Development of Antimicrobial Surfaces Using Diamond-like Carbon or Diamond-like Carbon-Based Coatings.

The medical device market is a high-growth sector expected to sustain an annual growth rate of over 5%, even in developed countries. Daily, numerous patients have medical devices implanted or inserted within their bodies. While medical devices have significantly improved patient outcomes, as foreign objects, their wider use can lead to an increase in device-related infections, thereby imposing a burden on healthcare systems. Multiple materials with significant societal impact have evolved over time: the 19th century was the age of iron, the 20th century was dominated by silicon, and the 21st century is often referred to as the era of carbon. In particular, the development of nanocarbon materials and their potential applications in medicine are being explored, although the scope of these applications remains limited. Technological innovations in carbon materials are remarkable, and their application in medicine is expected to advance greatly. For example, diamond-like carbon (DLC) has garnered considerable attention for the development of antimicrobial surfaces. Both DLC itself and its derivatives have been reported to exhibit anti-microbial properties. This review discusses the current state of DLC-based antimicrobial surface development.

Diamond-like carbon coating to inner surface of polyurethane tube reduces Staphylococcus aureus bacterial adhesion and biofilm formation.

Staphylococcus aureus is one of the main causative bacteria for polyurethane catheter and artificial graft infection. Recently, we developed a unique technique for coating diamond-like carbon (DLC) inside the luminal resin structure of polyurethane tubes. This study aimed to elucidate the infection-preventing effects of diamond-like carbon (DLC) coating on a polyurethane surface against S. aureus. We applied DLC to polyurethane tubes and rolled polyurethane sheets with our newly developed DLC coating technique for resin tubes. The DLC-coated and uncoated polyurethane surfaces were tested in smoothness, hydrophilicity, zeta-potential, and anti-bacterial properties against S. aureus (biofilm formation and bacterial attachment) by contact with bacterial fluids under static and flow conditions. The DLC-coated polyurethane surface was significantly smoother, more hydrophilic, and had a more negative zeta-potential than did the uncoated polyurethane surface. Upon exposure to bacterial fluid under both static and flow conditions, DLC-coated polyurethane exhibited significantly less biofilm formation than uncoated polyurethane, based on absorbance measurements. In addition, the adherence of S. aureus was significantly lower for DLC-coated polyurethane than for uncoated polyurethane under both conditions, based on scanning electron microscopy. These results show that applying DLC coating to the luminal resin of polyurethane tubes may impart antimicrobial effects against S. aureus to implantable medical polyurethane devices, such as vascular grafts and central venous catheters.

Antireflection in Green Lacewing Wings with Random Height Surface Protrusions.

Wings of insects exhibit many functions apart from flying. In particular, their antireflection function is important for insects to avoid detection by their enemies. This function can be applied to antireflection biomimetic films in engineering fields. For such applications, confirming the antireflection mechanisms of insect wings is important. Herein, we used electron microscopy to compare the surfaces of green lacewing wings with and without a surface wax structure and recorded the transmittance spectra to clarify the surface structural and optical properties of insect wings. The spectral transmittance was higher for wings with a surface wax structure than for wings without a wax layer in the light wavelength regime from 500 to 750 nm. We constructed a concise model of the green lacewing wing with flake-like surface structure with a graded effective refractive index corresponding to the wing samples with a surface wax layer; we also constructed a simple thin-film model corresponding to the wing samples without a wax layer. The graded refractive indices were calculated using the effective medium theory, and the transmittance spectra of such models were then calculated using the transfer-matrix method. It was observed that the calculated spectra are in good agreement with the experimental results. In addition, wing samples without a surface structure induce thin-film interference. These results suggest that a wax structure can reduce the reflectance and increase the transmittance enabling the green lacewings to avoid detection by their enemies. These findings may lead to further advances in both the biomimetic field and fundamental research fields.

Why Do Carbonate Anions Have Extremely High Stability in the Interlayer Space of Layered Double Hydroxides? Case Study of Layered Double Hydroxide Consisting of Mg and Al (Mg/Al = 2).

