[Digital and anatomical study of posterior atlantooccipital joint-occipital condyle-clivus screw technique].

Objective: To investigate the screw placement parameters, feasibility and safety of posterior atlantooccipital joint-occipital condyle-clivus screw technique in Chinese people. Methods: Upper cervical spine CT images of 46 patients, including 24 males and 22 females, were collected with random number table from June 2019 to May 2020 in Ningbo No.6 Hospital. The patients aged 20-55 years, with a mean age of (39±9) years. Total of 92 sides of upper cervical spine models were obtained by Mimics 19.0 digital three-dimensional reconstruction, and screw placement was conducted simulately. The midpoint of transition zone between the posterior arch of atlas and the inferior articular process of lateral mass was selected as the screw entry point. The diameter and length of screws was 3.5 mm and 50 mm, respectively. Detailed morphometric measurements of the 92 atlantooccipital joint-occipital condyle-clivus screws were conducted. The distance between the screw and its surrounding important structures, screw inside and upper tilting angles, the length of screw trajectory in atlas and the length of screw trajectory on occipital side (occipital condyle-clivus) were all measured. Paired t test was performed on the parameters of left and right screw placement to confirm whether there was difference between the two sides. Results: In the 46 cases of upper cervical spine digital three-dimensional models, 92 posterior atlantooccipital joint-occipital condyle-clivus screws were implanted. All the screws were completely fixed in the clivus, without breaking through the upper sphenoid sinus, entering into the canalis spinalis and foramen magnum, and damaging the surrounding structures such as hypoglossal canal. The screw trajectory parameters between the left and right sides were slightly different, but there was no statistical differences between the two sides (P>0.05). The vertical distance between the screw entry point and the upper edge of atlas was (12.6±1.0) mm, the vertical distance between the screw entry point and the lower edge of atlas was (6.5±0.6) mm, the distance between the screw and the medial border of atlas vertebral artery foramen was (6.7±0.6) mm, the distance between the screw entry point and the medial wall of atlas was (6.6±0.7) mm, the distance between the screw outer margin and the hypoglossal canal was (5.5±0.6) mm, screw inside tilting angle was 21.2°±2.5°, screw upper tilting angle was 52.0°±3.4°, the length of screw trajectory in atlas was (12.1±0.9) mm, the length of screw trajectory on occipital side (occipital condyle-clivus) was (37.9±0.9) mm. Conclusion: The posterior atlantooccipital joint-occipital condyle-clivus screw technique can serve as a feasible and safe treatment for instability of the occipitocervical junction, which can be used as a new posterior occipitocervical fusion technique.

[Biomechanical study of anterior occipital condyle screw plate system].

Objective: To analyze the feasibility of anterior occipitocervical fusion biomechanical characteristic of craniovertebral reconstruction by anterior occipital condyle screw plate system. Methods: Six cervical vertebra specimens including 4 males and 2 females were enrolled, whose mean age of death was (49.3±7.5) years. The normal models were established by soft tissue dissection, and the instability models were established by destroy bone and ligament structure including, anterior arch of the atlas, part of the lateral mass of the atlas, the odontoid process, the odontoid apical ligament, the pterygoid ligament, the transverse ligament of the atlas the joint capsule. The clivus screw fixation models were established by anterior clivus screw fixation, and then those models were performed by anterior occipital condyle screw fixation. All four groups were loaded with a 1.5 N·m continuous pure force in flexion-extension, lateral bending, and axial rotation. Then measured the range of motion of specimen C0-C1 and C0-C2. And the pull-out force test was conducted to compare the effects of unicortical and bicortical fixation on the pull-out force of screws. Results: In the C0-C1 segment, the range of motion in flexion-extension (forward and posterior), lateral bending and axial rotation in the clivus group was 6.46°±0.85°, 5.14°±0.76°, 2.73°±0.36°, 1.12°±0.41°, respectively; and it was 5.92°±0.90°, 4.16°±1.06°, 2.86°±0.50°, 1.05°±0.27°, respectively in the occipital condyle group. As for C0-C2 segment, the range of motion in the clivus group was 9.55°±1.99°, 10.46°±2.03°, 6.90°±1.29°, 13.51°±1.37°, respectively; and it was 8.14°±1.38°, 9.53°±1.55°, 4.75°±1.06°, 7.90°±1.68°, respectively, in the occipital condyle group. The ranges of motion in the occipital condyle group were significantly lower than clivus group (all P<0.05). The maximum pull out force by bicortical fixation was significantly better than unicortical fixation ((439±33) N vs (408±28) N, P<0.05). Conclusion: The anterior occipital condyle screw plate system provides better stability especially in anti-bending and anti-rotation than the anterior clival screw fixation.

