Radium-223 dichloride (radium-223, Xofigo), a targeted alpha therapy, is currently used for the treatment of patients with castration-resistant prostate cancer (CRPC) with bone metastases. This study ...examines the mode-of-action and antitumor efficacy of radium-223 in two prostate cancer xenograft models.
Mice bearing intratibial LNCaP or LuCaP 58 tumors were randomized into groups (
= 12-17) based on lesion grade and/or serum PSA level and administered radium-223 (300 kBq/kg) or vehicle, twice at 4-week intervals. X-rays and serum samples were obtained biweekly. Soft tissue tumors were observed macroscopically at sacrifice. Tibiae were analyzed by gamma counter, micro-CT, autoradiography and histology.
Radium-223 inhibited tumor-induced osteoblastic bone growth and protected normal bone architecture, leading to reduced bone volume in LNCaP and abiraterone-resistant LuCaP 58 models. Furthermore, radium-223 resulted in lower PSA values and reduced total tissue and tumor areas, indicating that treatment constrains prostate cancer growth in bone. In addition, radium-223 suppressed abnormal bone metabolic activity as evidenced by decreased number of osteoblasts and osteoclasts and reduced level of the bone formation marker PINP. Mode-of-action studies revealed that radium-223 was deposited in the intratumoral bone matrix. DNA double-strand breaks were induced in cancer cells within 24 hours after radium-223 treatment, and PSA levels were significantly lower 72 hours after treatment, providing further evidence of the antitumor effects.
Taken together, radium-223 therapy exhibits a dual targeting mode-of-action that induces tumor cell death and suppresses tumor-induced pathologic bone formation in tumor microenvironment of osseous CRPC growth in mice.
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A checklist of trichopteran species in the middle and lower basins of the Jinsha River (southwestern China) is compiled for the first time. upon collected materials. It recorded ten families, 13 ...genera, and 23 species were recorded. Among them, the male of a new species Cheumatopsyche latisecta Ge & Sun, sp. nov., which can be diagnosed by its genitalia, is described and illustrated. In addition, nine other species are recorded for the first time from China, six species and three ones are recorded for the first time for Yunnan and Sichuan provinces, respectively. This trichopteran species list can provide guidance for caddisfly identification of the river and the region.
Purpose:
To study the effects of estrogen withdrawal on osteoclast number and osteoclast activity in the rat ovariectomy (OVX) model.
Methods:
We first cultured human CD34+ osteoclast precursor cells ...on bovine bone slices, allowing them to differentiate into mature resorbing osteoclasts. Secreted tartrate-resistant acid phosphatase 5b (TRACP 5b) and C-terminal cross-linked telopeptides of type I collagen (CTX) were determined from the culture medium. TRACP 5b correlated strongly with osteoclast number and CTX with osteoclast activity, facilitating their subsequent use in the rat OVX model. An 8 week OVX study was then performed including sham-operated rats receiving vehicle, OVX rats receiving vehicle, and OVX rats receiving 10 μg/kg/day 17β-estradiol (E2). Trabecular bone parameters were determined from the tibial metaphysis using peripheral quantitative computed tomography and histomorphometry. Osteoclast number was normalized with bone perimeter (N.Oc/B.Pm) and tissue area (N.Oc/T.Ar, indicating absolute number of osteoclasts). TRACP 5b and CTX were determined from fasting serum samples.
Results:
Trabecular bone parameters indicated substantial bone loss after OVX that was prevented by E2. N.Oc/B.Pm increased after OVX, while N.Oc/T.Ar and TRACP 5b decreased, and TRACP 5b correlated strongly with N.Oc/T.Ar. However, CTX values increased after OVX, and the “resorption index” CTX/TRACP 5b showed more substantial changes than either CTX or TRACP 5b alone.
Conclusion:
These results show that TRACP 5b is a reliable marker of osteoclast number, and the index CTX/TRACP 5b is a useful parameter in rat OVX model. The high elevation of CTX/TRACP 5b values by OVX demonstrates that estrogen withdrawal generates high activity of osteoclasts in the rat OVX model.
Osteocytes have been suggested to play a role in the regulation of bone resorption, although their effect on bone turnover has remained controversial. In order to study this open question, we ...developed an organ culture system based on isolated rat calvaria, where the osteocyte viability and its effect on osteoclastic bone resorption can be monitored. Our results suggest that osteocytes are constitutively negative regulators of osteoclastic activity. Osteoclasts, which were cultured on calvarial slices with living osteocytes inside, failed to form actin rings which are the hallmarks of resorbing cells. A similar inhibitory effect was also achieved by the conditioned medium obtained from calvarial organ culture, suggesting that living osteocytes produce yet unrecognized osteoclast inhibitors. On the contrary, when osteocyte apoptosis was induced, this inhibitory effect disappeared and strong osteoclastic bone resorption activity was observed. Thus, local apoptosis of osteocytes may play a major role in triggering local bone remodeling.