Layered double hydroxides (LDHs) are promising compounds in a wide range of fields. However, exchange of CO32- anions with other anions is necessary, because the CO32- anions are strongly affixed in the LDH interlayer space. To elucidate the reason for the extremely high stability of CO32- anions intercalated in LDHs, we investigated in detail the chemical states of CO32- anions and hydrated water molecules in the LDH interlayer space by synchrotron radiation X-ray diffraction, solid-state NMR spectroscopy, and Raman spectroscopy. We found the rigidity of the network structure formed between the CO32- anions, hydrated water molecules, and the hydroxyl groups on the metal hydroxide layer surface to be a crucial factor underlying the stability of CO32- anions in the LDH interlayer space.

[A Case of Suspected Therapy-Related Leukemia after Chemotherapy for Breast Cancer].

Therapy-related leukemia(TRL)is a distinctive clinical syndrome that occurs after exposure to chemotherapy or radiotherapy. We report a case of suspected TRLafter chemotherapy in a patient with breast cancer. A 61-year-old woman underwent total mastectomy and sentinel lymph node biopsy(negative)for her breast cancer. Histopathologic analysis showed invasive ductal carcinoma, pStage I. Her subtype histology was Luminal B-type, and postoperative adjuvant chemotherapy and endocrine therapy were administered. Four years after chemotherapy, a blood examination showed pancytopenia. Bone marrow examination showed acute promyelocytic leukemia. She was treated with chemotherapy and achieved complete remission. Breast cancer provides long-term survival after treatment. Attention should be paid to the occurrence of TRLin breast cancer surveillance.

Decreased Serum Levels of High Mobility Group Box 1 (HMGB-1) after Graft Replacement or Stenting of Abdominal Aortic Aneurysm.

BACKGROUND: High-mobility group box 1 (HMGB-1) is a key substance mediating inflammation and development of atherosclerotic lesions (ALs), including abdominal aortic aneurysms (AAA). Serum levels of HMGB-1 are increased in patients with AAA than those in normal controls because the ALs in AAAs secrete HMGB-1. We therefore postulate that the serum HMGB-1 level should decrease after endovascular aortic repair (EVAR) or open aortic repair (OAR). However, there is no evidence of this in the literature. The purpose of this study was to investigate the changes in HMGB-1 levels after surgical intervention for AAA. We also aimed to determine if the HMGB-1 levels varied between the two procedures. METHODS: Serum HMGB-1 levels were determined in 24 patients with AAA and 25 healthy controls. Twelve of the 24 AAA patients underwent EVAR, whereas the other half underwent OAR. The relationship between HMGB-1 levels and presence of AAA or influence of operative methods on the serum HMGB-1 level were prospectively investigated. RESULTS: Serum HMGB-1 levels in AAA patients were significantly higher than those in healthy controls (9.4 ± 5.7 vs. 4.1 ± 2.0 ng/mL, P < 0.01). The serum HMGB-1 levels in both the EVAR group and the OAR group were significantly decreased from baseline at both 3 mo and 1 y after surgery. CONCLUSIONS: Removal or isolation of AL via surgical intervention significantly decreases serum HMGB-1 levels. The significant postoperative reduction in HMGB-1 levels suggests that important endocrinological changes occur after surgical treatment of AAA.

[Delayed Diagnosis of Aortic Dissection Following Thrombolytic Therapy in a Patient with Acute Ischemic Stroke;Report of a Case].

Diagnosis of aortic dissection complicating cerebral ischemic stroke is difficult. A 60-year-old patient presented at an emergency department of a hospital with a sudden development of left-sided weakness, but without chest pain. During administration of recombinant tissue plasminogen activator with diagnosis of cerebral infarction, he developed symptomatic hypotension and was transferred to our hospital. His chest computed tomography revealed Stanford type A aortic dissection. Replacement of the ascending aorta and aortic arch was successfully performed on the 4th day.

[A Case of StageIV Gastric Cancer with Development of Trousseau's Syndrome during Neoadjuvant Chemotherapy].

