. These data suggest that anthropometric factors have an important influence on the different bone measurements. They also draw attention on the importance of preventive measures to achieve and to maintain an optimal bone reserve in premenopausal women.

Adult↗