秋田 新介

Absorbable bone fixation materials are commonly used in facial bone fracture surgery. However, reports on the microstructure of infected implants are rare. This study presents a case involving a 74-year-old male patient who developed an alpha-Streptococcus infection 2.5 months after zygomatic bone fracture surgery and the ultrastructure of an infected absorbable plate observed under a scanning electron microscope (SEM). The patient sustained a right zygomatic bone fracture due to a fall and underwent open reduction and internal fixation with SonicWeld on the seventh day after the injury. The postoperative course was uneventful, but 2.5 months after the surgery, the patient presented with redness, swelling, and pain in the right lower eyelid, along with purulent discharge, leading to the removal of the bone fixation material. The SEM observation of the extracted implant revealed a biphasic pattern, with areas showing signs of infection and areas without such effects. The infected regions showed wide cracks, bacterial clusters, and biofilm formation, whereas noninfected areas exhibited narrow cracks and distinct geometric striations. These findings suggest a link between crack formation and bacterial proliferation, emphasizing the importance of proper handling and implantation techniques. Although the infection was controlled and bone healing achieved after the removal of infected implants, the patient experienced lower eyelid retraction due to adhesion between the skin and underlying bone, leading to persistent cosmetic issues. This case report presents a rare visualization of the ultrastructural characteristics of infected absorbable implants, offering insights into the potential role of SEM in understanding these changes and processes.

Albumin andγ-globulin concentrations in subcutaneous adipose tissues (SAT) have been quantified by multivariate regression based on admittance relaxation time distribution (mrARTD) under the fluctuated background of sodium electrolyte concentration. ThemrARTD formulatesP=Ac+Ξ(P: peak matrix of distribution function magnitudeγˆand relaxation timesτˆ,c: concentration matrix of albumincAlb,γ-globulinGloc, and sodium electrolyteNac,A: coefficient matrix of a multivariate regression model, andΞ: error matrix). ThemrARTD is implemented by two processes which are: (1) the training process ofAthrough the maximum likelihood estimation ofPand (2) the quantification process ofcAlb,Gloc, andNacthrough the model prediction. In the training process, a positive correlation is present betweencAlb,Gloc, andNactoγˆ1atτˆ1= 0.1 as well asγˆ2atτˆ2= 1.40 μs as under a fixed concentration of proteins solution into a porcine SAT (cAlb= 0.800-2.400 g/dL,Gloc= 0.400-1.200 g dl-1andNac= 0.700-0.750 g dl-1). ThemrARTD method quantifiescAlb,Gloc, andNacin SAT with an absolute error of 33.79%, 44.60%, and 2.18%, respectively.

PURPOSE: Keloid formation in toes area is rare. However, occurrence of this phenomenon in toes after the surgery of syndactyly repair has been reported. Risk factors of keloid formation in toes after syndactyly reconstructions are currently unknown. This study aimed to investigate the risk factors of keloid formation after the surgery of syndactyly repair of the toes. METHODS: We retrospectively reviewed our case series including patients who were treated surgically at our institution. We hypothesized some key factors of keloid formation and analyzed each of them statistically. RESULTS: A total of 105 patients were treated surgically at our hospital, and 9 patients were involved keloid formations after operations. Among our hypothesized key factors, the results of multivariate logistic regression analysis revealed the number of affected web spaces (OR 0.031; 95%CI 0.001-0.684; p = 0.028) was significantly different. Digital enlargement was not a significant factor (OR 17.731; 95%CI 0.686-458.174; p = 0.091). CONCLUSION: Involving multiple web space was associated with keloid formation after syndactyly release, on the other hand, toe enlargement did not show a significant difference. However, the digital enlargement showed high Odds ratio, we could not deny its high relativity for keloid formation. Further investigations are needed to clarify the key risk factors of keloid formation after the surgery of syndactyly repair of the toes.

BACKGROUND: Platelet-rich plasma (PRP), which is prepared by concentrating platelets in autologous blood, shows efficacy in chronic skin wounds via multiple growth factors. However, it exhibits heterogeneity across patients, leading to unstable therapeutic efficacy. Human induced pluripotent stem cell (iPSC)-derived megakaryocytes and platelets (iMPs) are capable of providing a stable supply, holding promise as materials for novel platelet concentrate-based therapies. In this context, we evaluated the effect of iMPs on wound healing and validated lyophilization for clinical applications. METHODS: The growth factors released by activated iMPs were measured. The effect of the administration of iMPs on human fibroblasts and human umbilical vein endothelial cells (HUVECs) was investigated in vitro. iMPs were applied to dorsal skin defects of diabetic mice to assess the wound closure rate and quantify collagen deposition and angiogenesis. Following the storage of freeze-dried iMPs (FD-iMPs) for three months, the stability of growth factors and their efficacy in animal models were determined. RESULT: Multiple growth factors that promote wound healing were detected in activated iMPs. iMPs specifically released FGF2 and exhibited a superior enhancement of HUVEC proliferation compared to PRP. Moreover, an RNA-seq analysis revealed that iMPs induce polarization to stalk cells and enhance ANGPTL4 gene expression in HUVECs. Animal studies demonstrated that iMPs promoted wound closure and angiogenesis in chronic wounds caused by diabetes. We also confirmed the long-term stability of growth factors in FD-iMPs and their comparable effects to those of original iMPs in the animal model. CONCLUSION: Our study demonstrates that iMPs promote angiogenesis and wound healing through the activation of vascular endothelial cells. iMPs exhibited more effectiveness than PRP, an effect attributed to the exclusive presence of specific factors including FGF2. Lyophilization enabled the long-term maintenance of the composition of the growth factors and efficacy of the iMPs, therefore contributing to stable supply for clinical application. These findings suggest that iMPs provide a novel treatment for chronic wounds.