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P Burckhardt

Publications and source records attributed to P Burckhardt.

At least 19 recordsLinked to original sources
PubMed1996

[Importance of the clinical profile in the postmenopausal osteoporosis screening by densitometry].

In order to test the impact of a given risk profile on the incidence of osteoporosis which could justify BMD measurement, and that of a low risk profile which could render it unnecessary, BMD was measured in 217 women under 72 in whom menopause had occurred at least 6 years previously and who corresponded to one of the two following profiles: high risk (A, n = 102) = BMI < 27 kg/m2, with no estrogen replacement treatment, and with at least one of the following risk factors: BMI < 20, early menopause, positive family history, no dairy products associated with tobacco consumption (> 10 cigarettes/day for > 20 years and/or alcohol consumption of > 0.5 l wine/day during > 10 years, corticotherapy of > 6 months, rickets, anorexia nervosa. Low risk (B, n = 115) = absence of characteristics of group A, BMI > 27 kg/m2 with (B+, n = 24) or without estrogen therapy (B-, n = 91). BMD was measured by DXA in 4 centers using Lunar or Hologic equipment. Results were expressed in % of the mean of the respective young adult control groups. As expected, BMD was significantly different in these two subgroups of the population. Osteoporosis was diagnosed (BMD < 75% = < -2.5 SD, according to WHO) in 72% of group A, and in 17% (B+) and 19% (B-) respectively of group B. There was no difference between the various risk factors in group A concerning their impact on BMD, but concerning incidence, low BMI and early menopause were the most frequent. The high risk profile of group A seems to justify densitometry, since it leads to the diagnosis of osteoporosis in over 70%. However, the protective profile of group B does not exclude osteoporosis (risk still 20%); only in severe obesity (BMI > 33) does it drop to 1%.

Absorptiometry, Photon↗
PubMed1996

[Evaluation of bones using quantitative ultrasonography].

The evaluation of bone by ultrasound is a new, transportable and non-irradiating method. It measures attenuation of ultrasound (BUA), as well as velocity (SOS) of ultrasound in a given tissue. For the measurement of bone, the most frequently used bone is the calcaneus. We have used this technique (Achilles, Lunar) to evaluate the reproducibility of measurements in healthy volunteers and to determine the correlations between the results of ultrasound measurements and those of conventional densitometry (DXA) in a population of postmenopausal females who consulted for screening or diagnosis of osteoporosis. Although several publications have already dealt with the same questions, it is important to reexamine them locally before the technique is uncritically used even in unspecialized centers. The coefficients of variation corresponded to that reported by others: 1.8% for BUA and 0.3% for SOS. The correlations between the ultrasound measurements and the results of DXA at lumbar spine, femoral neck and calcaneus in 57 postmenopausal women aged +/- 59 (43-78) years and in part osteoporotic (DXA results below 2.5 SD-T-score) (Hologic QDR 2000) were all significant (p < 0.001). The best correlation between the two techniques (DEXA and ultrasound) is found when applied to the same site, i.e. the calcaneus (r > 0.8). These results also agree with the literature. Low ultrasound values (BUA < 100 dB/MHz, SOS < 1495 m/s) are highly suggestive of osteoporosis, while high ultrasound values are almost exclusively found in non-osteoporotic women. This information provides the basis for further investigations, such as correlation with fracture risk, in cross-sectional and longitudinal studies.

Absorptiometry, Photon↗
PubMed1996

Quantitative ultrasound of bone in institutionalized elderly women: a cross-sectional and longitudinal study.

