Design method for the relocation of plastic hinges in prefabricated steel beams with corrugated webs.

The plastic hinge is a key factor in the ductile and plastic design of structures and an important basis for the seismic strengthening of structures. The formation and behavior of plastic hinges is critical for the seismic performance of an entire structure. The relocation of plastic hinges away from the beam end is an effective way of addressing brittle failure. In this paper, the cause of the shear buckling failure of prefabricated steel beams with corrugated webs and the strain variation at the flanges of steel beams are theoretically analyzed through structural tests. Based on the analysis results, a local strengthening method is proposed, and the effects of the beam sizes and the strengthening steel plate on the plastic hinges are obtained. In addition, a calculation method for determining the size of the strengthening steel plate that promotes the relocation of the plastic zone away from the beam end is given, a design method for plastic hinge relocation is proposed based on the test data, and its validity is verified.

Attenuation of a virulent swine acute diarrhea syndrome coronavirus strain via cell culture passage.

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a newly identified enteric alphacoronavirus that causes fatal diarrhea in newborn piglets in China. Here, we propagated a virulent strain SADS-CoV/CN/GDWT/2017 in Vero cells for up to 83 passages. Four strains of SADS-CoV/GDWT-P7, -P18, -P48 and -P83 were isolated and characterized. Sequence alignments showed that these four novel strains exhibited 16 nucleotide mutations and resultant 10 amino acid substitutions in open reading frame 1a/1b, spike, NS3a, envelope, membrane and nucleocapsid proteins. Furthermore, a 58-bp deletion in NS7a/7b was found in P48 and P83 strains, which led to the loss of NS7b and 38 amino acid changes of NS7a. Pig infection studies showed that the P7 strain caused typical watery diarrhea, while the P83 strain induced none-to-mild, delayed and transient diarrhea. This is the first report on cell adaption of a virulent SADS-CoV strain, which gives information on the potential virulence determinants of SADS-CoV.

12 novel atypical porcine pestivirus genomes from neonatal piglets with congenital tremors: A newly emerging branch and high prevalence in China.

Atypical porcine pestivirus (APPV), a newly discovered member of the genus Pestivirus, is considered to be associated with congenital tremors (CT) in piglets. From June 2016 to January 2018, 440 serum and tissue samples from CT-affected piglets in Anhui, Guangdong and Guangxi provinces were collected to detect APPV. The results showed a high level of 63.4% preference for APPV in 27 swine farms and complicated co-infection cases between APPV and other 12 swine viruses. Meanwhile, 12 novel APPV genomes were screened and identified. Results showed that complete genomes, Npro and NS5A genes of these novel 12 APPV sequences revealed 80.5%-99.8%, 78%-100% and 76.9%-99.8% nucleotide identities, respectively. Phylogenetic analyses based on sequences of full-length genomes, Npro and NS5A genes of APPV indicated three well-defined clades including a newly emerging branch in China. This study provides novel epidemiological information of APPV in China.

Estrogen regulates the expression and activity of epithelial sodium channel in mouse osteoblasts.

Estrogen plays an important role in bone metabolism and only high dose can stimulate osteoblast bone formation. However, the underlying mechanisms have not been elucidated. The epithelial sodium channel (ENaC) is a key pathway for sodium transport in epithelia, vascular endothelium, and other tissues; although the expressions of α and γ ENaC mRNA were found in osteoblasts, the regulation of ENaC by estrogen in osteoblasts has not been studied. Our recent data confirmed the ENaC expression in mouse primary osteoblasts by immunocytofluorescence, RT-PCR, western blot, and patch clamp. Furthermore, we found estrogen (10(-5)M) increased the expression of α and γ ENaC subunits at both the mRNA and protein levels in osteoblasts. On the other hand, 17ß estradiol (20 nM) increased inward Na+ currents which were inhibited by amiloride. The estrogen dose used in patch clamp is much lower than those of mRNA and protein analysis, which means single cell ENaC electrophoretic mobility is much more sensitive to estrogen than the mRNA and protein production by estrogen stimulation. Our results suggest that estrogen regulates expression and function of ENaC in osteoblasts may provide a new clue that the mechanism of high dose of estrogen influence osteoblast bone formation via ENaC activity.

