bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of the lrp gene in Bradyrhizobium japonicum and its role in regulation of delta-aminolevulinic acid uptake
Authors: King N D , O'Brian M R
Published: November 2016

The heme precursor delta-aminolevulinic acid (ALA) is taken up by the dipeptide permease (Dpp) system in Escherichia coli. In this study, we identified a Bradyrhizobium japonicum genomic library clone that complemented both ALA and dipeptide uptake activities in E. coli dpp mutants. The complementing B. japonicum DNA encoded a product with 58% identity to the E. coli global transcriptional regulator Lrp (leucine-responsive regulatory protein), implying the presence of Dpp-independent ALA uptake activity in those cells. Data support the conclusion that the Lrp homolog induced the oligopeptide permease system in the complemented cells by interfering with the repressor activity of the endogenous Lrp, thus conferring oligopeptide and ALA uptake activities. ALA uptake by B. japonicum was effectively inhibited by a tripeptide and, to a lesser extent, by a dipeptide, and a mutant strain that expressed the lrp homolog from a constitutive promoter was deficient in ALA uptake activity. The data show that Lrp negatively affects ALA uptake in E. coli and B. japonicum. Furthermore, the product of the isolated B. japonicum gene is both a functional and structural homolog of E. coli Lrp, and thus the regulator is not restricted to enteric bacteria.
Modulation of EcoKI restriction in vivo: role of the lambda Gam protein and plasmid metabolism
Authors: Salaj-Smic E , Marsić N , Trgovcević Z , Lloyd R G
Published: November 2016

Two novel types of alleviation of DNA restriction by the EcoKI restriction endonuclease are described. The first type depends on the presence of the gam gene product (Gam protein) of bacteriophage lambda. The efficiency of plating of unmodified phage lambda is greatly increased when the restricting Escherichia coli K-12 host carries a gam+ plasmid. The effect is particularly striking in wild-type strains and, to a lesser extent, in the presence of sbcC and recA mutations. In all cases, Gam-dependent alleviation of restriction requires active recBCD genes of the host and recombination (red) genes of the infecting phage. The enhanced capacity of Gam-expressing cells to repair DNA strand breaks might account for this phenomenon. The second type is caused by the presence of a plasmid in a restricting host lacking RecBCD enzyme. Commonly used plasmids such as the cloning vector pACYC184 can produce such an effect in strains carrying recB single mutations or in recBC sbcBC strains. Plasmid-mediated restriction alleviation in recBC sbcBC strains is independent of the host RecF, RecJ, and RecA proteins and phage recombination functions. The presence of plasmids can also relieve restriction in recD strains. This effect depends, however, on the RecA function in the host. The molecular mechanism of the plasmid-mediated restriction alleviation remains unclear.
Analysis of DNA inversions in the shufflon of plasmid R64
Authors: Gyohda A , Funayama N , Komano T
Published: November 2016

The shufflon, a multiple DNA inversion system in the plasmid R64, consists of four DNA segments flanked and separated by seven 19-bp repeat sequences. Site-specific recombinations mediated by the rci product occur between each inverted repeat sequence, resulting in inversions of the four segments independently or in groups. The seven 19-bp repeat sequences are classified into four types (repeat-a, -b, -c, and -d), according to their 3-bp variable sequences. We individually cloned A, B, and C segments of the R64 shufflon and determined the in vivo inversion frequency of each segment. The inversion frequencies of three segments differed greatly. The inversion frequency declined in the following order: segments A, B, and C. Synthetic 19-mer oligonucleotides corresponding to both strands of repeat-a, -b, -c, and -d sequences were inserted into appropriate sites of pBR322. The rci-mediated DNA inversion occurred between two synthetic inverted repeats, indicating that the 19-bp inverted repeat sequences are the sole elements required in cis for the shufflon system. The inversion frequencies of DNA segments flanked by various sequences indicate that the four types of repeat sequences determine the inversion frequency of the four DNA segments of the R64 shufflon. Deletion of a DNA segment flanked by direct repeat sequences could not be detected.
Heterologous expression of biphenyl dioxygenase-encoding genes from a gram-positive broad-spectrum polychlorinated biphenyl degrader and characterization of chlorobiphenyl oxidation by the gene products
Authors: McKay D B , Seeger M , Zielinski M , Hofer B , Timmis K N
Published: November 2016

The bphA1A2A3A4 gene cluster, encoding a biphenyl dioxygenase from Rhodococcus globerulus P6, a gram-positive microorganism able to degrade a wide spectrum of polychlorobiphenyls (PCBs), was expressed in Pseudomonas putida, thereby allowing characterization of chlorobiphenyl oxidation by this enzyme. While P6 biphenyl dioxygenase activity was observed in P. putida containing bphA1A2A3A4, no activity was detected in Escherichia coli cells containing the same gene cluster. In E. coli, transcription of genes bphB and bphCl, located downstream of bphA1A2A3A4, was shown to be driven solely by a vector promoter, which indicated that the lack of biphenyl dioxygenase activity was not due to a lack of mRNA synthesis. Radioactive labelling of bph gene products in E. coli implied inefficient translation of the bphA gene cluster or rapid degradation of the gene products. The biosynthesis of functional P6 biphenyl dioxygenase in P. putida cells containing the same plasmid construct that yielded no activity in E. coli emphasizes the importance of the host strain for heterologous expression and shows that synthesis, correct folding, and assembly of a Rhodococcus biphenyl dioxygenase can be achieved in a gram-negative organism. Dioxygenation of six mono- and dichlorinated PCB congeners by P. putida containing the P6 bphA gene cluster indicates the following ring substitution preference for this reaction (from most to least preferred): un-, meta-, para-, and ortho-substitution. No indications were found for dioxygenation of meta/para carbon pairs, or for hydroxylation of chlorinated carbons at any position of a monochlorinated ring, suggesting a strict specificity of this biphenyl dioxygenase for attack at nonhalogenated ortho/meta vicinal carbons. This contrasts the properties of an analogous enzyme from Pseudomonas sp. strain LB400, which can both dioxygenate at meta and para positions and dehalogenate substituted ortho carbons during ortho and meta dioxygenation.
Outer membrane translocation arrest of the TcpA pilin subunit in rfb mutants of Vibrio cholerae O1 strain 569B
Authors: Iredell J R , Manning P A
Published: November 2016