Quantitative ultrasound of bone is a promising method for bone assessment: radiation-free, portable and predictive of hip fracture. Its portability allowed us to study the relationships between ultrasonic parameters of bone with age and with non-vertebral fractures in elderly women living in 19 nursing homes. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) of the calcaneus were measured (and the stiffness index calculated) in a sample of 270 institutionalized women, aged 85 +/- 7 years, using an Achilles bone densitometer (Lunar). The effects of age, history of non-vertebral and non-traumatic fractures, body mass index, triceps skinfold and arm circumference were assessed on BUA, SOS and stiffness index. Furthermore, to evaluate longitudinally the influence of aging on the ultrasound parameters of bone, 60 subjects from the same group had a second ultrasound measurement after 1 year. The cross-sectional analysis of the data on all 270 women showed a significant decrease (p < 0.001) with age in BUA, SOS and stiffness index (-0.47%, -0.06%, and -1.01% respectively per year). In the 94 women, (35%) with a history of previous non-vertebral fractures, ultrasound parameters were significantly lower (p < 0.0001) than in the 176 women with no history of fracture (-8.3% for BUA, -1.3% for SOS, -18.9% for stiffness index). In contrast, there was no significant difference in anthropometric measurements between the groups with and without previous non-vertebral fractures, although the measurements decreased significantly with age. In the longitudinal study, repeated quantitative ultrasound after 11.4 +/- 0.8 months showed no significant decrease in BUA (-1%) but a significant decrease in SOS (-0.3%, p < 0.0001) and in stiffness index (-3.6%, p < 0.0002). In conclusion, quantitative ultrasound of the calcaneus measures properties of bone which continue to decline in institutionalized elderly women, and is able to discriminate women with previous non-vertebral fractures.

Aged↗
PubMed1996

Interleukin-6 and tumor necrosis factor alpha levels after bisphosphonates treatment in vitro and in patients with malignancy.

Bisphosphonates are potent inhibitors of bone resorption and are widely used in the treatment of bone diseases. One of the side effects of administered aminobisphosphonates is transient fever and some biological changes that are suggestive of an acute phase response. Pamidronate [(3-amino-1-hydroxypropylidene).1, 1-bisphosphonate] and ibandronate [1-hydroxy-3-(methylpentylamino) propylidenebisphosphonate] incubated in heparinized whole blood at doses of 10(-4) and 10(-5) mol/L, induced the production of tumor necrosis factor alpha (TNFalpha). Moreover, pamidronate was found to slightly stimulate interleukin-6 IL-6 production. In contrast, clodronate (dichloromethylenebisphosphonate) did not increase IL-6 or TNFalpha. To investigate these phenomena in vivo, acute phase reaction was assessed in patients with malignant disease treated with 60 mg of pamidronate (n = 29), 1500 mg of clodronate (n = 8), or 0.5-2 mg of ibandronate (n = 6), all given intravenously. A significant decrease in lymphocyte and leukocyte count was observed in the pamidronate group. In the same group, seven patients (24%) showed a transient increase of body temperature above 37 degrees C with an increase > or = 0.5 degrees C at 24 h. These changes were not found in the patients treated with clodronate or ibandronate. Plasma IL-6 and TNFalpha levels increased significantly after pamidronate treatment, whereas no change was seen after clodronate infusion. The peak of IL-6 level (53.7 +/- 14.1 [SEM] pg/mL) was observed at 24 h, and that of TNFalpha level (26.9 +/- 3.4 pg/mL) at 48 h after the beginning of pamidronate administration (values before treatment, respectively: 28.6 +/- 7.1 pg/mL, p < 0.006; and 13.1 +/- 1.5 pg/mL, p = 0.0001). The peak of C-reactive protein (CRP) level was found at 48 h (41.0 +/- 7.8 vs. 25.5 +/- 5.6 mg/L before treatment, p < 0.01) and CRP levels were strongly correlated with IL-6 levels (p = 0.65,p < 0.001). Only one patient treated with ibandronate showed an increase in IL-6 and CRP levels. Patients treated with pamidronate, whose body temperatures were increased at 24 h, had a greater increases of circulating IL-6, TNFalpha, and CRP at 24 h and 48 h than patients without temperature increase. These results suggest that pamidronate treatment, but not clodronate and possibly not ibandronate at the doses used, induced an increase in the plasma levels of IL-6 and TNFalpha, which may be responsible for the acute phase reaction observed clinically.

