DEVELOPMENT OF A NEW SECONDARY STANDARD FOR H*(10).

A secondary standard for ambient dose equivalent, H*(10), is necessary for the dissemination of the unit Sievert (Sv), but there is no such standard commercially available currently. Furthermore, the measurement of H*(10) instead of calculating H*(10) from air kerma and conversion coefficients is needed for unknown radiation fields. We developed a prototype of a new secondary standard for H*(10) based on a spherical 1 l ionization chamber for air kerma. This chamber was modified with copper wires at the inner surface to adjust the response of the chamber according to H*(10). Additionally, a Makrolon shell and an aluminium coating were added to optimize the response at energies below 50 keV. The prototype fulfils the requirements given in ISO 4037-2 in the energy range from 12 keV to 7 MeV. In combination with an electrometer, it can be used as area dosemeter, suitable for pulsed fields and for low energy radiation.

Novel spectrometers for environmental dose rate monitoring.

A new generation of dosemeters, based on the scintillators LaBr3, CeBr3 and SrI2, read out with conventional photomultipliers, to be used in the field of environmental gamma-radiation monitoring, was investigated. The main features of these new instruments and especially their outdoor performance, studied by long-term investigations under real weather conditions, are presented. The systems were tested at the reference sites for environmental radiation of the Physikalisch-Technische Bundesanstalt. The measurements are compared with that of well characterized classical dose rate reference instruments to demonstrate the suitability of new spectrometers for environmental dose rate monitoring even in adverse weather conditions. Their potential to replace the (mainly Geiger Müller based) dose rate meters operated in about 5000 European early waning network stations as well as in environmental radiation monitoring in general is shown.

CAN HALF VALUE LAYER MEASUREMENTS BE USED TOGETHER WITH THE EFFECTIVE ENERGY TO OBTAIN CONVERSION COEFFICIENTS FOR X-RAY SPECTRA?

Conversion coefficients are a substantial vehicle in practical radiation protection to determine the dose (rate) of a given radiation field. According to ICRU report 57, their values shall be obtained by means of spectrometry. This is, however, a time-consuming complicated procedure that cannot be performed by all dosimetry laboratories. Therefore, it is desired to find acceptable alternative methods to replace spectrometry. One possibility is to set up the X-ray facility in accordance with international standard ISO 4037-1:1997 and use the tabulated values from that standard. However, this needs to be considered during the construction phase of the X-ray facility. In this work, the combined usage of half-value layer measurements and the effective energy (both with respect to air kerma) to determine the conversion coefficients is investigated and compared with the values obtained by spectrometry. The investigations utilise all combinations of the H-, W-, N- and L-series, reference distances of 1 and 2.5 m and aluminium and copper as attenuation materials. We find that for most of the radiation qualities, the investigated method results in conversion coefficients that show an unacceptable deviation from the conventionally true values. However, the values of conversion coefficients of selected N- and L-qualities could be reproduced with high accuracy (within ±1 %).

Effect of X-ray High-voltage Variations on the Conversion Coefficients.

Conversion coefficients (CCs) are an essential vehicle in radiation protection for the determination of the dose (rate) of a given radiation field. According to the current draft of the revision of international standard ISO 4037, an X-ray field is a reference field if the CCs of the field match the tabulated ISO values within 2%. Deviations of the high-voltage (HV) tube-potential from its nominal value influence the resulting spectra and change the corresponding CCs. This work investigates the maximum allowable deviation of the HV from its nominal value such that the requirements of ISO 4037 remain fulfilled. This is achieved using both synthetic spectra created by a software simulation program and spectra measured at one of the X-ray facilities of the Physikalisch-Technische Bundesanstalt. The results are summarised in form of a new proposal for upper limit values which are suggested to be used in the next version of ISO 4037.

Implications of X-ray tube parameter deviations in X-ray reference fields.

