Development of a cryogen-free sub-3 K low-temperature scanning probe microscope by remote liquefaction scheme.

We developed a new scheme for cryogen-free cooling down to sub-3 K temperature range and ultra-low vibration level. An ultra-high-vacuum cryogen-free scanning probe microscope (SPM) system was built based on the new scheme. Instead of mounting a below-decoupled cryocooler directly onto the system, the new design was realized by integrating a Gifford-McMahon cryocooler into a separate liquefying chamber, providing two-stage heat exchangers in a remote way. About 10 L of helium gas inside the gas handling system was cooled, liquefied in the liquefying chamber, and then transferred to a continuous-flow cryostat on the SPM chamber through an ∼2 m flexible helium transfer line. The exhausted helium gas from the continuous-flow cryostat was then returned to the liquefying chamber for reliquefaction. A base temperature of ∼2.84 K at the scanner sample stage and a temperature fluctuation of almost within ±0.1 mK at 4 K were achieved. The cooling curves, tunneling current noise, variable-temperature test, scanning tunneling microscopy and non-contact atomic force microscopy imaging, and first and second derivatives of I(V) spectra are characterized to verify that the performance of our cryogen-free SPM system is comparable to the bath cryostat-based low-temperature SPM system. This remote liquefaction close-cycle scheme shows conveniency to upgrade the existing bath cryostat-based SPM system, upgradeability of realizing even lower temperature down to sub-1 K range, and great compatibility of other physical environments, such as high magnetic field and optical accesses. We believe that the new scheme could also pave a way for other cryogenic applications requiring low temperature but sensitive to vibration.

Comparison of microscopic transsphenoidal surgery and neuroendoscopic transsphenoidal surgery in pituitary adenoma resection and the risk factors of postoperative cerebrospinal fluid leakage.

OBJECTIVE: To compare microscopic transsphenoidal surgery (MTS) and neuroendoscopic transsphenoidal surgery (NTS) in pituitary adenoma (PA) resection and analyze the risk factors of postoperative cerebrospinal fluid leakage (CFL). METHODS: The clinical data of 127 patients with PA treated in Xi'an International Medical Center Hospital from January 2019 to January 2021 were analyzed retrospectively. Among them, 54 patients treated by MTS for PA resection were assigned to the control group, while the rest of the 73 patients treated by NTS for PA resection were assigned to the study group. The total tumor resection rate, decrease of hormone levels after operation, alleviation of primary symptoms and complications were compared between the two groups. Logistics regression analysis was conducted to analyze the risk factors of CFL. RESULTS: The control group experienced a shorter operation time than the study group (P<0.001). The resection rates of the control and study groups were comparable, but the study group showed a lower incidence of postoperative complications than the control group (P = 0.004). In addition, the study group showed better alleviation of primary symptoms than the control group (P = 0.013). After surgery, the two groups presented decreased levels of prolactin and growth hormone (P<0.001), and also showed decreased average adrenocorticotropic hormone (P<0.001). Moreover, the two groups were not significantly different in the levels of prolactin, growth hormone and adrenocorticotropic hormone after surgery (P>0.05). According to multivariate logistics regression analysis, body mass index (BMI) (P = 0.003, OR = 8.791, 95% CI: 2.050-37.693), intraoperative CFL (P = 0.002, OR = 21.614, 95% CI: 0.305-153.162) and therapeutic regimen (P = 0.011, OR = 7.060, 95% CI: 1.554-32.076) were independent risk factors for postoperative CFL. CONCLUSION: Compared with MTS, endoscopic transsphenoidal surgery requires a notably longer time, but it can strongly improve the total resection rate of patients and reduce the incidence of postoperative complications. Endoscopic surgery is a protective factor of postoperative CFL.

Systems pharmacology approach to investigate the mechanism of Artemisia argyi in treating rheumatic diseases.

Artemisia argyi (AA) has been proven to be effective in the adjuvant treatment of rheumatism (RA), but the mechanism of its action in RA is not clear. This study aims to clarify the molecular mechanism of AA as a potential therapy for RA by using network pharmacology. The TCM systems pharmacology (TCMSP) was used to screen the active components of AA, and identification of the potential target genes of active compounds and rheumatism was performed with PharmMapper and GeneCards, respectively. Construction of complex target networks and protein-protein interaction networks was based on the Cytoscape software. The biological functions and pathway analysis of targets and effective targets were analyzed using DAVID. Our study demonstrated that 105 target genes were associated with these active compounds and RA. ALB, AKT1, and MAPK1 were the first three hub genes, and the metabolic and signaling pathways related to these hub genes were remarkably abundant. Results showed that AA might play a role in RA by affecting multiple targets and multiple ways, reflecting that TCM was characterized by multicomponents and multitargets. AA has the potential to be a promising new candidate for the treatment of RA and has value for further research and development.