Effects of alendronate and strontium ranelate on cancellous and cortical bone mass in glucocorticoid-treated adult rats.

We studied the effects of alendronate (Aln) and strontium ranelate (SrR) administration on cancellous and cortical bone in glucocorticoid (GC)-treated rats. Thirty-two 3.5-month male Sprague-Dawley rats were randomized into four groups: age-matched normal control (Nrm), methylprednisolone (Met; 5.0 mg/kg/day, sc, for 5 days/week), Met plus Aln orally (1.0 mg/kg/day), and Met plus SrR orally (900 mg/kg/day). The study period was 9 weeks. DXA was used to evaluate the femoral diaphysis and fifth lumbar vertebra (L5). Histomorphometry was performed in the proximal tibial metaphysis and tibial diaphysis. Met significantly decreased body weight and bone mineral density (BMD) compared with Nrm. Aln and SrR significantly increased body weight and BMD compared with Met. SrR resulted in significantly higher BMD than Aln. Met markedly decreased BV/TV, Tb.Th, and Tb.N and increased Tb.Sp compared with Nrm. Aln and SrR showed significantly increased of BV/TV, Tb.Th, and Tb.N and improved bone architecture. Moreover, Met reduced %Ct.Ar, enlarged %Ma.Ar, and decreased bone formation indices in the periosteum as well as increased ES/BS in the endosteum compared with Nrm. Aln significantly decreased endosteal ES/BS compared with Met. SrR significantly increased %Ct.Ar and bone formation indices in the periosteum as well as the endosteum and decreased endosteal ES/BS compared with Met. Furthermore, SrR led to a significantly higher cancellous and endocortical MS/BS and endocortical bone formation compared with Aln. Our findings suggest SrR at a dose of 900 mg/kg has a greater effect than Aln at 1.0 mg/kg, according to BMD and histomorphometric analysis, in preventing GC-induced osteopenia. Therefore, SrR might be applicable as a bone therapeutic agent to treat secondary osteoporosis in the clinic.

The pulmonary toxicity of multi-wall carbon nanotubes in mice 30 and 60 days after inhalation exposure.

The pulmonary toxicity, induced by multi-wall carbon nanotubes in mice, was studied after 30-day and 60-day inhalation exposure. The mice were exposed to multi-wall carbon nanotubes aerosol with weighted mean concentration of 32.61 mg/m3, once in very two days, 6 hours in an exposure day. After 30-day and 60-day inhalation exposure, the pulmonary toxicity of multi-wall carbon nanotubes was assessed using biochemical indices in bronchoalveolar lavage fluid and pathological examination. It was found that the aerosolized multi-wall carbon nanotubes did not induce obvious pulmonary toxicity in 30-day exposure group, but induced severe pulmonary toxicity in 60-day exposure group.

Preventive effects of ginsenosides on osteopenia of rats induced by ovariectomy.

AIM: To determine the effect of ginsenosides (GSL) on ovariectomized rats by analysis of cancellous bone histomorphometry. METHODS: Forty Sprague-Dawley female rats at age of 3 months were sham-operated (Sham, n = 8) and treated orally with vehicle, or ovariectomized (OVX, n = 32 which were divided into three group with n = 8 per group) and treated orally with either vehicle, 17alpha-ethynylestradiol (EE, 100 microg . kg-1 . d-1), or ginsenosides (GSL) at 100 or 300 mg . kg-1 . d-1 for 10 weeks. Double in vivo fluorochrome labeling was administrated. The undecalcified longitudinal proximal tibial metaphyseal sections were cut and stained with Goldner's Trichrome (4-micron thickness) or unstained (8-micron thickness) for the bone histomorphometric analysis. RESULTS: After 10 weeks post OVX the cancellous bone mass was lost markedly and showed high bone turnover indices (increased bone resorption and formation). EE decreased the resorptive surface and bone formation rate related to bone turnover and prevented bone loss. GSL at the two doses (100 and 300 mg . kg-1 . d-1) reduced the resorptive surfaces as did EE, but did not depress the mineral bone formation. High dose of GSL greatly increased bone mass and had a tendency to decrease bone turnover when compared with OVX group. CONCLUSION: GSL partially prevented OVX-induced cancellous bone loss by inhibiting osteoclast bone resorption and by a mild depression of bone turnover.