For the purpose of radiation protection, ICRU Report 57/ICRP Publication 74 provides a list of monoenergetic conversion coefficients to be used with, among others, photon reference fields generated with X-ray tubes. A comprehensive definition of these photon reference fields can be found in international standard ISO 4037; however, it lacks thorough indication of the allowed deviations of essential parameters that influence these X-ray reference fields. These parameters are the high-voltage tube potential, the thickness of the beryllium window and the purity and thickness of the filter materials used to create different radiation qualities. Small variations of these parameters can lead to significant changes in the created X-ray spectra and, hence, the spectra-dependent conversion coefficients for phantom-related radiation-protection quantities. This can lead to situations in which the conversion coefficients listed in ISO 4037 cannot be used, resulting in time-consuming spectrometry measurements. In this work, the impact on the resulting conversion coefficients is investigated using a simplified mathematical approximation model. The findings are validated with an independent X-ray spectra calculation programme. As a result, well-founded upper limit values on the allowed deviations of the essential X-ray tube parameters are proposed to be used in a future revision of ISO 4037.

Mitochondrial adaptations evoked with exercise are associated with a reduction in age-induced testicular atrophy in Fischer-344 rats.

Mitochondrial dysfunction in various tissues has been associated with numerous conditions including aging. In testes, aging induces atrophy and a decline in male reproductive function but the involvement of mitochondria is not clear. The purpose of this study was to examine whether the mitochondrial profile differed with (1) aging, and (2) 10-weeks of treadmill exercise training, in the testes of young (6 month) and old (24 month) Fischer-344 (F344) animals. Old animals exhibited significant atrophy (30 % decline; P < 0.05) in testes compared to young animals. However, relative mitochondrial content was not reduced with age and this was consistent with the lack of change in the mitochondrial biogenesis regulator protein, peroxisome proliferator-activated receptor gamma coactivator 1-alpha and its downstream targets nuclear respiratory factor-1 and mitochondrial transcription factor A. No effect was observed in the pro- or anti-apoptotic proteins, Bax and Bcl-2, respectively, but age increased apoptosis inducing factor levels. Endurance training induced beneficial mitochondrial adaptations that were more prominent in old animals including greater increases in relative mtDNA content, biogenesis/remodeling (mitofusin 2), antioxidant capacity (mitochondrial superoxide dismutase) and lower levels of phosphorylated histone H2AX, an early marker of DNA damage (P < 0.05). Importantly, these exercise-induced changes were associated with an attenuation of testes atrophy in older sedentary animals (P < 0.05). Our results indicate that aging-induced atrophy in testes may not be associated with changes in relative mitochondrial content and key regulatory proteins and that exercise started in late-life elicits beneficial changes in mitochondria that may protect against age-induced testicular atrophy.

Directional limits on persistent gravitational waves using LIGO S5 science data.

The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50) strain(2) Hz(-1) and 5-35×10(-49) strain(2) Hz(-1) sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz.

An upper limit on the stochastic gravitational-wave background of cosmological origin.

A stochastic background of gravitational waves is expected to arise from a superposition of a large number of unresolved gravitational-wave sources of astrophysical and cosmological origin. It should carry unique signatures from the earliest epochs in the evolution of the Universe, inaccessible to standard astrophysical observations. Direct measurements of the amplitude of this background are therefore of fundamental importance for understanding the evolution of the Universe when it was younger than one minute. Here we report limits on the amplitude of the stochastic gravitational-wave background using the data from a two-year science run of the Laser Interferometer Gravitational-wave Observatory (LIGO). Our result constrains the energy density of the stochastic gravitational-wave background normalized by the critical energy density of the Universe, in the frequency band around 100 Hz, to be <6.9 x 10(-6) at 95% confidence. The data rule out models of early Universe evolution with relatively large equation-of-state parameter, as well as cosmic (super)string models with relatively small string tension that are favoured in some string theory models. This search for the stochastic background improves on the indirect limits from Big Bang nucleosynthesis and cosmic microwave background at 100 Hz.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data.

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

Downhill treadmill running trains the rat spinotrapezius muscle.