The toxin-coregulated pilus (TCP) of Vibrio cholerae is a type 4-related fimbrial adhesin and a useful model for the study of type 4 pilus biogenesis and related bacterial macromolecular transport pathways. Transposon mutagenesis of the putative perosamine biosynthesis genes in the rfb operon of V. cholerae 569B eliminates lipopolysaccharide (LPS) O-antigen biosynthesis but also leads to a specific defect in TCP export. Localization of TcpA is made difficult by the hydrophobic nature of this bundle-forming pilin, which floats anomalously in sucrose density gradients, but the processed form of TcpA can be found in membrane and periplasmic fractions prepared from these strains. While TcpA cannot be detected by surface immunogold labelling in transmission electron microscope preparations, EDTA pretreatment facilitates immunofluorescent antibody labelling of whole cells, and ultrathin cryosectioning techniques confirm membrane and periplasmic accumulation of TcpA. Salt and detergent extraction, protease accessibility, and chemical cross-linking experiments suggest that although TcpA has not been assembled on the cell surface, subunit interactions are otherwise identical to those within TCP. In addition, TcpA-mediated fucose-resistant hemagglutination of murine erythrocytes is preserved in whole-cell lysates, suggesting that TcpA has obtained its mature conformation. These data localize a stage of type 4 pilin translocation to the outer membrane, at which stage export failure leads to the accumulation of pilin subunits in a configuration similar to that within the mature fiber. Possible candidates for the outer membrane defect are discussed.
Characterization of a thiol-dependent endopeptidase from Lactobacillus helveticus CNRZ32
Authors: Fenster K M , Parkin K L , Steele J L
Published: November 2016

An endopeptidase gene (pepE) was isolated from a previously constructed genomic library of Lactobacillus helveticus CNRZ32. The pepE gene consisted of a 1,314-bp open reading frame encoding a putative peptide of 52.1 kDa. Significant identity was found between the deduced amino acid sequence of pepE and the sequences for aminopeptidase C from Lactobacillus delbrueckii subsp. lactis DSM7290, L. helveticus CNRZ32, Streptococcus thermophilus CNRZ302, and Lactococcus lactis subsp. cremoris AM2. A recombinant PepE fusion protein containing an N-terminal six-histidine tag was constructed and purified to electrophoretic homogeneity. Characterization of PepE revealed that it was a thiol-dependent protease having a monomeric mass of 50 kDa, with optimum temperature, NaCl concentration, and pH for activity at 32 to 37 degrees C, 0.5%, and 4.5, respectively. PepE had significant activity under conditions which simulate those of ripening cheese (10 degrees C, 4% NaCl, pH 5.1). PepE hydrolyzed internal peptide bonds in Met-enkephalin and bradykinin; however, hydrolysis of alpha-, beta-, and kappa-caseins was not detected.
Inhibition of cell wall turnover and autolysis by vancomycin in a highly vancomycin-resistant mutant of Staphylococcus aureus
Authors: Sieradzki K , Tomasz A
Published: November 2016

A highly vancomycin-resistant mutant (MIC = 100 microg/ml) of Staphylococcus aureus, mutant VM, which was isolated in the laboratory by a step-pressure procedure, continued to grow and synthesize peptidoglycan in the presence of vancomycin (50 microg/ml) in the medium, but the antibiotic completely inhibited cell wall turnover and autolysis, resulting in the accumulation of cell wall material at the cell surface and inhibition of daughter cell separation. Cultures of mutant VM removed vancomycin from the growth medium through binding the antibiotic to the cell walls, from which the antibiotic could be quantitatively recovered in biologically active form. Vancomycin blocked the in vitro hydrolysis of cell walls by autolytic enzyme extracts, lysostaphin and mutanolysin. Analysis of UDP-linked peptidoglycan precursors showed no evidence for the presence of D-lactate-terminating muropeptides. While there was no significant difference in the composition of muropeptide units of mutant and parental cell walls, the peptidoglycan of VM had a significantly lower degree of cross-linkage. These observations and the results of vancomycin-binding studies suggest alterations in the structural organization of the mutant cell walls such that access of the vancomycin molecules to the sites of wall biosynthesis is blocked.
Cytochrome c(y) of Rhodobacter capsulatus is attached to the cytoplasmic membrane by an uncleaved signal sequence-like anchor
Authors: Myllykallio H , Jenney F E , Moomaw C R , Slaughter C A , Daldal F
Published: November 2016

