Safety and immunogenicity of the Pfizer/BioNTech SARS-CoV-2 mRNA third booster vaccine dose against the BA.1 and BA.2 Omicron variants.

Background: The Omicron variant of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) was identified in Japan in November 2021. This variant contains up to 36 mutations in the spike protein, the target of neutralizing antibodies, and can escape vaccine-induced immunity. A booster vaccination campaign began with healthcare workers and high-risk groups.

Increased migratory activity and cartilage regeneration by superficial-zone chondrocytes in enzymatically treated cartilage explants.

Background: Limited chondrocyte migration and impaired cartilage-to-cartilage healing is a barrier in cartilage regenerative therapy. Collagenase treatment and delivery of a chemotactic agent may play a positive role in chondrocyte repopulation at the site of cartilage damage. This study evaluated chondrocyte migratory activity after enzymatic treatment in cultured cartilage explant.

The Contribution of Deleterious Rare Alleles in ENPP1 and Osteomalacia Causative Genes to Atypical Femoral Fracture.

Context: Atypical femoral fractures (AFFs) are very rare atraumatic or mild trauma fractures in the subtrochanteric region or femoral shaft. Some unique genetic variants in Asian populations might confer susceptibility to AFF, since the incidence of AFFs is higher in Asian populations.

Objective: Because rare variants have been found to be causative in some diseases and the roles of osteomalacia causative genes have not been reported, we investigated rare variants in genes causing abnormal mineralization.

Epidemiological patterns of traumatic musculoskeletal injuries and non-traumatic disorders in Japan Self-Defense Forces.

Background: The epidemiological patterns of musculoskeletal injuries or disorders in military personnel have not been well documented and a better understanding is required for proper preventative measures and treatment. Here, we investigated musculoskeletal injuries or disorders among members of the Japan Self-Defense Forces.

Methods: All orthopedic patients (n = 22,340) who consulted to Japan Self-Defense Forces Hospitals were investigated for their type of injury or disorder, the injured body part, the mechanism, and the cause of injuries.

Comparison of Pedicle Screw Fixation Strength Among Different Transpedicular Trajectories: A Finite Element Study.

Study Design: Comparative biomechanical study by finite element (FE) method.

Objective: To investigate the pullout strength of pedicle screws using different insertional trajectories.

Summary Of Background Data: Pedicle screw fixation has become the gold standard for spinal fusion, however, not much has been done to clarify how the fixation strength of pedicle screws are affected by insertional trajectories and bone properties.

Therapeutic effect of exendin-4, a long-acting analogue of glucagon-like peptide-1 receptor agonist, on nerve regeneration after the crush nerve injury.

Glucagon-like peptide-1 (GLP-1) is glucose-dependent insulinotropic hormone secreted from enteroendocrine L cells. Its long-acting analogue, exendin-4, is equipotent to GLP-1 and is used to treat type 2 diabetes mellitus. In addition, exendin-4 has effects on the central and peripheral nervous system.

Linezolid and vancomycin decrease the therapeutic effect of methylene blue-photodynamic therapy in a mouse model of MRSA bacterial arthritis.

We previously reported that photodynamic therapy (PDT) using intra-articular methylene blue (MB) could be used to treat arthritis in mice caused by bioluminescent methicillin-resistant Staphylococcus aureus (MRSA) either in a therapeutic or in a preventative mode. PDT accumulated neutrophils into the mouse knee via activation of chemoattractants such as inflammatory cytokines or chemokines. In this study, we asked whether PDT combined with antibiotics used for MRSA could provide added benefit in controlling the infection.

Photodynamic therapy can induce a protective innate immune response against murine bacterial arthritis via neutrophil accumulation.

Background: Local microbial infections induced by multiple-drug-resistant bacteria in the orthopedic field can be intractable, therefore development of new therapeutic modalities is needed. Photodynamic therapy (PDT) is a promising alternative modality to antibiotics for intractable microbial infections, and we recently reported that PDT has the potential to accumulate neutrophils into the infected site which leads to resolution of the infection. PDT for cancer has long been known to be able to stimulate the innate and adaptive arms of the immune system.

Optimal photosensitizers for photodynamic therapy of infections should kill bacteria but spare neutrophils.

