Publications by authors named "Jan C Roos"

25 Publications

  • Page 1 of 1

Aggravated bone density decline following symptomatic osteonecrosis in children with acute lymphoblastic leukemia.

Haematologica 2015 Dec 24;100(12):1564-70. Epub 2015 Sep 24.

Dutch Childhood Oncology Group, The Hague, The Netherlands Princess Maxima Center, Utrecht, The Netherlands

Osteonecrosis and decline of bone density are serious side effects during and after treatment of childhood acute lymphoblastic leukemia. It is unknown whether osteonecrosis and low bone density occur together in the same patients, or whether these two osteogenic side-effects can mutually influence each other's development. Bone density and the incidence of symptomatic osteonecrosis were prospectively assessed in a national cohort of 466 patients with acute lymphoblastic leukemia (4-18 years of age) who were treated according to the dexamethasone-based Dutch Child Oncology Group-ALL9 protocol. Bone mineral density of the lumbar spine (BMDLS) (n=466) and of the total body (BMDTB) (n=106) was measured by dual X-ray absorptiometry. Bone density was expressed as age- and gender-matched standard deviation scores. Thirty patients (6.4%) suffered from symptomatic osteonecrosis. At baseline, BMDLS and BMDTB did not differ between patients who did or did not develop osteonecrosis. At cessation of treatment, patients with osteonecrosis had lower mean BMDLS and BMDTB than patients without osteonecrosis (respectively, with osteonecrosis: -2.16 versus without osteonecrosis: -1.21, P<0.01 and with osteonecrosis: -1.73 versus without osteonecrosis: -0.57, P<0.01). Multivariate linear models showed that patients with osteonecrosis had steeper BMDLS and BMDTB declines during follow-up than patients without osteonecrosis (interaction group time, P<0.01 and P<0.01). We conclude that bone density status at the diagnosis of acute lymphoblastic leukemia does not seem to influence the occurrence of symptomatic osteonecrosis. Bone density declines from the time that osteonecrosis is diagnosed; this suggests that the already existing decrease in bone density during acute lymphoblastic leukemia therapy is further aggravated by factors such as restriction of weight-bearing activities and destruction of bone architecture due to osteonecrosis. Osteonecrosis can, therefore, be considered a risk factor for low bone density in children with acute lymphoblastic leukemia.
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http://dx.doi.org/10.3324/haematol.2015.125583DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4666332PMC
December 2015

Bone mineral density at diagnosis determines fracture rate in children with acute lymphoblastic leukemia treated according to the DCOG-ALL9 protocol.

Bone 2014 Feb 25;59:223-8. Epub 2013 Nov 25.

Department of Pediatric Oncology/Hematology, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands; Dutch Childhood Oncology Group, The Hague, The Netherlands. Electronic address:

Purpose: To elucidate incidence and risk factors of bone mineral density and fracture risk in children with Acute Lymphoblastic Leukemia (ALL).

Methods: Prospectively, cumulative fracture incidence, calculated from diagnosis until one year after cessation of treatment, was assessed in 672 patients. This fracture incidence was compared between subgroups of treatment stratification and age subgroups (Log-Rank test). Serial measurements of bone mineral density of the lumbar spine (BMDLS) were performed in 399 ALL patients using dual energy X-ray absorptiometry. We evaluated risk factors for a low BMD (multivariate regression analysis). Osteoporosis was defined as a BMDLS≤-2 SDS combined with clinical significant fractures.

Results: The 3-year cumulative fracture incidence was 17.8%. At diagnosis, mean BMDLS of ALL patients was lower than of healthy peers (mean BMDLS=-1.10 SDS, P<0.001), and remained lower during/after treatment (8months: BMDLS=-1.10 SDS, P<0.001; 24months: BMDLS=-1.27 SDS, P<0.001; 36months: BMDLS=-0.95 SDS, P<0.001). Younger age, lower weight and B-cell-immunophenotype were associated with a lower BMDLS at diagnosis. After correction for weight, height, gender and immunophenotype, stratification to the high risk (HR)-protocol arm and older age lead to a larger decline of BMDLS (HR group: β=-0.52, P<0.01; age: β=-0.16, P<0.001). Cumulative fracture incidences were not different between ALL risk groups and age groups. Patients with fractures had a lower BMDLS during treatment than those without fractures. Treatment-related bone loss was similar in patients with and without fractures (respectively: ΔBMDLS=-0.36 SDS and ΔBMDLS=-0.12 SDS; interaction group time, P=0.30). Twenty of the 399 patients (5%) met the criteria of osteoporosis.

Conclusion: Low values of BMDLS at diagnosis and during treatment, rather than the treatment-related decline of BMDLS, determine the increased fracture risk of 17.8% in children with ALL.
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http://dx.doi.org/10.1016/j.bone.2013.11.017DOI Listing
February 2014

Treatment of bone loss in osteopenic patients with Crohn's disease: a double-blind, randomised trial of oral risedronate 35 mg once weekly or placebo, concomitant with calcium and vitamin D supplementation.

Gut 2014 Sep 21;63(9):1424-30. Epub 2013 Oct 21.

Department of Internal Medicine, Endocrine Section, MOVE Research Institute, VU University Medical Center, Amsterdam, The Netherlands.

Objective: Osteoporosis and fractures are frequently encountered in patients with Crohn's disease. In order to prevent fractures, treatment with bone protecting drugs appears warranted early in the course of bone disease when bone loss is not yet prominent. We therefore aimed to demonstrate a beneficial effect on bone density of the bisphosphonate risedronate in osteopenic Crohn's disease patients.

Methods: This double-blind, placebo-controlled randomised trial of risedronate with calcium and vitamin D supplementation was performed in osteopenic Crohn's disease patients. Patients were treated for 2 years with follow-up after 3 and after every 6 months. Disease characteristics and activity and bone turnover markers were assessed at all visits; dual x-ray absorptiometry was performed at baseline, 12 and 24 months; radiographs of the spine at baseline and 24 months.

Results: Of 132 consenting patients, 131 were randomised (67 placebo and 64 risedronate). Patient characteristics were similar in both groups, although the risedronate group was slightly heavier (body mass index 24.3 vs 23.0 kg/m(2)). Bone mineral density at lumbar spine increased 0.04 g/cm(2) on average in the risedronate group versus 0.01 g/cm(2) in the placebo group (p=0.007). The mean increase in total hip bone mineral density was 0.03 versus 0.01 g/cm(2), respectively (p=0.071). Fracture prevalence and incidence were similar. Change of T-scores and concentrations of bone turnover markers were consistent with a beneficial effect of risedronate when compared with placebo. The effect of risedronate was primarily demonstrated in the first 12 months of treatment. No serious unexpected suspected adverse events were observed.

