Pre-implantation evaluation of a small-diameter, long vascular graft (Biotube®) for below-knee bypass surgery in goats.

There are no small-diameter, long artificial vascular grafts for below-knee bypass surgery in chronic limb-threatening ischemia. We have developed tissue-engineered vascular grafts called "Biotubes®" using a completely autologous approach called in-body tissue architecture (iBTA). This study aimed at pre-implantation evaluation of Biotube and its in vivo preparation device, Biotube Maker, for use in below-knee bypass surgery. Forty nine makers were subcutaneously embedded into 17 goats for predetermined periods (1, 2, or 3 months). All makers produced Biotubes as designed without inflammation over all periods, with the exception of a few cases with minor defects (success rate: 94%). Small hole formation occurred in only a few cases. All Biotubes obtained had an inner diameter of 4 mm and a length of 51 to 52 cm with a wall thickness of 594 ± 97 µm. All Biotubes did not kink when completely bent under an internal pressure of 100 mmHg and did not leak without any deformation under a water pressure of 200 mmHg. Their burst strength was 2409 ± 473 mmHg, and suture retention strength was 1.75 ± 0.27 N, regardless of the embedding period, whereas tensile strength increased from 7.5 ± 1.3 N at 1 month to 9.7 ± 2.0 N at 3 months with the embedding period. The amount of water leakage from the needle holes prepared in the Biotube wall was approximately 1/7th of that in expanded polytetrafluoroethylene vascular grafts. The Biotubes could be easily connected to each other without cutting or anastomosis leaks. They could be stored for at least 1 year at room temperature. This study confirmed that even Biotubes formed 1 month after embedding of Biotube Makers had properties comparable to arteries.

Efficacy of a silicone plug for patulous eustachian tube: A prospective, multicenter case series.

OBJECTIVES/HYPOTHESIS: To report the efficacy and safety of transtympanic plugging of the eustachian tube (ET) using a silicone plug (Kobayashi plug) for chronic patulous ET (PET). STUDY DESIGN: Prospective and multicenter trial conducted in which 30 PET patients were resistant to at least 6 months of conservative treatment. METHODS: The efficacy and safety of 28 and 27 patients, respectively, were analyzed. All patients fulfilled inclusion and exclusion criteria. The primary end point used the patulous eustachian tube handicap inventory-10 (PHI-10), and the secondary end point used ET function tests such as sonotubometry, tubo-tympano-aerodynamic-graphy, and respiratory movement of the tympanic membrane and auscultation of voice sounds transmitted from the nose through the ET to the external auditory canal at 3months after surgery. RESULTS: PHI-10 scores were 34.4 ± 4.2, 6.4 ± 9, and 5.7 ± 8.6 at screening, and 3 and 6 months after surgery. Twenty-three cases (82.1%, 95% confidence interval: 63.1%-93.9%) were judged as successes. There were five cases (17.2%) of middle ear effusion, four cases (13.8%) of tympanic membrane perforation, and one case of tinnitus due to surgery to remove the plug. No severe or life-threatening complications were found. CONCLUSIONS: This study revealed the efficacy and safety of silicone plug insertion for severe PET patients. LEVEL OF EVIDENCE: 2 Laryngoscope, 130:1304-1309, 2020.

A mitochondria-targeted fluorescent probe for selective detection of mitochondrial labile Fe(ii).

Mitochondria are iron-rich organelles that are involved in the process of energy production through the electron-transporting system and heme synthesis. We developed a new mitochondria-targeted fluorescent probe, MtFluNox/Ac-MtFluNox, for Fe(ii) based on N-oxide chemistry, which we recently established as a Fe(ii)-selective fluorogenic switch. The deacetylated form MtFluNox showed a turn-on response towards Fe(ii) with high metal selectivity in cuvette experiments, and an imaging study using its cell-compatible analogue Ac-MtFluNox demonstrated mitochondria-specific fluorescence enhancement in response to Fe(ii) in living cells. Furthermore, the probe was able to detect endogenously accumulated Fe(ii) induced as a result of the inhibition of heme synthesis.

A universal fluorogenic switch for Fe(ii) ion based on N-oxide chemistry permits the visualization of intracellular redox equilibrium shift towards labile iron in hypoxic tumor cells.

Iron (Fe) species play a number of biologically and pathologically important roles. In particular, iron is a key element in oxygen sensing in living tissue where its metabolism is intimately linked with oxygen metabolism. Regulation of redox balance of labile iron species to prevent the generation of iron-catalyzed reactive oxygen species (ROS) is critical to survival. However, studies on the redox homeostasis of iron species are challenging because of a lack of a redox-state-specific detection method for iron, in particular, labile Fe2+. In this study, a universal fluorogenic switching system is established, which is responsive to Fe2+ ion based on a unique N-oxide chemistry in which dialkylarylamine N-oxide is selectively deoxygenized by Fe2+ to generate various fluorescent probes of Fe2+-CoNox-1 (blue), FluNox-1 (green), and SiRhoNox-1 (red). All the probes exhibited fluorescence enhancement against Fe2+ with high selectivity both in cuvette and in living cells. Among the probes, SiRhoNox-1 showed an excellent fluorescence response with respect to both reaction rate and off/on signal contrast. Imaging studies were performed showing the intracellular redox equilibrium shift towards labile iron in response to reduced oxygen tension in living cells and 3D tumor spheroids using SiRhoNox-1, and it was found that the hypoxia induction of labile Fe2+ is independent of iron uptake, hypoxia-induced signaling, and hypoxia-activated enzymes. The present studies demonstrate the feasibility of developing sensitive and specific fluorescent probes for Fe2+ with refined photophysical characteristics that enable their broad application in the study of iron in various physiological and pathological conditions.