Gut microbiota in preterm infants with late-onset sepsis and pneumonia: a pilot case-control study.

BACKGROUND: Late-onset sepsis (LOS) and pneumonia are common infectious diseases, with high morbidity and mortality in neonates. This study aimed to investigate the differences in the gut microbiota among preterm infants with LOS, or pneumonia, and full-term infants. Furthermore, this study aimed to determine whether there is a correlation between intestinal pathogenic colonization and LOS. METHODS: In a single-center case‒control study, 16 S rRNA gene sequencing technology was used to compare gut microbiota characteristics and differences among the LOS group, pneumonia group, and control group. RESULTS: Our study revealed that the gut microbiota in the control group was more diverse than that in the LOS group and pneumonia group (P < 0.05). No significant differences in diversity were detected between the LOS and pneumonia groups (P > 0.05). Compared with the control group, the abundances of Akkermansia, Escherichia/Shigella, and Enterococcus increased, while the abundances of Bacteroides and Stenotrophomonas decreased in the LOS and pneumonia groups. The pathogenic bacteria in infants with LOS were consistent with the distribution of the main bacteria in the intestinal microbiota. An increase in Escherichia/Shigella abundance may predict a high risk of LOS occurrence, with an area under the curve (AUC) of 0.773. CONCLUSION: Changes in the gut microbiota composition were associated with an increased risk of LOS and pneumonia. The dominant bacteria in the gut microbiota of the LOS group were found to be associated with the causative pathogen of LOS. Moreover, preterm infants exhibiting an elevated abundance of Escherichia/Shigella may be considered potential candidates for predicting the onset of LOS.

Single-Atom-Layer Catalysis in a MoS2 Monolayer Activated by Long-Range Ferromagnetism for the Hydrogen Evolution Reaction: Beyond Single-Atom Catalysis.

Single-atom-layer catalysts with fully activated basal-atoms will provide a solution to the low loading-density bottleneck of single-atom catalysts. Herein, we activate the majority of the basal sites of monolayer MoS2 , by doping Co ions to induce long-range ferromagnetic order. This strategy, as revealed by in situ synchrotron radiation microscopic infrared spectroscopy and electrochemical measurements, could activate more than 50 % of the originally inert basal-plane S atoms in the ferromagnetic monolayer for the hydrogen evolution reaction (HER). Consequently, on a single monolayer of ferromagnetic MoS2 measured by on-chip micro-cell, a current density of 10 mA cm-2 could be achieved at the overpotential of 137 mV, corresponding to a mass activity of 28, 571 Ag-1 , which is two orders of magnitude higher than the multilayer counterpart. Its exchange current density of 75 µA cm-2 also surpasses most other MoS2 -based catalysts. Experimental results and theoretical calculations show the activation of basal plane S atoms arises from an increase of electronic density around the Fermi level, promoting the H adsorption ability of basal-plane S atoms.

[A case of neonatal lipoprotein lipase deficiency caused by novel compound heterozygous variants of LPL gene].

OBJECTIVE: To explore the genetic basis for a Chinese neonate with lipoprotein lipase deficiency. METHODS: Targeted capture and next-generation sequencing (NGS) were carried out to detect variants of genes associated with inborn errors of metabolism. Suspected variants were validated by Sanger sequencing. RESULTS: Genetic testing revealed novel complex heterozygous variants, namely c.347G>C (p.Arg116Pro) and c.472T>G (p.Tyr158Asp), of the LPL gene, which were respectively inherited from his father and mother. CONCLUSION: Compound heterozygous variants c.347G>C and c.472T>G of the LPL gene probably underlie the lipoprotein lipase deficiency in this child.

[Genetic analysis of a child affected with Crigler-Najjar syndrome type II].

OBJECTIVE: To detect potential mutation of the UGT1A1 gene in a child affected with Crigler-Najjar syndrome type II. METHODS: Blood samples were collected from the patient and his parents for the extraction of genomic DNA. Potential mutation of the UGT1A1 gene was detected with polymerase chain reaction (PCR) and direct sequencing. The child was followed up until the age of 3 years and 6 months. RESULTS: The patient showed persistent unconjugated hyperbilirubinemia. Sequencing of the UGT1A1 gene has detected a rare heterozygous c.610 A>G (p.Met204Val) mutation in the exon 1, in addition with a heterozygous c.1091 C>T (p.Pro364Leu) mutation in exon 4. The two mutations were inherited from his father and mother, respectively. The patient was diagnosed with Crigler-Najjar syndrome type II and received oral phenobarbital treatment. CONCLUSION: The compound UGT1A1 gene mutation probably accounts for the disease in the patient manifesting persistent mild unconjugated hyperbilirubinemia. Genetic counseling and prenatal diagnosis should be provided for his family.