Photodynamic therapy (PDT) for localized microbial infections exerts its therapeutic effect both by direct bacterial killing and also by the bactericidal effects of host neutrophils stimulated by PDT. Therefore, PDT-induced damage to neutrophils must be minimized, while direct photoinactivation of bacteria is maintained to maximize the therapeutic efficacy of antimicrobial PDT in vivo. However, there has been no study in which the cytocidal effect of PDT on neutrophils was investigated.

Photodynamic therapy using intra-articular Photofrin for murine MRSA arthritis: biphasic light dose response for neutrophil-mediated antibacterial effect.

Background And Objective: Bacterial arthritis does not respond well to antibiotics and moreover multidrug resistance is spreading. We previously tested photodynamic therapy (PDT) mediated by systemic Photofrin® in a mouse model of methicillin-resistant Staphylococcus aureus (MRSA) arthritis, but found that neutrophils were killed by PDT and therefore the infection was potentiated.

Study Design/materials And Methods: The present study used an intra-articular injection of Photofrin® and optimized the light dosimetry in order to maximize bacterial killing and minimize killing of host neutrophils.

Cortical layer V neurons in the auditory and visual cortices of normal, reeler, and yotari mice.

Both in the Reelin-deficient reeler and Dab1-deficient yotari mice, layer V corticospinal tract neurons in the sensory-motor cortex are radially spread instead of being confined to a single cortical layer. In the present study, we examined distribution pattern of cortical layer V neurons in the visual and auditory cortices of reeler and yotari mice with the injection of HRP into the superior and inferior colliculi of the adult animals, respectively. After the injection of HRP into the superior colliculus of the normal mouse, retrogradely labeled cells were distributed in layer V of the visual cortex, while the similar injection of HRP in the reeler and yotari mice produced radial dispersion of retrograde labeling through all of the depths of the visual cortex of these mutant mice.

Axonal-transport-mediated gene transduction in the interior of rat bone.

Background: Gene transduction has been considered advantageous for the sustained delivery of proteins to specific target tissues. However, in the case of hard tissues, such as bone, local gene delivery remains problematic owing to anatomical accessibility limitations of the target sites.

Methodology/principal Findings: Here, we evaluated the feasibility of exogenous gene transduction in the interior of bone via axonal transport following intramuscular administration of a nonviral vector.

Influence of intra-articular neutrophils on the effects of photodynamic therapy for murine MRSA arthritis.

Although there have been some reports about the cytotoxic effects of photodynamic therapy (PDT) on multidrug-resistant bacteria, there have been few reports in which favorable results of PDT on a local infection site are described. This study aimed to verify the hypothesis that the low efficacy of PDT on a local infection site is due to the cytotoxic effect of PDT on leukocytes. PDT using Photofrin exerted significant cytotoxicity for cultured methicillin-resistant Staphylococcus aureus (MRSA).

CD4(+)CD8(+) thymocytes are induced to cell death by a small dose of puromycin via ER stress.

When the CD4(+)CD8(+) thymic lymphoma cells were treated with puromycin, we found that most of the cells died at 0.3-1 microg/ml of puromycin within 24h. However, cell death was greatly reduced when the dose of puromycin was increased.

Cementless total hip replacement: past, present, and future.

Cementless total hip replacement (THR) is rapidly being accepted as the surgery for arthritic diseases of the hip joint. The bone-ingrowth rate in porous-type cementless implants was about 90% over 10 years after surgery, showing that biological fixation of cementless THR was well maintained on both the stem and cup sides. As for the stress shielding of the femur operated using a distal fixation-type stem, severe bone resorption was observed.

Skeletal unloading induces a full-thickness patellar cartilage defect with increase of urinary collagen II CTx degradation marker in growing rats.

Mechanical stress plays an important role in tissue morphogenesis and extracellular matrix metabolism. However, little is known about the effects of reduced loading without restriction of joint motion on the patella. We investigated the effects of long-term skeletal unloading on patellar cartilage and subchondral bone and systemic collagen II metabolism.

Effects of reloading after simulated microgravity on proteoglycan metabolism in the nucleus pulposus and anulus fibrosus of the lumbar intervertebral disc: an experimental study using a rat tail suspension model.

