Long-term changes in mouse lung following inhalation of a fibrosis-inducing dose of 239PuO2: changes in collagen synthesis and degradation rates.

Mice were exposed by nose-only inhalation to 239PuO2, which resulted in an IAD of 1110 +/- 29 Bq. At various times after exposure, rates of collagen metabolism were measured using validated in vivo methods based on the administration of radiolabelled proline, together with a large flooding dose of unlabelled proline and measurement of its incorporation into lung collagen as hydroxyproline. Dramatic increases in both synthesis and degradation rates of collagen were observed. At 54 days after exposure the fractional synthesis rates in experimental mice were almost five times those in controls (control: 3.2 +/- 0.6%/day, 239PuO2-exposed: 14.5 +/- 0.4%/day) and by 300 days synthesis rates, although declining, were still more than double the control values. A similar pattern of change was observed for collagen degradation. The combination of changes in synthesis and degradation rates led to a 60% increase in lung collagen content by 300 days (control: 3.05 +/- 0.24 mg/lung, 239PuO2-exposed: 4.88 +/- 0.42 mg/lung). The data suggest that extensive remodelling of the lung connective tissue matrix occurs during development of fibrosis and that, over long periods of time, small imbalances between synthesis and degradation may result in quite large increases in protein content.     

Radiation Biology and Medicine

Young Beagle dogs were exposed by inhalation to aerosols of ²³⁹PuO₂ and observed for their lifespans as part of a large, ongoing study of the biological effects of inhaled radionuclides. The purpose of our study was to compare certain immune responses of the ²³⁹PuO₂-exposed dogs at middle age (7–10 years old) and old age (12–14 years old), with those of unexposed, age-matched or young (3–4 years old) animals. Some of the aged, exposed dogs had developed lung tumours. Lymphocyte proliferative responses to phytohaemagglutinin (PHA) were lower in aged control dogs than in either young or middle-aged control dogs. Both aged and middle-aged, radiation-exposed dogs had decreased responses to PHA when compared to age-matched controls. Responses to concanavalin A (Con A) were not affected by age in control dogs, but tended to decrease in the oldest group of radiation-exposed dogs. Responses to both PHA and Con A were severely depressed in tumour-bearing dogs. The cytolytic activity of natural killer cells was not affected by age, radiation exposure, or tumour presence. We concluded that inhalation of ²³⁹PuO₂ by young Beagle dogs resulted in an earlier-than-normal decrease in the ability of T cells to respond to mitogenic stimulation. In other words the depressed responses to PHA that were observed might represent radiation-induced, accelerated ageing of the T cell response.     

Preliminary Studies of the Interaction between 239PuO2 and Cigarette Smoke in the Mouse Lung

Summary

Our current experiments were designed to show whether 12 months' exposure to cigarette smoke enhances the incidence of lung tumours in mice that had previously inhaled ²³⁹PuO₂. These periods of smoke exposure are almost complete. After death their lungs will be cleared and any nodules found will be sectioned for histopathology. This paper reports the results of two preliminary experiments conducted earlier.

The first study showed that mice could tolerate the proposed smoking regime for 3 months, with no sign of ill health in any animal throughout. The major difference found was a reduced growth rate in both smoke- and sham-exposed mice relative to that of cage controls. After 3 months of treatment, histopathology and morphometry of lung sections found only slight smoke-induced changes. These included a reduced proportion of alveolar space and an increased number of pulmonary alveolar macrophages (PAM) per unit area. Bronchopulmonary lavage showed that the PAM from smoke-exposed mice were larger than those from sham-exposed or control mice and that an increased proportion of cells were binucleate.

All mice in the second study were initially exposed to ²³⁹PuO₂, then subsequently divided into three treatment groups as above. Cigarette smoke exposure was shown to inhibit the removal of ²³⁹Pu from the lung whilst sham exposure had no effect. Smoke exposure also produced an increase and sham exposure a decrease in lung weights relative to those of cage controls. The latter was probably as a result of their lower growth rate. In our current experiments it is likely that the group receiving ²³⁹PuO₂, then smoke, will receive a higher radiation dose to lung than those receiving ²³⁹PuO₂ only. Any increased tumour incidence found will be considered in conjunction with this evidence.     

