[Research Advances on Strategies to Promote Homing and Engraftment of Hematopoietic Stem Cells--Review].

The homing and engraftment of hematopoietic stem cells (HSC) into bone marrow is the first critical step for successful clinical hematopoietic stem cell transplantation (HSCT). SDF-1 / CXCR4 is considered to be a very promising target to promote HSC homing. In recent years, with the in-depth research on the HSC homing, a variety of new strategies for promoting HSC homing and engraftment have been explored, such as nuclear hormone receptor, histone deacetylase inhibitor, prostaglandin and metabolic regulation, so as to increase the success rate of HSCT and improve the survival of patients. In this review, the recent research advances in the mechanism of HSC homing and strategies to promote HSC homing and engraftment were summarized and discussed.

Intrathecal Dexmedetomidine Combined With Ropivacaine in Cesarean Section: A Prospective Randomized Double-Blind Controlled Study.

Objective: This study aimed to find the best dose of dexmedetomidine in spinal anesthesia for cesarean section. Methods: 120 American Society of Anesthesiologists (ASA) Class I and II parturients undergoing elective cesarean delivery under spinal anesthesia were randomly allocated into four groups treated with intrathecal ropivacaine (12 mg) alone (Group R) or in combination with dexmedetomidine 5 µg (Group RD1), 7.5 µg (Group RD2) and 10 µg (Group RD3). Characteristics of spinal anesthesia, hemodynamic changes, adverse effects, stress reactions and neonatal outcomes were recorded in the four groups. Results: Patients in Group RD1, RD2, and RD3 had significantly longer sustained sensory and motor block time than patients in Group R. All four groups had comparable onset times of sensory and motor block. The time for the level of sensory block to lower to S1 was longer in Group RD1 (411.07 ± 106.66 min), Group RD2 (397.03 ± 125.39 min) and Group RD3 (468.63 ± 116.43 min) than in Group R (273.60 ± 88.34 min) (p < 0.001). The time to recover from motor block to a Bromage score of IV was longer in Group RD1 (353.60.07 ± 137.28 min), Group RD2 (350.57 ± 118.01 min) and Group RD3 (404.67 ± 112.83 min) than in Group R (232.70 ± 93.29) (p < 0.01). The incidence of chills was significantly lower in the Group RD1, RD2, and RD3 than in the Group R (p < 0.001). There was no significant difference in the incidence of adverse effects such as hypotension, bradycardia, nausea, vomiting, hypoxemia and pruritus in the four groups (p > 0.05). There was no statistically significant visceral traction response or fentanyl use in the four groups (p > 0.05). Phenylephrine dosing was significantly higher in Group RD2 and RD3 than in Group R (p < 0.05), and there was no significant difference in phenylephrine dosing between Group RD1 and Group R (p > 0.05). There were no statistical differences in postnatal Apgar scores (1 min, 5 min after birth) (p > 0.05). The postoperative concentrations of ß-endorphin (ß-EP), cortisol (Cor) and tumor necrosis factor-α (TNF-α) in the Group RD1, RD2, and RD3 were lower than that in Group R (p < 0.05). Conclusion: Intrathecal 5µg of dexmedetomidine as an adjuvant to ropivacaine relieved intraoperative chills, did not increase intraoperative and postoperative adverse effects, did not increase the amount of intraoperative vasoconstrictor used, and reduced intraoperative stress reactions as well as prolonged the duration of maternal sensory and motor block, so this dose is appropriate for cesarean section. Clinical Trial Registration: [www.chictr.org.cn/], identifier [ChiCTR2200056052].

Urinary Bile Acid Profile of Newborns Born by Cesarean Section Is Characterized by Oxidative Metabolism of Primary Bile Acids: Limited Roles of Fetal-Specific CYP3A7 in Cholate Oxidations.