In October 2012, a man in his 60s was hospitalized for the examination of ascites, and was diagnosed with gastric cancer and carcinomatous peritonitis. S-1+cisplatin (CDDP) therapy was administered as neoadjuvant chemotherapy; however, during therapy, he developed cerebral infarction. We suspected that the cerebral infarction was caused by a coagulation disorder owing to Trousseau's syndrome. After completing 5 courses of chemotherapy, total gastrectomy was performed. Thereafter, the treatment was changed to S-1+docetaxel(DTX), followed by nab-paclitaxel (PTX). Although cerebral infarction did not relapse after the administration of an anticoagulant agent, the patient died of gastric cancer 1 year and 5 months after the operation. Trousseau's syndrome is a coagulation disorder in cancer patients. Cerebral infarctions caused by Trousseau's syndrome have a high tendency to relapse, and the prognosis is poor. This syndrome should be kept in mind when treating cancer patients.

A paracrine mechanism involving renal tubular cells, adipocytes and macrophages promotes kidney stone formation in a simulated metabolic syndrome environment.

PURPOSE: We developed an in vitro system composed of renal tubular cells, adipocytes and macrophages to simulate metabolic syndrome conditions. We investigated the molecular communication mechanism of these cells and their involvement in kidney stone formation. MATERIALS AND METHODS: Mouse renal tubular cells (M-1) were cocultured with adipocytes (3T3-L1) and/or macrophages (RAW264.7). Calcium oxalate monohydrate crystals were exposed to M-1 cells after 48-hour coculture and the number of calcium oxalate monohydrate crystals adherent to the cells was quantified. The expression of cocultured medium and M-1 cell inflammatory factors was analyzed by enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. RESULTS: The inflammatory markers MCP-1, OPN and TNF-α were markedly up-regulated in cocultured M-1 cells. OPN expression increased in M-1 cells cocultured with RAW264.7 cells while MCP-1 and TNF-α were over expressed in M-1 cells cocultured with 3T3-L1 cells. Coculturing M-1 cells simultaneously with 3T3-L1 and RAW264.7 cells resulted in a significant increase in calcium oxalate monohydrate crystal adherence to M-1 cells. CONCLUSIONS: Inflammatory cytokine changes were induced by coculturing renal tubular cells with adipocytes and/or macrophages without direct contact, indicating that crosstalk between adipocytes/macrophages and renal tubular cells was mediated by soluble factors. The susceptibility to urolithiasis of patients with metabolic syndrome might be due to aggravated inflammation of renal tubular cells triggered by a paracrine mechanism involving these 3 cell types.

Real-time observation of liposome bursting induced by acetonitrile.

We show the bursting process of dioleoylphosphatidylcholine (DOPC) liposomes in response to the addition of acetonitrile, a small toxic molecule widely used in the fields of chemistry and industry. The percentage of destroyed liposomes is reduced upon decreasing the acetonitrile fraction in the aqueous solution and vesicle bursting is not observed at volume ratios of 4:6 and below. This indicates that a high fraction of acetonitrile causes the bursting of liposomes, and it is proposed that this occurs through insertion of the molecules into outer leaflet of the lipid bilayer. The elapsed time between initial addition of acetonitrile and liposome bursting at each vesicle is also measured and demonstrated to be dependent on the volume fraction of acetonitrile and the vesicle size.

Effects of atrial natriuretic peptide after prolonged hypothermic storage of the isolated rat heart.

Primary graft failure (PGF) caused by ischemia-reperfusion injury (IRI) is the strongest determinant of perioperative mortality after heart transplantation. Atrial natriuretic peptide (ANP) has been found to reduce the IRI of cardiomyocytes and may be beneficial in alleviating PGF after heart transplantation, although there is a lack of evidence to support this issue. The purpose of this study was to investigate the cardioprotective effects of ANP after prolonged hypothermic storage. For this purpose, an isolated working-heart rat model was used. After the preparation, the hearts were arrested with and stored in an extracellular-based cardioplegic solution at 3-4°C for 6 h and followed by 25 min of reperfusion. The hearts were divided into four groups (n = 7 in each group) according to the timing of ANP administration: Group 1 (in perfusate before storage), Group 2 (in cardioplegia), Group 3 (in reperfusate), and control (no administration of ANP). Left ventricular functional recovery and the incidence of ventricular fibrillation (VF) were compared. ANP administration at the time of reperfusion improved the percent recovery of left ventricular developed pressure (control, 45.5 ± 10.2; Group 1, 47.4 ± 8.8; Group 2, 45.3 ± 12 vs. Group 3, 76.3 ± 7; P < 0.05) and maximum first derivative of the left ventricular pressure (control, 47.9 ± 8.7; Group 1, 46.7 ± 8.8; Group 2, 49.6 ± 10.8 vs. Group 3, 76.6 ± 7.5; P < 0.05). The incidence of VF after reperfusion did not differ significantly among these four groups (71.4, 85.7, 57.1, and 85.7% in Groups 1, 2, 3, and control, respectively). This result suggests that the administration of ANP at the time of reperfusion may have the potential to decrease the incidence of PGF after heart transplantation.

