Bone marrow adipose tissue (BMAT) is hypothesized to serve as an expandable/contractible fat depot which functions, in part, to minimize energy requirements for sustaining optimal hematopoiesis. We ...investigated whether BMAT is required for immune reconstitution following injury. Male wild type (WBB6F1, WT) and BMAT-deficient WBB6F1/J-
/J (
) mice were lethally irradiated. Irradiation was followed by adoptive transfer of 1000 purified WT hematopoietic stem cells (HSCs). The extent of immune reconstitution in blood, bone marrow, and lymph nodes in the irradiated mice was determined using HSCs from green fluorescent protein (GFP)-expressing mice. We also evaluated skeletal response to treatment. Detection of GFP-positive B and T cells in peripheral blood at 4 and 9 weeks following adoptive transfer and in bone marrow and lymph nodes following necropsy revealed excellent immune reconstitution in both WT and BMAT-deficient mice. Adipocytes were numerous in the distal femur of WT mice but absent or rare in
mice. Bone parameters, including length, mass, density, bone volume, microarchitecture, and turnover balance, exhibited few differences between WT and BMAT-deficient mice. The minimal differences suggest that BMAT is not required for reconstitution of the immune system following lethal radiation and is not a major contributor to the skeletal phenotypes of kit signaling-deficient mice.
Total-body irradiation (TBI) followed by transfer of bone marrow cells from donors is routinely performed in immunology research and can be used to manipulate differentiation and/or function of bone ...cells. However, exposure to high-dose radiation can result in irreversible osteopenia, and transfer of heterogeneous cell populations can complicate interpretation of results. The goal of this research was to establish an approach for reconstituting bone marrow using small numbers of purified donor-derived hematopoietic stem cells (HSCs) without negatively affecting bone metabolism. Gamma-irradiated (9 Gy) WBB6F1 mice were engrafted with bone marrow cells (5 × 10
cells) or purified HSCs (3,000 cells) obtained from GFP transgenic mice.
analysis and
differentiation assays performed two months later established that both methods were effective in reconstituting the hematopoietic compartment with donor-derived cells. We confirmed these findings by engrafting C57Bl/6 (B6) mice with bone marrow cells or purified HSCs from CD45.1 B6 congenic mice. We next performed adoptive transfer of purified HSCs (750 cells) into WBB6F1 and radiosensitive Kit
mice and evaluated the skeleton two months later. Minimal differences were observed between controls and WBB6F1-engrafted mice that received fractionated doses of 2 × 5 Gy. Kit
mice lost weight and became osteopenic after 2 × 5 Gy irradiations but these abnormalities were negligible after 5 Gy irradiation. Importantly, adoptive transfer of wild-type cells into Kit
mice restored normal Kit expression in bone marrow. Together, these findings provide strong evidence for efficient engraftment with purified HSCs after lethal TBI with minimal collateral damage to bone. This approach will be useful for investigating mechanisms by which hematopoietic lineage cells regulate bone metabolism.
Abstract The present studies investigated the cellular mechanisms for the detrimental effects of high dose whole body γ-irradiation on bone. In addition, radioadaptation and bone marrow ...transplantation were assessed as interventions to mitigate the skeletal complications of irradiation. Increased trabecular thickness and separation and reduced cancellous bone volume fraction, connectivity density, and trabecular number were detected in proximal tibia and lumbar vertebra 14 days following γ-irradiation with 6 Gy. To establish the cellular mechanism for the architectural changes, vertebrae were analyzed by histomorphometry 1, 3, and 14 days following irradiation. Marrow cell density decreased within 1 day (67% reduction, p < 0.0001), reached a minimum value after 3 days (86% reduction, p < 0.0001), and partially rebounded by 14 days (30% reduction, p = 0.0025) following irradiation. In contrast, osteoblast-lined bone perimeter was increased by 290% (1 day, p = 0.04), 1230% (3 days, p < 0.0001), and 530% (14 days, p = 0.003), respectively. There was a strong association between radiation-induced marrow cell death and activation of bone lining cells to express the osteoblast phenotype (Pearson correlation − 0.85, p < 0.0001). An increase (p = 0.004) in osteoclast-lined bone perimeter was also detected with irradiation. A priming dose of γ-radiation (0.5 mGy), previously shown to reduce mortality, had minimal effect on the cellular responses to radiation and did not prevent detrimental changes in bone architecture. Bone marrow transplantation normalized marrow cell density, bone turnover, and most indices of bone architecture following irradiation. In summary, radiation-induced death of marrow cells is associated with 1) a transient increase in bone formation due, at least in part, to activation of bone lining cells, and 2) an increase in bone resorption due to increased osteoclast perimeter. Bone marrow transplantation is effective in mitigating the detrimental effects of acute exposure to high dose whole body γ-radiation on bone turnover.