There are currently no models of exercise that recruit and train muscles, such as the rat spinotrapezius, that are suitable for transmission intravital microscopic investigation of the microcirculation. Recent experimental evidence supports the concept that running downhill on a motorized treadmill recruits the spinotrapezius muscle of the rat. Based on these results, we tested the hypothesis that 6 wk of downhill running (-14 degrees grade) for 1 h/day, 5 days/wk, at a speed of up to 35 m/min, would 1) increase whole body peak oxygen uptake (Vo(2 peak)), 2) increase spinotrapezius citrate synthase activity, and 3) reduce the fatigability of the spinotrapezius during electrically induced 1-Hz submaximal tetanic contractions. Trained rats (n = 6) elicited a 24% higher Vo(2 peak) (in ml.min(-1).kg(-1): sedentary 58.5 +/- 2.0, trained 72.7 +/- 2.0; P < 0.001) and a 41% greater spinotrapezius citrate synthase activity (in mumol.min(-1).g(-1): sedentary 14.1 +/- 0.7, trained 19.9 +/- 0.9; P < 0.001) compared with sedentary controls (n = 6). In addition, at the end of 15 min of electrical stimulation, trained rats sustained a greater percentage of the initial tension than their sedentary counterparts (control 34.3 +/- 3.1%, trained 59.0 +/- 7.2%; P < 0.05). These results demonstrate that downhill running is successful in promoting training adaptations in the spinotrapezius muscle, including increased oxidative capacity and resistance to fatigue. Since the spinotrapezius muscle is commonly used in studies using intravital microscopy to examine microcirculatory function at rest and during contractions, our results suggest that downhill running is an effective training paradigm that can be used to investigate the mechanisms for improved microcirculatory function following exercise training in health and disease.

A multivalent HIV-vaccine: development of a plasmid DNA for the expression of HIV envelope glycoproteins with hypervariable V3-loop domains.

The third hypervariable (V3) loop of the HIV-1 envelope glycoprotein gp120 plays an essential role in the process of viral entry. It contributes to the tropism, coreceptor usage and immune-escape of the virus. We generated a monovalent plasmid DNA and demonstrated the expression of HIV-1 clade B subtype NL4-3 gp120 and gp160 in comparison to a multivalent plasmid DNA encoding for a variety of V3-variants. In contrast to the membrane-anchored gp160, preliminary data demonstrate the monovariant gp120 is expressed in and presented on a human dendritic cell (DC) line, due to a HIVenv-specific re-stimulation of naïve T-cells detected by IFNgamma-ELISPOT assay.

Activity of histone H1.2 in infected burn wounds.

OBJECTIVES: Infections with multidrug-resistant microorganisms (e.g. Pseudomonas aeruginosa and Staphylococcus aureus) cause immense complications in wound care and in the treatment of immunosuppressed patients. Like most antimicrobial peptides, histones are relatively small polycationic proteins located in each eukaryotic nucleus, which naturally supercoil DNA. The aim of this study was to investigate the in vitro and in vivo activity of histone H1.2 in infected burn wounds and its potential toxicity. METHODS: To characterize the antimicrobial properties of histone H1.2 against potential causative organisms of burn wound infections, the in vitro radial diffusion assay and modified NCCLS microbroth dilution MIC assay were carried out. Haemolytic and cytotoxic properties were determined in human red blood cells and primary human keratinocytes. In vivo antimicrobial activity was tested in an infected rat burn model with P. aeruginosa (ATCC 27853). All results were compared with the naturally occurring broad-spectrum antimicrobial peptide protegrin-1 and with antibiotics clinically used against the corresponding bacteria. RESULTS: Human histone H1.2 exerted good antimicrobial activity against all tested microorganisms without significant haemolytic activity. Surprisingly, histone H1.2 showed cytotoxicity with an LD50 of 7.91 mg/L in primary human keratinocytes. The in vivo burn model data revealed a significant three-fold higher reduction in bacterial counts within 4 h compared with carrier control. CONCLUSIONS: These findings indicate that histone H1.2 is a potential candidate for use as a local and, because of its low haemolytic activity, systemic antimicrobial agent. However, further investigations are needed to specify the cytotoxicity and the dose-response relationship for histone H1.2.

[Injury pattern caused by aggressive inline skating]. / Das Verletzungsrisiko beim Aggressive Inlineskating.