Comprehensive hemocompatibility analysis on the application of diamond-like carbon to ePTFE artificial vascular prosthesis.

The aim of this study was to obtain comprehensive data regarding the hemocompatibility of diamond-like carbon (DLC)-coated expanded polytetrafluoroethylene (ePTFE). DLC increased the hydrophilicity and smoothened the surface and fibrillar structure, respectively, of the ePTFE. DLC-coated ePTFE had more albumin and fibrinogen adsorption and less platelet adhesion than uncoated ePTFE. There were scarce red cell attachments in in vitro human and in vivo animal (rat and swine) whole blood contact tests in both DLC-coated and uncoated ePTFE. DLC-coated ePTFE had a similar but marginally thicker band movement than uncoated-ePTFE with SDS-PAGE after human whole blood contact test. In addition, survival studies of aortic graft replacement in rats (1.5 mm graft) and arteriovenous shunt in goats (4 mm graft) were performed to compare the patency and clot formation between DLC-coated and uncoated ePTFE grafts. Comparable patency was observed in both animal models. However, clots were observed in the luminal surface of the patent 1.5 mm DLC-coated ePTFE grafts, but not in that of uncoated ePTFE grafts. In conclusions, hemocompatibility of DLC-coated ePTFE was high and comparable to that of uncoated ePTFE. However, it failed to improve the hemocompatibility of 1.5 mm ePTFE graft probably because increased fibrinogen adsorption canceled the other beneficial effects of DLC.

A Multicenter, Prospective, Non-randomized Study Evaluating Surgical hand Preparation between Double-Gloving and Single-Gloving for Preventing Postoperative Infection in Robotic and Laparoscopic Minimally Invasive Surgeries.

PURPOSE: This study aimed to analyze a feasible and suitable surgical precautionary preparatory technique. The techniques of double-gloving with hygienic hand wash (DH) and single-gloving with surgical hand wash (SS) were compared for their ability to prevent postoperative infection in robotic and laparoscopic minimally invasive surgeries. MATERIALS AND METHODS: A prospective, non-randomized, multicenter study was conducted between January 2016 and June 2020. We divided the robotic and laparoscopic cases into two groups: DH and SS. Data on infectious outcomes were collected. Propensity score matching was performed to control for operative characteristics between the two groups. The primary endpoint was the presence of fever and surgical site infections (SSIs) indicating postoperative infection. RESULTS: Among four medical centers, seven surgeons were allocated to either the DH or the SS group. A total of 221 and 251 patients underwent DH and SS, respectively. Propensity score matching, which included 171 cases from each group, showed that the incidence of fever during hospitalization was significantly lower in the DH group than that in the SS group (11.7% vs. 23.4%, p=0.007). Multivariable analysis revealed that DH was associated with a reduced odds ratio for developing postoperative fever during hospitalization (risk ratio: 0.49, p=0.043). No differences were found in SSI before and after hospitalization between the two groups. CONCLUSION: DH resulted in less postoperative fever and had a comparable effect in preventing SSIs. This procedure could be an alternative to the SS protocol in some minimally invasive surgeries.

Biomolecular mechanism of urinary stone formation involving osteopontin.

