bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermoelectric figure of merit of semimetal and semiconductor Bi1–xSbx alloy foils
Authors: Nikolaeva A. , Konopko L. , Ghergishan I. , Rogacki K. , Stachowiak P. , Jeżowski A. , Shepelevich V. , Prokoshin V. , Gusakova S.
Published: August 2018

The temperature dependencies of thermal conductivity χ(Т), electrical conductivity σ(Т), and thermopower α(Т) in foils of Bi1–xSbx alloys in the semimetal and semiconductor states, in a temperature range of 4.2–300 K, were experimentally studied. Foils of Bi1–xSbx alloys were prepared by high-speed crystallization of a thin layer of the melt on the polished inner surface of a rotating copper cylinder. High crystallization rates (v = 5 × 105 m/s) enabled a uniform distribution of the components throughout the volume. The thickness of the foils was 10–30 μm with the texture 101¯2 parallel to the foil plane and the С3 axis coinciding with the normal to the foil surface. It was shown that, in the low-temperature range (T < 10 K), the thermal conductivities of the semimetal (Bi–3 at.% of Sb) and semiconductor (Bi–16 at.% of Sb) foils are, respectively, two orders of magnitude and an order of magnitude lower than the thermal conductivities of the bulk samples of the same composition. This effect is interpreted from the viewpoint of combined additional phonon scattering on both the surface and boundaries of the foil grains. The thermoelectric figure of merit of the foils ZT = α2σ/χ was calculated from the ρ(Т), α(Т), and χ(Т) dependencies in the temperature range of 5–300 K. It was found that the thermoelectric figure of merit ZT in the semiconductor foils of n-type Bi1–xSbx alloys at 100 K is 2 times higher than that of the bulk samples of the same composition and crystallographic orientation, which may be used in low-temperature thermoelectric energy converters.
Collective modes in strongly anisotropic conductors with multisheeted Fermi surface
Authors: Stepanenko D. I.
Published: August 2018

It was shown that weakly damped electromagnetic waves can propagate in highly anisotropic organic conductors with multisheeted Fermi surface, including both quasi-one-dimensional and quasi-two-dimensional topological elements placed in a magnetic field. Simple analytical expressions for their spectrum in short-wave and long-wave ranges were obtained. A numerical analysis of dispersion equations for arbitrary values of the wave vector is presented.
Shubnikov–de Haas Oscillations in the Magnetoresistance of Layered Conductors in Proximity to the Topological Lifshitz Transition
Authors: Peschansky V. G. , Kartsovnik M. V. , Fust S.
Published: August 2018

The dependence of the resistance of a layered conductor with a quasi-two-dimensional charge carrier energy spectrum on the strength and orientation of a quantizing magnetic field is studied. The case of an organic conductor with a multisheet Fermi surface consisting of a weakly warped cylinder and two adjoining planar sheets is considered. By applying an external pressure to the conductor or doping it with impurity atoms, the gap between the cylinder and the planar sheets of the Fermi surface (FS) may be reduced so that electrons start wandering on the FS, tunneling between its different parts due to magnetic breakdown. If an electron can pass through all the different sheets of the FS several times during the mean free time, its motion in the plane orthogonal to the magnetic field becomes finite. This leads to Shubnikov–de Haas oscillations with a period determined by the area enclosed by the closed breakdown orbit of an electron in momentum space. However, even at a slight tilting of the field from the normal to the layers by an angle ϑ, the equidistance is broken and at certain angles ϑk the probability of the magnetic breakdown to one of the planar FS sheets may become so low that the electron cannot complete the magnetic-breakdown orbit and its motion over the other planar sheet and the cylindrical part of the FS becomes infinite. As a result, magnetic-breakdown quantum oscillations of magnetization and all kinetic properties vanish. This vanishing repeats periodically as a function of tan ϑ with changing the tilt angle. Possibilities for experimental observation and investigation of the influence of magnetic breakdown on quantum oscillation phenomena are discussed.
The overheating effects in germanium quantum well with two subbands occupied
Authors: Berkutov I. B. , Andrievskii V. V. , Kolesnichenko Yu. A. , Komnik Yu. F. , Mironov O. A.
Published: August 2018

The charge carrier overheating effect was studied in the p-type Si0.4Ge0.6/Ge/Si0.4Ge0.6 heterostructure with two subband occupy. The temperature dependences of hole-phonon relaxation time τh-ph sat weak magnetic fields demonstrated transition of the 2D system from regime of “partial inelasticity” characterized by dependence τh-ph−1 ∝ T2 to regime of small-angle scattering, described by dependence τh-ph−1 ∝ T5 with temperature increase. But in higher magnetic fields the dependence τh-ph−1 ∝ T3 manifests itself on dependences τh-ph(Th-ph). The possible explanations of such dependences are discussed.