In order to evaluate the special injury pattern of aggressive inline skating, a field study was conducted in a local, non-commercial skate park equipped with all the typical features like ramps, halfpipes, gully areas. 66 unselected aggressive inline skaters were randomly enrolled and interviewed concerning their skating habits and their skating injury history. Average age was 15 (10 to 41) years, skating was performed since 2.1 (0.1 to 6) years, as aggressive skating since 1.3 (0.1 to 4) years. Medical treatment in a doctor's practice or in a hospital had been necessary in 66 cases, averaging 1.4 times per skater and year, averaging one injury per 586 hours of aggressive skating. The injury pattern reflected the regions typically injured in fitness skating, too, with a higher percentage of injuries concerning knee, tibia and ankle region. The use of protective devices varied from 41 % (wrist guards) to 94 % (knee pads), with an average of 69 %. Only 32 % of skaters wore all protective devices. As the personal thrill is an important motivation for aggressive skating, safer skating campaigns are quite unlikely to decrease the risk of injury in aggressive skaters.

Effects of chronic heart failure on microvascular oxygen exchange dynamics in muscles of contrasting fiber type.

UNLABELLED: In rat spinotrapezius muscle, chronic heart failure (CHF) speeds microvascular O2 pressure (pO2; index of O2 delivery-to-O2 uptake) dynamics across the rest-contractions transition [Cardiovasc. Res. 56 (2002) 479]. Due to the mosaic nature of this muscle, the effect of CHF on microvascular pO2 dynamics in different fiber types remains unclear. OBJECTIVE: Based upon derangements of endothelial function and blood flow responses, we hypothesized that CHF would speed microvascular pO2 dynamics (reduced O2 delivery-to-O2 uptake ratio) in type I muscle (soleus, approximately 84% type I), but not in type II muscle (peroneal, approximately 86% type II [J. Appl. Physiol. 80 (1996) 261]). METHODS: Using phosphorescence quenching, microvascular pO2 was measured at rest and across the rest-contractions transition (1 Hz) in soleus and peroneal of non-infarcted control (control; n=7), and Sprague-Dawley rats with moderate (moderate; elevated left ventricular end-diastolic pressure (LVEDP) 10 +/- 2 mm Hg; n=10) and severe (severe; LVEDP 28 +/- 4 mm Hg; n=5) CHF. RESULTS: The microvascular pO2 mean response time (time delay+time constant) was progressively speeded with increasing severity of CHF in soleus (control, 38.7 +/- 2.0; moderate, 29.1 +/- 1.5; severe, 22.5 +/- 3.9 s; P< or =0.05), but not in peroneal (control=moderate=severe). CONCLUSION: As type I fibers are recruited predominately for moderate intensity exercise, the more rapid lowering of soleus microvascular pO2 in CHF would reduce the blood-muscle O2 driving gradient, exacerbate phosphocreatine and glycogen breakdown, and provide a mechanism for slowed O2 uptake kinetics and premature fatigue in CHF.

[Experiences after 150 cartilage-bone-transplantations of the knee: a prospective analysis of the results]. / Erfahrungen nach 150 Knorpel-Knochen-Transplantationen (KKT) am Kniegelenk: Eine prospektive Ergebnisanalyse.

INTRODUCTION: To evaluate the clinical outcome of cartilage-bone-transplantations of the knee in patients with different indications, we studied the clinical results of 45 patients with a follow-up of 24 months after operation. PATIENTS AND METHODS: 29 male and 16 female patients with a mean age of 37.7 yrs (16-58 yrs) were included. Indications for operation were osteochondritis dissecans (OD) (n=13), limited arthritis (n=20), traumatic lesions (n=5) and retropatellar lesions (n=7). The results were evaluated by clinical score (McDermott Score; preoperatively, and 3, 6, 12, 24 months postoperatively), magnetic resonance imaging, and re-arthroscopy for most patients. RESULTS: 42 of 45 patients judged the operation as successful. The mean score value of all patients raised from 66.3 pts (out of 100 pts) preoperatively to 92.7 pts 24 months postoperatively. The results of the patients with circumscript arthritic lesions (62.9 pts. preoperatively vs. 91.5 pts. postoperatively) were comparable to those of the other patients. CONCLUSION: We conclude that cartilage-bone-transplantation of the knee is a valuable procedure to improve joint function not only after OD or trauma, but also in joints with local arthritic lesions on condition that there is an adequate quality of the donor site.

Dynamics of microvascular oxygen partial pressure in contracting skeletal muscle of rats with chronic heart failure.