During the photosynthetic growth of Rhodobacter capsulatus, electrons are conveyed from the cytochrome (cyt) bc1 complex to the photochemical reaction center by either the periplasmic cyt c2 or the membrane-bound cyt c(y). Cyt c(y) is a member of a recently established subclass of bipartite c-type cytochromes consisting of an amino (N)-terminal domain functioning as a membrane anchor and a carboxyl (C)-terminal domain homologous to cyt c of various sources. Structural homologs of cyt c(y) have now been found in several bacterial species, including Rhodobacter sphaeroides. In this work, a C-terminally epitope-tagged and functional derivative of R. capsulatus cyt c(y) was purified from intracytoplasmic membranes to homogeneity. Analyses of isolated cyt c(y) indicated that its spectral and thermodynamic properties are very similar to those of other c-type cytochromes, in particular to those from bacterial and plant mitochondrial sources. Amino acid sequence determination for purified cyt c(y) revealed that its signal sequence-like N-terminal portion is uncleaved; hence, it is anchored to the membrane. To demonstrate that the N-terminal domain of cyt c(y) is indeed its membrane anchor, this sequence was fused to the N terminus of cyt c2. The resulting hybrid cyt c (MA-c2) remained membrane bound and was able to support photosynthetic growth of R. capsulatus in the absence of the cyt c(y) and c2. Therefore, cyt c2 can support cyclic electron transfer during photosynthetic growth in either a freely diffusible or a membrane-anchored form. These findings should now allow for the first time the comparison of electron transfer properties of a given electron carrier when it is anchored to the membrane or is freely diffusible in the periplasm.
In vivo and in vitro bioconversion of epsilon-rhodomycinone glycoside to doxorubicin: functions of DauP, DauK, and DoxA
Authors: Dickens M L , Priestley N D , Strohl W R
Published: November 2016

We recently determined the function of the gene product of Streptomyces sp. strain C5 doxA, a cytochrome P-450-like protein, to be daunorubicin C-14 hydroxylase (M. L. Dickens and W. R. Strohl, J. Bacteriol. 178: 3389-3395, 1996). In the present study, we show that DoxA also catalyzes the hydroxylation of 13-deoxycarminomycin and 13-deoxydaunorubicin to 13-dihydrocarminomycin and 13-dihydrodaunorubicin, respectively, as well as oxidizing the 13-dihydro-anthracyclines to their respective 13-keto forms. The Streptomyces sp. strain C5 dauP gene product also was shown unequivocally to remove the carbomethoxy group of the epsilon-rhodomycinone-glycoside (rhodomycin D) to form 10-carboxy-13-deoxycarminomycin. Additionally, Streptomyces sp. strain C5 DauK was found to methylate the anthracyclines rhodomycin D, 10-carboxy-13-deoxycarminomycin, and 13-deoxy-carminomycin, at the 4-hydroxyl position, indicating a broader substrate specificity than was previously known. The products of Streptomyces sp. strain C5 doxA, dauK, and dauP were sufficient and necessary to confer on Streptomyces lividans TK24 the ability to convert rhodomycin D, the first glycoside in daunorubicin and doxorubicin biosynthesis, to doxorubicin.
Minimal Streptomyces sp. strain C5 daunorubicin polyketide biosynthesis genes required for aklanonic acid biosynthesis
Authors: Rajgarhia V B , Strohl W R
Published: November 2016

The structure of the Streptomyces sp. strain C5 daunorubicin type II polyketide synthase (PKS) gene region is different from that of other known type II PKS gene clusters. Directly downstream of the genes encoding ketoacylsynthase alpha and beta (KS alpha, KS beta) are two genes (dpsC, dpsD) encoding proteins of unproven function, both absent from other type II PKS gene clusters. Also in contrast to other type II PKS clusters, the gene encoding the acyl carrier protein (ACP), dpsG, is located about 6.8 kbp upstream of the genes encoding the daunorubicin KS alpha and KS beta. In this work, we demonstrate that the minimal genes required to produce aklanonic acid in heterologous hosts are dpsG (ACP), dauI (regulatory activator), dpsA (KS alpha), dpsB (KS beta), dpsF (aromatase), dpsE (polyketide reductase), and dauG (putative deoxyaklanonic acid oxygenase). The two unusual open reading frames, dpsC (KASIII homolog lacking a known active site) and dpsD (acyltransferase homolog), are not required to synthesize aklanonic acid. Additionally, replacement of dpsD or dpsCD in Streptomyces sp. strain C5 with a neomycin resistance gene (aphI) results in mutant strains that still produced anthracyclines.
Identification, cloning, and characterization of the Ima operon, whose gene products are unique to Listeria monocytogenes
Authors: Schäferkordt S , Chakraborty T
Published: November 2016