Effects of jugular infusions of isoleucine, leucine, methionine, threonine, and other amino acids on insulin and glucagon concentrations, mammalian target of rapamycin (mTOR) signaling, and lactational performance in goats.

The supply and profile of absorbed AA may affect milk protein synthesis through hormonal changes and mammalian target of rapamycin (mTOR) signaling pathways; and Ile, Leu, Met, and Thr (ILMT) are the 4 AA that have been reported to have the greatest effect on mammary mTOR signaling. The extent to which ILMT and the other remaining AA (RAA) differ in their effects on milk protein synthesis needs to be systematically investigated. In this study, 5 lactating goats, averaging 120 ± 10 d in milk, fitted with jugular vein and carotid artery catheters, were fasted for 24 h, followed by intravenous infusions of a mixture containing AA and glucose for 8 h in a 5 × 5 Latin square design. The AA mixtures were formulated according to the profile of casein. The amounts of AA infused were calculated based on supplies of AA when metabolizable protein (MP) was at requirement (MR). Treatments were an infusate containing glucose without AA (NTAA); an infusate containing 3 × the MR of Ile, Leu, Met and Thr (3F0R); and infusates containing 3F0R plus 1, 2, or 3 × MR of RAA (3F1R, 3F2R, and 3F3R, respectively) according to amounts provided when fed to meet MP requirements for maintenance and lactation for each goat. Milk, arterial blood, and mammary tissue samples were collected immediately after halting the infusion. Relative to NTAA, supplementation of ILMT tended to increase milk protein production and plasma glucose concentrations, and increased milk and lactose production, but had no effects on production or content of milk fat. Graded supplementation of RAA tended to quadratically affect production of milk and lactose. Arterial glucose and glucagon concentrations decreased linearly, and plasma insulin concentrations decreased quadratically with increased RAA. Mammary p70-S6K1 phosphorylation was decreased by addition of ILMT compared with NTAA but increased linearly with increased RAA infusion. Furthermore, EIF4EBP1 gene expression was much lower for 3F-treated goats than for the NTAA treatment. Both MTOR and RPS6KB1 gene expressions were decreased quadratically with increased RAA supply. These results suggested that short-term milk protein yield tended to be increased by elevated ILMT availability, and this trend was not explained by variations in mammary mTOR signaling or pancreatic hormone secretions, whereas graded increase of RAA in combination with ILMT appeared to regulate the efficiency of conversion of glucose to lactose in a manner not involving milk protein production.

Effects of rumen-protected methionine and other essential amino acid supplementation on milk and milk component yields in lactating Holstein cows.

Objectives of this study were to investigate the effects of supplementing rumen-protected methionine (RP-Met), threonine (RP-Thr), isoleucine (RP-Ile), and leucine (RP-Leu) individually or jointly to a low-protein diet, on the performance of lactating dairy cows, as well as to determine the effects of these amino acids (AA) on the mammalian target of rapamycin (mTOR) in vivo. Ten lactating Holstein cows were randomly allocated to a repeated 5 × 5 Latin square experiment with five 19-d periods. Treatments were high-protein diet (16% crude protein, positive control; HP), low-protein diet (12% crude protein, negative control; LP), LP plus RP-Met (LPM), LP plus RP-Met and RP-Thr (LPMT), and LP plus RP-Met, RP-Thr, RP-Ile, and RP-Leu (LPMTIL). The dry matter intakes (DMI) of the LP, LPM, and LPMT diets were lower than that of the HP diet, whereas the DMI of the LPMTIL diet was intermediate between the HP diet and the other LP diets. Supplementing RP-Met to the LP diet increased the yields of milk and milk protein, increased the content of milk urea N, and tended to increase milk N efficiency. Co-supplementation of RP-Thr with RP-Met resulted in no further milk production increase. Co-supplementation of all 4 rumen-protected amino acids (RP-AA) increased milk and lactose yields to the level of the HP diet and tended to increase milk protein yield compared with the LPMT diet. We found no significant differences in the contents and yields of milk components between the LPMTIL and HP diets except for a lower milk urea N content in the LPMTIL diet. Venous concentrations of the measured AA were similar across the LP and LP diets supplemented with RP-AA. Relative to levels of the HP diet, LP diets had higher venous concentrations of Met and Gly and tended to have higher Phe concentration and lower concentrations of Val and BCAA. The LPMTIL diet had higher venous concentrations of Arg, Lys, Met, Phe, and Glu, and a lower Val concentration. Phosphorylation status of the measured mTOR components in LPM and LPMT treatments were similar to those in the LP treatment but phosphorylation status of mTOR and eIF4E-binding protein 1 (4eBP1) in LPMTIL treatment were higher. The phosphorylation rates of eukaryotic elongation factor 2 (eEF2) in the 4 LP and LP plus RP-AA diets were higher than that of the HP diet. Overall, results of the present study supported the concept that under the relatively short time of this experiment, supplementing RP-AA, which are believed to stimulate the mTOR signal pathway, can lead to increased milk protein yield. This increase appears to be due to increased DMI, greater mTOR signaling, and greater eEF2 activity.