This work aims to investigate how the bile acid metabolism of newborns differs from that of adults along the axis of primary, secondary, and tertiary bile acids (BAs). The total unconjugated BA profiles were quantitatively determined by enzyme digestion techniques in urine of 21 newborns born by cesarean section, 29 healthy parturient women, 30 healthy males, and 28 healthy nonpregnant females. As expected, because of a lack of developed gut microbiota, newborns exhibited poor metabolism of secondary BAs. Accordingly, the tertiary BAs contributed limitedly to the urinary excretion of BAs in newborns despite their tertiary-to-secondary ratios significantly increasing. As a result, the primary BAs of newborns underwent extensive oxidative metabolism, resulting in elevated urinary levels of some fetal-specific BAs, including 3-dehydroCA, 3ß,7α,12α-trihydroxy-5ß-cholan-24-oic acid, 3α,12-oxo-hydroxy-5ß-cholan-24-oic acid, and nine tetrahydroxy-cholan-24-oic acids (Tetra-BAs). Parturient women had significantly elevated urinary levels of tertiary BAs and fetal-specific BAs compared with female control, indicating that they may be excreted into amniotic fluid for maternal disposition. An in vitro metabolism assay in infant liver microsomes showed that four Tetra-BAs and 3-dehydroCA were hydroxylated metabolites of cholate, glycocholate, and particularly taurocholate. However, the recombinant cytochrome P450 enzyme assay found that the fetal-specific CYP3A7 did not contribute to these oxidation metabolisms as much as expected compared with CYP3A4. In conclusion, newborns show a BA metabolism pattern predominated by primary BA oxidations due to immaturity of secondary BA metabolism. Translational studies following this finding may bring new ideas and strategies for both pediatric pharmacology and diagnosis and treatment of perinatal cholestasis-associated diseases. SIGNIFICANCE STATEMENT: The prenatal BA disposition is different from adults because of a lack of gut microbiota. However, how the BA metabolism of newborns differs from that of adults along the axis of primary, secondary, and tertiary BAs remains poorly defined. This work demonstrated that the urinary BA profiles of newborns born by cesarean section are characterized by oxidative metabolism of primary BAs, in which the fetal-specific CYP3A7 plays a limited role in the downstream oxidation metabolism of cholate.

Stereoselective Oxidation Kinetics of Deoxycholate in Recombinant and Microsomal CYP3A Enzymes: Deoxycholate 19-Hydroxylation Is an In Vitro Marker of CYP3A7 Activity.

The primary bile acids (BAs) synthesized from cholesterol in the liver are converted to secondary BAs by gut microbiota. It was recently disclosed that the major secondary BA, deoxycholate (DCA) species, is stereoselectively oxidized to tertiary BAs exclusively by CYP3A enzymes. This work subsequently investigated the in vitro oxidation kinetics of DCA at C-1ß, C-3ß, C-4ß, C-5ß, C-6α, C-6ß, and C-19 in recombinant CYP3A enzymes and naive enzymes in human liver microsomes (HLMs). The stereoselective oxidation of DCA fit well with Hill kinetics at 1-300 µM in both recombinant CYP3A enzymes and pooled HLMs. With no contributions or trace contributions from CYP3A5, CYP3A7 favors oxidation at C-19, C-4ß, C-6α, C-3ß, and C-1ß, whereas CYP3A4 favors the oxidation at C-5ß and C-6ß compared with each other. Correlation between DCA oxidation and testosterone 6ß-hydroxylation in 14 adult single-donor HLMs provided proof-of-concept evidence that DCA 19-hydroxylation is an in vitro marker reaction for CYP3A7 activity, whereas oxidation at other sites represents mixed indicators for CYP3A4 and CYP3A7 activities. Deactivation caused by DCA-induced cytochrome P450-cytochrome P420 conversion, as shown by the spectral titrations of isolated CYP3A proteins, was observed when DCA levels were near or higher than the critical micelle concentration (about 1500 µM). Unlike CYP3A4, CYP3A7 showed abnormally elevated activities at 500 and 750 µM, which might be associated with an altered affinity for DCA multimers. The disclosed kinetic and functional roles of CYP3A isoforms in disposing of the gut bacteria-derived DCA may help in understanding the structural and functional mechanisms of CYP3A.

Continuum of Host-Gut Microbial Co-metabolism: Host CYP3A4/3A7 are Responsible for Tertiary Oxidations of Deoxycholate Species.

The gut microbiota modifies endogenous primary bile acids (BAs) to produce exogenous secondary BAs, which may be further metabolized by cytochrome P450 enzymes (P450s). Our primary aim was to examine how the host adapts to the stress of microbe-derived secondary BAs by P450-mediated oxidative modifications on the steroid nucleus. Five unconjugated tri-hydroxyl BAs that were structurally and/or biologically associated with deoxycholate (DCA) were determined in human biologic samples by liquid chromatography-tandem mass spectrometry in combination with enzyme-digestion techniques. They were identified as DCA-19-ol, DCA-6ß-ol, DCA-5ß-ol, DCA-6α-ol, DCA-1ß-ol, and DCA-4ß-ol based on matching in-laboratory synthesized standards. Metabolic inhibition assays in human liver microsomes and recombinant P450 assays revealed that CYP3A4 and CYP3A7 were responsible for the regioselective oxidations of both DCA and its conjugated forms, glycodeoxycholate (GDCA) and taurodeoxycholate (TDCA). The modification of secondary BAs to tertiary BAs defines a host liver (primary BAs)-gut microbiota (secondary BAs)-host liver (tertiary BAs) axis. The regioselective oxidations of DCA, GDCA, and TDCA by CYP3A4 and CYP3A7 may help eliminate host-toxic DCA species. The 19- and 4ß-hydroxylation of DCA species demonstrated outstanding CYP3A7 selectivity and may be useful as indicators of CYP3A7 activity.