Nutrition influences peak bone mass development in early adulthood. The effect of high dietary phosphate intake on the growing skeleton of 1‐month‐old male rats (n = 30) was assessed in an 8‐week ...intervention. High dietary phosphate intake increased bone remodeling and impaired bone material properties, diminishing bone mechanical strength.
Introduction: High dietary phosphate intake is typical in the Western diet. Abundant phosphate intake enhances parathyroid secretion and bone metabolism. To study the influence of high dietary phosphate intake on growing bone homeostasis and structure, we submitted growing rats to experimental diets that varied in their phosphate content.
Materials and Methods: One‐month‐old intact male rats (n = 30) were fed a control diet (Ca:P 1:1) or an experimental diet of either Ca:P 1:2 or Ca:P 1:3 for 8 weeks. At the beginning and the end of the study period, the right femurs were measured using DXA. Double labeling with tetracycline injection was performed 12 and 2 days before death. After death, hind legs were cut loose. Left femurs were processed for histomorphometry. Right femurs were measured with pQCT. Mechanical testing was performed on the right femoral neck and tibial shaft. Six right tibias were analyzed with μCT. Serum PTH, calcium, and phosphate contents were analyzed.
Results: High‐phosphate intake impaired growth of the animal, limited bone longitudinal growth, and restricted femur BMC and BMD build‐up. Osteoclast number, osteoblast perimeter, and mineral apposition rate were increased, and trabecular area and width were decreased. Phosphate decreased femur midshaft total bone BMD, cortical bone BMD, and mean cortical thickness. High‐phosphate diet reduced femoral neck and tibial shaft ultimate strength and tibia stiffness and toughness. In addition, serum PTH increased.
Conclusions: High dietary phosphate intake reduced growth, skeletal material, and structural properties and decreased bone strength in growing male rats. Adequate calcium could not overcome this.
Abstract Daily injections of human parathyroid hormone (1-34), hPTH(1-34), provide a highly effective treatment option for severe osteoporosis. However, PTH analogs shorter than 28 amino acids do not ...retain any bone augmenting potential. Here, we present ZP2307 (Ac5 c1 , Aib3 , Leu8 , Gln10 , Har11 , Ala12 , Trp14 , Asp17 PTH(1-17)-NH2 ), a novel, chemically modified and cyclized hPTH(1-17) analog, that augments bone mass in ovariectomized, osteopenic rats. Subcutaneous administration of this structurally constrained, K13 -D17 side-chain-to-side-chain cyclized peptide reversed bone loss and increased bone mineral density (BMD) up to or above baseline levels in rat long bones and vertebrae. Highly significant effects of ZP2307 were achieved at doses of 40–320 nmol/kg. Micro-CT and histomorphometric analyses showed that ZP2307 improved quantitative and qualitative parameters of bone structure. Biomechanical testing of rat femora confirmed that ZP2307 dramatically increased bone strength. Over a broad maximally effective dose range (40–160 nmol/kg) ZP2307 did not increase serum concentrations of ionized free calcium above normal levels. Only at the highest dose (320 nmol/kg) ZP2307 induced hypercalcemic calcium levels in the ovariectomized rats. To our knowledge ZP2307 is the smallest PTH peptide analog known to exert augmentation of bone. Our findings suggest that ZP2307 has the potential to effectively augment bone mass over a broad dose range without a concomitant increase in the serum concentration of ionized free calcium above the normal range.
Serum procollagen I N-terminal propeptide (PINP) is a sensitive bone formation marker in humans. We have developed a nonradioactive immunoassay for rat PINP and studied PINP as a bone formation ...marker in the rat ovariectomy (OVX) model. Two OVX studies were performed with 3-month-old rats, both including measurement of PINP, C-terminal cross-linked telopeptide of type I collagen (CTX), and N-terminal mid-fragment of osteocalcin. A pilot 14-day study contained a sham-operated control group and an OVX group, and an extensive 8-week study contained a sham-operated control group and OVX groups receiving vehicle and 17β-estradiol (E
2
, 10 μg/kg/day s.c.). The bone markers were measured before the operation and at days 2, 4, 7, 10, and 14 in the pilot study and before the operations and at 2 and 8 weeks in the extensive study. Trabecular bone parameters were determined by peripheral quantitative computed tomography and histomorphometry from tibial metaphysis in the extensive study. The rat PINP immunoassay had the following characteristics: intra-assay coefficient of variation (CV) 2.8%, interassay CV 7.5%, dilution linearity 95%, and recovery 107%. PINP increased significantly during the first 2 weeks after OVX and returned to sham level at 8 weeks. E
2
prevented the increase caused by OVX. Changes in PINP at 2 weeks correlated strongly with changes in CTX and osteocalcin at 2 weeks and with trabecular bone parameters at 8 weeks. As a conclusion, short-term changes in PINP predict long-term changes in trabecular bone parameters, suggesting that PINP is a reliable marker of bone formation in the rat OVX model.