The lmaA gene of Listeria monocytogenes encodes a protein capable of inducing delayed-type hypersensitivity reactions in L. monocytogenes-immune mice (S. Göhmann, M. Leimeister-Wachter, E. Schiltz, W. Goebel, and T. Chakraborty, M. Microbiol. 4:1091-1099, 1990). Here we show that it is the last gene of the lma operon, which now comprises four genes, lmaDCBA. Maxicell analysis of peptides encoded by the lma operon identified four polypeptides of 16.7, 16.4, 14.9, and 21 kDa which correspond to the gene products encoded by the lmaD, -C, -B, and -A genes, respectively. Northern blot analysis of the lma operon showed that lmaA is expressed by two transcripts: the longer lmaDCBA transcript of 2,100 nucleotides, which was observed at growth temperatures of 37 and 20 degrees C, and a shorter transcript consisting of lmaBA, which is detected only at low temperatures (20 degrees C). Two promoters, one preceding the lmaD gene and another located upstream of the lmaB gene, were detected. An extended stem-loop structure resembling box elements found in other gram-positive pathogens was also present in the lmaC-lmaB intergenic region. By immunoblot analysis, we found that although LmaA was produced at both temperatures (20 and 37 degrees C), it was secreted into culture supernatants only at 20 degrees C. However, LmaA lacks a bona fide signal peptide sequence and could, like flagellin, be secreted by a type III transport system. DNA hybridization studies indicate that the lma operon is species specific and restricted to pathogenic strains of L. monocytogenes.
The Bacteroides mobilizable transposon Tn4555 integrates by a site-specific recombination mechanism similar to that of the gram-positive bacterial element Tn916
Authors: Tribble G D , Parker A C , Smith C J
Published: November 2016

The Bacteroides mobilizable transposon Tn4555 is a 12.2-kb molecule that encodes resistance to cefoxitin. Conjugal transposition is hypothesized to occur via a circular intermediate and is stimulated by coresident tetracycline resistance elements and low levels of tetracycline. In this work, the ends of the transposon were identified and found to consist of 12-bp imperfect inverted repeats, with an extra base at one end. In the circular form, the ends were separated by a 6-bp "coupling sequence" which was associated with either the left or the right transposon terminus when the transposon was inserted into the chromosome. Tn4555 does not duplicate its target site upon insertion. Using a conjugation-based transposition assay, we showed that the coupling sequence originated from 6 bases of genomic DNA flanking either side of the transposon prior to excision. Tn4555 preferentially transposed into a 589-bp genomic locus containing a 207-bp direct repeat. Integration occurred before or after the repeated sequence, with one integration site between the two repeats. These observations are consistent with a transposition model based on site-specific recombination. In the bacteriophage lambda model for site-specific recombination, the bacteriophage recombines with the Escherichia coli chromosome via a 7-bp "crossover" region. We propose that the coupling sequence of Tn4555 is analogous in function to the crossover region of lambda but that unlike the situation in lambda, recombination occurs between regions of nonhomologous DNA. This ability to recombine into divergent target sites is also a feature of the gram-positive bacterial transposon Tn916.
Characterization of large linear plasmids in mycobacteria
Authors: Picardeau M , Vincent V
Published: November 2016

Linear plasmids were found in Mycobacterium xenopi, M. branderi, and M. celatum. These elements represented a wide size range (from 20 to 320 kb), had Streptomyces-like terminal structures, and defined five hybridization groups. Cross-hybridization and common restriction fragment length polymorphism patterns of plasmids from the different species suggest either genetic exchange or a common ancestry of the species.
Insertional inactivation of dsbA produces sensitivity to cadmium and zinc in Escherichia coli
Authors: Rensing C , Mitra B , Rosen B P
Published: November 2016

In a search for genes that produce hypersensitivity to cadmium salts in Escherichia coli, random transposon mutagenesis with TnphoA was used. One of the mutant strains obtained was sensitive to Cd2+ and Zn2+. Sequence analysis showed that the TnphoA insertion was located in the dsbA gene coding for a periplasmic protein required for disulfide bond formation.
Emergence of Multidrug-Resistant Pneumococcal Serotype 35B among Children in the United States
Authors: Olarte Liset , Kaplan Sheldon L. , Barson William J. , Romero José R. , Lin Philana Ling , Tan Tina Q. , Hoffman Jill A. , Bradley John S. , Givner Laurence B. , Mason Edward O. , Hultén Kristina G.
Published: November 2016

Streptococcus pneumoniae
serotype 35B is a nonvaccine serotype associated with high rates of penicillin nonsusceptibility. An increase in the proportion of multidrug-resistant (MDR) 35B isolates has recently been reported. The genetic events contributing to the emergence of MDR serotype 35B are unknown. The sequence type (ST) composition of 78 serotype 35B isolates obtained from pediatric patients with invasive pneumococcal disease from 1994 to 2014 and 48 isolates from pediatric patients with otitis media (noninvasive) from 2011 to 2014 was characterized by multilocus sequence typing (MLST). The most common STs were ST558 (69.2%), ST156 (10.3%), and ST452 (3.8%). Two major clonal complexes (CC), CC558 and CC156, were identified by eBURST analysis. Overall, 91% (71/78) of isolates were penicillin nonsusceptible and 16.7% (13/78) were MDR. Among all invasive serotype 35B isolates, MDR isolates increased significantly, from 2.9% (1/35) to 27.9% (12/43) (
P
= 0.004), after the 13-valent pneumococcal conjugate vaccine (PCV13) was introduced. All CC156 isolates were identified after the introduction of PCV13 (0/35 [0%] before versus 9/43 [20.9%] after;
P
= 0.003) and were MDR. All CC156 isolates had similar antimicrobial susceptibility patterns; in contrast, high variability in antimicrobial susceptibility was observed among CC558 isolates. The distributions of CC558 and CC156 among invasive and noninvasive isolates were not different. The increased prevalence of MDR serotype 35B after the introduction of PCV13 was directly associated with the emergence of ST156. Genotyping suggests that capsular switching has occurred between MDR vaccine serotypes belonging to ST156 (e.g., 9V, 14, and 19A) and serotype 35B.
Visualization of HIV T Cell Virological Synapses and Virus-Containing Compartments by Three-Dimensional Correlative Light and Electron Microscopy
Authors: Wang Lili , Eng Edward T. , Law Kenneth , Gordon Ronald E. , Rice William J. , Chen Benjamin K.
Published: November 2016