Additivity of Type O and Type N Damage in Diploid Yeast

Summary

Idiopathic pneumonitis is a major cause of morbidity and mortality in patients with leukaemia undergoing total body irradiation (TBI) and bone marrow transplantation (BMT). The effect of variation in dose rate of TBI on the development of lethal and sublethal lung damage has been investigated in mice by measuring changes in carbon monoxide uptake. CBA mice were irradiated using a ⁶⁰Co source at 0·02, 0·05, 0·1, 0·2, 0·5 and 1·0 Gy min^?1 to a total dose of 15·5 Gy. A log–linear relationship between the severity of impairment of carbon monoxide uptake (V_CO) and dose rate was found. Ventilatory requirement (ventilation rate/V_CO) was raised 20 to 40 weeks after TBI at dose rates above 0·1 Gy min^?1. Time of onset and extent of elevation of ventilatory requirement were also dose-rate dependent. The implications of these findings for clinical practice are discussed.     

One-electron Reduction of 8-hydroxy-5-deazaisoalloxazine in Aqueous Solution: A Pulse Radiolysis Study

Summary

The one-electron reduction of 8-hydroxy-5-deazaisoalloxazine (HMDI) has been studied in aqueous solution in the acidity range pH0 to 13 using the reducing species CO₂·^?, e^?_aq and (CH₃)₂COH radicals. The spectral and other properties of the HMDI radicals were found to be independent of the reductant used. Four protolytic forms of the radical were distinguished with associated pK_a values of 2·3 ± 0·3, 6·0 ± 0·3 and 10·1 ± 0·3.     

One-electron Reduction of 5-deazalumiflavin in Aqueous Solution: A Pulse Radiolysis Study

Summary

The one-electron reduction of 5-deazalumiflavin has been studied in aqueous solution in the acidity range H₀ = ?1 to pH 13 using the reducing species CO₂^?, e^?_aq and (CH₃)₂?OH radicals. The spectral and other properties of the deazaflavin radicals formed were found to be independent of the reductant used. Four protolytic forms of the radical were distinguished with associated pK_a values of 1·3 ± 0·3, 6·0 ± 0·3 and 10·7 ± 0·3.     

Age-dependent Variation of Zinc-65 Metabolism in LACA Mice

Summary

Mice were gavaged with zinc-65 solution, 8·6–19·3 kBq per mouse, and the whole-body retention and organ content of zinc-65 were measured at different times after administration. The age-dependence of the fractional absorption of zinc-65 from the gastrointesinal tract (f₁), the endogenous faecal excretion fraction of zinc-65 (EFEF), tissue distribution and whole-body retention were determined. The f₁ values obtained were 0·86 ± 0·15, 0·64 ± 0·11, 0·52 ± 0·07 and 0·39 ± 0·02 in suckling, adolescent, young adult and older mice, respectively. The EFEF values determined were 0·083 ± 0·008, 0·099 ± 0·004, 0·122 ± 0·018 and 0·144 ± 0·005 of intraperitoneally injected zinc-65 in suckling, adolescent, young adult and older mice at administration. Zinc-65 mainly distributed in the liver, muscle, lung, kidneys and bone. In some tissues, there was an inverse relationship between the relative content of gavaged zinc-65 and the animal's age at administration. The whole-body biological half-lives of zinc-65 increased with animal age. The influence of the age-dependent variation of zinc-65 metabolism on internal dose and on radiation protection is discussed.     

Stem Cells in Bone and Bone Marrow after Contamination with Bone-seeking Radionuclides