PACS: 72.15.Lh Relaxation times and mean free path; 72.20. My Galvanomagnetic and other magnetotransport effects; 72.20. −i Conductivity phenomena in semiconductors and insulators.
The energy spectra of the graphene-based quasi-periodic superlattice
Authors: Korol A. M. , Sokolenko A. I. , Sokolenko I. V.
Published: August 2018

The spectra of the Dirac quasi-electrons transmission through the Fibonacci quasi-periodical superlattice (SL) are calculated and analyzed in the continuum model with the help of the transfer matrix method. The onedimensional SL based on a monolayer graphene modulated by the Fermi velocity barriers is studied. A new quasi-periodical factor is proposed to be considered. We show that the Fibonacci quasi-periodic modulation in graphene superlattices with the velocity barriers can be effectively realized by virtue of a difference in the velocity barrier values (no additional factor is needed and we keep in mind that not each factor can provide the quasi-periodicity). This fact is true for a case of normal incidence of quasi-electrons on a lattice. In contrast to the case of other types of the graphene SL spectra studied reveal the remarkable property, namely the periodic character over all the energy scale and the transmission coefficient doesn’t tend asymptotically to unity at rather large energies. Both the conductance (using the known Landauer-Buttiker formula) and the Fano factor for the structure considered are also calculated and analyzed. The dependence of spectra on the Fermi velocity magnitude and on the external electrostatic potential as well as on the SL geometrical parameters (width of barriers and quantum wells) is analyzed. Using the quasi-periodical SL one can control the transport properties of the graphene structures in a wide range. The obtained results can be used for applications in the graphene-based electronics.
Single-photon superradiance in a single-crystal semiconductor film in the saturation mode
Authors: Moiseev A. G. , Greenberg Ya. S.
Published: August 2018

Single-photon superradiance was studied at cyclotron resonance in an ideal single-crystal semiconductor p-type film, with a cubic structure placed in a homogeneous static strong magnetic field perpendicular to the film surface. The analysis was performed at a low temperature, at which the density of holes at the Landau level n = 0 was maximum, and at the Landau level n = 1 was zero. The current density in the film was calculated using the Lindblad equation for the density matrix, and the parameters of electromagnetic field radiated by the film in the saturation mode, when the radiated electric field strength was high, were studied. It was shown that the universal loss power per unit area of the film depends only on the fundamental constants c, qe, and me, and on the induction of the magnetic field. The conductivity of the film was calculated.
IR Studies of Thermally Stimulated Structural Phase Transformations in Cryovacuum Condensates of Freon 134a
Authors: Drobyshev A. , Aldiyarov A. , Nurmukan A. , Sokolov D. , Shinbayeva A.
Published: August 2018

The method of cryovacuum condensation of thin gas films and, in particular, condensation involving the formation of glassy states, provides ample opportunities for precise control and maintenance of the formation conditions of studied samples. This has prompted researchers to formulate and address the question of the relationship between the formation conditions/structure of molecules and the degree of kinetic stability of cryocondensates, including organic glasses. This study focused on thin films of Freon 134a cryovacuum condensates condensed on a cooled metal substrate comprised of gas at deposition temperatures ranging from 16–100 K and gas phase pressures from 10–4 to 10–6 Torr. A comparison between the vibrational spectra of Freon 134a in the gas phase and in the cryocondensed state is provided. The results of IR spectrometric studies of cryovacuum condensates of Freon 134a (2.5 μm thick) in the frequency range 400–4200 cm–1 are presented. Based on the obtained spectra and data on their thermally stimulated transformations, an assumption is made that, in the temperature range 16–60 K, Freon 134a cryocondensates are in an amorphous state with different degrees of amorphization. At the vitrification temperature of 70 K, transition from the amorphous glassy state to the state of the supercooled liquid phase takes place, followed by its crystallization into the state of a plastic crystal. In the temperature range of 78–80 K, the transition of a plastic crystal to a crystalline state with a monoclinic lattice begins.
Production of tailor-welded blanks by vertical compensation friction stir welding technique
Authors: Abu–Okail Mohamed , Ata Moataz H. , Abu-oqail Ahmed , Essa Ghada M. F. , Mahmoud T. S. , Hassab–Allah Ibrahim
Published: August 2018