Aged↗
PubMed1996

Bone densitometry of the forearm: comparison of single-photon and dual-energy X-ray absorptiometry.

Forearm bone mineral densitometry was performed initially by single-photon absorptiometry (SPA), but is now achievable by dual-energy X-ray absorptiometry (DXA) as well, with a good correlation between both measurements. However, it is still unknown whether: (1) short-term precision of DXA is superior to SPA and (2) identical regions of interest (ROI) are mandatory to correlate SPA with DXA. The aim of this study was to answer these questions using a commercial system for DXA (DXA-FAS) and to test an in-house system using spine DXA and a soft-tissue compensator (DXA-STC). In ten subjects, four measurements on the same day showed significantly lower (p < 0.05) coefficients of variation (CV) for bone mineral density (BMD) by DXA-FAS (proximal site: 0.74%; ultradistal site: 1.20%) than by SPA (1.26% and 2.25%). However, the CV for bone mineral content (BMC) were similar for DXA-FAS (0.73% and 1.58%) and SPA (0.79% and 1.34%). The significant difference (p < 0.05) for surface calculation by DXA-FAS (1.24% and 0.93%) compared with SPA (2.36% and 1.28%) explains all the advantages of DXA-FAS for short-term precision. The measurements taken on the same day on the ulna and the radius or on the radius alone by SPA, DXA-FAS, and DXA-STC on 108 subjects aged 18-80 years were highly correlated [r ranging from 0.925 to 0.995 (p < 0.0001) and standard error of the estimate from 3.15% to 8.89%]. The need for a manual adjustment of the ROI was found to be mandatory for BMC but not BMD assessment. The use of DXA-STC is a fast method for forearm bone densitometry and its correlation with SPA is very high. However, its short-term precision for BMC (3.00% and 1.54%), BMD (2.15% and 1.12%), and surfaces (1.99% and 1.12%) is significantly higher (p < 0.05) than that of DXA-FAS. We conclude that short-term precision of DXA is better than that of SPA only for BMD and surface measurement but not for BMC. ROI should be adjusted manually for the assessment of BMC but not for that of BMD.

Absorptiometry, Photon↗
PubMed1996

Cyclosporine induces high bone turnover and may contribute to bone loss after heart transplantation.

Cardiac transplantation has become a successful therapy for end-stage heart disease. However, increased bone loss has been observed in heart transplant recipients, sometimes being responsible for osteoporotic fractures. Glucocorticoids cause dose-related bone loss, particularly in the first 6-12 months of use, but cyclosporine might play a role as well. The evolution of bone mineral density (BMD) and biochemical parameters was prospectively assessed in 24 patients (mean age 52 years) from cardiac transplantation. All patients received cyclosporin A (CsA) and prednisone, the latter at decreasing dosage. The mean current daily dose of CsA was 321 mg and serum levels of CsA were constant. All patients received calcium (500 mg day-1) and vitamin D (1000 U day-1) for prevention of bone loss. BMD (gcm-2) was measured in 17 patients at the lumbar spine, femoral neck and total hip with dual energy X-ray absorptiometry every 6 months. Spinal BMD as well as neck and total hip BMD decreased at 6 and 12 months after transplantation, being statistically significant at the three sites: -5.6 and -3.4% for the lumbar spine, -9.3 and -8.5% for the femoral neck, -4.8% and -6.0% for the total hip respectively. Parathyroid hormone (PTH) and osteocalcin (BGP) increased by 90% and 800% respectively between pretransplantation values and 18 months after transplantation. BGP levels measured every 2 months from transplantation increased continuously from 8.7 micrograms L-1 (mean +/- SEM) before transplantation to 31.3 +/- 10.1 (P < 0.05) at 4 months, to 59.1 +/- 8.8 (P < 0.01) at 6 months and to 72.2 +/- 9.9 (P < 0.01) at 18 months (Kruskal-Wallis analysis: P < 0.0001). PTH showed a biphasic pattern with an initial decrease from 39.3 +/- 4.1 ng L-1 at baseline to 22.0 +/- 2.8 ng L-1 at 2 months, but increasing thereafter to 45.9 +/- 5.7 at 6 months and 74.2 +/- 8.9 at 18 months (Kruskal-Wallis analysis: P < 0.001). These variations represent a glucocorticoid-induced osteoporosis. In summary, cardiac transplant patients lose bone immediately after transplantation at the spine and the hip. Later on, the loss in BMD discontinues at all sites of the skeleton, but predominantly at the spine, and a few patients still lose bone at the hip. This is probably a result of the high bone turnover either due to secondary hyperparathyroidism or induced by cyclosporin A.