Conclusions: A 24-month treatment course with risedronate 35 mg once weekly, concomitant with calcium and vitamin D supplementation, in osteopenic Crohn's disease patients improved bone density at lumbar spine. NTR 163 Dutch Trial Register.
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http://dx.doi.org/10.1136/gutjnl-2013-305523DOI Listing
September 2014

A reliable method for measuring proximal tibia and distal femur bone mineral density using dual-energy X-ray absorptiometry.

Med Eng Phys 2014 Mar 27;36(3):387-90. Epub 2013 Sep 27.

Amsterdam Rehabilitation Research Center | Reade, Amsterdam, The Netherlands; University of Groningen, University Medical Centre Groningen, Center for Human Movement Sciences, The Netherlands.

Purpose: To assess the intra- and inter-rater reliability of a standardized protocol for measuring proximal tibia and distal femur bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA).

Methods: Ten able-bodied individuals (7 males) participated in this study. During one measurement session, the knee of each participant was scanned twice by rater 1 using DXA. Both scans were analyzed twice by rater 1 as well as once by a second rater. Intraclass correlation coefficients (ICCs), standard error of measurements (SEMs) and smallest detectable differences (SDDs) were calculated for the outcome measures proximal tibia and distal femur BMD. A decision study was performed to determine the effect of study protocol adjustments (i.e. increasing the number of scan repetitions, or scan analyses by the same rater) on SEM and SDD values.

Results: High intra- and inter-rater ICCs (0.97-0.98) were found for both proximal tibia and distal femur BMD. Low SEMs (0.017-0.028 g/cm(2)) and SDDs (0.047-0.077 g/cm(2)) were found, with a slightly better result for proximal tibia BMD. Increasing the number of scan analyses by the same rater did not markedly reduce SEM and SDD values, while increasing the number of scan repetitions did.

Conclusions: Proximal tibia and distal femur BMD can be reliably assessed with this method.
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http://dx.doi.org/10.1016/j.medengphy.2013.08.010DOI Listing
March 2014

Increase in bone mineral density in strictly treated Crohn's disease patients with concomitant calcium and vitamin D supplementation.

J Crohns Colitis 2013 Jun 27;7(5):377-84. Epub 2012 Jun 27.

Department of Gastroenterology and Hepatology, VU University Medical Centre, PO Box 7057, The Netherlands.

Background And Aims: Decreased bone mineral density (BMD) is common in Crohn's disease (CD) patients. This paper reports on the prevalence of decreased BMD in a referral cohort study of CD-patients next to the change of BMD over time in relation with CD-associated clinical characteristics.

Methods: 205 CD patients of a referral hospital were enrolled between January1998-January 2010 when measurement of BMD by dual X-ray absorptiometry (DXA) was available. Follow-up DXA scan was performed in subjects with known risk factors besides Crohn indicative for low BMD. Treatment of CD patients was according to a protocol which is comparable to the current (inter)national guidelines. In osteopenic patients, supplemental vitamin D (800 IU) and Calcium (500-1000 mg) were prescribed.

Results: Mean BMD at baseline was 0.97 ± 0.16 gram/cm(2) in lumbar spine and 0.87 ± 0.12 gram/cm(2) in the total hip. At baseline, higher age and low Body Mass Index (BMI), were negatively correlated with BMD. Eighty-four patients underwent a second BMD assessment with a median interval period of 4 years (IQR 3-6). A mean annual increase of +0.76% (95%CI: -2.63%; +3.87%) in lumbar spine and +0.43% (95%CI: -2.65% ; +1.11%) in total hip was observed.

Conclusions: Higher age, male sex, low BMI, and a higher age at diagnosis of CD were associated with low BMD. Follow-up of BMD in CD patients showed a contraintuitive small increase of BMD at lumbar spine and total hip in CD patients only using supplemental vitamin D and calcium next to strict treatment of CD.
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http://dx.doi.org/10.1016/j.crohns.2012.06.003DOI Listing
June 2013

The impact of bone mineral density and disc degeneration on shear strength and stiffness of the lumbar spine following laminectomy.

Eur Spine J 2012 Mar 24;21(3):530-6. Epub 2011 Aug 24.

Department of Orthopedic Surgery, Research Institute MOVE, VU University Medical Center, De Boelelaan 1117, P.O. Box 7057, 1081 HV, Amsterdam, The Netherlands.

Purpose: Laminectomy is a standard surgical procedure for elderly patients with symptomatic degenerative lumbar stenosis. The procedure aims at decompression of the affected nerves, but it also causes a reduction of spinal shear strength and shear stiffness. The magnitude of this reduction and the influence of bone mineral density (BMD) and disc degeneration are unknown. We studied the influence of laminectomy, BMD, and disc degeneration on shear force to failure (SFF) and shear stiffness (SS).

Methods: Ten human cadaveric lumbar spines were obtained (mean age 72.1 years, range 53-89 years). Laminectomy was performed either on L2 or L4, equally divided within the group of ten spines. BMD was assessed by dual X-ray absorptiometry (DXA). Low BMD was defined as a BMD value below the median. Intervertebral discs were assessed for degeneration by MRI (Pfirrmann) and scaled in mild and severe degeneration groups. Motion segments L2-L3 and L4-L5 were isolated from each spine. SFF and SS were measured, while loading simultaneously with 1,600 N axial compression.

Results: Low BMD had a significant negative effect on SFF. In addition, a significant interaction between low BMD and laminectomy was found. In the high BMD group, SFF was 2,482 N (range 1,678-3,284) and decreased to 1,371 N (range 940-1,886) after laminectomy. In the low BMD group, SFF was 1,339 N (range 909-1,628) and decreased to 761 N (range 561-1,221). Disc degeneration did not affect SFF, nor did it interact with laminectomy. Neither low BMD nor the interaction of low BMD and laminectomy did affect SS. Degeneration and its interaction with laminectomy did not significantly affect SS.

Conclusions: In conclusion, low BMD significantly decreased SFF before and after lumbar laminectomy. Therefore, DXA assessment may be an important asset to preoperative screening. Lumbar disc degeneration did not affect shear properties of lumbar segments before or after laminectomy.
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http://dx.doi.org/10.1007/s00586-011-1968-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3296849PMC
March 2012

Radiation dosimetry of 89Zr-labeled chimeric monoclonal antibody U36 as used for immuno-PET in head and neck cancer patients.