Current recommendations for the prevention of foot ulceration and amputation include screening at-risk individuals by testing for loss of protective sensation at eight sites using 10-g (5.07) nylon ...monofilaments. Yet measurement of the cutaneous pressure threshold to differentiate one-point from two-point static touch stimuli may allow identification of these at-risk individuals earlier in the clinical course of diabetic neuropathy. The present study tested this hypothesis using a prospective, cross-sectional, multicenter design that included sensibility testing of 496 patients with diabetic neuropathy, 17 of whom had a history of ulceration or amputation. Considering the cutaneous pressure threshold of the 5.07 Semmes-Weinstein nylon monofilament to be equivalent to the 95 g/mm(2) one-point static touch measured using the Pressure-Specified Sensory Device (Sensory Management Services LLC, Baltimore, Maryland), only 3 of these 17 patients with a history of foot ulceration or amputation would have been identified using the Semmes-Weinstein nylon monofilament screening technique. In contrast, using the Pressure-Specified Sensory Device, all 17 patients were identified as having abnormal sensibility, defined as greater than the 99% confidence limit for age, for two-point static touch on the hallux pulp. We conclude that patients at risk for foot ulceration can best be identified by actual measurement of the cutaneous sensibility of the hallux pulp.
Seasonal variations in serum concentrations of 17β-estradiol (E2), vitellogenin (Vg), testosterone (T), 11 ketotestosterone (11-KT), and thyroid hormones (T4, l-thyroxine; and T3, ...3,5,3′-triiodo-l-thyronine) were investigated during the first, second, and third reproductive cycles in intensively reared populations of common dentex, Dentex dentex, and correlated with gonadal development and spawning. In females, there were baseline E2 values (<0.10 ng/ml) and negligible Vg concentrations during the postspawning and pregametogenesis period (June to December), and these increased thereafter to peak during the spawning period. Maximum T3 and T4 serum concentrations were found around spawning. There was a positive correlation during vitellogenesis and final maturation between Vg and T3 (r2=0.366). In addition, Vg and T3 concentrations were statistically higher in the stages of vitellogenesis and final maturation than at the other stages (P<0.001). Minimum T3 and T4 concentrations (October) coincided with the decrease in water temperature and the associated decrease in the daily feeding rate and the specific growth rate. In males, as in females, seasonal changes in serum levels of T and 11-KT were well correlated with gonadal development. The presence of males in the stage of completed spermiogenesis in December coincided with the surge in both androgens and this increase lasted until the end of the spawning period. There were no significant differences in serum T3 and T4 levels among the maturity stages. The observed seasonal changes in serum gonadal steroids and Vg reflected the pattern of oocyte development and the spawning behavior of common dentex and were typical of the patterns described in most multiple spawners studied to date. Thyroid hormones may enhance early ovarian development and stimulate vitellogenesis in female dentex.
The optimum counting geometry was determined for low energy (59.6 keV) photon emitting hot particles contained in a coral sand matrix using NaI(Tl) detectors and count times less than (3600 s). The ...efficiency as a function of particle location within the sample was calculated and experimentally determined. A comparison was made between absolute efficiency of each detector for volume and point source standards. Three cylindrical well detectors (12.7 x 12.7 cm (2.58 cm well diam.), 7.62 x 10.16 cm (1.61 cm well diam.), and 5.08 cm x 5.08 cm (1.80 cm well diam.)) were used. The detectors were also modeled using the Monte Carlo N-Particle (MCNP) code under the same conditions employed in the experimental work. In each case, a point source of 241Am was moved up the central axis of the detector in 0.5 cm increments and then also along the side of the well in the same manner with counts taken at each location. A solid (12.7 x 7.62 cm) NaI(Tl) detector was also used to determine if a variation of conjugate counting could be used as an alternative method to accurately assess hot particle activity in soil. The change in detector efficiency with respect to particle location was most pronounced in the larger diameter well detectors due to source geometry and attenuation effects. The efficiencies as a function of hot particle location varied as much as 15% (using MCNP) and 20% (experimentally determined). The minimum detectable activities were on the order of 0.01 Bq g−1 (3600 s count times) with total uncertainties of less than 10%. The homogeneously distributed volume source did not provide an accurate estimation of the activity of a 59.6 keV hot particle. The performance of the 7.62 x 10.16 cm cylindrical detector was the best of the four examined. Its observed efficiency was within one standard deviation irrespective of the hot particle location. It also had a low minimum detectable activity. Based on modeled and experimental results, a 12.7 x 12.7 cm detector with a 1.61 cm diameter well would provide the optimum detector geometry for low-energy hot particle detection.
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