Reversible photo-gated transmembrane channel assembled from an acylhydrazone-containing crown ether triad.

We have prepared a crown ether triad containing acylhydrazone units. In solution, the triad can self-assemble linearly to form an organogel. UV light-induced E/Z isomerization of the C[double bond, length as m-dash]N bond of the acylhydrazone unit endows the assembly with photo-sensitivity. The triad was able to insert into the lipid bilayer to form a supramolecular transmembrane channel which showed transport selectivity for NH4+ over K+. The channel exhibited photo-gating properties under microscopic and macroscopic conditions. The transport of the channel could be reversibly switched off and on by irradiation with alternating 320 and 365 nm UV light as supported by the conductance measurements.

Synthetic Channel Specifically Inserts into the Lipid Bilayer of Gram-Positive Bacteria but not that of Mammalian Erythrocytes.

A series of tubular molecules with different lengths have been synthesized by attaching Trp-incorporated peptides to the pillar[5]arene backbone. The tubular molecules are able to insert into the lipid bilayer to form unimolecular transmembrane channels. One of the channels has been revealed to specifically insert into the bilayer of the Gram-positive bacteria. In contrast, this channel cannot insert into the membranes of the mammalian rat erythrocytes even at the high concentration of 100 µm. It was further demonstrated that, as a result of this high membrane selectivity, the channel exhibits efficient antimicrobial activity for the Gram-positive bacteria and very low hemolytic toxicity for mammalian erythrocytes.

LncSox4 promotes the self-renewal of liver tumour-initiating cells through Stat3-mediated Sox4 expression.

Liver cancer has a tendency to develop asymptomatically in patients, so most patients are diagnosed at a later stage. Accumulating evidence implicates that liver tumour-initiating cells (TICs) as being responsible for liver cancer initiation and recurrence. However, the molecular mechanism of liver TIC self-renewal is poorly understood. Here we discover that a long noncoding RNA (lncRNA) termed LncSox4 is highly expressed in hepatocellular carcinoma (HCC) tissues and in liver TICs. We find that LncSox4 is required for liver TIC self-renewal and tumour initiation. LncSox4 interacts with and recruits Stat3 to the Sox4 promoter to initiate the expression of Sox4, which is highly expressed in liver TICs and required for liver TIC self-renewal. The expression level of Sox4 correlates with HCC development, clinical severity and prognosis of patients. Altogether, we find that LncSox4 is highly expressed in liver TICs and is required for their self-renewal.

Paracoccus siganidrum sp. nov., isolated from fish gastrointestinal tract.

A bacterial strain, designated M26(T), was isolated from a fish gastrointestinal tract, collected from Zhanjiang Port, South China. 16S rRNA gene sequence analysis indicated that strain M26(T) belongs to the subclass α-Proteobacteria, being related to the genus Paracoccus, and sharing highest sequence similarity with Paracoccus alcaliphilus JCM 7364(T) (98.1 %), Paracoccus huijuniae FLN-7(T) (97.3 %), Paracoccus stylophorae KTW-16(T) (97.1 %) and Paracoccus seriniphilus DSM 14827(T) (96.9 %). The major quinone was determined to be ubiquinone Q-10, with Q-9 and Q-8 as minor components. The major fatty acid was identified as C18:1ω7c, with smaller amounts of C18:0 and C16:0. The G+C content of the genomic DNA was determined to be 64.3 mol%. The DNA hybridization value between strain M26(T) and the most closely related type strain, P. alcaliphilus, was 29.0 ± 1.0 %. The results of physiological and biochemical tests and low DNA-DNA relatedness showed that the strain could be readily distinguished from closely related species. On the basis of these phenotypic and genotypic data, strain M26(T) is concluded to represent a novel species of the genus Paracoccus, for which the name Paracoccus siganidrum sp. nov. is proposed. The type strain is M26(T) (=CCTCC AB 2012865(T) = DSM 26381(T)).