J Nucl Med 2009 Nov 16;50(11):1828-36. Epub 2009 Oct 16.

Department of Otolaryngology/Head and Neck Surgery, VU University Medical Center, Amsterdam, The Netherlands.

Unlabelled: Immuno-PET is an appealing concept in the detection of tumors and planning of antibody-based therapy. For this purpose, the long-lived positron emitter (89)Zr (half-life, 78.4 h) recently became available. The aim of the present first-in-humans (89)Zr immuno-PET study was to assess safety, biodistribution, radiation dose, and quantification of the (89)Zr-labeled chimeric monoclonal antibody (cmAb) U36 in patients with head and neck squamous cell carcinoma (HNSCC). In addition, the performance of immuno-PET for detecting lymph node metastases was evaluated, as described previously.

Methods: Twenty HNSCC patients, scheduled to undergo surgical tumor resection, received 75 MBq of (89)Zr-cmAb U36 (10 mg). Immuno-PET scans were acquired at 1, 24, 72, or 144 h after injection. The biodistribution of the radioimmunoconjugate was evaluated by ex vivo radioactivity measurement in blood and in biopsies from the surgical specimen obtained at 168 h after injection. Uptake levels and residence times in blood, tumors, and organs of interest were derived from quantitative immuno-PET studies, and absorbed doses were calculated using OLINDA/EXM 1.0. The red marrow dose was calculated using the residence time for blood.

Results: (89)Zr-cmAb U36 was well tolerated by all subjects. PET quantification of blood-pool activity in the left ventricle of the heart showed a good agreement with sampled blood activity (difference equals 0.2% +/- 16.9% [mean +/- SD]) except for heavy-weight patients (>100 kg). A good agreement was also found for the assessment of mAb uptake in primary tumors (mean deviation, -8.4% +/- 34.5%). The mean absorbed red marrow dose was 0.07 +/- 0.02 mSv/MBq and 0.09 +/- 0.01 mSv/MBq in men and women, respectively. The normal organ with the highest absorbed dose was the liver (mean dose, 1.25 +/- 0.27 mSv/MBq in men and 1.35 +/- 0.21 mSv/MBq in women), thereafter followed by kidneys, thyroid, lungs, and spleen. The mean effective dose was 0.53 +/- 0.03 mSv/MBq in men and 0.66 +/- 0.03 mSv/MBq in women. Measured excretion via the urinary tract was less than 3% during the first 72 h.

Conclusion: (89)Zr immuno-PET can be safely used to quantitatively assess biodistribution, uptake, organ residence times, and radiation dose, justifying its further clinical exploitation in the detection of tumors and planning of mAb-based therapy.
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http://dx.doi.org/10.2967/jnumed.109.065862DOI Listing
November 2009

Positive association between the course of vitamin D intake and bone mineral density at 36 years in men.

Bone 2009 Mar 13;44(3):437-41. Epub 2008 Nov 13.

Netherlands Institute for Health Services Research (NIVEL), LINH, Utrecht, The Netherlands.

Introduction: Studies on the association of vitamin D and bone mineral density (BMD) in adolescence and young adults have shown contrasting results. None of these studies have examined the course and baseline in vitamin D intake. The purpose of this study was to examine the association between baseline and the course of dietary vitamin D intake on the BMD.

Methods: Vitamin D intake was assessed 3-8 times between the age of 13 and 36 years in 152 men and 168 women from the Amsterdam Growth and Health Longitudinal Study. The BMD of the femoral neck, lumbar spine, total hip and total body was measured at the age of 36 years with dual-energy X-ray absorptiometry. Linear regression analyses were used to determine the vitamin D intake pattern in time for each subject. The models provide a baseline, course and fluctuation of the vitamin D intake for each subject. These were used in separate regression analyses with the dependent variable BMD.

Results: Mean baseline vitamin D was 6.86 (SD: 2.18) microg/day for men and 4.90 (1.19) microg/day for women. Mean course of vitamin D was -0.10 (0.12) microg/day/year and -0.05 (0.18) microg/day/year for men and women respectively. After adjustment for potential confounders and correcting for the other parameters of vitamin D intake, the associations between baseline vitamin D intake and BMD were significant in the total hip (0.018 g/cm(2) per -1 microg/day; 95% CI 0.001-0.035) and total body (0.015 per -1 microg/day; 0.001-0.029). The course of vitamin D intake was associated with BMD in the lumbar spine (0.50 g/cm(2) per -1 microg/day/year; 0.130-0.867), femoral neck (0.42 g/cm(2) per -1 microg/day/year; 0.10-0.743), total body (0.34 g/cm(2) per -1 microg/day/year; 0.09-0.59) and total hip (0.44 g/cm(2) per -1 microg/day/year; 0.11-0.77) in men. No significant associations were found in women.

Conclusion: In men, the level of vitamin D intake in adolescence and the course of vitamin D intake from adolescence into adulthood are positively related with BMD in adulthood. In women, however, no significant associations are found.
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http://dx.doi.org/10.1016/j.bone.2008.10.055DOI Listing
March 2009

Body composition in children and adolescents born after in vitro fertilization or spontaneous conception.

J Clin Endocrinol Metab 2007 Sep 26;92(9):3417-23. Epub 2007 Jun 26.

Departments of Paediatrics, Institute for Clinical and Experimental Neuroscience, VU University Medical Center, 1081 HV Amsterdam, The Netherlands.

Context: Increasing evidence suggests that adverse conditions during prenatal life are associated with the development of chronic diseases in adult life. It is still unclear whether in vitro fertilization (IVF) conception could affect the vulnerable developmental processes in humans occurring during early prenatal development with long-term perturbations of developmental pathways.

Objective: Our objective was to examine body composition in 8- to 18-yr-old IVF singletons and spontaneously conceived controls born from subfertile parents.

Design And Setting: This follow-up study was conducted at the VU University Medical Center in Amsterdam, The Netherlands.

Participants: Participants included 233 IVF children (139 pubertal children) and 233 age- and gender-matched control children (143 pubertal children).

Main Outcome Measures: Body composition measures were assessed by anthropometry and dual-energy x-ray absorptiometry in the pubertal subpopulation.