Urinary stones consist of two phases-an inorganic (mineral) phase and an organic (matrix) phase. Studies on the organic components of kidney stones have been undertaken later than those on the inorganic components. After osteopontin was identified as one of the matrix components, the biomolecular mechanism of urinary stone formation became clearer. It also triggered the development of new preventive treatments. Osteopontin expression is sporadically observed in normal distal tubular cells and is markedly increased in stone-forming kidneys. Calcium oxalate crystals adhering to renal tubular cells are incorporated into cells by the involvement of osteopontin. Stimulation of crystal-cell adhesion impairs the opening of mitochondrial permeability transition pores (mPTP) in tubular cells and produces oxidative stress, apoptosis, and osteopontin expression. Macrophages phagocytose and digest a small amount of crystals, but many crystals aggregate into a mass containing osteopontin and epithelial cell debris and are excreted into the renal tubular lumen, becoming nuclei of urinary stones. This biomolecular mechanism is similar to atherosclerotic calcification. Based on these findings, new preventive treatments have been developed. Dietary control such as low-cholesterol intake and the ingestion of antioxidative foods and vegetables have successfully reduced the 5-year recurrence rate. Osteopontin antibodies and cyclosporine A, which blocks the opening of mPTP, have markedly inhibited the expression of osteopontin and urinary stone formation in animal models.

Atrionatriuretic peptide improves left ventricular function after myocardial global ischemia-reperfusion in hypoxic hearts.

Atrionatriuretic peptide (ANP) is reported to be useful for attenuating myocardial ischemia-reperfusion injury and improving left ventricular function after reperfusion. However, ANP may be either ineffectual or harmful in cases where the myocardium has been chronically hypoxic since birth. This can be a result of the concomitant high levels of cyclic guanosine monophosphate (cGMP) produced within the myocardium. This study aimed to verify the validity of using ANP to improve left ventricular function after myocardial ischemia-reperfusion injury. For this purpose, a cyanotic congenital disease model that was developed using isolated rat hearts was used. Hearts were obtained from Sprague-Dawley rats that were housed from birth until 6 weeks of age either in a hypoxic environment with 13-14% FiO(2) (hypoxic group) or in ambient air (normoxic group). These hearts were subjected to 30min of normothermic global ischemia followed by 30min of reperfusion using the Langendorff technique. Left ventricular functional recovery in hearts administered ANP (0.1µM) into the reperfusion solution was compared with those hearts that were not administered ANP in both hypoxic (without ANP: n=6, with ANP: n=6, with ANP and HS-142-1[an antagonist of ANP]: n=6) and normoxic hearts (without ANP: n =6, with ANP: n=6). In the hypoxic hearts, ANP administration improved the percent recovery of the left ventricular developed pressure (76.3±9.2% without ANP vs. 86.9±6.7% with ANP), maximum first derivative of the left ventricular pressure (82.4±1.1% without ANP vs. 95.8±6.5% with ANP), and heart rate (85.6±4.7% without ANP vs. 96.1±5.2% with ANP) after reperfusion. The improvement and recovery of these cardiac functions were closely related to significantly increased levels of postischemic cGMP release after ANP administration. The effect of ANP was blocked by HS-142-1. The improvements observed in the hypoxic group were similar to those found in the normoxic group. ANP administration during reperfusion improved left ventricular function after myocardial acute global ischemia-reperfusion equally in both the chronically hypoxic and age-matched normoxic groups.

Atrioventricular valve repair for patient with heterotaxy syndrome and a functional single ventricle.

Heterotaxy syndrome is a mortality risk factor for patients with complex heart disease. These patients often have common atrioventricular valve (CAVV) morphology and significant atrioventricular valve regurgitation - yet another mortality risk factor in congenital heart disease. Thus, patients with both heterotaxy syndrome and atrioventricular valve regurgitation are at highest risk of mortality. A large number of patients with heterotaxy syndrome have CAVV and a functional single ventricle. These patients are more difficult to operate than patients with biventricular morphology because in the former, the CAVV is often less adapted to systemic afterload than the mitral valve. Herein, we present the results of atrioventricular valve repair surgeries performed at the Okayama University Hospital on patients with heterotaxy syndrome, atrial isomerism, and a functional single ventricle. In addition, we review the current literature in this typically challenging patient population. In-depth understanding of reasonable management strategies and resolution of technical issues will help guide surgeons during this procedure.