Adult↗
PubMed1996

Bone mineral content in cystic fibrosis patients: correlation with fat-free mass.

OBJECTIVE: To assess the bone mineral content in well nourished patients with cystic fibrosis and to seek a correlation with fat-free mass. METHODS: Fourteen cystic fibrosis patients aged 6 to 20 years were studied and compared to 14 healthy controls matched for gender, age, and nutritional status. Bone mineral content was determined by dual energy x ray absorptiometry (DEXA). RESULTS: Nutritional inquiry showed higher ingestion of macronutrients and micronutrients by cystic fibrosis patients than by controls. Mean whole skeleton bone mineral content was 1.184 (SD 0.536) kg in cystic fibrosis patients and 1.229 (0.576) kg in controls (p = 0.84). Mean lumbar spine bone mineral content was 0.031 (0.013) kg and 0.031 (0.016) kg, respectively (p = 0.99). Anthropometry, bioelectrical impedance analysis, and DEXA showed that fat-free mass was similar in the two groups. Bone mineral content was strongly correlated to fat-free mass. Mean blood calcium, phosphorus, serum 25-hydroxyvitamin D (25-OHD), parathyroid hormone (PTH), and osteocalcin were similar in both groups. CONCLUSIONS: Bone mineral content and body composition are normal in a well nourished young cystic fibrosis population. Osteopenia previously reported in cystic fibrosis patients probably has nutritional origins and is therefore not related to a primary defect in bone mineral metabolism.

Adolescent↗
PubMed1996

Segmental body composition assessed by bioelectrical impedance analysis and DEXA in humans.

The present study assessed the relative contribution of each body segment to whole body fat-free mass (FFM) and impedance and explored the use of segmental bioelectrical impedance analysis to estimate segmental tissue composition. Multiple frequencies of whole body and segmental impedances were measured in 51 normal and overweight women. Segmental tissue composition was independently assessed by dual-energy X-ray absorptiometry. The sum of the segmental impedance values corresponded to the whole body value (100.5 +/- 1.9% at 50 kHz). The arms and legs contributed to 47.6 and 43.0%, respectively, of whole body impedance at 50 kHz, whereas they represented only 10.6 and 34.8% of total FFM, as determined by dual-energy X-ray absorptiometry. The trunk averaged 10.0% of total impedance but represented 48.2% of FFM. For each segment, there was an excellent correlation between the specific impedance index (length2/impedance) and FFM (r = 0.55, 0.62, and 0.64 for arm, trunk, and leg, respectively). The specific resistivity was in a similar range for the limbs (159 +/- 23 cm for the arm and 193 +/- 39 cm for the leg at 50 kHz) but was higher for the trunk (457 +/- 71 cm). This study shows the potential interest of segmental body composition by bioelectrical impedance analysis and provides specific segmental body composition equations for use in normal and overweight women.

Absorptiometry, Photon↗
PubMed1996

Influences of body weight, body composition, and substrate oxidation rate on resting postabsorptive glucose production and gluconeogenesis.