Results: IVF children had a significantly lower subscapular-triceps skinfold ratio and a significantly higher sum of peripheral skinfolds, peripheral body mass, and percentage of peripheral body fat as compared with controls. Although not reaching statistical significance, both dual-energy x-ray absorptiometry and skinfold measurements suggested that total body fat in IVF children is increased. Neither current and early risk factors nor parental factors, such as subfertility cause, could explain the differences in peripheral fat assessed by anthropometry between IVF children and controls. No differences in bone mineral composition between IVF children and controls were found.

Conclusions: Our observations indicate that body fat composition in IVF children is disturbed. Follow-up of IVF children to monitor body fat pattern and potentially related health problems from adolescence into adulthood is of great importance.
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http://dx.doi.org/10.1210/jc.2006-2896DOI Listing
September 2007

Final height outcome after three years of growth hormone and gonadotropin-releasing hormone agonist treatment in short adolescents with relatively early puberty.

J Clin Endocrinol Metab 2007 Apr 6;92(4):1402-8. Epub 2007 Feb 6.

Leiden University Medical Center, Department of Pediatrics, and Tergooi Hospital, Blaricum, The Netherlands.

Objective: Our objective was to assess final height (FH) and adverse effects of combined GH and GnRH agonist (GnRHa) treatment in short adolescents born small for gestational age or with normal birth size (idiopathic short stature).

Design And Patients: Thirty-two adolescents with Tanner stage 2-3, age and bone age (BA) less than 12 yr for girls or less than 13 yr for boys, height sd score (SDS) less than -2.0 SDS or between -1.0 and -2.0 SDS plus a predicted adult height (PAH0) less than -2.0 SDS were randomly allocated to receive GH plus GnRHa (n=17) or no treatment (n=15) for 3 yr. FH was assessed at the age of 18 yr or older in girls or 19 yr or older in boys.

Results: FH was not different between treatment and control groups. Treated children had a larger height gain (FH-PAH0) than controls: 4.4 (4.9) and -0.5 (6.4) cm, respectively (P<0.05). FH was higher than PAH0 in 76 and 60% of treated and control subjects, respectively. During follow-up, 50% of the predicted height gain at treatment withdrawal was lost, resulting in a mean gain of 4.9 cm (range, -4.0 to 12.3 cm) compared with controls. Treatment did not affect body mass index or hip bone mineral density. Mean lumbar spine bone mineral density and bone mineral apparent density tended to be lower in treated boys, albeit statistically not significant.

Conclusion: Given the expensive and intensive treatment regimen, its modest height gain results, and the possible adverse effect on peak bone mineralization in males, GH plus GnRHa cannot be considered routine treatment for children with idiopathic short stature or persistent short stature after being born small for gestational age.
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http://dx.doi.org/10.1210/jc.2006-2272DOI Listing
April 2007

Swallowing after major surgery of the oral cavity or oropharynx: a prospective and longitudinal assessment of patients treated by microvascular soft tissue reconstruction.

Head Neck 2007 Jul;29(7):638-47

Department of Otolaryngology/Head and Neck Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands.

Background: The aim of this study was to analyze swallowing outcome in advanced oral/oropharyngeal cancer patients treated with microvascular reconstructive surgery and adjuvant radiotherapy.

Methods: Eighty patients were included. Patient, tumor, and treatment factors were assessed. Postoperative videofluoroscopic swallowing studies (VFSS) and scintigraphy tests were performed at 6 (n = 54 vs 44) and 12 (n = 32 vs 37) months. Swallowing parameters such as the oropharyngeal swallow efficiency and the Penetration/Aspiration Scale were analyzed.

Results: Impaired swallowing status was found at 6 months, which remained stationary at 12 months. Comorbid condition, larger tumors (T3-T4 vs T2), and resections of the base of tongue and soft palate combined (vs defects of other dynamic structures) were associated with most profound swallowing problems (p < .05).

Conclusions: Swallowing difficulties are relatively frequent and can to a large extent be predicted. With the knowledge of this study, better counseling and vigilance as to swallowing difficulties may be possible.
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http://dx.doi.org/10.1002/hed.20582DOI Listing
July 2007

Performance of immuno-positron emission tomography with zirconium-89-labeled chimeric monoclonal antibody U36 in the detection of lymph node metastases in head and neck cancer patients.

Clin Cancer Res 2006 Apr;12(7 Pt 1):2133-40

Department of Otolaryngology/Head and Neck Surgery, Nuclear Medicine and Positron Emission Tomography Research, Radiology, Amsterdam, The Netherlands.

Purpose: Immuno-positron emission tomography (PET), the combination of PET with monoclonal antibodies (mAb), is an attractive option to improve tumor detection and to guide mAb-based therapy. The long-lived positron emitter zirconium-89 ((89)Zr) has ideal physical characteristics for immuno-PET with intact mAbs but has never been used in a clinical setting. In the present feasibility study, we aimed to evaluate the diagnostic imaging performance of immuno-PET with (89)Zr-labeled-chimeric mAb (cmAb) U36 in patients with squamous cell carcinoma of the head and neck (HNSCC), who were at high risk of having neck lymph node metastases.

Experimental Design: Twenty HNSCC patients, scheduled to undergo neck dissection with or without resection of the primary tumor, received 75 MBq (89)Zr coupled to the anti-CD44v6 cmAb U36 (10 mg). All patients were examined by computed tomography (CT) and/or magnetic resonance imaging (MRI) and immuno-PET before surgery. Six patients also underwent PET with (18)F-fluoro-2-deoxy-d-glucose. Immuno-PET scans were acquired up to 144 hours after injection. Diagnostic findings were recorded per neck side (left or right) as well as per lymph node level (six levels per side), and compared with histopathologic outcome. For this purpose, the CT/MRI scores were combined and the best of both scores was used for analysis.

Results: Immuno-PET detected all primary tumors (n = 17) as well as lymph node metastases in 18 of 25 positive levels (sensitivity 72%) and in 11 of 15 positive sides (sensitivity 73%). Interpretation of immuno-PET was correct in 112 of 121 operated levels (accuracy 93%) and in 19 of 25 operated sides (accuracy 76%). For CT/MRI, sensitivities of 60% and 73% and accuracies of 90% and 80% were found per level and side, respectively. In the six patients with seven tumor-involved neck levels and sides, immuno-PET and (18)F-fluoro-2-deoxy-d-glucose PET gave comparable diagnostic results.

Conclusion: In this study, immuno-PET with (89)Zr-cmAb U36 performed at least as good as CT/MRI for detection of HNSCC lymph node metastases.
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http://dx.doi.org/10.1158/1078-0432.CCR-05-2137DOI Listing
April 2006

Effect of long-term growth hormone treatment on bone mass and bone metabolism in growth hormone-deficient men.