Virological synapses (VS) are adhesive structures that form between infected and uninfected cells to enhance the spread of HIV-1. During T cell VS formation, viral proteins are actively recruited to the site of cell-cell contact where the viral material is efficiently translocated to target cells into heterogeneous, protease-resistant, antibody-inaccessible compartments. Using correlative light and electron microscopy (CLEM), we define the membrane topography of the virus-containing compartments (VCC) where HIV is found following VS-mediated transfer. Focused ion beam scanning electron microscopy (FIB-SEM) and serial sectioning transmission electron microscopy (SS-TEM) were used to better resolve the fluorescent Gag-containing structures within the VCC. We found that small punctate fluorescent signals correlated with single viral particles in enclosed vesicular compartments or surface-localized virus particles and that large fluorescent signals correlated with membranous Gag-containing structures with unknown pathological function. CLEM imaging revealed distinct pools of newly deposited viral proteins within endocytic and nonendocytic compartments in VS target T cells.

IMPORTANCE
This study directly correlates individual virus-associated objects observed in light microscopy with ultrastructural features seen by electron microscopy in the HIV-1 virological synapse. This approach elucidates which infection-associated ultrastructural features represent bona fide HIV protein complexes. We define the morphology of some HIV cell-to-cell transfer intermediates as true endocytic compartments and resolve unique synapse-associated viral structures created by transfer across virological synapses.
Functional Characterization of Adaptive Mutations during the West African Ebola Virus Outbreak
Authors: Dietzel Erik , Schudt Gordian , Krähling Verena , Matrosovich Mikhail , Becker Stephan
Published: November 2016

The Ebola virus (EBOV) outbreak in West Africa started in December 2013, claimed more than 11,000 lives, threatened to destabilize a whole region, and showed how easily health crises can turn into humanitarian disasters. EBOV genomic sequences of the West African outbreak revealed nonsynonymous mutations, which induced considerable public attention, but their role in virus spread and disease remains obscure. In this study, we investigated the functional significance of three nonsynonymous mutations that emerged early during the West African EBOV outbreak. Almost 90% of more than 1,000 EBOV genomes sequenced during the outbreak carried the signature of three mutations: a D759G substitution in the active center of the L polymerase, an A82V substitution in the receptor binding domain of surface glycoprotein GP, and an R111C substitution in the self-assembly domain of RNA-encapsidating nucleoprotein NP. Using a newly developed virus-like particle system and reverse genetics, we found that the mutations have an impact on the functions of the respective viral proteins and on the growth of recombinant EBOVs. The mutation in L increased viral transcription and replication, whereas the mutation in NP decreased viral transcription and replication. The mutation in the receptor binding domain of the glycoprotein GP improved the efficiency of GP-mediated viral entry into target cells. Recombinant EBOVs with combinations of the three mutations showed a growth advantage over the prototype isolate Makona C7 lacking the mutations. This study showed that virus variants with improved fitness emerged early during the West African EBOV outbreak.

IMPORTANCE
The dimension of the Ebola virus outbreak in West Africa was unprecedented. Amino acid substitutions in the viral L polymerase, surface glycoprotein GP, and nucleocapsid protein NP emerged, were fixed early in the outbreak, and were found in almost 90% of the sequences. Here we showed that these mutations affected the functional activity of viral proteins and improved viral growth in cell culture. Our results demonstrate emergence of adaptive changes in the Ebola virus genome during virus circulation in humans and prompt further studies on the potential role of these changes in virus transmissibility and pathogenicity.
Impact of screen time on mental health problems progression in youth: a 1-year follow-up study
Authors: Wu Xiaoyan , Tao Shuman , Zhang Shichen , Zhang Yukun , Chen Kaihua , Yang Yajuan , Hao Jiahu , Tao Fangbiao
Published: November 2016

Objectives

We examined the relationships between screen time (ST) and mental health problems and also increment of ST and progression of mental health problems in a college-based sample of Chinese youth.

Methods

We assessed 2521 Chinese college freshmen from October 2013 to December 2014. At baseline, the mean age of participants was 18.43 years (SD 0.96 years), and 1215 (48.2%) participants reported ST >2 h/day. We estimated multivariable-adjusted ORs by using logistic regression models for the risk of developing mental health problems (anxiety, depression and psychopathological symptoms) and/or progression of these problems, according to baseline ST exposure and changes in exposure at follow-up.

Results

At baseline, when ST >2 h/day was compared with ST ≤2 h/day, the OR was 1.38 (95% CI 1.15 to 1.65) for anxiety, 1.55 (95% CI 1.25 to 1.93) for depression and 1.49 (95% CI 1.22 to 1.83) for psychopathological symptoms. The results remained unchanged for depressive and psychopathological symptoms but not for anxiety, after additional adjustment for sex, age, residential background, body mass index, perceived family economy, sleep quality, smoking, alcohol intake, exercise after school and physical activity. When participants who had increased their ST exposure to >2 h/day were compared with those with no change and ST ≤2 h/day, the OR was 1.78 (95% CI 1.12 to 2.83) for anxiety, 1.92 (95% CI 1.23 to 2.83) for depression and 1.93 (95% CI 1.16 to 3.21) for psychopathological symptoms. These associations also remained after additional adjustment.