OBJECTIVE: This investigation tested the hypothesis that the dynamics of muscle microvascular O(2) pressure (PO(2)m, which reflects the ratio of O(2) utilization [V*O(2)] to O(2) delivery [Q*O(2)]) following the onset of contractions would be altered in chronic heart failure (CHF). METHODS: Female Sprague-Dawley rats were subjected to a myocardial infarction (MI) or a sham operation (Sham). Six to 10 weeks post Sham (n=6) or MI (n=17), phosphorescence quenching techniques were utilized to determine PO(2)m dynamics at the onset of spinotrapezius muscle contractions (1 Hz). RESULTS: MI rats were separated into groups with Moderate (n=10) and Severe (n=7) CHF based upon the degree of left ventricular (LV) dysfunction as indicated by structural abnormalities (increased right ventricle weight and lung weight normalized to body weight). LV end-diastolic pressure was elevated significantly in both CHF groups compared with Sham (Sham, 3+/-1; Moderate CHF, 9+/-2; Severe CHF, 27+/-4 mmHg, P<0.05). The PO(2)m response was modeled using time delay and exponential components to fit the PO(2)m response to the steady-state. Compared with Shams, the time constant (tau) of the primary PO(2)m response was significantly speeded in Moderate CHF (tau, Sham, 19.0+/-1.5; Moderate CHF, 13.2+/-1.9 s, P<0.05) and slowed in Severe CHF (tau, 28.2+/-3.4 s, P<0.05). Within the Severe CHF group, tau increased linearly with the product of right ventricular and lung weight (r=0.83, P<0.05). CONCLUSIONS: These results suggest that CHF alters the dynamic matching of muscle V*O(2)-to-Q*O(2) across the transition from rest to contractions and that the nature of that perturbation is dependent upon the severity of cardiac dysfunction.

Effect of body incline on cardiac performance.

Maximal cardiac performance is improved in man during upright compared to supine exercise. Whether cardiac performance in quadrupeds is dependent upon body position is unknown. Therefore, we undertook the present investigation to determine if peak cardiac output (Qpeak) would be influenced by body inclination in the Thoroughbred horse. To test the hypothesis, four Thoroughbred horses performed an incremental exercise protocol (speed increased by 1 m/s/min to fatigue) on both a level (L) and inclined (I: 6 degrees) treadmill. Specifically, we hypothesised that Qpeak would be increased on the incline, as this represents a progression towards upright exercise. Cardiac output was determined using the Fick relationship from continuous measurements of pulmonary VO2 and paired arterial (carotid artery or transverse facial) and mixed venous (pulmonary artery) samples. Qpeak was significantly increased on the incline (L: 279 +/- 20; I: 336 +/- 17 l/min; P<0.05), while CaO2 was not significantly different (L: 25.5 +/- 1.1; I: 25.4 +/- 1.9 ml/100 ml), and therefore, whole body O2 delivery (QO2) was significantly increased (L: 70.7 +/- 4.9; I: 84.4 +/- 3.1 l/min; P<0.05). In conclusion, within the scope of this investigation, these data suggest that cardiac performance, as judged by increased Qpeak and QO2, is enhanced in the inclined body position. Furthermore, these findings provide preliminary information that level and incline treadmill exercise tests may yield significantly different results in the Thoroughbred horse and consequently this factor should be considered when interpreting exercise testing and performance data.

Effects of the antirheumatic remedy hox alpha--a new stinging nettle leaf extract--on matrix metalloproteinases in human chondrocytes in vitro.

Inflammatory joint diseases are characterized by enhanced extracellular matrix degradation which is predominantly mediated by cytokine-stimulated upregulation of matrix metalloproteinase (MMP) expression. Besides tumour necrosis factor-alpha (TNF-alpha), Interleukin-1beta (IL-1beta) produced by articular chondrocytes and synovial macrophages, is the most important cytokine stimulating MMP expression under inflammatory conditions. Blockade of these two cytokines and their downstream effectors are suitable molecular targets of antirheumatic therapy. Hox alpha is a novel stinging nettle (Urtica dioica/Urtica urens) leaf extract used for treatment of rheumatic diseases. The aim of the present study was to clarify the effects of Hox alpha and the monosubstance 13-HOTrE (13-Hydroxyoctadecatrienic acid) on the expression of matrix metalloproteinase-1, -3 and -9 proteins (MMP-1, -3, -9). Human chondrocytes were cultured on collagen type-II-coated petri dishes, exposed to IL-1beta and treated with or without Hox alpha and 13-HOTrE. A close analysis by immunofluorescence microscopy and western blot analysis showed that Hox alpha and 13-HOTrE significantly suppressed IL-1beta-induced expression of matrix metalloproteinase-1, -3 and -9 proteins on the chondrocytes in vitro. The potential of Hox alpha and 13-HOTrE to suppress the expression of matrix metalloproteinases may explain the clinical efficacy of stinging nettle leaf extracts in treatment of rheumatoid arthritis. These results suggest that the monosubstance 13-HOTrE is one of the more active antiinflammatory substances in Hox alpha and that Hox alpha may be a promising remedy for therapy of inflammatory joint diseases.