To understand the function of human hydroxysteroid (17β) dehydrogenase 2 (HSD17B2) in the peripheral tissues in vivo, we studied the bone development in transgenic male mice ubiquitously expressing ...human HSD17B2. Bones of HSD17B2TG and WT males (26 days and 2 and 6 mo old) were analyzed by pQCT and histomorphometry, and data were correlated with serum testosterone (T), IGF‐I, and osteocalcin concentrations. At the age of 26 days, the body weight of HSD17B2TG males was significantly lower, and the lengths of the tibia and femur of the HSD17B2TG males were significantly shorter. Histomorphometric and pQCT analyses showed lower trabecular and cortical BMD, a markedly smaller area of cortical bone at both of the diaphyses, and a smaller percentage of trabecular bone volume and thickness in the HSD17B2TG males. The data suggested slower osteoblast differentiation and a slower bone formation rate of femoral diaphysis on the periosteum but faster on the endocortical surface in HSD17B2TG males. The altered bone parameters were correlated with low serum T, IGF‐I, and osteocalcin concentrations at the prepubertal age. Interestingly, after puberty, the bone parameters analyzed in the adult HSD17B2TG males were mostly normal, consistent with the normal body weight and normalized serum concentrations of IGF‐I and T. In conclusion, HSD17B2TG males presented with growth retardation and a decreased bone formation rate at prepubertal age. These changes were associated with lower serum IGF‐I, osteocalcin, and T concentrations. It is concluded that the enforced constitutive expression of HSD17B2 disturbs the coordinated action of IGF‐I and sex steroids essential for pubertal bone growth.
Although the beneficial effects of estrogen on bone are well known, the roles of estrogen receptors (ERs) in mediating these effects are not fully understood.
To study the effects of long-term ER ...alpha deficiency, bone phenotype was studied in aged ER alpha knockout (ERKO) mice. In addition, ERKO osteoclasts and osteoblasts were cultured in vitro.
Histomorphometric analysis showed that the trabecular bone volume and thickness were significantly increased and the rate of bone formation enhanced in both male and female ERKO mice in comparison to the wild-type animals. In ERKO males, however, the bones were thinner and their maximal bending strengths decreased. Consistent with previous reports, the bones of knockout mice, especially of female mice, were shorter than those of wild-type mice. In addition, the growth plates were totally absent in the tibiae of aged ERKO females, whereas the growth plate cartilages were detectable in wild-type females as well as in all the males. Analysis of cultured bone marrow cells from 10- to 12-week-old mice demonstrated that 17 beta-estradiol could stimulate osteoblastic differentiation of bone marrow cells derived from ERKO mice relatively to the same extent as those derived from wild-type mice. This was demonstrated by increases in synthesis of type I collagen, activity of alkaline phosphatase and accumulation of calcium in cultures. Total protein content was, however, reduced in ERKO osteoblast cultures.
These results show altered bone phenotype in ERKO mice and demonstrate the stimulatory effect of estrogen on osteoblasts even in the absence of full-length ER alpha.
Land‐use change, particularly urbanisation, has led to an unprecedented decline in species and functional diversity worldwide. However, the mechanism through which such species loss affects ...functional diversity remains unclear. Here, we aimed to elucidate this mechanism from the perspectives of the association between species sensitivity and functional uniqueness (i.e., their relative contribution to functional diversity) and their related functional traits.
We collected stream macroinvertebrates and measured environmental and land‐use variables from 152 sites in the highly urbanised Qiantang River Basin in the Zhejiang Province of eastern China. Firstly, we evaluated the sensitivity to urbanisation and functional uniqueness of each macroinvertebrate taxon to identify their association patterns. Secondly, we examined the decline in functional diversity in response to taxon loss by comparing simulated ordered and random taxon loss scenarios. Finally, we identified sensitivity‐related traits (SRT) and functional uniqueness‐related traits (URT) using the Mann–Whitney U‐test to elucidate their role in shaping functional response patterns to taxon loss.
Urbanisation showed a remarkable effect on the taxonomic and functional diversity of macroinvertebrates. Functional diversity declined nonlinearly with taxon loss, with the threshold response shifting to a rapid decline after 29.7%–60.0% taxa were lost. The sensitivities of ephemeropteran, plecopteran and trichopteran taxa (EPT) were negatively associated with their functional uniqueness, although this association was not detected when considering all macroinvertebrates. We identified 11 SRT and nine URT, but only one URT overlapped SRT.
The association between species sensitivity and its functional uniqueness shapes functional decline patterns in response to taxon loss. Overlap patterns of SRT and URT offer novel insights into mechanisms underlying stress‐induced decline in functional diversity.
The process of functional diversity decline in response to species loss caused by urbanisation also may be affected by species turnover or even compensated for by non‐native species in real world ecosystems. How functional diversity responds to species loss remains an open topic that needs to be cautiously addressed.
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