Skeletal effects of constant and terminated use of risedronate on cortical bone in ovariectomized rats.

To study the skeletal effects of continual and terminated use of risedronate treatment on cortical bone in ovariectomized (Ovx) rats, we used risedronate (Ris), 5 microg x kg(-1), by subcutaneous injections, twice per week. The middle part of the tibial shafts (Tx) were processed undecalcified for quantitive bone histomorphometry. Cortical bone and the marrow areas of the tibial shaft did not change in either sham-Ovx or Ovx rats during the 150-day experimental period. Continued administration of Ris for 150 days decreased the marrow area and increased the percentage of cortical area compared with the matching sham and Ovx group. A decrease in bone formation indices in both periosteal and endocortical surfaces of Tx in sham-operated rats between the age of 5 and 8 months was seen. Ovariectomy increased the percentage of labeled perimeter in the periosteal area, and markedly increased the percentage of eroded perimeter in the endocortical surface compared with sham control groups in 81 and 150 days. Bone formation indices of Ris treatment were increased in periosteal surfaces, and percentages of eroded perimeter were decreased more in endocortical surfaces in 150 days than in the matching sham and Ovx groups. These data matched our static data, which showed a significantly increased percentage of cortical bone area and decreased percentage of marrow area. These bone gains were not maintained in the 90-day Ris withdrawal group. For cancellous bone, the 60-day Ris-treated high bone mass was maintained in the withdrawal group and not maintained in Ris continmuously treated group. These results indicate the effects of constant and terminated use of Ris in cortical bone were different from those in trabecular bone in the proximal tibial metaphysis.

Skeletal effects of constant and terminated use of sodium risedronate in ovariectomized rats.

AIM: To study the skeletal effects of constant and terminated use of sodium risedronate (Ris) treatment in the ovariectomized (Ova) rats. METHODS: Ris 5 micrograms.kg-1, s.c., twice a wk. The proximal tibial metaphysis (PTM) were processed undecalcified for quantitive bone histomorphometry. RESULTS: (1) Placebo-treated (normal saline) Ova rats were characterized by decreased trabecular area (TA) on d 60, d 81, and d 150 compared with aging controls, and bone resorption was over formation with high bone turnover. (2) Ova rats were treated with Ris for 60, 81, and 150 d (Ris-on) increased. (TA 217%, 108%, and 101%) respectively, vs Ova rats and depressed bone turnover indices to aging control level, but bone mass did not maintain at high level in 150-d group as in the early stage. (3) Ova rats were pretreated with Ris for 60 d and then terminated (Ris-on/off), followed by sequential sacrifice of rats on 21 and 90 d. Withdrawal on 21 d showed the same results as the match-age Ris-on group. Withdrawal on 90 d still maintained cancellous bone mass at a high level vs 150 d Ris-on groups (+26%) and aging control group (+27%). CONCLUSION: Regimen of Ris 60 d on then 90 d off prevented the development of osteoporosis in Ova rats.

[Effects of fructus cnidii coumarins compared with nilestriol on osteoporosis in ovariectomized rats].