J Bone Miner Res 2005 Oct 26;20(10):1778-84. Epub 2005 Jun 26.

Department of Endocrinology, VU University Medical Center, Amsterdam, The Netherlands.

Unlabelled: Long-term GH treatment in GH-deficient men resulted in a continuous increase in bone turnover as shown by histomorphometry. BMD continuously increased in all regions of interest, but more in the regions with predominantly cortical bone.

Introduction: Adults with growth hormone (GH) deficiency have reduced rates of bone turnover and subnormal BMD. GH treatment is effective in enhancing bone turnover as shown by biochemical markers and bone histomorphometric studies. However, it is uncertain whether long-term treatment will result in higher bone mass. In this study, we present BMD and histomorphometric data on 5 years of GH treatment in GH-deficient men.

Materials And Methods: Thirty-eight adult men with childhood onset GH deficiency (20-35 years) were included in the study. Twenty-six of these had multiple pituitary hormone deficiencies and were on stable conventional hormone replacement. BMC (total body) and BMD (lumbar spine and hip) were measured before and after 1, 2, 3, 4, and 5 years of treatment. BMD in various regions of the total body was calculated by computer software (head, trunk, arms, and legs). Transiliac bone biopsies were obtained before and after 1 and 5 years of GH treatment.

Results: Total body BMC increased 18% after 5 years of treatment. This increase was observed in all regions of interest: head, 13.7%; trunk, 27.8%; arms, 24.4%; legs, 13.8%. BMD also increased in all separately measured regions: lumbar spine, 9%; femoral neck, 11%; femoral trochanter, 16%. Lumbar spine area significantly increased (p=0.0002). Histomorphometric data showed increased osteoid surface (p<0.02), osteoid volume (p<0.01), and activation frequency (p<0.006), but trabecular bone volume did not increase significantly. Qualitative assessment of the cortical bone showed endosteal and periosteal bone formation.

Conclusions: In conclusion, GH considerably increases BMC after long-term treatment. The combination of BMD and histomorphometric data suggests that GH has a greater effect on cortical than on trabecular bone.
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http://dx.doi.org/10.1359/JBMR.050613DOI Listing
October 2005

Effects of 10 years of growth hormone (GH) replacement therapy in adult GH-deficient men.

Clin Endocrinol (Oxf) 2005 Sep;63(3):310-6

Department of Endocrinology, VU University Medical Center, Amsterdam, The Netherlands.

Objective: GH-deficient adults have changes in body composition, bone mineral density (BMD) and lipid profile that can be altered by GH substitution. However, long-term data on GH substitution (up to 10 years of follow-up) are limited.

Design: The effects of 10 years of GH replacement therapy on BMD, body composition, bone parameters, serum lipids and glucose metabolism were studied.

Patients: Twenty-three childhood-onset GH-deficient men (mean age at baseline 28.6 years) were studied during 10 years of GH substitution therapy. A group of 19 age-matched healthy men served as a control group for BMD measurements at baseline and after 10 years.

Results: BMD of the lumbar spine increased during the 10 years of GH therapy. Bone markers and BMD in the hip increased during the first 5 years of GH therapy, but were not different from baseline after 10 years. BMD changes over time in the lumbar spine and femoral neck were significantly different in the patients compared to the controls. After 10 years the difference between the groups had decreased, but BMD was still higher in the controls than in the patients. Lipid profile had improved after 10 years of GH therapy, but body mass index (BMI), waist-hip ratio (WHR), fasting glucose and glycosylated haemoglobin (HbA1c) had increased compared to baseline.

Conclusions: This long-term follow-up study found that 10 years of GH substitution in GH-deficient men causes sustained improvements in BMD in the lumbar spine and lipid profile but not in body composition.
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http://dx.doi.org/10.1111/j.1365-2265.2005.02343.xDOI Listing
September 2005

Radioimmunodetection and radioimmunotherapy of head and neck cancer.

Oral Oncol 2004 Sep;40(8):761-72

Department of Otolaryngology/Head and Neck Surgery, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.

Radiolabeled monoclonal antibodies (MAbs) can add a dimension to diagnostic imaging and staging of metastatic head and neck cancer, as well as in eradication of this disease. The vast majority of malignancies arising in the oral cavity, pharynx and larynx are squamous cell carcinomas. This common cellular origin makes it attractive to search for appropriate tumor-associated antigens, which are preferentially expressed in these neoplasms. Radiolabeled MAbs directed against these antigens can be used for tumor detection and selective therapy, known as radioimmunoscintigraphy and radioimmunotherapy, respectively. The combination of MAbs with positron emission tomography (PET) is an attractive novel option to improve tumor detection and to facilitate MAb quantification in a therapeutic setting. Basic aspects of tumor targeting with MAbs, as well as a review of the clinical trials reported in the literature, including own results, are presented.
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http://dx.doi.org/10.1016/j.oraloncology.2003.11.009DOI Listing
September 2004

Body composition and bone measurements in intra-uterine growth retarded and early postnatally undernourished male and female rats at the age of 6 months: comparison with puberty.

Bone 2004 Jan;34(1):180-6

Department of Clinical Chemistry, The Research Institute for Endocrinology, Reproduction and Metabolism, VU University Medical Center, 1007 MB Amsterdam, The Netherlands.