NO inhalation reduces pulmonary arterial pressure but not hemorrhage in maximally exercising horses.

In horses, the exercise-induced elevation of pulmonary arterial pressure (Ppa) is thought to play a deterministic role in exercise-induced pulmonary hemorrhage (EIPH), and thus treatment designed to lower Ppa might reasonably be expected to reduce EIPH. Five Thoroughbred horses were run on a treadmill to volitional fatigue (incremental step test) under nitric oxide (NO; inhaled 80 ppm) and control (N(2), same flow rate as per NO run) conditions (2 wk between trials; order randomized) to test the hypothesis that NO inhalation would reduce maximal Ppa but that this reduction may not necessarily reduce EIPH. Before each investigation, a microtipped pressure transducer was placed in the pulmonary artery 8 cm past the pulmonic valve to monitor Ppa. EIPH severity was assessed via bronchoalveolar lavage (BAL) 30 min postrun. Exercise time did not differ between the two trials (P > 0.05). NO administration resulted in a small but consistent and significant reduction in peak Ppa (N(2), 102.3 +/- 4.4; NO, 98.6 +/- 4.3 mmHg, P < 0.05). In the face of lowered Ppa, EIPH severity was significantly higher in the NO trial (N(2), 22.4 +/- 6.8; NO, 42.6 +/- 15.4 x 10(6) red blood cells/ml BAL fluid, P < 0.05). These findings support the notion that extremely high Ppa may reflect, in part, an arteriolar vasoconstriction that serves to protect the capillary bed from the extraordinarily high Ppa evoked during maximal exercise in the Thoroughbred horse. Furthermore, these data suggest that exogenous NO treatment during exercise in horses may not only be poor prophylaxis but may actually exacerbate the severity of EIPH.

Bone mineral density in children with primary hyperoxaluria type I.

BACKGROUND: In primary hyperoxaluria type I (PH 1), hepatic overproduction of oxalate leads to its deposition in various organ systems including bone (oxalosis). To evaluate skeletal status non-invasively in PH 1 we measured bone mineral density (BMD). METHODS: Peripheral quantitative computed tomography of the distal radius was performed in 10 children with PH 1 (mean chronological age 9+/-3.1, mean skeletal age 8.3+/-3.0 years): seven were on conservative treatment (CT) including one patient after pre-emptive liver transplantation (PH1-CT) and three were studied with end-stage renal disease on peritoneal dialysis (PH1-ESRD). RESULTS: Mean trabecular bone density (TBD) was significantly increased in PH1-ESRD compared with both age-matched healthy and uraemic controls (65227 vs. 168+/-63 and 256+/-80 mg/cm(3); P<0.002 and P<0.007, respectively), while cortical bone density (CBD) was elevated to a lesser degree (517+/-23 vs. 348+/-81 vs. 385+/-113 mg/cm(3); P<0.02 and P<0.04, respectively). In PH 1, CBD and, even more so, TBD were significantly correlated with serum creatinine (r=0.91 and r=0.96, P<0.0001, respectively) and plasma oxalate levels (r=0.86 and r=0.94, P<0.001 and P<0.0001, respectively). In children with PH 1 and normal glomerular function, both CBD and TBD were comparable with healthy controls. CONCLUSION: These preliminary data suggest that in PH 1 BMD is significantly increased in ESRD, probably due to oxalate disposal. Measurement of BMD may be a valuable and non-invasive tool in determining and monitoring oxalate burden in this disorder.