Summary

The effects of time, mass and oxidation state on plutonium gastrointestinal absorption and tooth adsorption were studied during and after chronic ingestion of plutonium-238 (IV) or (VI) (1·55–15·60 kBq/ml) in 6·5 mm bicarbonate medium by fed rats via drinking water for 8 days to 3 months. Animals were killed during the ingestion to follow the kinetics of whole-body storage and clearance of plutonium. At 1·55 kBq/ml the amount of plutonium retained in the skeleton increased continuously during the 85 days of ingestion and reached a plateau thereafter. This plutonium retention was therefore dependent on the total mass administered but not proportional to this mass, as the fraction of administered plutonium retained decreased during the first 22 days of ingestion and then stabilized. This is reflected by the gastrointestinal transfer (f₁), which had risen to (3·80 ± 0·82) × 10^?5 on Day 3 of ingestion and then decreased to a stabilized value of (1·07 ± 0·06) × 10^?5 from Day 30 to the end of the ingestion period. In the liver, the amount of plutonium retained reached a plateau, which lasted from Day 30 to the end of ingestion. The kidneys and spleen were also found to be retention sites. By Day 3 of ingestion, for a mass ingested of 5 × 10^?7 g/kg of body mass, the maximum mean value of f₁ we found was smaller than the 10^?4 recommended by ICRP Report 30. The oxidation state had no effect on f₁. Large plutonium deposition was observed on the teeth. For both oxidation states (IV) and (VI), about 0·10% of the administered dose was deposited on the teeth after 3 days of ingestion, whatever the plutonium concentration administered. However, whereas the amount of plutonium (IV) deposited did not change throughout the ingestion period, tooth deposition of plutonium (VI) decreased.     

Translocation of Plutonium from Rat and Monkey Lung after Inhalation of Industrial Plutonium Oxide and Mixed Uranium and Plutonium Oxide

This study was designed to compare the translocation from lung of the Pu contained in the pure and mixed industrial oxides PuO₂ and (U,Pu)O₂. The latter had a Pu content of 20% w/w. For this purpose, young adult male rats and male and female baboons were exposed to a single inhalation of these oxides. Two baboons were exposed to the reference PuO₂, i.e. ²³⁹PuO₂. Rats were killed under anaesthesia 1, 15, 30, 90 and 180 days after exposure, and baboons, also under anaesthesia, 1 year thereafter. The results indicate that lung retention of Pu was independent of the oxide inhaled, but was smaller in rat (12–15% of the initial pulmonary burden, 6 months after exposure) than in baboon (56–80% of this burden, 1 year after exposure). In rat, Pu translocation kinetics were similar for the two industrial oxides, but as from day 15 after inhalation until 6 months thereafter, measurement of Pu deposits in the liver and skeleton showed that translocation of Pu from the mixed oxide was 2–3 times greater than that from the industrial Pu oxide. In baboon, the largest amounts of Pu were retained in the lung and thoracic lymph nodes for the three oxides inhaled. Pu translocation to the liver, skeleton and kidneys, and also urinary Pu excretion, were greater after inhalation of the mixed oxide than after inhalation of the industrial and reference Pu oxides. Nevertheless, the amount of mixed oxide Pu translocated to these sites and excreted in urine remained under 3% of the initial pulmonary burden.     

The Kinetics of Repair in Mouse Lung after Fractionated Irradiation

Summary

The kinetics of repair of sublethal damage in mouse lung was studied after fractionated doses of ¹³⁷Cs γ-rays. A wide range of doses per fraction (1·7–12 Gy) was given with interfraction intervals ranging from 0·5 to 24 h. The data were analysed by a direct method of analysis using the incomplete repair model. The half-time of repair (T_1/2) was 0·76 h for the pneumonitis phase of damage (up to 8 months) and 0·65 h for the later phase of damage up to 12 months. The rate of repair was dependent on fraction size for both phases of lung damage and was faster after large dose fractions than after small fractions. The T_1/2 was 0·6 h (95 per cent c.1. 0·53, 0·69) for doses per fraction greater than 5 Gy and 0·83 h (95 per cent c.1. 0·76, 0·92) for doses per fraction of 2 Gy. Repair was nearly complete by 6 h, at least for the pneumonitis phase of damage. To the extent that extrapolation of these data to humans may be valid, these results imply that treatments with multiple fractions per day that involve the lung will not be limited by the necessity for interfraction intervals much longer than 6 h.     