[Mechanisms of fosfomycin resistance of extended-spectrum ß-lactamases-producing Escherichia coli and Klebsiella pneumoniae].

Objective: To study the in vitro activity of fosfomycin to extended-spectrum ß-lactamases (ESBLs)-producing Escherichia coli and Klebsiella pneumoniae and to explore the mechanisms of fosfomycin resistance. Methods: A total of 1 052 ESBLs-producing E. coli(ESBL-EC) and K. pneumoniae(ESBL-KP) isolates were collected from bloodstream infections of 28 hospitals of 22 provinces and municipalities, which were stored by our laboratory.Minimum inhibitory concentrations (MICs) of fosfomycin against these clinical isolates were determined by agar dilution methods according to the Clinical and Laboratory Standards Institute (CLSI)(2015). The genes related to fosfomycin resistance were confirmed by Polymerase Chain Reaction (PCR) and sequencing. Results: The susceptibility rates of ESBL-EC and ESBL-KP isolates to fosfomycin were 91.3% (818/896) and 91.7% (143/156), respectively. A total of 91 fosfomycin-non-susceptible isolates were detected, of which 73 (80.2%) isolates carried fosA3 genes.Amongst 18 fosA3-negative isolates, 16 isolates were detected to have chromosomal mutations or insertion inactivation, while the rest two isolates had not been detected any resistant mechanisms. Conclusions: Fosfomycin shows great in vitro antimicrobial activity to ESBL-EC and ESBL-KP. The primary mechanism of fosfomycin-non-susceptible isolates is fosA3 gene.Chromosomal mutations may also involve in the fosfomycin resistance.

A genome-wide association study suggests new candidate genes for milk production traits in Chinese Holstein cattle.

A genome-wide association study (GWAS) was conducted on 15 milk production traits in Chinese Holstein. The experimental population consisted of 445 cattle, each genotyped by the GGP (GeneSeek genomic profiling)-BovineLD V3 SNP chip, which had 26 151 public SNPs in its manifest file. After data cleaning, 20 326 SNPs were retained for the GWAS. The phenotypes were estimated breeding values of traits, provided by a public dairy herd improvement program center that had been collected once a month for 3 years. Two statistical models, a fixed-effect linear regression model and a mixed-effect linear model, were used to estimate the association effects of SNPs on each of the phenotypes. Genome-wide significant and suggestive thresholds were set at 2.46E-06 and 4.95E-05 respectively. The two statistical models concurrently identified two genome-wide significant (P < 0.05) SNPs on milk production traits in this Chinese Holstein population. The positional candidate genes, which were the ones closest to these two identified SNPs, were EEF2K (eukaryotic elongation factor 2 kinase) and KLHL1 (kelch like family member 1). These two genes could serve as new candidate genes for milk yield and lactation persistence, yet their roles need to be verified in further function studies.

[Effects of miR-93 on proliferation and apoptosis of osteosarcoma cells].

Objective: To investigate the effects of miR-93 on proliferation and apoptosis of osteosarcoma cells and the possible mechanism. Methods: The expression levels of miR-93 and the naked cuticle homolog 2 (NKD2) in 6 osteosarcoma cell lines (143B, HuO9, Saos2, MG63, U2OS and G292) and one osteoblast cell line hFOB1.19 were determined by quantitative real-time PCR and Western blot assays, respectively. MiR-93 down-regulated 143B and HuO9 cells were constructed by lipofection transfection, and their proliferation and apoptosis were detected by MTT and flow cytometry assays, respectively. Luciferase reporter assay was used to determine whether the 3'UTR of NKD2 mRNA was a binding target of miR-93. In addition, 143B cells were transfected with NKD2 cDNA, and the effects of NKD2 on proliferation and apoptosis of osteosarcoma cells were investigated. Results: Up-regulation of miR-93 and down-regulation of NKD2 were detected in osteosarcoma cell lines. MTT and flow cytometry assays showed that miR-93 promoted proliferation and inhibited apoptosis in osteosarcoma cells. Luciferase assay confirmed that miR-93 targeted NKD2 directly. In addition, overexpression of NKD2 inhibited proliferation and promoted apoptosis of osteosarcoma cells were found. Conclusions: MiR-93 targets NKD2 to promote proliferation and inhibit apoptosis of osteosarcoma cells. The findings may have significant implications in the diagnosis and treatment of osteosarcoma.