A calcitonin-like action of prostaglandin E1

The pharmacological effects of PGE₁ (6 and 9 days, 21,250 μg/kg per day subcutaneously) upon the growth and the bone resorption of mammals were studied using the proximal tibia and upper incisor of immature rats along with lead acetate as a time marker, and upon the serum calcium and inorganic phosphorus levels. The following results were obtained. 1. PGE₁ hardly affected the body weight or the weight of organs of the rats but apparently inhibited the longitudinal growth of proximal tibia in a dose related manner. 2. PGE₁ clearly inhibited not only the longitudinal growth (incisor growth) but also the appositional growth (dentin formation) of incisal dentin. 3. The grade of the inhibitory effect on the growth was in the order of bone growth >dentin formation >incisor growth. 4. The occurrence of osteoporosis due to a low calcium diet was inhibited by the simultaneous administration of PGE₁, the mechanism being considered to be mainly due to the inhibitory effect on the bone resorption. 5. PGE₁ lowered the level of serum calcium and the lowering effect was not observed in the thyro-parathyroidectomized rat. From the facts that the above effects were exactly the same as those of calcitonin (1), the possibility that the subcutaneous injection of PGE₁ may induce a calcitonin-like action, a part of which may dependent on the calcinonin secretion is suggested.     

Experimental study of changes in osteoblastic shape induced by calcitonin and parathyroid extract in an organ culture system

Summary Neonate rat endocranial osteoblasts were cultured on their bone surfaces in control medium (CC) or medium to which either parathyroid extract (PTE) or calcitonin (CT) had been added for 2, 4, 8 or 24 h. Some were cultured for 24 h in CC, then for 2, 4, 8 or 24 h in either CT or PTE medium; or for 24 h in PTE, then for 2, 4, 8 or 24 h in either CC or CT; or 24 h in CT and 2, 4, 8 or 24 h in CC. The dorsal ruffling of the cells in CC was found to be suppressed by later culturing with PTE and the disoriented cells reorganized to form arrays of parallel cells. The effects of PTE were also reversed by CC or CT: the osteoblasts in the second culture (CC) lost elongation and order, and proceeded through a proliferative phase before exhibiting the ruffling form similar to a single CC 24 h culture. PTE-cultured osteoblasts showed an increase in cell overlap and contact so that a more competent barrier was formed separating the bone from the medium. In control or CT medium, however, intercellular gaps were greater than in vivo.We are grateful for the expert technical assistance of Elaine Bailey, for laboratory facilities kindly provided by Dr. Martin Evans, and for financial support from the Medical Research Council     

Creating Rigidly Stabilized Fractures for Assessing Intramembranous Ossification,Distraction Osteogenesis,or Healing of Critical Sized Defects

Assessing modes of skeletal repair is essential for developing therapies to be used clinically to treat fractures. Mechanical stability plays a large role in healing of bone injuries. In the worst-case scenario mechanical instability can lead to delayed or non-union in humans. However, motion can also stimulate the healing process. In fractures that have motion cartilage forms to stabilize the fracture bone ends, and this cartilage is gradually replaced by bone through recapitulation of the developmental process of endochondral ossification. In contrast, if a bone fracture is rigidly stabilized bone forms directly via intramembranous ossification. Clinically, both endochondral and intramembranous ossification occur simultaneously. To effectively replicate this process investigators insert a pin into the medullary canal of the fractured bone as described by Bonnarens⁴. This experimental method provides excellent lateral stability while allowing rotational instability to persist. However, our understanding of the mechanisms that regulate these two distinct processes can also be enhanced by experimentally isolating each of these processes. We have developed a stabilization protocol that provides rotational and lateral stabilization. In this model, intramembranous ossification is the only mode of healing that is observed, and healing parameters can be compared among different strains of genetically modified mice ^5-7, after application of bioactive molecules ^8,9, after altering physiological parameters of healing ¹⁰, after modifying the amount or time of stabilization ¹¹, after distraction osteogenesis ¹², after creation of a non-union ¹³, or after creation of a critical sized defect. Here, we illustrate how to apply the modified Ilizarov fixators for studying tibial fracture healing and distraction osteogenesis in mice.     

Should biochemical markers of bone turnover be considered standard practice for safety pharmacology?