Conclusions

The overall effects are consistent yet small for ST/ST increment on mental health problems and its progression. Given the small effect size of the current results, it remains unclear the degree to which ST is a practically significant risk factor for mental health outcomes. Future studies of high quality are necessary to further examine this association and the direction of causality.
Qualitative study of paramedics' experiences of managing seizures: a national perspective from England
Authors: Noble Adam J , Snape Darlene , Goodacre Steve , Jackson Mike , Sherratt Frances C , Pearson Mike , Marson Anthony
Published: November 2016

Objectives

The UK ambulance service is expected to now manage more patients in the community and avoid unnecessary transportations to hospital emergency departments (ED). Most people it attends who have experienced seizures have established epilepsy, have experienced uncomplicated seizures and so do not require the full facilities of an ED. Despite this, most are transported there. To understand why, we explored paramedics’ experiences of managing seizures.

Design and setting

Semistructured interviews were conducted with a purposive sample of paramedics from the English ambulance service. Interviews were transcribed and thematically analysed.

Participants

A diverse sample of 19 professionals was recruited from 5 different ambulance NHS trusts and the College of Paramedics.

Results

Participants’ confirmed how most seizure patients attended to do not clinically require an ED. They explained, however, that a number of factors influence their care decisions and create a momentum for these patients to still be taken. Of particular importance was the lack of access paramedics have to background medical information on patients. This, and the limited seizure training paramedics receive, meant paramedics often cannot interpret with confidence the normality of a seizure presentation and so transport patients out of precaution. The restricted time paramedics are expected to spend ‘on scene’ due to the way the ambulance services’ performance is measured and that are few alternative care pathways which can be used for seizure patients also made conveyance likely.

Conclusions

Paramedics are working within a system that does not currently facilitate non-conveyance of seizure patients. Organisational, structural, professional and educational factors impact care decisions and means transportation to ED remains the default option. Improving paramedics access to medical histories, their seizure management training and developing performance measures for the service that incentivise care that is cost-effective for all of the health service might reduce unnecessary conveyances to ED.
Anthelmintic resistance in equine helminths and mitigating its effects
Authors: Tzelos Thomas , Matthews Jacqueline
Published: November 2016

Helminth control in horses has been based on the administration of broad‐spectrum anthelmintics for over 50 years, but although this has reduced clinical disease, anthelmintic‐resistant populations of nematodes (for example, cyathostomins and Parascaris equorum) have developed due to frequent ‘blanket’ treatments. Resistance to benzimidazole, pyrantel and, more recently, macrocyclic lactones is not uncommon so strategies that balance the use of anthelmintics for parasite control with the need to limit selection pressure for resistance should be adopted. An inability to control burdens of these nematodes could cause serious health problems, particularly in younger horses, as well as in the small number of individuals that have a higher susceptibility to high levels of infection throughout life. This article reviews anthelmintic resistance in equine nematodes and the measures that can be taken in practice to try to mitigate its spread.
Efficacy and safety of the target puncture technique for treatment of osteoporotic vertebral compression fractures with intravertebral clefts
Authors: Yu Weibo , Liang De , Jiang Xiaobing , Yao Zhensong , Qiu Ting , Ye Linqiang
Published: November 2016

Objective

To compare the efficacy and safety of our target puncture technique with the traditional technique during percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fractures (OVCFs) with intravertebral clefts (IVCs).

Methods

104 patients treated with PKP for single OVCFs with IVCs were retrospectively reviewed. All patients were divided into three groups: cleft filling by the traditional technique (Group A, n=18); interdigitated filling (Group B, n=50); and overfilling by the target technique (Group C, n=36). Oswestry disability index (ODI) and visual analog scale (VAS) scores and radiological evidence of vertebral body height and kyphotic angle, cement leakage, and adjacent vertebral fractures were studied before and after surgery (immediate, 1 and 2 years).

Results

The ODI and VAS scores decreased for all patients and no significant difference was found between the three groups after treatment. However, 1 and 2 years after surgery a greater increase in ODI and VAS scores was observed in Group A compared with the other two groups. The initial correction of vertebral body height and kyphotic angle was not significant among the three groups. However, loss of correction was greater in Group A. No significant difference was found in cement leakage. The incidence of adjacent vertebral fractures in Group C was higher than in the other two groups.

Conclusions

Different puncture techniques were initially effective for all patients with IVCs. However, cement cleft filling by the traditional technique was found to have less stability causing higher VAS/ODI scores and greater loss of correction. Hence, our target puncture technique was recommended in this study.
Utility of perfusion imaging in acute stroke treatment: a systematic review and meta-analysis
Authors: Ryu Won Hyung A , Avery Michael B , Dharampal Navjit , Allen Isabel E , Hetts Steven W
Published: November 2016

Background

Variability in imaging protocols and techniques has resulted in a lack of consensus regarding the incorporation of perfusion imaging into stroke triage and treatment. The objective of our study was to evaluate the available scientific evidence regarding the utility of perfusion imaging in determining treatment eligibility in patients with acute stroke and in predicting their clinical outcome.

