[Incidence of leptospirosis in Fujian province, 2015-2020]

Objective: To analyze the incidence of leptospirosis in Fujian province from 2015 to 2020 and provide the scientific evidences for the risk assessment, prevention and control of leptospirosis. Methods: The incidence data of leptospirosis in Fujian during 2015-2020 were collected from China Information System for Disease Control and Prevention for a descriptive analysis, and software ArcGIS 10.3.1 was used for spatial autocorrelation analysis, and rats were captured in 17 surveillance areas during the same period, and the rat organs were collected for pathogen culture, the level of Leptospira antibody was detected in serum samples of rats, healthy population and the serum samples of patients sent by the hospitals. The infection status of Leptospira in human and rats were analyzed. Results: The incidence of leptospirosis in Fujian showed a downward trend from 2015 to 2020. A total of 176 cases of leptospirosis were reported. There were obvious seasonality and bimodal distribution. The majority of cases were farmers, accounting for 49.43% (87/176). Most cases were aged 30-69 years (85.80%, 151/176). The male to female ratio of the cases was 3.51∶1 (137∶39). Spatial autocorrelation analysis showed that leptospirosis had high or low clustering areas. From 2015 to 2020, the average capture rate of rats in 17 surveillance areas was 6.96% (1 519/21 838), Rattus losea, Rattus flavipectus and Niviventer fulvescens were the main species. The average positive rate of Leptospira antibody in rats was 28.64% (252/880). Java and Autumnalis were the predominant serogroups, accounting for 56.75% (143/252) and 17.46% (44/252), respectively. The average positive rate of Leptospira antibody in healthy population was 16.13% (254/1 575), and Autumnalis and Australis were the predominant serogroups, accounting for 71.65% (182/254). The confirmation rate of leptospirosis in patient serum samples sent by the hospitals was 2.23% (188/8 431), Autumnalis (56.38%, 106/188) and Hebdomadis (19.68%, 37/188) were the major serogroups. Conclusions: The incidence of leptospirosis in Fujian showed a downward trend from 2015 to 2020, there were obvious area clustering and seasonality. The high clustering areas were mainly distributed in northern, western and central Fujian. Java and Autumnalis were the predominant serogroups in rats. The infection rate in healthy population decreased year by year. Autumnalis and Hebdomadis were the main serogroups in population in Fujian.

Hypoxia improves hair inductivity of dermal papilla cells via nuclear NADPH oxidase 4-mediated reactive oxygen species generation'

BACKGROUND

Dermal papilla cells (DPCs) play a key role in hair regeneration and morphogenesis. Therefore, tremendous efforts have been made to promote DPC hair inductivity.

OBJECTIVES

The aim of this study was to investigate the mitogenic and hair inductive effects of hypoxia on DPCs and examine the underlying mechanism of hypoxia-induced stimulation of DPCs.

METHODS

DPCs' hair inductivity was examined under normoxia (20% O₂ ) and hypoxia (2% O₂ ).

RESULTS

Hypoxia significantly increased the proliferation and delayed senescence of DPCs via Akt phosphorylation and downstream pathways. Hypoxia upregulated growth factor secretion of DPCs through the mitogen-activated protein kinase pathway. Hypoxia-preconditioned DPCs induced the telogen-to-anagen transition in C₃ H mice, and also enhanced hair neogenesis in a hair reconstitution assay. Injected green fluorescent protein-labelled DPCs migrated to the outer root sheath of the hair follicle, and hypoxia-preconditioning increased survival and migration of DPCs in vivo. Conditioned medium obtained from hypoxia increased the hair length of mouse vibrissa follicles via upregulation of alkaline phosphatase, vascular endothelial growth factor, and glial cell line-derived neurotrophic factor. We examined the mechanism of this hypoxia-induced stimulation, and found that reactive oxygen species (ROS) play a key role. For example, inhibition of ROS generation by N-acetylcysteine or diphenyleneiodonium treatment attenuated DPCs' hypoxia-induced stimulation, but treatment with ROS donors induced mitogenic effects and anagen transition. NADPH oxidase 4 is highly expressed in the DPC nuclear region, and NOX4 knockout by CRISPR-Cas9 attenuated the hypoxia-induced stimulation of DPCs.

CONCLUSIONS

Our results suggest that DPC culture under hypoxia has great advantages over normoxia, and is a novel solution for producing DPCs for cell therapy. What's already known about this topic? Dermal papilla cells (DPCs) play a key role in hair regeneration and morphogenesis, but they are difficult to isolate and expand for use in cell therapy. Tremendous efforts have been made to increase proliferation of DPCs and promote their hair formation ability. What does this study add? Hypoxia (2% O₂ ) culture of DPCs increases proliferation, delays senescence and enhances hair inductivity of DPCs. Reactive oxygen species play a key role in hypoxia-induced stimulation of DPC. What is the translational message? Preconditioning DPCs under hypoxia improves their hair regenerative potential, and is a novel solution for producing DPCs for cell therapy to treat hair loss.

Effect of growth condition on enzymes of the citric acid cycle and the glyoxylate cycle in the photosynthetic bacterium Rhodopseudomonas palustris

The enzymes of the citric acid and glyoxylate cycles as well as RuBP4 carboxylase were measured in cell-free extracts from Rhodopseudomonas palustris after growth under chemoheterotrophic, photoheterotrophic and photolithotrophic conditions. Although the citric acid cycle was found to be complete under all growth conditions, significant differences in certain enzyme activities occurred as a function of the different energy sources applied. The glyoxylate cycle also was complete under all growth conditions with highest isocitrate lyase activity seen after photoheterotrophic growth on acetate. Photo- and chemoheterotrophic growth on malate reduced the isocitrate lyase. The activity was not repressed further by photolithotrophic growth on thiosulfate. RuBP carboxylase activity, present under photolithotrophic conditions, was repressed by chemoheterotrophic growth but was not decreased by the presence of organic substrates during photoheterotrophic growth.