Study Design: An experiment to measure proteoglycan (PG) content and PG-related gene mRNA expressions in the lumbar intervertebral disc (IVD) of rats tail-suspended (TS) for up to 6 weeks with subsequent reloading.

Objective: To assess the effects of reloading after simulated microgravity on PG metabolism in nucleus pulposus (NP) and anulus fibrosus (AF).

Summary Of Background Data: Although the PG content of rat lumbar IVD is reportedly decreased by low compressive force (due to so-called microgravity) during spaceflight, it is unknown whether it recovers completely on reloading and whether these effects differ between NP and AF.

[Matrix metalloproteinases and cartilage matrix degradation in rheumatoid arthritis].

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disorder characterized by the progressive destruction of articular cartilage. Matrix metalloproteinases (MMPs) constitute a major group among the neutral proteinases that degrade the extracellular matrix of cartilage, including various types of collagen, and aggrecan. Various MMPs are highly produced in synovial fluid and in sera from patients with RA, and are reported to play a pivotal role in cartilage matrix degradation in RA.

Upregulated expression of inducible nitric oxide synthase plays a key role in early apoptosis after anterior cruciate ligament injury.

The reason that the anterior cruciate ligament (ACL) has a very poor healing potential after injury is not well understood. In this study, we investigated the role of nitric oxide (NO) in the apoptotic cell death of ACL cells using a rabbit model and in vitro cell culture. The apoptosis of ACL cells in vivo was analyzed by TUNEL assay and electron microscopy.

Tissue engineering of articular cartilage with autologous cultured adipose tissue-derived stromal cells using atelocollagen honeycomb-shaped scaffold with a membrane sealing in rabbits.

Adipose tissue derived stromal cells (ATSCs), which were isolated from adipose tissue of rabbit, have shown to possess multipotential, that is, they differentiate into osteoblasts and adipocytes in plate-culturing and into chondrocytes in an established aggregate culture using defined differentiation-inductive medium. The aim of this study was to evaluate the utility of ATSCs in tissue engineering procedures for repair of articular cartilage-defects using the atelocollagen honeycomb-shaped scaffold with a membrane sealing (ACHMS-scaffold). We intended to repair full-thickness articular cartilage defects in rabbit knees using autologously cultured ATSCs embedded in the ACHMS-scaffold.

Joint biomarkers in idiopathic femoral head osteonecrosis: comparison with hip osteoarthritis.

Objective: To compare concentrations of joint biomarkers in synovial fluid (SF) between idiopathic osteonecrosis of the femoral head (ION) and osteoarthritis (OA) of the hip joint.

Methods: Levels of the joint biomarkers cartilage oligomeric matrix protein (COMP), antigenic keratan sulfate (AgKS), and hyaluronan (HA) in SF samples from 21 cases of ION and their relationship to disease stage and history of steroid use were assessed and compared to the result of 29 cases of hip OA.

Results: In both the ION and hip OA groups, levels of COMP and AgKS in SF showed a significant positive correlation.

Tissue engineering of articular cartilage using an allograft of cultured chondrocytes in a membrane-sealed atelocollagen honeycomb-shaped scaffold (ACHMS scaffold).

The aim of this study was to investigate with tissue engineering procedures the possibility of using atelocollagen honeycomb-shaped scaffolds sealed with a membrane (ACHMS scaffold) for the culturing of chondrocytes to repair articular cartilage defects. Chondrocytes from the articular cartilage of Japanese white rabbits were cultured in ACHMS scaffolds to allow a high-density, three-dimensional culturing for up to 21 days. Although the DNA content in the scaffold increased at a lower rate than monolayer culturing, scanning electron microscopy data showed that the scaffold was filled with grown chondrocytes and their produced extracellular matrix after 21 days.

[Mechanism of cartilage destruction in rheumatoid arthritis].

Destruction of cartilage in rheumatoid arthritis (RA) is mediated mainly by proteinases which can degrade cartilage matrix including type II collagen and aggrecan. Of these proteinases, matrix metalloproteinases (MMP) play significant roles in RA pathology, however recent studies show that a disintegrin and metalloproteinase (ADAM) families are another candidates. These proteinases are mainly produced from synovial cells and inflammatory cells, and concentrations of these proteinases in synovial fluid are significantly higher in RA than in OA.