A novel nitrilase from Rhodobacter sphaeroides LHS-305: cloning, heterologous expression and biochemical characterization.

In this study, a novel nitrilase gene from Rhodobacter sphaeroides was cloned and overexpressed in Escherichia coli. The open reading frame of the nitrilase gene includes 969 base pairs, which encodes a putative polypeptide of 322 amino acid residues. The molecular weight of the purified native nitrilase was about 560 kDa determined by size exclusion chromatography. This nitrilase showed one single band on SDS-PAGE with a molecular weight of 40 kDa. This suggested that the native nitrilase consisted of 14 subunits with identical size. The optimal pH and temperature of the purified enzyme were 7.0 and 40 °C, respectively. The kinetic parameters V max and K m toward 3-cyanopyridine were 77.5 µmol min(-1) mg(-1) and 73.1 mmol/l, respectively. The enzyme can easily convert aliphatic nitrile and aromatic nitriles to their corresponding acids. Furthermore, this enzyme demonstrated regioselectivity in hydrolysis of aliphatic dinitriles. This specific characteristic makes this nitrilase have a great potential for commercial production of various cyanocarboxylic acids by hydrolyzing readily available dinitriles.

[Relationship of B/A ratio and acidosis with abnormal brainstem auditory evoked potentials in neonates with severe hyperbilirubinemia].

OBJECTIVE: To investigate the relationship of bilirubin/albumin (B/A) ratio and acidosis with abnormal brainstem auditory evoked potentials (BAEPs) in neonates with severe hyperbilirubinemia and its clinical significance. METHODS: A total of 967 neonates with severe hyperbilirubinemia between November 2008 and October 2009 were enrolled in the study. They were divided into two groups according to their BAEPs: normal BAEP group (n=799) and abnormal BAEP group (n=168). Univariate analysis and age-stratified Chi-square test were used to determine the relationship of B/A ratio and acidosis with BAEP. RESULTS: The univariate analysis showed that the abnormal BAEP group had significantly lower pH and base excess values and a significantly higher B/A ratio compared with the normal BAEP group (P<0.05). The age-stratified Chi-square test showed that neonates with acidosis or with a B/A ratio greater than 1.0 had a significantly higher incidence of abnormal BAEPs than those without acidosis or with a B/A ratio less than 1.0 in any age (days) group of neonates with severe hyperbilirubinemia (P<0.05). CONCLUSIONS: High B/A ratio and acidosis are the risk factors for abnormal BAEPs in neonates with severe hyperbilirubinemia, which is the case for those in any age group. In order to reduce the incidence of hearing loss in any age group of neonates with severe hyperbilirubinemia, we should correct the acidosis and lower the B/A ratio as soon as possible.

Intrinsic Room-Temperature Ferromagnetism in V2C MXene Nanosheets.

Two-dimensional (2D) materials with intrinsic magnetic properties are intensively explored due to their potential applications in low-power-consumption electronics and spintronics. To date, only a handful of intrinsic magnetic 2D materials have been reported. Here, we report a realization of intrinsic ferromagnetic behavior in 2D V2C MXene nanosheets through layer mismatch engineering. The V2C MXene nanosheets with a small-angle twisting show a robust intrinsic ferromagnetic response with a saturation magnetic moment of 0.013 emu/g at room temperature. An in-depth study has been performed by X-ray absorption spectroscopy as well as electron paramagnetic resonance (EPR) and photoelectron spectroscopy analyses. It has been revealed that the symmetry-broken interlayer twisting reduced the degeneracy of V 3d states and the van Hove singularity. This led to a redistribution of the density of electronic states near the Fermi level and consequently activated the Stoner ferromagnetism with improved density of itinerant d electrons. This work highlights V2C MXene as a promising intrinsic room-temperature ferromagnetic material with potential applications in spintronics or spin-based electronics.