Maximal oxygen consumption and energy cost of running after a long-lasting running race: the 100 km of Sahara

The purpose of this study was to investigate the effects of a 120 km desert running race (5 stages over 4 days) on the main physiologic parameters related to the individual aerobic work capacity. Incremental treadmill tests were carried out on 7 recreational long-distance runners (age: 50.4±11.8 years; body mass: 76.0±8.5 kg; mean±SD) before and 3–5 days after the competition. Maximal oxygen consumption (), ventilatory threshold and heart rate were obtained by standard methods; the mean energy cost of running (Cr) above resting was calculated during the same protocol from the slope of the oxygen consumption versus running speed. After the race, the subjects exhibited significant (p<0.05) reductions only in (averaging 7%; from 46.7±5.1 to 43.2±4.4 ml · kg⁻¹ · mm⁻¹) and in maximal heart rate (averaging 3%; from 172.4±14.1 to 166.7±14.5 beats · min⁻¹). Knowledge of Cr (3.78±0.31 J · kg⁻¹ · m⁻¹ and 3.74±0.48 J · kg⁻¹ · m⁻¹, before and after the race respectively) allowed us to estimate the overall daily energy requirement, about 20 850 kJ. and the maximal heart rate seem to be the main variables affected by prolonged strenuous runs followed by insufficient rest periods.     

The Combined Effects of α-particles and X-rays on Cell Killing and Micronuclei Induction in Lung Epithelial Cells

Summary

Understanding how cellular damage produced by high-linear energy transfer (LET) radiation interacts with that produced by low-LET is important both in radiation therapy and in evaluating risk. To study such interactions, rat lung epithelial cells (LEC) were grown on Mylar® films and exposed to both X-rays and α-particles, separately or simultaneously. Cell killing, and the numbers of binucleated cells and micronuclei, were measured as indicators of damage. X-rays and α-particles given separately caused dose-related increases in cell cycle time, with α-particles producing greater mitotic delay than X-rays. Damage from α-particles and X-rays given simultaneously did not interact to alter further the cell cycle. Cell survival data following exposure to X-rays and α-particles, combined or individually, were fitted by linear-quadratic models. Survival curves following exposure to α-particles only, or to 1·0 Gy α-particles plus graded X-ray doses, were adequately described using only the linear (α) term of a linear-quadratic model with α coefficients of 0·9 ± 0·04 and 1·03 ± 0·18 Gy^?1, respectively. Survival following exposure to X-rays only or to 0·06 Gy α-particles combined with X-rays was best fitted using both α and β terms of the linear-quadratic model (0·12 ± 0·03)D + (0·007 ± 0·002)D² and (0·57 ± 0·08)D + (0·3 ± 0·02)D², respectively. The numbers of micronuclei produced by exposure to α-particles or X-rays alone increased linearly with dose, with slopes of 0·48 ± 0·07 and 0·19 ± 0·05 micronuclei/binucleated cell per Gy for α and X-rays, respectively. Simultaneous exposure to graded levels of X-rays and a constant α dose of either 1·0 or 0·06 Gy increased micronuclei frequency, with a slope of 0·74 ± 0·05 or 0·58 ± 0·04 micronuclei/binucleated cell per Gy, respectively. These slopes are similar to that produced by α-particles alone. These studies demonstrated that both cell killing and the induction of micronuclei were increased by combined exposure compared with that predicted for separate exposures.     

DNA Strand Breaks from Tritium Decay: A Local Effect for Cytosine-6-3H

Summary

Twelve-week-old female (C3H × 101)F₁ mice were injected intravenously with an ultrafiltered solution of ²³⁹Pu in 1 per cent trisodium citrate, and mated to uninjected PCT males. The plutonium content was examined radiochemically and autoradiographically in placentae and foetuses on the 12th and 18th days of gestation, and in neonates during the 24 hours after birth and also at 18 days post-natally.

Plutonium was distributed in most tissues of the late foetus and the suckling as it is in adult mice. However, on both the 12th and 18th days of gestation the concentration in the yolk-sac splanchnopleure was much higher than in any other foetal tissue. The amount of ²³⁹Pu in 18-day-old sucklings was between two and seven times as great as in 1-day-old neonates because of ingestion of milk from the lactating dams. In the first litter following administration of the radionuclide to the dam, about 0·02 per cent of the plutonium injected was transferred to an individual offspring by the time of birth, and a further 0·08 per cent by the time of weaning.     

