Comparative Biomechanical Stability of the Fixation of Different Miniplates in Restorative Laminoplasty after Laminectomy: A Finite Element Study.

A novel H-shaped miniplate (HSM) was specifically designed for restorative laminoplasties to restore patients' posterior elements after laminectomies. A validated finite element (FE) model of L2/4 was utilized to create a laminectomy model, as well as three restorative laminoplasty models based on the fixation of different miniplates after a laminectomy (the RL-HSM model, the RL-LSM model, and the RL-THM model). The biomechanical effects of motion and displacement on a laminectomy and restorative laminoplasty with three different shapes for the fixation of miniplates were compared under the same mechanical conditions. This study aimed to validate the biomechanical stability, efficacy, and feasibility of a restorative laminoplasty with the fixation of miniplates post laminectomy. The laminectomy model demonstrated the greatest increase in motion and displacement, especially in axial rotation, followed by extension, flexion, and lateral bending. The restorative laminoplasty was exceptional in preserving the motion and displacement of surgical segments when compared to the intact state. This preservation was particularly evident in lateral bending and flexion/extension, with a slight maintenance efficacy observed in axial rotation. Compared to the laminectomy model, the restorative laminoplasties with the investigated miniplates demonstrated a motion-limiting effect for all directions and resulted in excellent stability levels under axial rotation and flexion/extension. The greatest reduction in motion and displacement was observed in the RL-HSM model, followed by the RL-LSM model and then the RL-THM model. When comparing the fixation of different miniplates in restorative laminoplasties, the HSMs were found to be superior to the LSMs and THMs in maintaining postoperative stability, particularly in axial rotation. The evidence suggests that a restorative laminoplasty with the fixation of miniplates is more effective than a conventional laminectomy due to the biomechanical effects of restoring posterior elements, which helps patients regain motion and limit load displacement responses in the spine after surgery, especially in axial rotation and flexion/extension. Additionally, our evaluation in this research study could benefit from further research and provide a methodological and modeling basis for the design and optimization of restorative laminoplasties.

Antibacterial activity of a novel glycyrrhizic acid-loaded chitosan composite nanogel in vitro against Staphylococcus aureus small colony variants.

Background This study aimed to improve the sustained and controlled release of glycyrrhizic acid to the infected site of Staphylococcus aureus small colony variants (SCVs). Methods The glycyrrhizic acid-loaded chitosan composite nanogel was prepared by inclusion action, Schiff's base formation, and electrostatic action. Furthermore, the formulation screening, characteristics, in vitro release, and antibacterial activity of the glycyrrhizic acid composite nanogel were explored. Results The final optimal formula comprised 10 mg/mL (chitosan) and 50 µL (glutaraldehyde). The loading capacity, encapsulation efficiency, mean size, polydispersity index, and zeta potential were 8.8%±1.6%, 92.1%±2.8%, 478.3±2.8 nm, 0.37±0.10, and 25.3±3.6 mv, respectively. Scanning electron microscope images showed a spherical shape with a relatively uniform distribution. The in vitro release study showed that glycyrrhizic acid composite nanogel exhibited a biphasic pattern with a sustained release of 52.1%±2.0% at 48 h in the pH 5.5 PBS. The minimum inhibitory and minimum biofilm inhibitory concentrations of glycyrrhizic acid composite nanogel against SCVs were 0.625 µg/mL. The time-killing curves and live/dead bacterial staining showed that glycyrrhizic acid composite nanogel had a stronger curative effect against SCVs strain with concentration-dependent. Conclusion This study provides promising glycyrrhizic acid composite nanogel to improve the treatment of SCV infection.

Antibacterial activity of florfenicol composite nanogels against Staphylococcus aureus small colony variants.

BACKGROUND: Florfenicol might be ineffective for treating Staphylococcus aureus small colony variants (SCVs) mastitis. OBJECTIVES: In this study, florfenicol-loaded chitosan (CS)-sodium tripolyphosphate (TPP) composite nanogels were prepared to allow targeted delivery to SCV infected sites. METHODS: The formulation screening, the characteristics, in vitro release, antibacterial activity, therapeutic efficacy, and biosafety of the florfenicol composite nanogels were studied. RESULTS: The optimized formulation was obtained when the CS and TPP were 10 and 5 mg/mL, respectively. The encapsulation efficiency, loading capacity, size, polydispersity index, and zeta potential of the optimized florfenicol composite nanogels were 87.3% ± 2.7%, 5.8% ± 1.4%, 280.3 ± 1.5 nm, 0.15 ± 0.03, and 36.3 ± 1.4 mv, respectively. Optical and scanning electron microscopy showed that spherical particles with a relatively uniform distribution and drugs might be incorporated in cross-linked polymeric networks. The in vitro release study showed that the florfenicol composite nanogels exhibited a biphasic pattern with the sustained release of 72.2% ± 1.8% at 48 h in pH 5.5 phosphate-buffered saline. The minimal inhibitory concentrations of commercial florfenicol solution and florfenicol composite nanogels against SCVs were 1 and 0.25 µg/mL, respectively. The time-killing curves and live-dead bacterial staining showed that the florfenicol composite nanogels were concentration-dependent. Furthermore, the florfenicol composite nanogels displayed good therapeutic efficacy against SCVs mastitis. Biological safety studies showed that the florfenicol composite nanogels might be a biocompatible preparation because of their non-toxic effects on the renal tissue and liver. CONCLUSIONS: Florfenicol composite nanogels might improve the treatment of SCV infections.