Embedding atomic cobalt into graphene lattices to activate room-temperature ferromagnetism.

Graphene is extremely promising for next-generation spintronics applications; however, realizing graphene-based room-temperature magnets remains a great challenge. Here, we demonstrate that robust room-temperature ferromagnetism with TC up to ∼400 K and saturation magnetization of 0.11 emu g-1 (300 K) can be achieved in graphene by embedding isolated Co atoms with the aid of coordinated N atoms. Extensive structural characterizations show that square-planar Co-N4 moieties were formed in the graphene lattices, where atomically dispersed Co atoms provide local magnetic moments. Detailed electronic structure calculations reveal that the hybridization between the d electrons of Co atoms and delocalized pz electrons of N/C atoms enhances the conduction-electron mediated long-range magnetic coupling. This work provides an effective means to induce room-temperature ferromagnetism in graphene and may open possibilities for developing graphene-based spintronics devices.

Synergetic Effect of Substitutional Dopants and Sulfur Vacancy in Modulating the Ferromagnetism of MoS2 Nanosheets.

The activation and modulation of the magnetism of MoS2 nanosheets are critical to the development of their application in next-generation spintronics. Here, we report a synergetic strategy to induce and modulate the ferromagnetism of the originally nonmagnetic MoS2 nanosheets. A two-step experimental method was used to simultaneously introduce substitutional V dopants and sulfur vacancy (Vs) in the MoS2 nanosheet host, showing an air-stable and adjustable ferromagnetic response at room temperature. The ferromagnetism could be modulated by varying the content of Vs through Ar plasma irradiation of different periods, with a maximum saturation magnetization of 0.011 emu g-1 reached at the irradiation time of 6 s (s). Experimental characterizations and first-principles calculations suggest that the adjustable magnetization is attributed to the synergetic effect of the substitutional V dopants and Vs in modulating the band structure of MoS2 nanosheets, resulting from the strong hybridization between the V 3d state and the Vs-induced impurity bands. This work suggests that the synergetic effect of substitutional V atoms and Vs is a promising route for tuning the magnetic interactions in two-dimensional nanostructures.

Interlayer Photoelectron Transfer Boosted by Bridged RuIV Atoms in GaS Nanosheets for Efficient Water Splitting.

Photocatalytic water splitting over layered nanosheet (NS) catalysts has caught a lot of attention for renewable hydrogen fuel production. However, the weak van der Waals interlayer interactions make it a great challenge to realize an effective dissociation of photogenerated excitons and efficient charge transfer across the interior of layered catalysts during the photocatalysis process. Here, we propose an intercalation strategy of high-valence RuIV atoms to render two-dimensional GaS NS photocatalysts with rapid electron-hole dissociation and long photocarrier lifetime in visible-light-driven water splitting. Experimental and theoretical results unravel that the intercalated single-site Ru, confined in interlayer of GaS NSs, with a hexagonal structural configuration of "Ru1-S6", can serve as an electron-trapped high-speed channel toward simultaneously accelerating electron-hole pairs dissociation and promoting photoelectron transportation through the van der Waals interlayer. Consequently, the as-developed Ru-intercalated GaS NSs can give a notable H2 production rate of 340 µmol g-1 h-1 under visible-light irradiation and an apparent yield of 7% at 420 nm, 38 times that of pure GaS NSs. This study opens up a feasible way for a new design of highly active layered photocatalysts toward high-efficiency solar energy conversion.

Reversible Tuning of the Ferromagnetic Behavior in Mn-Doped MoS2 Nanosheets via Interface Charge Transfer.

Reversible manipulation of the magnetic behavior of two-dimensional van der Waals crystals is crucial for expanding their applications in spin-based information-processing technologies. However, to date, most experimental approaches to tune the magnetic properties are single way and have very limited practical applications. Here, we report an interface charge-transfer method for obtaining a reversible and air-stable magnetic response at room temperature in Mn-doped MoS2 nanosheets. By adsorption of benzyl viologen (BV) molecules as the charge donor, the saturation magnetization of Mn-doped MoS2 nanosheets is enhanced by a magnitude of 60%, and the magnetization can be restored to the original value when the adsorbed BV molecules are removed. This cycle can be repeated many times on the same sample without detectable degradation. Experimental characterizations and first-principles calculations suggest that the enhanced magnetization can be attributed to the increase of Mn magnetic moment because of the enriched electrons transferred from BV molecules. This work shows that interface charge transfer may open up a new pathway for reversibly tuning the exchange interactions in two-dimensional nanostructures.