Undernutrition in early life may permanently change body structure, physiology and metabolism and leads to chronic diseases in later life. To test whether malnutrition during different critical time periods around birth in the rat has long-lasting effects on body composition and skeletal growth, we examined body weight and body composition in pubertal rats and adult rats of 6 months after pre- and postnatal malnutrition. Prenatal malnutrition or intra-uterine growth retardation (IUGR) was induced by ligation of the uterine arteries on day 17 of gestation and postnatal food restriction (FR) by litter enlargement to 20 pups per mother from day 2 after birth until weaning (day 24). Pubertal markers were balanopreputial separation (BPS) in the male and vaginal opening (VO) in the female. IUGR as well as FR resulted in a persistent growth retardation. From birth in IUGR rats and from day 4 after birth in FR rats until 6 months of age body weight in male and female rats was significantly lower compared with controls (P < 0.01 and P < 0.05). Although total body bone mineral content (TBBMC) did not differ between male IUGR rats and controls at BPS, at the age of 6 months TBBMC was significantly lower (P < 0.01) compared with controls. At BPS as well as at 6 months of age, TBBMC was significantly lower in male FR rats compared with controls (P < 0.05 and P < 0.01). In the female IUGR rats TBBMC was significantly lower compared with controls at VO (P < 0.01) and 6 months (P < 0.05). TBBMC in the female FR rats was significantly lower at VO (P < 0.01), but did not differ from controls at the age of 6 months. For both IUGR and FR male and female rats these differences disappeared after adjusting for body weight. Body composition in terms of total fat mass, percentage fat and percentage lean did not differ from controls in male and female IUGR rats at 6 months and the same results were observed in the female FR rats. However, in the male FR rats, total fat mass and percentage fat were significantly lower compared with controls (P < 0.01 and P < 0.05), while the percentage lean mass was significantly higher (P < 0.05). We conclude that different critical time periods of malnutrition around birth have different effects later in life on growth, which do not disappear at least after 6 months of life. With respect to body composition, only in the FR male rats, differences are found in total fat mass and the balance of percentage fat mass and lean mass. At time of puberty and at the age of 6 months bone mass adjusted for body weight does not seem to be affected by perinatal undernutrition.
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http://dx.doi.org/10.1016/j.bone.2003.04.001DOI Listing
January 2004

Variations in diagnostic performances of dual-energy X-ray absorptiometry in the northwest of The Netherlands.

Osteoporos Int 2004 Apr 20;15(4):335-44. Epub 2003 Nov 20.

Department of Nuclear Medicine, VU University Medical Centre, 1007 MB, Amsterdam, The Netherlands.

Between-center variation in bone densitometry may influence the frequency of the diagnosis of osteoporosis. To evaluate this problem, dual-energy X-ray absorptiometry (DXA) machines of the medical centers in the northwest of The Netherlands were evaluated. Four phantoms were used to test the 17 DXA machines of 16 participating centers. Each phantom was measured 10 times and the data were analyzed on the corresponding DXA machine using the software delivered by the manufacturer. The analyses were done with the reference population as used in daily practice. There were DXA devices of seven different brands and types, using four different reference populations for the lumbar spine and seven for the hip. The observed differences in bone mineral densities (BMD) were up to 0.20 g/cm(2) for the lumbar spine, 0.15 g/cm(2) for the femoral neck, and 0.12 g/cm(2) for the total hip. The coefficients of variation (CV) of the repeated phantom measurements ranged between 0.3% and 1.3% for the lumbar spine, 1.6% and 4.6% for the femoral neck, and 0.3% and 0.9% for the total hip. The mean female T-scores of 10 phantom measurements differed up to 0.6 SD between the DXA machines for the lumbar spine and up to 0.8 SD for the total hip. Mathematically, replacing a Hologic 2000 DXA machine with a newer type of the same brand (a Hologic 4500) caused a shift in diagnosis from osteoporosis to osteopenia of +1.1% for the lumbar spine and -4.5% for the total hip. When the Hologic 2000 was replaced by a Hologic 4500 with NHANES reference values, the shift from osteoporosis to osteopenia was also +1.1% for the lumbar spine, and -13.4% for the total hip. The clinical impact of the observed differences is difficult to estimate. One may conclude that the differences of the tested DXA devices are partly based on differences in DXA machines, but for the most part on the use of different reference populations. It is recommended to standardize the reference population, although the consequent shift in diagnosis will be confusing for physicians and patients, and adaptation of the reference values on the DXA devices of different brands with different technical qualities and measurement specifications will be difficult.
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http://dx.doi.org/10.1007/s00198-003-1541-xDOI Listing
April 2004

Safety, biodistribution, pharmacokinetics, and immunogenicity of 99mTc-labeled humanized monoclonal antibody BIWA 4 (bivatuzumab) in patients with squamous cell carcinoma of the head and neck.

Cancer Immunol Immunother 2003 Sep;52(9):576-82

Department of Otolaryngology/Head and Neck Surgery, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam, The Netherlands.

Unlabelled: Previous studies have shown the potential of murine and chimeric anti-CD44v6 monoclonal antibodies (MAbs) for radioimmunotherapy (RIT) of head and neck squamous cell carcinoma (HNSCC). A limitation of these MAbs, however, appeared to be their immunogenicity. Therefore, humanized monoclonal antibody BIWA 4 (bivatuzumab), with an intermediate affinity for CD44v6, was recently selected. As a prelude to RIT, we evaluated the safety, tumor-targeting potential, pharmacokinetics, and immunogenicity of technetium-99m-labeled BIWA 4 in patients undergoing operations for primary HNSCC in this study. Ten patients were treated at BIWA 4 dose levels of 25 mg (n=3), 50 mg (n=4), and 100 mg (n=3). Patients received 2 mg of 750 MBq 99mTc-BIWA 4, together with 23-, 48-, and 98-mg unlabeled BIWA 4, respectively. Radioimmunoscintigraphy (RIS) was performed within 1 h and after 21 h, and patients underwent surgery at 48 h after injection. Biodistribution of 99mTc-BIWA 4 was evaluated by radioactivity measurements in blood, bone marrow, and in biopsies of a surgical specimen obtained 48 h after injection. BIWA 4 concentration in blood was assessed by ELISA and high performance liquid chromatography and related to soluble CD44v6 levels in serum samples. The development of human anti-human antibody (HAHA) responses was determined. Administration of 99mTc-BIWA 4 was well tolerated by all patients and no HAHA responses were observed. A mean t1/2 in plasma of 54.8 +/- 11.5 h, 76.1 +/- 21.8 h, and 68.5 +/- 21.2 h was found for the 25-, 50-, and 100-mg dose group, respectively. No complex formation of BIWA 4 with soluble CD44v6 in blood was observed. RIS showed targeting of primary tumors and lymph node metastases in 8 of 10 and 1 of 5 patients, respectively. The highest tumor uptake and tumor to nontumor ratios were observed for the 50-mg dose group. Tumor uptake was 12.9 +/- 5.9, 26.2 +/- 3.1, and 15.4 +/- 1.9% of the injected dose (ID)/kg for the 25-, 50-, and 100-mg dose group, respectively, while the tumor to bone marrow ratios for these groups were 1.7 +/- 0.5, 3.2 +/- 1.1, and 2.0 +/- 0.6, respectively.

Conclusion: 99mTc-BIWA 4 can safely be administered to patients with HNSCC, with absence of detectable HAHA responses. The 50-mg dose level showed the highest tumor uptake and tumor to nontumor ratios. These findings support the use of BIWA 4 for RIT studies in patients with HNSCC.
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http://dx.doi.org/10.1007/s00262-003-0396-5DOI Listing
September 2003

Dosimetric analysis of radioimmunotherapy with 186Re-labeled bivatuzumab in patients with head and neck cancer.