Association for Radiation Research/Netherlands Radiobiological Society

Summary

The kinetics of pulse radiolytically induced intramolecular radical transformations: Trp/N^·→Tyr/O^·, Tyr/O^·→Trp/N^·, Met/S∴Br→Trp/N^· and Met/S∴Br→Tyr/O^· has been investigated at various pH levels and temperatures in model peptides: Trp-(Pro)_n-Tyr, Trp-(Gly)_n-Tyr, Trp-(Pro)_n-Met (n = 0–3), Tyr-Phe-Met-Arg-Phe-NH₂·2AcOH, Met⁵-enkephaline and [d-Ala]²Met⁵-enkephaline. The rate constants of the Trp/N^·→Tyr/O^· transformation at pH 8 were found to decrease exponentially with the distance between Trp and Tyr in the proline peptides, while in the glycine peptides the rate of the transformation is less dependent on the number of bridging glycine residues. The activation energies determined fall into the range 10–20 kJ mol^?1 irrespective of: (i) the ionization state of tryptophyl radical and tyrosine, (ii) type of bridging amino acids, and (iii) reversal of the direction of the electron transfer upon tyrosine OH group ionization. The activation entropies at 298 K for the peptides of the glycine and proline series are negative and rather high, and fall into the relatively narrow range of ?90 to ?140 J mol^?1 deg^?1. These activation parameters seem to indicate that a tunnelling mechanism is involved in the electron transfer between strictly oriented aromatic moieties of Trp and Tyr. The variation of the activation parameters with average separation distance in the case of Trp-(Pro)_n-Tyr shows a predominance of the electronic factor over the nuclear in determining the distance dependence of the electron transfer rate. The intramolecular Met/S∴Br→Tyr/O^· transfer proceeds with the rate constant of 1·1 × 10⁵ s^?1 in Met⁵-enkephaline and 5·7 × 10⁴ s^?1 in [d-Ala]²Met⁵-enkephaline. The activation parameters for this transformation E_a = 30 kJ mol^?1 and ΔS⁴₂₉₈ = ?62 J mol^?1 deg^?1 are close to those of the Trp/N^·→Tyr/O^· transformation, suggesting a similar mechanism for the electron transfer.     

Men's lacrosse protective equipment increases strain during exercise in the heat

ObjectivesThe purpose of this study was to determine thermoregulatory and cardiovascular effects of wearing men's lacrosse protective equipment during simulated lacrosse activities in the heat.DesignWe conducted a randomized, controlled, crossover study.MethodsThirteen healthy men (22 ± 3 y, 76.2 ± 8.9 kg, 181 ± 6 cm, 16.06 ± 6.16% body fat) completed two matched exercise trials in the heat (WBGT: 25.5 ± 0.8 °C). In randomized order, participants donned full men's lacrosse equipment (helmet, shoulder/elbow pads, and gloves) in one trial while the other included no equipment. Participants completed a topography body scan to determine specific body surface area covered with equipment. Rectal temperature (T_re), heart rate (HR), and mean weighted skin temperature (T_sk) were measured throughout trials. Whole body sweat rate was assessed for trial comparisons.ResultsThe equipment covered 32.62 ± 2.53% body surface area in our participants. Post-exercise T_re was significantly greater with equipment (39.36 ± 0.04 °C) compared to control (38.98 ± 0.49 °C; p = .007). The overall rate of rise of T_re was significantly greater with equipment (0.043 ± 0.015 °C·min⁻¹) compared to control (0.031 ± 0.008 °Cmin⁻¹; p = .041). Regardless of time point, HR and T_sk were significantly elevated with equipment compared to control trial (p ≤ .026). Sweat rates were elevated with equipment (1.76 ± 0.74 L·h⁻¹) compared to shorts and t-shirt (1.13 ± 0.26 L·h⁻¹), but this difference was not significant (p = .058).ConclusionsOur data indicate impairments in heat dissipation and increased cardiovascular strain imposed by men's lacrosse equipment.     

No changes in time trial performance of master endurance athletes after 4 weeks on a low carbohydrate diet