OBJECTIVE: To determine the influence of body weight, fat mass, and fat distribution on resting endogenous glucose production in healthy lean and overweight individuals. DESIGN: measurements were performed in the resting postabsorptive state in individuals receiving an unrestricted diet. SETTING: Institute of Physiology of Lausanne University. MEASUREMENTS: resting post absorptive glucose production, glycogenolysis and gluconeogenesis; resting energy expenditure and net substrate oxidation. RESULTS: Endogenous glucose production was positively correlated with body weight, lean body mass, energy expenditure and carbohydrate oxidation. Gluconeogenesis was positively correlated with net lipid oxidation and energy expenditure, and negatively correlated with net carbohydrate oxidation. No correlation with body fat or fat distribution was observed. CONCLUSIONS: Gluconeogenesis shows a large interindividual variability. Net lipid oxidation and not body fat appears to be a major determinant of gluconeogenesis.

Adult↗
PubMed1995

[The value of enteroscopy in recurrent digestive hemorrhages of undetermined origin].

conventional endoscopic procedures do not allow direct visual access to the small bowel. Small bowel bleeding can be investigated by enteroclysis, radionuclide bleeding scan and angiography of the mesenteric artery. However, localization of the bleeding can only be determined with these diagnostic tools in 15% of cases. A case of small bowel bleeding diagnosis by enteroscopy is presented, followed by an overview of the literature related to this novel endoscopic technic.

Adult↗
PubMed1995

[Prevention of osteoporosis and role of densitometry].

Osteoporosis is a major public health problem in countries with aging populations, resulting in excess morbidity and mortality. Osteoporosis is defined as a systemic skeletal disease characterized by low bone mass and micro-architectural deterioration of bone tissue, with the consequent increase in bone fragility and susceptibility to fractures. Therefore, the bone loss that precedes fractures is a continuous process that is often mostly irreversible in the aging. The most efficient method of preventing fractures is the prevention of bone loss. The measurement of bone mass and other skeletal characteristics can effectively identify women at high risk for fractures. The measurement of bone mass which can be carried out by osteo-densitometry is now widely available. It is the only clinical data that can provide accurate assessment of individual fracture risk. Treatments exist that will preserve bone mass and presumably reduce fracture risk; therefore there is a place for screening of patients at high risk of fractures. Many studies have shown recently that a reduced bone mass (at least 1 standard deviation below normal) was associated with a more than 100% increased risk of fracture. Thus the initial assessment of bone mass can be used to estimate future fracture risk and to start prevention measures for high risk patients. Primary prevention can be initiated during the adolescence to optimize peak bone mass. Later in life, secondary prevention can prevent excessive bone loss and more specific treatments can prevent postmenopausal and age related bone demineralization. Strategies of prevention should be promoted and validated as general health care strategies.

Absorptiometry, Photon↗
PubMed1994

[Hypercalcemia as incidental finding--what should be done?].

The discovery of a hypercalcemia validated by exclusion of hemoconcentration and follow-up calcium determinations opens the differential diagnosis of a malignancy and of hyperthyroidism whereas drug-induced causes can be recognized easily. A single determination of plasmatic parathyroid hormone (PTH) allows to safely distinguish between PTH-induced or PTH-independent, most often tumor-associated hypercalcemia. In both instances the patient may be free of symptoms particularly the very old one. Therapeutic measures are indicated in both instances: Treatment of malignancy-associated hypercalcemia is clinically effective and treatment of asymptomatic hyperthyroidism is likewise recommended, mainly to preserve bone mass and cerebral performance.

Calcium↗
PubMed1994

Effects of treatment of malignancy-associated hypercalcemia on serum parathyroid hormone-related protein.