J Nucl Med 2003 Oct;44(10):1690-9

Department of Nuclear Medicine, University Medical Center Nijmegen, Nijmegen, The Netherlands.

Unlabelled: From December 1999 until July 2001, a phase I dose escalation study was performed with (186)Re-labeled bivatuzumab, a humanized monoclonal antibody against CD44v6, on patients with inoperable recurrent or metastatic head and neck cancer. The aim of the trial was to assess the safety and tolerability of intravenously administered (186)Re-bivatuzumab and to determine the maximum tolerated dose (MTD) of (186)Re-bivatuzumab. The data were also used for dosimetric analysis of the treated patients. Dosimetry is used to estimate the absorbed doses by nontarget organs, as well as by tumors. It can also help to explain toxicity that is observed and to predict organs at risk because of the therapy given.

Methods: Whole-body scintigraphy was used to draw regions around sites or organs of interest. Residence times in these organs and sites were calculated and entered into the MIRDOSE3 program, to obtain absorbed doses in all target organs except for red marrow. The red marrow dose was calculated using a blood-derived method. Twenty-one studies on 18 patients, 5 female and 16 male, were used for dosimetry.

Results: The mean red marrow doses were 0.49 +/- 0.03 mGy/MBq for men and 0.64 +/- 0.03 mGy/MBq for women. The normal organ with the highest absorbed dose appeared to be the kidney (mean dose, 1.61 +/- 0.75 mGy/MBq in men and 2.15 +/- 0.95 mGy/MBq in women; maximum kidney dose in all patients, 11 Gy), but the doses absorbed are not expected to lead to renal toxicity. Other organs with doses exceeding 0.5 mGy/MBq were the lungs, the spleen, the heart, the liver, the bones, and the testes. The doses delivered to the tumor, recalculated to the MTD level of 1.85 GBq/m(2), ranged from 3.8 to 76.4 Gy, with a median of 12.4 Gy. A good correlation was found between platelet and white blood cell counts and the administered amount of activity per kilogram of body weight (r = -0.79).

Conclusion: Dosimetric analysis of the data revealed that the range of doses to normal organs seems to be well within acceptable and safe limits. Tumor doses ranged from 4 to 76 Gy. Given the acceptable tumor doses, (186)Re-labeled bivatuzumab could be a good candidate for future adjuvant radioimmunotherapy in patients with minimal residual disease.
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October 2003

Phase I therapy study with (186)Re-labeled humanized monoclonal antibody BIWA 4 (bivatuzumab) in patients with head and neck squamous cell carcinoma.

Clin Cancer Res 2003 Sep;9(10 Pt 2):3961S-72S

Department of Otolaryngology/Head and Neck Surgery, VU University Medical Center, 1081 HV Amsterdam, the Netherlands.

Purpose: In previous studies, we have shown the potential of radioimmunotherapy (RIT) with (186)Re-labeled chimeric monoclonal antibody (MAb) U36 for treatment of head and neck cancer. A limitation of this anti-CD44v6 MAb, however, appeared to be its immunogenicity, resulting in human antichimeric antibodies in 40% of the patients. Aiming for a less immunogenic anti-CD44v6 MAb, the humanized MAb BIWA 4 (bivatuzumab) was introduced. In the present Phase I RIT study, we determined the safety, maximum tolerated dose (MTD), pharmacokinetics, immunogenicity, and therapeutic potential of (186)Re-labeled BIWA 4 in patients with squamous cell carcinoma of the head and neck.

Experimental Design: Twenty patients with inoperable recurrent and/or metastatic head and neck squamous cell carcinoma received a single dose of (186)Re-labeled BIWA 4 in radiation dose-escalation steps of 20, 30, 40, 50, and 60 mCi/m(2). Three patients received a second dose at least 3 months after the initial dose. After each administration, whole-body images as well as planar and tomographic images of the head and neck region were obtained, and the pharmacokinetics and the development of human antihuman antibody responses were determined. Radiation absorbed doses were calculated for whole body, red marrow, organs, and tumor.

Results: First and second administrations were all well tolerated, and targeting of tumor lesions proved to be excellent. The only significant manifestations of toxicity were dose-limiting myelotoxicity consisting of thrombo- and leukocytopenia and, to a lesser extent, oral mucositis (grade 2). Grade 4 myelotoxicity was seen in two patients treated with 60 mCi/m(2). The MTD was established at 50 mCi/m(2), at which level dose-limiting myelotoxicity was seen in one of six patients. Stable disease, varying between 6 and 21 weeks, was observed in three of six patients treated at the MTD level. The median tumor dose, recalculated to MTD level, was 12.4 Gy. The absorbed dose in red marrow was 1.82 +/- 0.11 cGy/mCi for males and 2.35 +/- 0.10 for females. Two patients experienced a human antihuman antibody response. Pharmacokinetics showed consistency across patients and within the three patients receiving (186)Re-BIWA 4 on two occasions.

Conclusions: This study shows that (186)Re-labeled BIWA 4 can safely be administered, also in a repeated way. The MTD was established at 50 mCi/m(2). In comparison with the previously described anti-CD44v6 MAb U36, the humanized MAb BIWA 4 seems to be less immunogenic. The fact that antitumor effects were seen in incurable patients with bulky disease justifies the evaluation of RIT with (186)Re-labeled BIWA 4 in an adjuvant setting.
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September 2003

Ten-year longitudinal relationship between physical activity and lumbar bone mass in (young) adults.

J Bone Miner Res 2003 Feb;18(2):325-32

Institute for Research in Extramural Medicine (EMGO Institute), VU University Medical Center, Amsterdam, The Netherlands.