[OATP 1B1 T521C/A388G is an important polymorphism gene related to neonatal hyperbilirubinemia].

OBJECTIVE: Multiple genetic and environmental factors contribute to the onset of many human diseases, such as neonatal hyperbilirubinemia. OATP 1B1 is an important polymorphism gene which transmembrane transports unconjugated bilirubin(UCB). Genetic polymorphisms that affect the functionality of the protein may potentially lead to altered transport characteristics. The T521C/A388G polymorphism of this gene has been reported to considerably reduce the transporting property of drugs like pravastatin, and may be involved in the membrane translocation of bilirubin. Some studies have shown that OATP 1B1 mediates bilirubin uptake from blood into the liver, and the OATP 1B1 polymorphism is a likely mechanism explaining the differences of bilirubin level in peripheral blood. The aim of this study was to evaluate the relationship between OATP 1B1 polymorphisms and neonatal hyperbilirubinemia. METHODS: A total of 220 newborn infants with hyperbilirubinemia were recruited from Hunan Children Hospital from November 2008 to December 2009 according to the diagnostic criteria. Age and sex matched control subjects comprised of 200 unrelated, hyperbilirubinemia-free newborns. Biochemical and clinical data were collected from the case history. One ml venous blood samples in EDTA vials were taken from each subject and DNA was isolated from peripheral leukocytes by standard methods, preserved in 4°C. 1 - 2 ml venous blood samples were also taken for detecting the serum total bilirubin and direct bilirubin level by chemical oxidation method. OATP 1B1 T521C/A388G polymorphisms were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Allele and genotype frequencies were compared between patients and control. The gene polymorphism and risk of disease were also analyzed. Serum total bilirubin, conjugated bilirubin and unconjugated bilirubin levels were compared between different OATP 1B1 T521C/A388G genotypes. RESULTS: Allele frequencies in patients and control population were in Hardy-Weinberg equilibrium (P > 0.05). Allele and genotype frequencies of the OATP 1B1 T521C polymorphism in patients were significantly different from the controls. The OATP 1B1 521C allele frequency was only 8.2% in patients, while reached 14.0% in the control group which was very close to the frequency of common Chinese people. However, the proportion of wild type genotypes was significantly higher than those of the controls, reached 84.1%. The 521 C allele and genotypes carrying 521 C allele illustrated low risk for neonatal hyperbilirubinemia (OR = 0.530, 95%CI = 0.328 - 0.857; OR = 0.541, 95%CI = 0.344 - 0.851). However, the frequencies of alleles and genotypes of SLCO1B1 A388G did not differ significantly from those of the controls, and this polymorphism did not influence susceptibility to such disease. Among the three OATP 1B1 A388G genotypes, the level of total serum bilirubin (TSB), direct bilirubin (DB) and unconjugated bilirubin (UCB) were significantly different. Values of TSB, DB and UCB were the highest in wild type subjects, lower in heterozygotes, and the lowest in mutant homozygotes. TSB and UCB in patients with wild type genotypes reached 602.5 µmol/L and 585.0 µmol/L respectively, nearly twice the average value of homozygous patients. While the TSB and UCB in homozygotes were below the average value of all patients, only 351.7 µmol/L and 338.8 µmol/L respectively. CONCLUSIONS: Our findings indicated that OATP 1B1 A388G polymorphism has a notable influence on the serum bilirubin level in neonatal hyperbilirubinemia patients. The OATP 1B1 521T allele may be a potential risk factor of such disease. OATP 1B1 T521C/A388G was an important polymorphism gene which related with neonatal hyperbilirubinemia. Future study should involve other polymorphisms of OATP 1B1, more candidate genes and environmental risk factors. It is also necessary to investigate their association with the severity and prognosis of this disease in order to elucidate the genetic pathogenesis of neonatal hyperbilirubinemia as a complex disease. This study should be repeated in a larger population and different ethnic groups.