The success in biomedical sciences such as genomics and proteomics is not paralleled in the medical product development methods. The consequence of this is a lack of translation into improved drug safety and efficacy. Therefore the US Food and Drug Administration (FDA) introduced the Critical Path Initiative in 2004 to modernize drug development and safety pharmacology. Bone is that largest tissue by weight, and is continuously remodelled. Changes in bone turnover lead to complications such as osteoporosis and fracture, that is associated with an increased mortality. Recent findings have identified bone as a possible endocrine organ and the availability of valid biochemical bone markers suggests that assessing bone turnover should also play an important role in general safety pharmacology.     

A combination of genome-wide association study and selection signature analysis dissects the genetic architecture underlying bone traits in chickens

The bones of chicken play an important role in supporting and protecting the body. The growth and development of bones have a substantial influence on the health and production performance in chickens. However, genetic architecture underlying chicken bone traits is not well understood. The objectives of this study are to dissect the genetic basis of bone traits in chickens and to identify valuable genes and genetic markers for chicken breeding. We performed a combination of genome-wide association study (GWAS) and selection signature analysis (fixation index values and nucleotide diversity ratios) in an F₂ crossbred experimental population with different genetic backgrounds (broiler × layer) to identify candidate genes and significant variants related to femur, shank, keel length, chest width, metatarsal claw weight, metatarsal length, and metatarsal circumference. A total of 545 individuals were genotyped based on the whole genome re-sequencing method (26 F₀ individuals were re-sequenced at 10 × coverage; 519 F₂ individuals were re-sequenced at 3 × coverage). A total of 2 028 112 single-nucleotide polymorphisms (SNPs) remained to carry out analysis after quality control and imputation. The integration of GWAS and selection signature analysis indicated that all significant SNPs responsible for bone traits were mainly localized on chicken chromosomes 1, 4, and 27. Finally, we identified 21 positional candidate genes that might regulate chicken bone growth and development, including LRCH1, RB1, FNDC3A, MLNR, CAB39L, FOXO1, LHFP, TRPC4, POSTN, SMAD9, RBPJ, PPARGC1A, SLIT2, NCAPG, NKX3-2, CPZ, SPOP, NGFR, SOST, ZNF652, and HOXB3. Additionally, an array of uncharacterized genes was identified. The findings provide an in-depth understanding of the genetic architecture of chicken bone traits and offer a molecular basis for applying genomics in practical chicken breeding.     

A factor synthesized by rabbit periosteal fibroblasts stimulates bone resorption and collagenase production by connective tissue cells in vitro

Unstimulated monolayer cultures of confluent rabbit periosteal fibroblasts synthesize a factor that stimulates bone resorption in vitro. Furthermore it stimulates rabbit chondrocytes and mouse osteoblasts to synthesize collagenase. The factor has no effect on dead bone in culture, and its activity on live bone is mediated principally by osteoclasts, since it is 75% inhibited by salmon calcitonin. Characterization of the factor by gel filtration and isoelectric focusing indicates an M_r in the range 15 000–25 000 and a pI corresponding to approx. pH 4.7. These biological and physicochemical properties are similar to those reported for a factor released by peripheral blood monocytes. However, whereas human monocyte factor in both the crude and partially-purified state exhibits interleukin-1 activity, crude and fractionated periosteal fibroblast-conditioned medium does not. This is the first report of a conditioned medium containing a molecule like the monocyte-factor which appears to have no interleukin 1 activity. The factor may be synthesized by a wide range of cell types, and could have an important role in mediating connective tissue degradation during both physiological and pathological resorption.     

髓内固定对老年股骨转子间骨折患者关节功能的影响

摘要 目的：研究髓内固定对老年股骨转子间骨折患者关节功能的影响。方法：选取2016年9月~2019年9月我院收治的股骨转子间骨折的老年患者80例为研究对象,采用随机数字表法将其分为两组,每组各40例。对照组患者采用Gamma钉进行治疗,观察组患者采用股骨近端防旋髓内钉固定治疗。比较两组患者的围术期相关指标、骨折愈合时间、Harris评分、临床治疗效果及并发症的发生情况。结果：观察组患者的手术时间、切口长度、术中出血量、术后引流量、住院时间及骨折愈合时间均显著少于或短于对照组(P＜0.05)。术前,两组患者的Harris评分比较无统计学差异(P＞0.05);术后6个月及术后12个月,两组患者的Harris评分均较术前显著升高,且观察组显著高于对照组(P＜0.05)。观察组患者的治疗优良率为92.50 %,显著高于对照组(75.00 %,P＜0.05)。两组患者深静脉血栓、感染、褥疮、固定松动、股骨头坏死及严重疼痛的发生率比较无统计学差异(P＞0.05)。结论：股骨近端防旋髓内钉固定治疗老年股骨转子间骨折效果明显优于Gamma钉治疗,可有效缩短骨折愈合时间,提高髋关节功能。     