AIM: To compare the total coumarins from dried fruits of Cnidium monnieri (TCCM) and nilestriol (Nil) against osteoporosis. METHODS: SD rats (40, female, 3-month-old) were randomly divided into basal control, age control, ovariectomized (Ova), Ova + TCCM 67 mg.kg-1, Ova + TCCM 200 mg.kg-1, 6 times a week, and Ova + Nil 1 mg.kg-1, i.g. once a week. After 12 wk, sections (20 microns) of proximal tibiae were examined histologically. RESULTS: Ova reduced markedly the trabecular bone mass due to bone resorption excessed bone formation (% Tb. Ar -59%). Treatment with TCCM 67 mg.kg-1 partly suppressed bone turnover, but did not inhibit bone loss in Ova rats (% Tb.Ar -43%). Treatment with TCCM 200 mg.kg-1 and Nil 1 mg.kg-1 increased the trabecular area (% Tb. Ar +100% and +274%). CONCLUSION: Nil was more potent than TCCM in protecting against osteoporosis in Ova rats via supression of bone turnover.

Effects of total coumarins of Cnidium monnieri on bone density and biomechanics of glucocorticoids-induced osteoporosis in rats.

AIM: To evaluate the effects of total coumarins from dried fruits of Cnidium monnieri (TCCM) on glucocorticoids (GC)-induced osteoporosis (OP) in rats. METHODS: Single photon absorptiometric and biomechanical character measurements of femurs were used. RESULTS: The bone density (BD) indices in proximal, middle, and distal segments in GC group were decreased by 12% (P < 0.05), 14% (P < 0.05), and 12% (P < 0.05), respectively vs control group. The BD on proximal, middle, and distal segments in GC-TCCM group were increased by 26% (P < 0.01), 34% (P < 0.01), and 31% (P < 0.01), respectively vs GC group. The biomechanical competence in femoral middle segments in GC group tended to decrease vs control group. In GC-TCCM group, the torsional strength, energy, maximal torsional angle, and rigidity were increased by 15% (P < 0.05), 32% (P < 0.05), 14% (P > 0.05), and 13% (P > 0.05), respectively vs the GC group. CONCLUSION: TCCM not only prevented glucocorticoids-induced osteoporosis but also increased the torsional strength of femurs in rats.

Effects of short-term treatment with the bisphosphonates zoledronate and pamidronate on rat bone: a comparative histomorphometric study on the cancellous bone formed before, during, and after treatment.

To study the anti-resorptive effects of zoledronate and pamidronate on growing long bones we have performed a histomorphometric analysis of the three regions of the proximal tibial cancellous bone of bone formed before, during, and after drug treatment. Male rats (190-220 g) were treated subcutaneously for 10 days with zoledronate (0.028-2.8 microg/kg) or pamidronate (3.7-370 microg/kg) and sacrificed 5 days later. To delineate the three regions of cancellous bone, and for dynamic bone histomorphometry, calcein and demeclocycline were injected at various times. Both bisphosphonates caused a dose-dependent suppression of cancellous bone turnover and resorption to produce an increase in cancellous bone, but zoledronate was 100 times more potent than pamidronate. The increase in the bone amount and connectivity was more pronounced in the bone formed during treatment where transient bone resorption and normal bone formation led to a positive bone balance. In the bone formed before treatment, inhibition of bone resorption associated with reduced bone formation produced a net gain in amount of bone. Although both bone regions showed a positive bone balance, more bone accumulated in the bone formed during treatment probably because its trabecular bone surface was three times greater. In the primary spongiosa formed after treatment, a moderate increase in the bone amount and connectivity was observed only at the highest dose of both bisphosphonates. The bone formed before, during, and after treatment with bisphosphonates responds differently due to differences in bone architecture, rates of modeling and remodeling, and period of drug exposure.

[Quantitative study on the effect of osthole on proximal tibiae in ovariectomized (OVX) rats].