Small molecule RHP1 promotes root hair tip growth by acting upstream of the RHD6-RSL4-dependent transcriptional pathway and ROP signaling in plants.

Root hairs are single-cell projections in the root epidermis. The presence of root hairs greatly expands the root surface, which facilitates soil anchorage and the absorption of water and nutrients. Root hairs are also the ideal system to study the mechanism of polar growth. Previous research has identified many important factors that control different stages of root hair development. Using a chemical genetics screen, in this study we report the identification of a steroid molecule, RHP1, which promotes root hair growth at nanomolar concentrations without obvious change of other developmental processes. We further demonstrate that RHP1 specifically affects tip growth with no significant influence on cell fate or planar polarity. We also show that RHP1 promotes root hair tip growth via acting upstream of the RHD6-RSL4-dependent transcriptional pathway and ROP GTPase-guided local signaling. Finally, we demonstrate that RHP1 exhibits a wide range of effects on different plant species in both monocots and dicots. This study of RHP1 will not only help to dissect the mechanism of root hair tip growth, but also provide a new tool to modify root hair growth in different plant species.

The small GTPase RABA2a recruits SNARE proteins to regulate the secretory pathway in parallel with the exocyst complex in Arabidopsis.

Delivery of proteins to the plasma membrane occurs via secretion, which requires tethering, docking, priming, and fusion of vesicles. In yeast and mammalian cells, an evolutionarily conserved RAB GTPase activation cascade functions together with the exocyst and SNARE proteins to coordinate vesicle transport with fusion at the plasma membrane. However, it is unclear whether this is the case in plants. In this study, we show that the small GTPase RABA2a recruits and interacts with the VAMP721/722-SYP121-SNAP33 SNARE ternary complex for membrane fusion. Through immunoprecipitation coupled with mass spectrometry analysis followed by the validatation with a series of biochemical assays, we identified the SNARE proteins VAMP721 and SYP121 as the interactors and downstream effectors of RABA2a. Further expreiments showed that RABA2a interacts with all members of the SNARE complex in its GTP-bound form and modulates the assembly of the VAMP721/722-SYP121-SNAP33 SNARE ternary complex. Intriguingly, we did not observe the interaction of the exocyst subunits with either RABA2a or theSNARE proteins in several different experiments. Neither RABA2a inactivation affects the subcellular localization or assembly of the exocystnor the exocyst subunit mutant exo84b shows the disrupted RABA2a-SNARE association or SNARE assembly, suggesting that the RABA2a-SNARE- and exocyst-mediated secretory pathways are largely independent. Consistently, our live imaging experiments reveal that the two sets of proteins follow non-overlapping trafficking routes, and genetic and cell biologyanalyses indicate that the two pathways select different cargos. Finally, we demonstrate that the plant-specific RABA2a-SNARE pathway is essential for the maintenance of potassium homeostasis in Arabisopsis seedlings. Collectively, our findings imply that higher plants might have generated different endomembrane sorting pathways during evolution and may enable the highly conserved endomembrane proteins to participate in plant-specific trafficking mechanisms for adaptation to the changing environment.

Endoscopic Endonasal Transsphenoidal Approach for Third Ventriculostomy in the Management of Obstructive Hydrocephalus.

ABSTRACT: Endoscopic third ventriculostomy (ETV) is a safe and effective method for the management of obstructive hydrocephalus. Traditional approach is a transfrontal trajectory through the foramen of Monro to access and open the third ventricle floor. Though endoscopic endonasal transsphenoidal approach (EETA) for pituitary and skull base tumors has become increasingly popular, no published literature has explored its utility in performing an ETV. Here, the authors reported a successful ETV for obstructive hydrocephalus through the EETA. A 57-year-old male presenting with progressive headache and gait disturbance for 3 months was diagnosed with obstructive hydrocephalus. Brain MRI revealed an obstruction of cerebrospinal fluid (CSF) flow at the cerebral aqueduct and supratentorial hydrocephalus, accompanied with dilatation and downward herniation of the third ventricle floor. Considering the displacement of the third ventricle floor and the indication for surgery, an ETV was successfully performed through the EETA. No postoperative complication was observed. Both radiological and clinical evaluation postoperatively confirmed ETV success with decreased ventricular size, increased CSF flow across the floor of the third ventricle, and improved clinical signs. EETA is a feasible approach for ETV in selected cases of obstructive hydrocephalus. This approach provides a short trajectory to directly visualize and open the Liliequist's membrane and the displaced floor of the third ventricle, while minimizes damage to normal brain tissue. Skull base repair with nasoseptal flap ensures the success rate by preventing postoperative CSF leak and infection.