Little is known about the influence of long-term daily physical activity (PA) on lumbar bone mass after peak bone mass has been reached, that is, during [young] adulthood. The purpose of this study was to investigate the longitudinal relationship between PA and lumbar bone mineral density (LBMD) in healthy subjects over a 10-year period. The data reported here relate to 225 male and 241 female participants in the Amsterdam Growth and Health Longitudinal Study, who were measured at the mean ages of 27, 32, and/or 36. LBMD, habitual daily PA, total body weight, and calcium intake were assessed at each measurement point. The effects of two aspects of PA were analyzed: the mechanical (MECHPA; sum of all ground reaction forces) and metabolic (METPA; weighted metabolic score of intensity, frequency, and duration) components, each within a separate model. Multilevel analysis was used to investigate the relationship between PA and LBMD over the 10-year period. Gender, total body weight, and calcium intake were included in the analysis as covariates. The results indicated that MECHPA was a significant positive linear predictor of LBMD for males (r = 0.09; p < 0.001) but not for females. For the METPA, no linear longitudinal relationship with LBMD was found. The results suggest that there is a metabolic threshold at which extra PA becomes "deleterious" and METPA in its totality becomes ineffective for LBMD. It is concluded that during the (young) adult period, between 27 and 36 years of age, PA causing mechanical loading on the skeleton has a small positive influence on LBMD in males.
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http://dx.doi.org/10.1359/jbmr.2003.18.2.325DOI Listing
February 2003

Reinfusion of unprocessed, granulocyte colony-stimulating factor-stimulated whole blood allows dose escalation of 186Relabeled chimeric monoclonal antibody U36 radioimmunotherapy in a phase I dose escalation study.

Clin Cancer Res 2002 Nov;8(11):3401-6

Department of Otolaryngology/Head and Neck Surgery, Vrije Universiteit Medical Center, 1081 Hv Amsterdam, The Netherlands.

Purpose: In an earlier Phase I radioimmunotherapy (RIT) study with rhenium-186-labeled chimeric monoclonal antibody (cMAb) U36 in patients with refractory head and neck squamous cell carcinoma, the maximum tolerated activity was established at 1.0 GBq/m2, at which bone marrow doses ranged from 0.7 to 1.1 Gy. In the present study, further dose escalation in RIT was evaluated using a facile method of reinfusion of granulocyte colony-stimulating factor (G-CSF)-stimulated unprocessed whole blood.

Experimental Design: Nine patients with recurrent or metastatic head and neck squamous cell carcinoma were treated at radiation dose levels of 1.0, 1.5, and 2.0 GBq/m2. Before RIT, G-CSF (10 microg/kg/day) was administered s.c. at home during 5 days. On day 6, just before administration of 186Relabeled cMAb U36, 1 liter of whole blood was harvested and kept unprocessed at 4 degrees C until reinfusion after 72 h. Blood samples were taken for analysis of pharmacokinetics and bone marrow dosimetry. Patients were evaluated for myelotoxicity and tumor response.

Results: Blood harvesting, RIT, and reinfusion of whole blood were well tolerated by all patients. G-CSF stimulation resulted in a mean of 0.41 x 10(6) CD34+ cells/kg (range, 0.15-0.83 x 10(6) CD34+cells/kg) and a mean committed colony-forming units granulocyte macrophage count of 5.62 x 10(4)/kg (range, 0.62-13.37 x 10(4)/kg). The mean biological half-life of 186Relabeled cMAb U36 in blood was 72.6 +/- 16.0 h, and bone marrow doses ranged from 2.1 to 2.8 Gy at the highest dose level. Myelotoxicity exceeding grade 3 was not observed. Stable disease was observed in five of nine patients, ranging from 3 to 5 months, and was still ongoing in one of these patients.

Conclusions: This study indicates that a doubling of the maximum tolerated activity and bone marrow dose of 186Relabeled cMAb U36 can be achieved using reinfusion of G-CSF-stimulated unprocessed whole blood.
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November 2002

Daily oral pamidronate in women and men with osteoporosis: a 3-year randomized placebo-controlled clinical trial with a 2-year open extension.

J Bone Miner Res 2002 Jun;17(6):1057-64

Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, The Netherlands.

The efficacy and safety of oral pamidronate was examined in a double-blind, placebo-controlled trial in women and men with established osteoporosis. Seventy-eight postmenopausal women and 23 men with at least one prevalent vertebral fracture were randomized separately to 150 mg/day of pamidronate or placebo for 3 years followed by 150 mg/day of pamidronate for an additional 2 years. In addition, all patients received 400 U/day of cholecalciferol and 500 mg/day of elemental calcium. Pamidronate increased significantly bone mineral density of the lumbar spine (LS-BMD) and of the femoral neck (FN-BMD). The total increase in BMD of the spine after 5 years of treatment was 14.3%. Lateral spine radiographs were obtained at baseline and after 3 years of treatment. Fractures of previously normal vertebrae occurred in 15 of 45 patients treated with placebo (33.3%) and in 5 of 46 patients treated with pamidronate (11%). The relative risk was 0.33 (95% CI, 0.14-0.77). Treatment was well tolerated and there was no difference in gastrointestinal toxicity between pamidronate and placebo-treated patients. One hundred fifty milligrams daily of pamidronate is an effective and safe treatment of women and men with established osteoporosis.
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http://dx.doi.org/10.1359/jbmr.2002.17.6.1057DOI Listing
June 2002

Interobserver agreement on captopril renography for assessing renal vascular disease.

J Nucl Med 2002 Mar;43(3):330-7

Center for Clinical Decision Sciences, Department of Public Health, Erasmus University Rotterdam, Rotterdam, The Netherlands.

Unlabelled: Captopril-stimulated renography is widely used to screen selected groups of hypertensive patients for renal vascular disease. Evaluation of the test is a complex task. Lack of interobserver agreement on the assessment and interpretation of renographic parameters may contribute to differences in sensitivity and specificity between studies.

Methods: Three experienced nuclear medicine physicians evaluated 658 renograms of 503 hypertensive patients suspected of having renal vascular disease from a large Dutch multicenter study (the Dutch Renal Artery Stenosis Intervention Cooperative [DRASTIC] study). Interobserver agreement on several renographic parameters was assessed by the kappa statistic and the intraclass correlation coefficient (ICC).

Results: The interobserver agreement on the time to excretion was high: The pooled ICC was 0.90. The pooled kappa was > or = 0.65 for the pattern of the time--activity curves, the visual aspect of the scintigraphic images (visible uptake and kidney size), and the judgment on the presence of renal artery stenosis. However, the interobserver agreement on cortical retention and pelvic retention by visual inspection of the images was rather low (pooled kappa = 0.46 and 0.52, respectively). Pelvic retention was found to complicate the interpretation of renography.

Conclusion: Interobserver agreement on most of the renographic parameters was satisfactory, but the assessment of cortical retention was more difficult, in particular, in the presence of pelvic retention. Captopril renography should be interpreted with caution if pelvic retention is suspected. Interobserver variability offers one of several explanations for the differences in diagnostic test performance that are found between studies.
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March 2002