Thirty-one 3-month-old Female Sprague-Dawley rats were randomly divided into 5 groups, basal control (group 1, killed at the begining), aging control (group 2), ovariectomized (OVX, group 3), OVX with nilestriol treatment group (group 4) and OVX with osthole treatment group (group 5). Group 2 and group 3 ig with water 5 ml.kg-1 and group 5 ig with osthole 6.7 mg.kg-1, all once a day for 6 d; group 4 ig with nilestriol 1 mg.kg-1, once a week. After 12 weeks, all rats were killed. The proximal tibiae of rats were processed to undecalcified sections at 20 microns thickness for histomorphometric analysis. OVX was shown to reduce markedly the trabecular bone mass (%Tb. Ar-59%) due to increase of bone turnover with the result that bone resorption exceeded bone formation, as compared with aging controls. In contrast, treatment of OVX rats with Osthole and nilestriol increased significantly the trabecular area (increased 68% and 27.1% compared with that of OVX respectively). Our results indicate that osthole and nilestriol treatment provides protection against osteoporosis in OVX rats. The protective mechanism of osthole and nilestriol involves supression of bone turnover, but the effects of osthole is lower than that of nilestriol (trabecular area decreased 55% more in osthole group than that with nilestriol treatment). Our finding may provide theoretical evidence for the clinical use of osthole or nilestriol for treatment and prevention of osteoporosis.

Risedronate pretreatment does not hamper the anabolic effects of prostaglandin E2 in ovx rats.

Pretreatment of an anti-resorptive agent on the anabolic effects of prostaglandin E2 (PGE2) was studied on the proximal tibia and tibial shaft of ovariectomy (ovx) rats. Two days after ovx, rats were treated with either risedronate (Ris, 5 micrograms/kg twice weekly) or vehicle (V) for 60 days and then switched to 3 or 6 mg/kg/d PGE2 for 21 or 90 days. Bone area of both proximal tibial metaphysis (PTM) and tibial shaft (TX) were measured. Pretreatment with Ris increased the bone mass in PTM but not in TX of ovx rats. In the PTM, PGE2 produced the same percentage of new bone mass in both V- and Ris-pretreated ovx rats. The amount of new bone was almost the same after 3 weeks and 12 weeks of PGE2 treatment. There was no difference in the anabolic effects of 3 and 6 mg PGE2/kg/d in V-pretreated rats; however, the effects in Ris-pretreated groups were greater with 6 mg PGE2/kg/d than with 3 mg PGE2/kg/d. In TX, only the 6mg PGE2/kg/d administration added new bone on endocortical surfaces of both V- or Ris-pretreatment rats which leads to thickening the minimal cortical width, decreasing the marrow cavity and increasing total bone area. Both doses of PGE2 created new trabecular bone in the marrow cavity of tibial shaft in both vehicle- and Ris-pretreated ovx rats. These results suggest that Ris-pretreatment did not hamper the anabolic effects of PGE2 on either PTM or TX in ovx rats.

Effects of total coumarins of Fructus cnidii on skeleton of ovariectomized rats.

Total coumarins of Fructus Cnidii (TCFC), 5 g.kg-1 by intragastric gavage, 6 d/wk, x 7 wk, was effective for prevention of bone loss in ovariectomized (OVX) rats. In comparison to aging control rats, the proximal tibia of placebo-treated OVX rats were characterized by an increase in eroded perimeter (+298%), label perimeter (+77%), osteoid perimeter (+47%), mineral apposition rate (+32%) and bone formation rate (+130%). These changes indicated a high bone turnover in OVX rats leading to a rapid bone loss (-44%) in proximal tibial metaphysis. In contrast, the TCFC-treated OVX rats showed an increase of cancellous bone area (+41%) compared with placebo-treated OVX rats and decrease in all the above indices of bone turnover to near aging control levels except that of the osteoid area (+88%) which was higher than that in aging control, but mineralization lag time did not show significant changes. The results suggested that the TCFC inhibited the high bone turnover and reversed the bone loss at early menopausal stage.

[Effect of total coumarins from dried fruits of Cnidium monnieri on glucocorticoid-induced osteoporosis in rats].