The purpose of the present study was to evaluate the effects of a 4-week low-carbohydrate (CHO) diet regimen on body weight, exercise performance and hormonal response to running in master athletes. Six endurance master athletes performed three 30-min time trials, before (TT1), after 15 days (TT2) and after 30 days (TT3) on a low CHO diet. Blood samples were collected for hormonal and lactate measurements. After 15 days body weight had decreased (TT1 72.3 ± 2.4 kg, TT2 70.0 ± 2.7 kg; P = 0.006) and then remained stable. No differences were observed in performance (TT1 7,015 ± 273 m, TT2 6,920 ± 286 m, TT3 7,202 ± 315 m) and in the insulin/glucagon ratio. After 2 and 4 weeks, adrenocorticotropic hormone decreased significantly both at rest (baseline: TT1 42.5 ± 7.8 pg·ml^?1, TT3 21.6 ± 3.2 pg·ml^?1) and during exercise (end of exercise: TT1 120 ± 20 pg·ml^?1, TT2 80 ± 16 pg·ml^?1, TT3 31 ± 2 pg·ml^?1). Baseline cortisol concentrations had increased significantly after as little as 15 days on the low CHO diet. The results of the present study demonstrate no changes in time trial performance in master endurance athletes after 4 weeks on a low CHO diet. However, an effect on the hypothalamic pituitary adrenal axis emerged.     

Determinants of myocardial energetics and efficiency in symptomatic hypertrophic cardiomyopathy

Purpose

Next to hypertrophy, hypertrophic cardiomyopathy (HCM) is characterized by alterations in myocardial energetics. A small number of studies have shown that myocardial external efficiency (MEE), defined by external work (EW) in relation to myocardial oxidative metabolism (MVO₂), is reduced. The present study was conducted to identify determinants of MEE in patients with HCM by use of dynamic positron emission tomography (PET) and cardiovascular magnetic resonance imaging (CMR).

Methods

Twenty patients with HCM (12 men, mean age: 55.2 ± 13.9 years) and 11 healthy controls (7 men, mean age: 48.1 ± 10 years) were studied with [¹¹C]acetate PET to assess MVO₂. CMR was performed to determine left ventricular (LV) volumes and mass (LVM). Univariate and multivariate analyses were employed to determine independent predictors of myocardial efficiency.

Results

Between study groups, MVO₂ (controls: 0.12 ± 0.04 ml·min^?1·g^?1, HCM: 0.13 ± 0.05 ml·min^?1·g^?1, p = 0.64) and EW (controls: 9,139 ± 2,484 mmHg·ml, HCM: 9,368 ± 2,907 mmHg·ml, p = 0.83) were comparable, whereas LVM was significantly higher (controls: 99 ± 21 g, HCM: 200 ± 76 g, p < 0.001) and MEE was decreased in HCM patients (controls: 35 ± 8%, HCM: 21 ± 10%, p < 0.001). MEE was related to stroke volume (SV), LV outflow tract gradient, NH₂-terminal pro-brain natriuretic peptide (NT-proBNP) and serum free fatty acid levels (all p < 0.05). Multivariate analysis revealed that SV (ß = 0.74, p < 0.001) and LVM (ß = ?0.43, p = 0.013) were independently related to MEE.

Conclusion

HCM is characterized by unaltered MVO₂, impaired EW generation per gram of myocardial tissue and subsequent deteriorated myocardial efficiency. Mechanical external efficiency could independently be predicted by SV and LVM.     

The influence of the b‐value combination on apparent diffusion coefficient based differentiation between malignant and benign tissue in cervical cancer

Purpose:

To analyze the influence of different b‐value combinations on apparent diffusion coefficient (ADC)‐based differentiation of known malignant and benign tissue in cervical cancer patients.

Materials and Methods:

A total of 35 patients with stage IB1, IB2, IIA cervical cancer underwent a 3.0T MRI scan prior to radical hysterectomy and pelvic lymph node dissection. Conventional T1‐ and T2‐weighted sequences and a diffusion‐weighted sequence (b = 0, 150, 500, 1000 seconds/mm²) were performed. Regions‐of‐interest (ROI) were drawn on ADC maps derived from five different b‐value combinations (0, 500; 0, 150, 500; 0, 1000; 0, 150, 500, 1000; 150, 500, 1000 seconds/mm²). The influence of the b‐value combination on ADC‐based differentiation of benign and malignant tissue was analyzed using receiver‐operating‐characteristics curves.

Results:

For all b‐value combinations, ADCs were significantly lower (P < 0.001) in cervical malignancies (1.15 ± 0.21·10^?3; 1.10 ± 0.21·10^?3; 0.97 ± 0.18·10^?3; 0.97 ± 0.23·10^?3 and 0.85 ± 0.18·10^?3 mm²/second respectively to the aforementioned b‐value combinations) than in benign cervix (2.08 ± 0.31·10^?3; 2.00 ± 0.29·10^?3; 1.62 ± 0.23·10^?3; 1.54 ± 0.21·10^?3 and 1.42 ± 0.22·10^?3 mm²/second respectively). The diagnostic accuracy was high for all b‐value combinations and without statistical differences between the combinations.