Densification in transparent SiO2 glasses prepared by spark plasma sintering.

Recently, spark plasma sintering (SPS) has become an attractive method for the preparation of solid-state ceramics. As SPS is a pressure-assisted low-temperature process, it is important to examine the effects of temperature and pressure on the structural properties of the prepared samples. In the present study, we examined the correlation between the preparation conditions and the physical and structural properties of SiO2 glasses prepared by SPS. Compared with the conventional SiO2 glass, the SPS-SiO2 glasses exhibit a higher density and elastic modulus, but a lower-height first sharp diffraction peak of the X-ray total structure factor. Micro-Raman and micro-IR spectra suggest the formation of heterogeneous regions at the interface between the SiO2 powders and graphite die. Considering the defect formation observed in optical absorption spectra, reduction reaction mainly affects the densification of SPS-SiO2 glass. Hence, the reaction at the interface is important for tailoring the structure and physical properties of solid-state materials prepared by the SPS technique.

Investigation of the vibrational density of states of sodium carboxymethyl starch glass via terahertz time-domain spectroscopy.

We investigated the vibrational density of states of sodium carboxymethyl starch (CM-starch) by terahertz (THz) time-domain spectroscopy. The CM-starch showed a broad peak at ∼3 THz. The structure of the peak was similar to those corresponding to glucose-based polymer glasses possessing hydrogen bonds. The boson peak (BP) appeared at 1.16 THz at the lowest temperature and disappeared because of the existence of excess wing at higher temperatures. However, based on our novel BP frequency determination method using the inflection point of the extinction coefficient, the BP frequency showed almost no dependence on temperature. Further, the chain length dependence of the BP frequency of the glucose-based glasses showed that the BP frequency of the polymer glass was slightly lower than that of the monomer glass. The power law behaviour of the absorption coefficient suggested the existence of fractons, and the fractal dimension was estimated to be 2.33.

[Functional domains of osteopontin stimulate renal crystal formation: analysis of OPN-transgenic mice].

Osteopontin (OPN) has been described to play a nonredundant role in the formation of renal crystals. This biological activity of OPN may be attributed to its characteristic structure, which includes 2 calcium binding sites, Arg-Gly-Asp (RGD) sequences. To test this hypothesis, we evaluated wild-type mice (WT group), OPN-knockout mice (KO group), and two types of transgenic mice : (1) one type carrying a transgene in which the sequences coding for the 2 calcium-binding sites of the OPN were deleted (CaX group) and (2) the other type carrying a transgene in which the sequence that codes for the RGD sequence of the OPN was modified to one that codes for Arg-Gly-Glu (RGE ; RGE group). Changes occurring after intraperitoneal injection of glyoxylate for 9 d were analyzed. The amount of crystals deposited was the greatest in mice of the WT group and the least in those of the KO group. The number of crystal deposits in mice of the RGE and KO groups was approximately the same. Microscopic observations revealed that the crystal nuclei in mice in the CaX group were stratified and exhibited a disordered pattern ; this pattern was dissimilar to that observed in the mice in the WT and RGE groups, wherein the crystal nuclei exhibited a rosette petal-like radial pattern. The results indicate the possibility that each domain contributes to the mechanism by which OPN stimulates crystal formation.

[Molecular mechanism of renal stone formation].

Urolithiasis is a multifactorial disease involving environmental and gentic factors. Calcium-containing stones, which are>90% of all stones, detected most frequently ; however, radically effective prevention and detailed investigation of crystal formation have not been established. Renal stone formation is a complex multistep process that includes supersaturation, crystal nucleation, growth, and aggregation. In the early stage of crystal formation, exposure to high concentrations of oxalate can induce renal tubular cell injury, following crystal attachment to renal tubular cell in which stone matrix proteins or urinary high molecular substances play an important role as a promoter or inhibitor respectively. Recent study speculated that renal macrophage could englobe crystals and might digest them. In this part, we propose the molecular mechanism that has been newly investigated recently, in renal stone formation.