Twenty-four 3-month-old male SD rats were divided into 3 groups: Group 1--control (ig water). Group 2--ig prednisone 45 micrograms.kg-1 twice a week. Group 3--treated with total coumarins of dried fruits of Cnidium monnieri (L) Cuss (TCCM) and prednisone. TCCM was given ig 5 g.kg-1, 6 days per week. After 90 d, rats were killed. The proximal tibiae of rats were processed undecalcified for histomorphometric analysis. In comparison with control rats, the bone resorption was enhanced and bone formation decreased. The trabecular bone areas were characterized by reduction of 40% in rats which received prednisone. Trabecular bone areas of rats treated with TCCM increased 56% compared with rats receiving prednisone. All indices of bone histomorphometry were near to those in the control. The results showed that TCCM prevented glucocorticoid-induced osteoporosis.

Adaptation of cancellous bone to aging and immobilization in growing rats.

Two-and-half-month-old female rats were subjected to right hindlimb immobilization or served as controls for 0, 1, 2, 8, 14, and 20 weeks. The right hindlimb was immobilized by bandaging it against the abdomen, thus unloading it. Cancellous bone histomorphometry was performed on microradiographs and double-fluorescent labeled 20 microns sections of the distal femoral metaphyses. Primary spongiosa bone loss occurred rapidly by 2 weeks, and secondary spongiosa bone loss occurred rapidly by 8 weeks of immobilization, and then equilibrated at 60% less bone mass than age-related controls. The negative bone balance induced by immobilization was caused by transient increase in bone resorption, decrease in bone formation, and longitudinal bone growth. The dynamic data of secondary spongiosa cancellous bone showed that percent eroded perimeter was transiently elevated by 55 to 82% between 1 and 8 weeks, percent labeled perimeter was transiently depressed by 32% to 50% between 1 and 14 weeks, mineral apposition rate was depressed by 23% and 19% at 1 and 2 weeks, and bone formation rate-bone area referent was transiently depressed by 35% and 59% at 1 and 2 weeks. All the above parameters were at age-related control levels by 20 weeks of immobilization. However, bone formation rate-tissue area referent was depressed (-65%) throughout the study. Immobilization depressed completely longitudinal bone growth by 2 weeks and remained so. Only 0.65 mm of new metaphysis was generated in the immobilized versus 2.1 mm in controls during the study period. The immobilization induced an early cancellous bone loss which equilibrated at a new steady state with less bone and a normal (age-related control) bone turnover rate. When these findings were compared to an earlier study of 9-month-old virgin females subjected to right hindlimb immobilization up to 26 weeks, we found the adaptive responses of the cancellous bone were identical except that they occurred earlier and equilibrated sooner in younger rats.

[Quantitative study on DNA content and nucleolar organiser regions in astrocytoma].

Forty-one astrocytomas of different grades were studied by means of image analysis technique for measuring DNA content in situ, and in 28 tumors the numbers of nucleolar organiser region (NORs) associated proteins were also determined, and 12 cases of astrocytoma in frontal lobes were followed up. The results showed that the distribution of DNA content in grade I astrocytoma was 2C-4C, the peak values of grade I astrocytoma was 2C; while for grade II, 3C-4C and hypertetraploid. DNA contents of grade III and IV astrocytomas were much higher, their histograms were dispersed with many peaks, the peak values were aneuploid and heteroploid. The data confirm that heteroploid and aneuploid are the marks of malignancy. The grade II astrocytoma which possesses these features has a tendency to higher malignancy. Twenty-eight astrocytomas were stained by Argyrophil (Ag-NOR) for NOR associated proteins. The largest numbers of Ag-NORs were seen in grades III and IV astrocytoma (mean 11.71), and their Ag-NORs were irregular. Grade I astrocytoma possessed the fewest Ag-NORs (mean 6.5) which were small and uniform. The results suggest that the number of Ag-NORs is associated with the differentiation. The prognosis is significantly correlated with the numbers of Ag-NORs and the contents of DNA in astrocytomas.