Conclusion:

ADC‐based differentiation of benign from malignant cervical tissue is independent of the tested b‐value combinations. The results support the inclusion and possible pooling of studies using different b‐value combinations in meta‐analyses on ADC‐based tissue differentiation in cervical cancer. J. Magn. Reson. Imaging 2010;32:376–382. © 2010 Wiley‐Liss, Inc.

     

Foot pressure and center of pressure in athletes with ankle instability during lateral shuffling and running gait

This study evaluates foot pressure and center of pressure (COP) patterns in individuals with ankle instability during running and lateral shuffling. Eleven participants with ankle instability (AI) and 11 normal subjects (Normal) performed running and lateral shuffling tasks. The outcome measures were foot progression angle, peak pressure, and displacement of COP during stance phase. During running, the foot progression angle, that is, the angle of foot abduction, was lower in the AI group (Normal: 13.46° ± 4.45°; AI: 8.78° ± 3.91°), and the 1st metatarsal contact pressure (Normal: 0.76 ± 0.47 N/cm²·kg; AI: 1.05 ± 0.70 N/cm²·kg) and the 3rd metatarsal peak pressure were higher in the AI (Normal: 0.96 ± 0.60 N/cm²·kg; AI: 1.54 ± 0.68 N/cm²·kg). The medial‐lateral (M‐L) COP in the late‐stance phase of running for the AI group transferred faster from lateral to medial foot than the Normal group. For lateral shuffling, the AI group had greater peak pressure at the 1st (Normal: 0.76 ± 0.67 N/cm²·kg; AI: 1.49 ± 1.04 N/cm²·kg), 2nd (Normal: 0.57 ± 0.39 N/cm²·kg; AI: 0.87 ± 0.68 N/cm²·kg), 3rd (Normal: 0.70 ± 0.54 N/cm²·kg; AI: 1.42 ± 0.87 N/cm²·kg), and 4th (Normal: 0.52 ± 0.38 N/cm²·kg; AI: 1.12 ± 0.78 N/cm²·kg) metatarsal areas than the Normal group. The M‐L COP located more laterally from the early to mid‐stance phase in the AI compared with the Normal group. The findings suggest that COP displacement during lateral shuffle may be a factor in ankle instability while the foot progression angle during running may be a compensatory strategy.     

Spatial Distribution of Naturally Occurring 210Po and 226Ra in Children's Teeth

Deciduous and permanent teeth extracted from juveniles for orthodontic purposes have been analysed using α-sensitive plastic track detectors for the spatial distribution of total α-activity and naturally occurring ²¹⁰Pb-supported ²¹⁰Po and ²²⁶Ra. The distribution of these radionuclides is nonuniform, with ²¹⁰Po being primarily associated with outer enamel and ²²⁶Ra with the pulp. The observations suggest that ²¹⁰Pb/²¹⁰Po concentrates at the interface of enamel with saliva or blood, by means of unidirectional ionic exchange with calcium. In contrast, ²²⁶Ra concentrates in the predentine band at the interface with pulp and with systemic blood circulation, where its uptake is permitted by the incomplete calcification in this band. Activity concentration was measured in 900 teeth. Total concentration on the outer enamel surface of deciduous teeth, permanent teeth from children ?10 years and permanent teeth from children > 10 years give respective mean values of 8·63±0·26, 5·76±0.48 and 7·00±0·15 Bq kg^?1. ²²⁶Ra concentration on the corresponding longitudinal sections comprising pulp, dentine and annular enamel give respective mean values of 0·715±0·055, 0·418±0·083 and 0·514±0·029 Bq kg^?1. Mean activity concentration in 32 foetal teeth was 2·05±0·31 Bq kg^?1. The results form the basis of more detailed studies of (1) age-dependent uptake of α-radionuclides in teeth and their microdistribution, and (2) the geographical variation in activity concentration with respect to environmental factors such as domestic radon exposure.