The synergistic role of Pu.1 and Fms in zebrafish osteoclast-reducing osteopetrosis and possible therapeutic strategies

Osteoclasts are bone resorption cells of myeloid origin. Osteoclast defects can lead to osteopetrosis, a genetic disorder characterized by bone sclerosis for which there is no effective drug treatment. It is known that Pu.1 and Fms are key regulators in myelopoiesis, and their defects in mice can lead to reduced osteoclast numbers and consequent osteopetrosis. Yet how Pu.1 and Fms genetically interact in the development of osteoclasts and the pathogenesis of osteopetrosis is still unclear. Here, we characterized pu.1^G242D;fms^j4e1 double-deficient zebrafish, which exhibited a greater deficiency of functional osteoclasts and displayed more severe osteopetrotic symptoms than the pu.1^G242D or fms^j4e1 single mutants, suggesting a synergistic function of Pu.1 and Fms in the regulation of osteoclast development. We further demonstrated that Pu.1 plays a dominant role in osteoclastogenesis, whereas Fms plays a dominant role in osteoclast maturation. Importantly, treatment with the drug retinoic acid significantly relieved the different degrees of osteopetrosis symptoms in these models by increasing the number of functional osteoclasts. Thus, we report the development of valuable animal models of osteopetrosis, and our results shed light on drug development for antiosteopetrosis therapy.     

Effects of manganese-supplemented diets on growth performance,blood biochemistry,nitrogen metabolism and skeletal development of rex rabbits

(Background) Manganese (Mn) is an essential mineral, although its effects on rabbits is not clear. (Research Purpose) This study was conducted to investigate the effects of the level of supplementation of dietary manganese on growth performance, blood biochemistry, nitrogen metabolism and skeletal development of growing Rex rabbits. (Methods) Two hundred 3-month-old healthy Rex rabbits with similar body weights were randomly divided into 5 groups (A, B, C, D, E), with 40 replicates in each group. The rabbits in the 5 groups were fed a basal diet containing 0, 5, 10, 20 and 40 mg/kg manganese (in the form of manganese sulfate), respectively. The trial included 7 days for adaptation and 29 days of testing. Seven days before the end of feeding, eight rabbits from each group were transferred into a metabolic cage for metabolic testing. (Results) The results showed that supplemental dietary manganese levels did not significantly influence final body weight (FBW) or average daily feed intake (ADFI) (P＞0.05). Average daily gains (ADG) were significantly higher in the 20 mg/kg manganese group than in the other groups, and the ratio of feed to body weight gain (F/G) was significantly affected by manganese level (P < 0.05). No significant differences were found in the digestion coefficients among the groups (P > 0.05). Regarding carcass traits, the thymus index and total fat were significantly different (P < 0.05) among the groups, but there were no other significant differences (P > 0.05). The addition of manganese had no significant effect on the intake of nitrogen (IN), fecal nitrogen (FN), digestible nitrogen (DN) or the apparent digestibility of nitrogen (NAD). Compared to the other groups, urinary nitrogen (UN) was lower in the 20 mg/kg group, although nitrogen deposition (RN), nitrogen utilization (NUR) and the biological potency of nitrogen (NBV) were higher in this group (P < 0.05). As the amount of manganese added to the diet increased, serum triglycerides decreased (P < 0.05). Serum Mn-SOD was significantly lower in the 5 mg/kg manganese group than in the other groups (P < 0.05). The results of this study demonstrate that a diet with supplemented manganese can improve Rex rabbit growth performance and increase RN, NUR and NBV. There were no significant effects of different dietary levels of Mn on the ratio of bone to meat (P > 0.05) or bone strength (P < 0.05). (Conclusion) In conclusion, we determined that the optimal level of manganese supplementation in the diet of growing Rex rabbits was 20 mg/kg, which was also found to reduce nitrogen emissions into the environment.