[Role and mechanism of endoplasmic reticulum stress response induced by wear particles in osteolysis].

OBJECTIVE: To analyze the role of endoplasmic reticulum stress response in the development of osteoblast apoptosis and osteolysis in osteolytic bone tissue, and to explore the causes of artificial joint loosening, so as to provide new ideas and theoretical basis for the prevention and treatment of artificial joint loosening. METHODS: The animal model of osteolysis induced by wear particles was established by mouse skull, and randomly divided into 4 groups, 7 rats in each group:group 1, blank control group;group 2, wear particles tial6v4 nano alloy powder (TiNPs) group;group 3, endoplasmic reticulum stress response positive control (TiNPs+Tg) group; group 4, endoplasmic reticulum stress response inhibitor (TiNPs+4-PBA) group. The pathological changes of osteolysis were observed by toluidine blue staining, HE staining and ALP staining;the expression of endoplasmic reticulum stress response marker protein was detected by Western Blotting;the apoptosis of osteoblasts in osteolytic skull tissue was detected by TUNEL and Caspase-3 immunohistochemistry. RESULTS: Wear particles TiNPs can induce osteolysis in vitro, aggravate the infiltration of inflammatory cells and inhibit the differentiation and maturation of osteoblasts. At the same time, wear particles can also up regulate the markers of endoplasmic reticulum stress response and promote the apoptosis of osteoblasts in osteolytic bone tissue. After adding 4-PBA, an inhibitor of endoplasmic reticulum stress (4-PBA), on the basis of wear particles TiNPs, the symptoms of osteolysis were significantly relieved, bone erosion and inflammatory infiltration were significantly reduced, the differentiation and maturation of osteoblasts were improved, the number of apoptotic osteoblasts decreased sharply, and the expression of endoplasmic reticulum stress marker protein gradually decreased. CONCLUSION: Endoplasmic reticulum stress is involved in the formation of osteolysis and plays an important role in the occurrence and development of osteolysis. At the same time, endoplasmic reticulum stress can be used as a new therapeutic target to provide new ideas and methods for clinical reversal or treatment of osteolysis and aseptic loosening.

[The impact of perioperative function exercises on hidden blood loss in elderly patients with total hip replacement].

OBJECTIVE: To investigate the effects of initiative and passive perioperative function exercises on hidden blood loss (HBL). METHODS: Two hundreds and thirty elderly patients with hip fractures aging from 67 to 87 years (average age of 73.6 years) who underwent total hip replacement were included. By the intensity and the manner of perioperative function exercises, patients were divided into four groups: little initiative function exercises group (group A, n=51), little initiative and passive function exercises group (group B, n=54), normal initiative function exercises group (group C, n=65), normal initiative and passive function exercises group (group D, n=60). The true total blood loss, HBL and their proportion on the original blood volume and total blood loss was calculated depending on height, weight, intra-operative blood loss, post-operative blood loss, pre- and post-operative hematocrit, and blood transfused. According to the proportion of mean HBL on total blood loss, patients were divided into low HBL group and high HBL group. The data were analyzed by t test. RESULTS: The mean HBL was 517 ml, 41.9% of the total blood loss. Thereinto, the mean HBL was 695 ml in group A, 49.3% of the total blood loss, the prevalence of high HBL was 66.7% (34/51); the mean HBL was 625 ml in group B, 46.9% of the total blood loss, the prevalence of high HBL was 59.3% (32/54); the mean HBL was 446 ml in group C, 38.4% of the total blood loss, the prevalence of high HBL was 30.8% (20/65); the mean HBL was 346 ml in group D, 32.3% of the total blood loss, the prevalence of high HBL was 20.0% (12/60). Mean HBL, mean HBL/total blood loss, prevalence of high HBL were lower in group C than that in group A and group B (all P<0.05); and were lower in group D than that in group C (all P<0.05). The prevalence was 57.4% (132 cases) in low HBL group, and 42.6% (98 cases) in high HBL. The proportion of little initiative function exercises patients in high HBL group was obviously higher than that in low HBL group (P<0.05). CONCLUSIONS: The intensity and the manner of perioperative function exercises are strongly associated with the HBL in elderly patients with total hip replacement. The initiative combined with the passive function exercises could be effectively prevent and reduce the incidence of high HBL.