Methods

We performed a systematic review of the literature using PubMed, Web of Science, and Cochrane Library focusing on themes of medical imaging, stroke, treatment, and outcome (CRD42016037817). We included randomized controlled trials, cohort studies, and case-controlled studies published from 2011 to 2016. Two independent reviewers conducted the study appraisal, data abstraction, and quality assessments of the studies.

Results

Our literature search yielded 13 studies that met our inclusion criteria. In total, 994 patients were treated with the aid of perfusion imaging compared with 1819 patients treated with standard care. In the intervention group 51.1% of patients had a favorable outcome at 3 months compared with 45.6% of patients in the control group (p=0.06). Subgroup analysis of studies that used multimodal therapy (IV tissue plasminogen activator, endovascular thrombectomy) showed a significant benefit of perfusion imaging (OR 1.89, 95% CI 1.43 to 2.51, p<0.01).

Conclusions

Perfusion imaging may represent a complementary tool to standard radiographic assessment in enhancing patient selection for reperfusion therapy, with a subset of patients having up to 1.9 times the odds of achieving independent functional status at 3 months. This is particularly important as patients selected based on perfusion status often included individuals who did not meet the current treatment eligibility criteria.
Selective ophthalmic artery chemosurgery (SOAC) for retinoblastoma: fluoroscopic time and radiation dose parameters. A baseline study
Authors: Boddu Srikanth R , Abramson David H , Marr Brian P , Francis Jasmine H , Gobin Y Pierre
Published: November 2016

Objective

To evaluate fluoroscopic time and radiation dose parameters, and factors affecting these parameters, during selective ophthalmic artery chemosurgery (SOAC) for retinoblastoma.

Materials and methods

Retrospective review from the prospective database of all patients with retinoblastoma treated with SOAC over a 5-year period (September 2009–January 2015) at a single institution after receiving institutional review board approval. Patient demographics, arterial approach, access device, side of treatment, number of SOAC cycles/patient, number of drugs/SOAC, and radiation parameters (outcome variables), including the fluoroscopic time, dose–area product (DAP), and total radiation dose, were obtained from the database. Generalized linear regression was used for univariate and multivariate analysis of the outcome variables.

Results

In 218 patients (M:F=94:124), 272 eyes were treated by 833 SOAC infusions during 792 procedures. Mean age, weight, SOAC cycle/patient, and drugs/cycle were 19±19.5 months, 11.4±6.4 kg, 2.72±1.6, and 2.48±0.8, respectively. Mean fluoroscopic time, DAP, and doses were 10.2±8.4 min, 218.7±240.8 cGy.cm2, and 42.3±41.4 mGy, respectively. Radiation parameters (fluoroscopic time, DAP, and dose) were significantly lower (p<0.001) for the ophthalmic artery (OA) approach (7.5±5.4; 147.7±138.4; 28.5±29.4) than with middle meningeal artery (13.4±5.6; 242±138; 51.4±27) and balloon-assisted infusion in the internal carotid artery (ICA; 17.8±11.5; 449.8±361; 81.8±63.3). Radiation parameters for microcatheter access (8.6±7.1; 193.4±181.3; 42.3±37) were significantly lower (p<0.001) than with the ICA (17.8±11.5; 449.8±361; 81.8±63.3). Radiation parameters for bilateral IA chemotherapy (IAC; 16.8±11.6; 320.7±268.7; 60.8±45.6) were significantly higher (p<0.001) than for unilateral IAC (8.9±6.6; 212.7±247; 42±41).

Conclusions

In SOAC for retinoblastoma, the OA approach, microcatheter access, and unilateral treatment were associated with significantly lower radiation parameters. We established benchmark radiation parameters for retinoblastoma SOAC in our patient cohort.
Dominikia lithuanica and Kamienskia divaricata: new species in the Glomeromycota
Authors: Błaszkowski Janusz , Chwat Gerard , Góralska Anna
Published: November 2016

New species in the genera Dominikia and Kamienskia (Glomeromycota) are characterized based on morphology and sequences of SSU–ITS–LSU nrDNA and the RPB1 gene. Both species produce glomoid spores only in clusters. Spores of Dominikia lithuanica are hyaline to pale yellow and 22–52 μm in diameter when globose. In their three-layered spore wall, layers 1 and 2 are almost equal in thickness and much thinner than the structural laminate layer 3. Spore wall layers 1 and 3 usually stain faintly in Melzer’s reagent. Spores of Kamienskia divaricata remain hyaline regardless of age, are 10–24 μm in diameter and have a spore wall with two layers of nearly the same thickness. The laminate layer 2 usually shows a faint dextrinoid reaction in Melzer’s reagent. A further conspicuous character of K. divaricata spores is a relatively wide subtending hypha at the spore base. In the field, D. lithuanica and K. divaricata have so far been found only twice and once, respectively, and only in maritime sand dunes of the Curonian Spit, Lithuania (D. lithuanica), and South Africa (K. divaricata). Sequence data available in public databases suggest that D. lithuanica has not yet been detected by other researchers, and K. divaricata also occurs in Texas, USA.
Viscous extended holographic Ricci dark energy in the framework of standard Eckart theory
Authors: Chattopadhyay Surajit
Published: November 2016

