Phenolic Tyrosinase Substrate with a Formal Potential Lower than That of Phenol to Obtain a Sensitive Electrochemical Immunosensor.

The high and selective catalytic activities of tyrosinase (Tyr) have frequently led to its application in sensitive biosensors. However, in affinity-based biosensors, the use of Tyr as a catalytic label is less common compared to horseradish peroxidase and alkaline phosphatase owing to the fact that phenolic Tyr substrates have yet to be investigated in detail. Herein, four phenolic compounds that have lower formal potentials than phenol were examined for their applicability as Tyr substrates, and three reducing agents were examined as potential strong reducing agents for electrochemical-chemical (EC) redox cycling involving an electrode, a Tyr product, and a reducing agent. The combination of 4-methoxyphenol (MP) and ammonia-borane (AB) allows for (i) a high electrochemical signal level owing to rapid EC redox cycling and (ii) a low electrochemical background level owing to the slow oxidation of AB at a low applied potential and no reaction between MP and AB. When this combination was applied to an electrochemical immunosensor for parathyroid hormone (PTH) detection, a detection limit of 2 pg/mL was obtained. This detection limit is significantly lower than that obtained when a combination of phenol and AB was employed (300 pg/mL). It was also found that the developed immunosensor works well in PTH detection in clinical serum samples. This new phenolic substrate could therefore pave the way for Tyr to be more commonly used as a catalytic label in affinity-based biosensors.

Hair growth promotion by necrostatin-1s.

Necrostatins (Necs) have been developed as a receptor-interacting protein kinase 1 (RIPK1) inhibitor, thus inhibiting necroptosis. In this current study, we have investigated the possible involvement of necroptosis in the hair cycle regulation and further examined its underlying molecular mechanisms. Diverse RIPK1/3 inhibitors and siRNA were tested in the human outer-root sheath (ORS) cells and animal models. The expression and hair cycle-dependent expression of RIPK 1, respectively, were investigated in the hair follicles (HF) of human, pig, and the mouse. Resulting from the experiment, Nec-1s was most effective in the hair growth promotion among several inhibitors. Nec-1s induced the ORS cell proliferation and migration, and increased the HF length in mouse and pig organ cultures. In addition, it accelerated the telogen-to-anagen transition and elongated the anagen period in the mouse model. Both apoptosis and necroptosis were detected in hair cycle. RIPK1 and RIPK3 were highly expressed in ORS cells during the hair regression period. Nec-1s upregulated the mRNA expression of Wnt3a and Wnt5b, and the activity of ß-catenin. Collectively, Nec-1s promotes hair growth through inhibiting necroptosis and activating the Wnt/ß-catenin pathway. Necroptosis is involved in hair cycle regression, and Nec-1s is a promising target for hair-loss treatment.

Alterations of aqueous humor Aß levels in Aß-infused and transgenic mouse models of Alzheimer disease.

Alzheimer's disease (AD) is an ageing-related neurodegenerative disease characterized and diagnosed by deposition of insoluble amyloid-ß (Aß) plaques in the brain. The plaque accumulation in the brain directly affects reduced levels of Aß in cerebrospinal fluid (CSF) and blood, as Aß can freely transport the blood-brain barrier, and clinical investigations have suggested these two biofluids as promising samples for in vitro diagnosis. Given that the human eye structurally resembles the brain and Aß accumulation often observed in the ocular region of AD patients, in this study, we examined aqueous humor Aß as another possible surrogate biomarker. First, using the acute Aß-infused AD mouse model by injecting Aß to the CSF in intracerebroventricular region of normal ICR mice, we investigated whether Aß concentration in the aqueous humor in AD models is positively correlated with the concentration in the CSF. Then, we examined the correlation of aqueous humor Aß levels with increased plaque deposition in the brain and reduced Aß levels in both CSF and blood in adult and aged 5XFAD Alzheimer transgenic mice. Collectively, the synthetic Aß injected into CSF immediately migrate to the aqueous humor, however, the age-dependently reducing pattern of Aß levels in CSF and blood was not observed in the aqueous humor.