Effects of spaceflight and simulated microgravity on microbial growth and secondary metabolism

Spaceflight and ground-based microgravity analog experiments have suggested that microgravity can affect microbial growth and metabolism. Although the effects of microgravity and its analogs on microorganisms have been studied for more than 50 years, plausible conflicting and diverse results have frequently been reported in different experiments, especially regarding microbial growth and secondary metabolism. Until now, only the responses of a few typical microbes to microgravity have been investigated; systematic studies of the genetic and phenotypic responses of these microorganisms to microgravity in space are still insufficient due to technological and logistical hurdles. The use of different test strains and secondary metabolites in these studies appears to have caused diverse and conflicting results. Moreover, subtle changes in the extracellular microenvironments around microbial cells play a key role in the diverse responses of microbial growth and secondary metabolisms. Therefore, "indirect" effects represent a reasonable pathway to explain the occurrence of these phenomena in microorganisms. This review summarizes current knowledge on the changes in microbial growth and secondary metabolism in response to spaceflight and its analogs and discusses the diverse and conflicting results. In addition, recommendations are given for future studies on the effects of microgravity in space on microbial growth and secondary metabolism.

Change in drug resistance of staphylococcus aureus

Objective To analyze the change in drug resistance of staphylococcus aureus(SAU) in the PLA general hospital from January 2008 to December 2012, and to provide solid evidence to support the rational use of antibiotics for clinical applications. Methods The SAU strains isolated from clinical samples in the hospital were collected and subjected to the Kirby-Bauer disk diffusion test. The results were assessed based on the 2002 American National Committee for Clinical Laboratory Standards(NCCLS) guidelines. Results SAU strains were mainly isolated from sputum, urine, blood and wound excreta and distributed in penology, neurology wards, orthopedics and surgery ICU wards. Except for glycopeptide drugs, methicillinresistant staphylococcus aureus(MRSA) had a higher drug resistance rate than those of the other drugs and had significantly more resistance than methicillin-sensitive staphylococcus aureus(MSSA)(P<0.05). In the dynamic observation of drug resistance, we discovered a gradual increase in drug resistance to fourteen test drugs during the last five years. Conclusion Drug resistance rate of SAU stayed at a higher level over the last five years; moreover, the detection ratio of MRSA keeps rising year by year. It is crucial for physicians to use antibiotics rationally and monitor the change in drug resistance in a dynamic way.

Novel therapy for idiopathic pulmonary arterial hypertension： Can hepatocyte growth factor be beneficial？

Idiopathic pulmonary arterial hypertension （IPAH） is a progressive, nearly fatal condition that until recently has had very few treatment options. Median survival time for untreated IPAH was 2.8 years without effective drug intervention. IPAH is characterized by deregulated proliferation of pulmonary arterial endothelial and intimal smooth muscle cells resulting in progressive pulmonary vascular remodeling and an increase in pulmonary arterial pressure. In order to alleviate their symptoms, anticoagulants, diuretics, calcium channel blockers and inotropic agents have been used to treat patients with PAH. Moreover, specific targeted therapies using prostacyclins,