Two-photon optogenetics-based assessment of neuronal connectivity in healthy and chronic hypoperfusion mice.

Significance: Two-photon optogenetics and simultaneous calcium imaging can be used to visualize the response of surrounding neurons with respect to the activity of an optically stimulated target neuron, providing a direct method to assess neuronal connectivity. Aim: We aim to develop a two-photon optogenetics-based method for evaluating neuronal connectivity, compare it to the existing indirect resting-state synchrony method, and investigate the application of the method to brain pathophysiology. Approach: C1V1-mScarlet was introduced into GCaMP6s-expressing transgenic mice with an adeno-associated virus. Optical stimulation of a single target neuron and simultaneous calcium imaging of the target and surrounding cells were performed. Neuronal connectivity was evaluated from the correlation between the fluorescence intensity of the target and surrounding cells. Results: The neuronal connectivity in the living brain was evaluated using two-photon optogenetics. However, resting-state synchrony was not always consistent with two-photon optogenetics-based connectivity. Comparison with neuronal synchrony measured during sensory stimulation suggested that the disagreement was due to external sensory input. Two-photon optogenetics-based connectivity significantly decreased in the common carotid artery occlusion model, whereas there was no significant change in the control group. Conclusions: We successfully developed a direct method to evaluate neuronal connectivity in the living brain using two-photon optogenetics. The technique was successful in detecting connectivity impairment in hypoperfusion model mice.

Possible roles of short-chain fatty acids produced by oral bacteria in the development of alveolar osteitis.

PURPOSE: Alveolar osteitis (dry sockets) is a painful condition characterized by a limited immune response. It is typically caused by the removal of blood clots from extracted tooth sockets, which leads to the fermentation of trapped food remnants by oral bacteria in the cavities, producing high concentrations of short-chain fatty acids (SCFAs). This study examined the effects of SCFAs on immunity and bone metabolism. METHODS: Mouse macrophage Raw264.7 cells were treated with oral bacteria supernatants or SCFA mixtures, and inducible nitric oxide synthase (iNOS) levels were determined by western blot. The same cells were treated with SCFA mixtures in the presence of receptor activator of nuclear factor-kappa B ligand (RANKL), and osteoclast-like cells were counted. MC3T3-E1 cells were treated with SCFA mixtures and stained with alizarin red S. RESULTS: Raw264.7 cells treated with oral bacterial culture supernatants of Porphyromonas gingivalis and Fusobacterium nucleatum inhibited lipopolysaccharide (LPS)-induced iNOS production, likely due to SCFA content. SCFA mixtures mimicking these supernatants inhibited the number of RANKL-induced tartrate-resistant acid phosphatase (TRAP)-positive cells and MC3T3-E1 cell mineralization. CONCLUSION: These data suggest that SCFAs produced by P. gingivalis and F. nucleatum may reduce the inflammatory response and mildly induce mineralization of the alveolar walls. These results may contribute to the understanding of alveolar osteitis.

Analysis of the effect of different doses of oral tranexamic acid on melasma: a multicentre prospective study.

BACKGROUND: Melasma is pale brown to dark brown hyperpigmentation of the facial skin that commonly affects women of reproductive age. Treatment methods for melasma include oral and topical use of vitamin C, hydroquinone ointment, and laser treatment, with unsatisfactory results. Tranexamic acid (TA) has been shown to be effective against melasma, however, the optimal dose has not been investigated. OBJECTIVE: To analyse the therapeutic effect of different doses of oral TA on melasma. MATERIALS & METHODS: Patients with severe melasma were randomised to receive TA at a daily dose of 500 mg, 750 mg, 1,000 mg, or 1,500 mg. Clinical and VISIA photographs of the patients were taken at baseline, four weeks, eight weeks, six months, one year, and two years. The melasma area and severity index (MASI), as well as the melanin index, were measured. Routine blood and coagulation tests were performed at each time point. The photographs were divided into five groups according to level of improvement: apparent improvement, slight improvement, unchanged, and deterioration. RESULTS: Clinical photographs showed that all four doses of TA were effective in treating melasma, and the efficacy correlated with treatment time and dosage. However, there were no significant differences in the MASI or melanin index between the four doses. The treatment was generally safe for most patients and side effects included mild stomach upset and decreased menstruation. CONCLUSION: Oral TA was safe and effective for the treatment of melasma. Patient satisfaction was high and most patients could withstand long-term treatment.