Parathyroid hormone-related protein (PTHrP) is the primary mediator of hypercalcemia in patients with malignancy-associated hypercalcemia. We conducted this study to examine the effects of treatment with a bisphosphonate on serum PTHrP. We analyzed 41 episodes of hypercalcemia occurring in 38 patients: 22 patients received alendronate, and 16 were treated with pamidronate. At baseline, 29 patients had an increased serum PTHrP (group I) and 9 had low or undetectable levels (group II). The two groups did not differ significantly in baseline hypercalcemia (3.26 versus 3.41 mM) or the response of serum calcium to therapy. Serum calcium was normalized in 88% of group I and 70% of group II patients. Lowering of the mean calcium level was not associated with a change in the level of PTHrP in group I patients (40.2 versus 36.7 pgEq/ml) or group II patients. We also analyzed data on serum PTH and 1,25-(OH)2D in 20 of the patients. Serum PTH rose with treatment in group I patients (9.7-40.2 pg/ml, p < 0.05), as did the serum 1,25-(OH)2D (19.1-32.4 pg/ml, p < 0.001). Similarly, treatment of group II patients was associated with an increase in serum PTH (9.8-37.2 pg/ml) and serum 1,25-(OH)2D (22.9-40.2 pg/ml). The individual increases in 1,25-(OH)2D levels associated with therapy could not be predicted from the level of PTHrP or the changes in levels of serum calcium or PTH. Our data show that effective treatment of malignancy-associated hypercalcemia is not associated with a consistent change in serum levels of PTHrP. Therapy is associated with a variable increase in the serum levels of PTH and 1,25-(OH)2D.

Alendronate↗
PubMed1994

Regulation of collagen type I and biglycan mRNA levels by hormones and growth factors in normal and immortalized osteoblastic cell lines.

Growth factors, such as transforming growth factor beta (TGF-beta) and insulin-like growth factors (IGF) I and II, have been shown to exert anabolic effects on bone cells in vitro. Hormones, such as PTH and probably insulin and growth hormone, were recently shown to stimulate bone formation in vivo as well. The aim of the present study was to assess by northern blots, which were quantitated by densitometry, the effects of these anabolic growth factors and hormones in two osteogenic cell populations: CRP 10/30 cells, a clonal cell population derived from primary rat calvarial cells, and IRC 10/30-myc cells, which were established from CRP 10/30 by immortalization. Transcripts for alpha 1(I) collagen, biglycan, osteonectin, osteopontin, and osteocalcin were detected in both cell populations, which is consistent with the phenotype expressed by mature osteoblasts. There were no difference in the basal expression of bone matrix mRNAs between the two cell populations. PTH increased alpha 1(I) collagen mRNA levels in both osteoblastic cells but had no effect on the biglycan transcripts. Neither insulin nor growth hormone affected mRNA levels of either matrix protein after 24 h exposure. All three growth factors, TGF-beta, IGF-I, and IGF-II, increased alpha 1(I) collagen transcripts in a time- and dose-dependent manner in both cell populations. Biglycan mRNA levels were enhanced in both osteoblastic lines only by IGF-I and IGF-II, but not TGF-beta.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Two years' effectiveness of intravenous pamidronate (APD) versus oral fluoride for osteoporosis occurring in the postmenopause.

Bisphosphonates seem to be effective as antiresorptive agents in the prevention and treatment of osteoporosis. However, the optimal dose and route of administration as well as the specific effects on cortical or trabecular bone have not been clarified. To compare pamidronate (APD) with fluoride (F) in the therapy of postmenopausal osteoporosis, 32 osteoporotic women were treated for 2 years either with APD (30 mg as a single intravenous infusion over 1 h every 3 months, n = 16, mean age 65 years) or with fluoride orally (20-30 mg F/day, n = 16, mean age 67 years) in an open study. Both groups received 1 g calcium and 1000 U vitamin D per day, but no estrogens or other drugs acting on bone. Both groups showed the same initial mean number of fractures per patient (2.8 and 2.7). Bone densitometry was performed every 6 months at three sites: lumbar spine and hip with dual-energy X-ray absorptiometry (BMD), distal forearm with single photon absorptiometry and lumbar spine with quantitative computed tomography. Biochemical assessment was performed in blood and urine every 3 months. Lumbar BMD (g/cm2, mean +/- SEM) increased from 0.632 (+/- 0.030) at time 0 to 0.696 (+/- 0.028) at 24 months in the APD group (p < 0.001), and from 0.684 (+/- 0.025) to 0.769 (+/- 0.028) in the fluoride group (p < 0.001). Femoral neck BMD increased significantly from 0.558 (+/- 0.025) to 0.585 (+/- 0.025) (p < 0.01) in the APD group, whereas it did not change in the fluoride group.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