In this paper, we report a study on the viscous extended holographic Ricci dark energy (EHRDE) model under the assumption of existence of bulk viscosity in the linear barotropic fluid and the EHRDE in the framework of standard Eckart theory of relativistic irreversible thermodynamics and it has been observed that the non-equilibrium bulk viscous pressure is significantly smaller than the local equilibrium pressure. We have studied the equation of state (EoS) parameter and observed that the EoS behaves like “quintom” and is consistent with the constraints set by observational data sets from SNLS3, BAO and Planck + WMAP9 + WiggleZ measurements in [S. Kumar and L. Xu, Phys. Lett. B 737, 244 (2014)]. Analysis of statefinder parameters has shown the possibility of attainment of Lambda cold dark matter ([Formula: see text]CDM) phase under current model and at the same time it has been pointed out that the redshift z = 0, i.e. the current universe, the statefinder pair is different from that of [Formula: see text]CDM and the [Formula: see text]CDM can be attained in a later stage of the universe. An analysis of stability has shown that although the viscous EHRDE along with viscous barotropic is classically unstable in the present epoch, it can lead to a stable universe in very late stage. Considering an universe enveloped by event horizon, we have observed validity of generalized second law (GSL) of thermodynamics.
Changing reflections on the history of geology
Authors: Cooper Barry J.
Published: November 2016

The justification for studying the history of geology is analysed from an Australian perspective. It is considered that history is an essential part of all geological research. With the rise in geological employment, a natural interest in professional history has also developed. A long history of mining in Australia with geological involvement has also led to a greater appreciation of history by local communities. Human understanding of the world is enhanced by studying the history of the earth sciences. Much can be learned by studying the history of geology from an Australian perspective; however, the impact of European ideas and long-standing resource exploration has had a profound impact on Australian geology. Changing specializations in the earth sciences are also noteworthy, while, arguably, the historical role of some individual geologists has been significant.
Murchison in Sweden: consolidating Lower Silurian stratigraphy in the summer of 1844
Authors: Diemer John
Published: November 2016

Roderick Murchison traversed southern Sweden from Göteborg to Stockholm from 28 July to 8 August 1844. He was accompanied by Sven Lovén and they made extensive use of the geognostic map of Sweden published in 1834 by Wilhelm Hisinger. During that campaign, they visited numerous outcrops of Hisinger's ‘Transition’ rocks and Murchison recognized them as belonging to the Lower Silurian, which he had described previously in Britain, Norway and Russia. In addition, he inspected fossil collections at the natural history museum in Stockholm and recognized that Gotland was composed of Upper Silurian rocks. Thus the 1844 campaign established for the first time the occurrence of Silurian rocks in Sweden and it consolidated the usefulness of Palaeozoic system terminology in this part of Scandinavia. Murchison's efficient research methodology ensured his rapid progress in the field and the widespread dissemination of his findings.
International Commission on the History of Geological Sciences: the earliest events
Authors: Grigelis Algimantas , Czarniecki Stanisław
Published: November 2016

The article highlights the role of the Commission on Geological Exploration of the USSR (KOGI), formed in 1955 at the Geological Institute of the USSR Academy of Sciences. The valuable experience gained during work on the large KOGI project was later used by Moscow geologists in 1964 in the proposal leading to the establishment of the International Committee on the History of Geology (INHIGEO). At its Constituent Assembly held in Yerevan in 1967, the decision resulted in the election of 15 founding members, 20 corresponding members and a working agenda and its by-laws in the adoption of the committee statutes. The first INHIGEO membership was approved at the 23rd IGC in Prague in 1968 (12 members and 29 corresponding members).
CFTR-associated ligand is a negative regulator of Mrp2 expression
Authors: Li Man , Soroka Carol J. , Harry Kathy , Boyer James L.
Published: November 2016

The multidrug resistance-associated protein 2 (Mrp2) is an ATP-binding cassette transporter that transports a wide variety of organic anions across the apical membrane of epithelial cells. The expression of Mrp2 on the plasma membrane is regulated by protein-protein interactions. Cystic fibrosis transmembrane conductance regulator (CFTR)-associated ligand (CAL) interacts with transmembrane proteins via its PDZ domain and reduces their cell surface expression by increasing lysosomal degradation and intracellular retention. Our results showed that CAL is localized at the trans-Golgi network of rat hepatocytes. The expression of CAL is increased, and Mrp2 expression is decreased, in the liver of mice deficient in sodium/hydrogen exchanger regulatory factor-1. To determine whether CAL interacts with Mrp2 and is involved in the posttranscriptional regulation of Mrp2, we used glutathione S-transferase (GST) fusion proteins with or without the COOH-terminal PDZ binding motif of Mrp2 as the bait in GST pull-down assays. We demonstrated that Mrp2 binds to CAL via its COOH-terminal PDZ-binding motif in GST pull-down assays, an interaction verified by coimmunoprecipitation of these two proteins in cotransfected COS-7 cells. In COS-7 and LLC-PK1 cells transfected with Mrp2 alone, only a mature, high-molecular-mass band of Mrp2 was detected. However, when cells were cotransfected with Mrp2 and CAL, Mrp2 was expressed as both mature and immature forms. Biotinylation and streptavidin pull-down assays confirmed that CAL dramatically reduces the expression level of total and cell surface Mrp2 in Huh-7 cells. Our findings suggest that CAL interacts with Mrp2 and is a negative regulator of Mrp2 expression.