An attempt was made for the first time to fabricate tailor-welded blanks (TWBs) through the feasibility of selective alloying in the solid state of vertical compensation friction stir welding (VCFSW) technique. The results revealed that the production of TWBs by VCFSW technique had higher homogeneity without any defects when compared to the production of TWBs by conventional FSW process at constant tool rotational speed 2000 rpm, traverse speed 20 mm min−1 and an inclination angle 2.5°. The maximum mechanical properties of the fabricated TWBs were obtained when the width of compensation strip 1.5 mm was used. The fracture surface of TWB at the width of compensation strip 1.5 mm showed ductile fracture mode.
Evaluation of reference genes for RT-qPCR analysis in wild and cultivated Cannabis
Authors: Guo Rong , Guo Hongyan , Zhang Qingying , Guo Mengbi , Xu Yanping , Zeng Min , Lv Pin , Chen Xuan , Yang Ming
Published: August 2018

RT-qPCR has been widely used for gene expression analysis in recent years. The accuracy of this technique largely depends on the selection of suitable reference genes. In order to facilitate gene expression analysis in wild and cultivated Cannabis, the expression stability of seven candidate reference genes (ACT2, 18S rRNA, GAPDH, UBQ, TUB, PP2A and EF1α) were assessed in leaves samples of different development stages and different organs of both wild and cultivated Cannabis in the present study. Their expression stabilities were evaluated through three software packages (GeNorm, Normfinder and Bestkeeper). Results showed that UBQ and EF1α were the highly ranked genes in different leaves samples, and PP2A was the most stable reference gene in different organs, while GAPDH was the least stable one. And the validation of the reference genes selected was further confirmed by the expression patterns of MDS and OLS.
A novel porous Mo3N2/MoO3 hybrid nanobelts as supercapacitor electrode material
Authors: Yuan Yao , Li Xing-Ru , Zhang Xuyang , Wang Jiacheng , Zhou Yao , Lin Cheng-Te , Lin T.-W. , Yang M
Published: August 2018

This article is withdrawn as it is a duplicate of https://doi.org/10.1088/2399-1984/aad9b8.
Incidence and prognostic factors of ataxia in children with posterior fossa tumors
Authors: Hartley Helen , Pizer Barry , Lane Steven , Sneade Christine , Williams Rebecca , Mallucci Conor , Bunn Lisa , Kumar Ram
Published: August 2018

Background

There is minimal literature specific to motor outcomes in children with posterior fossa tumors (PFTs) despite ataxia being a significant problem in this group. This study aims to report children’s physical outcomes following management of PFT and determine which factors affect severity of ataxia and functional limitations.

Methods

Forty-two children aged between 5 and 17 and between 1 and 4 years following surgery for PFT were assessed using the Scale for the Assessment and Rating of Ataxia (SARA), the Brief Ataxia Rating Scale (BARS), and the mobility Pediatric Evaluation of Disability Inventory (PEDI) subscale to determine prevalence and severity of ataxia and a measure of physical function. Analysis was undertaken comparing impact of tumor location, tumor histology, adjuvant treatment, age at diagnosis, presence of preoperative ataxia, and presence of cerebellar mutism syndrome (CMS) on ataxia and physical function scores.

Results

Seventy-one percent of children demonstrated a SARA and BARS score greater than 2. A total of 48% of children had a PEDI-m score greater than 90. There was no correlation between age at diagnosis or preoperative ataxia and assessment scores. There was a significant difference in SARA/BARS and PEDI-mobility scores depending on tumor histology, tumor location, and presence of CMS.

Conclusions

A high proportion of children (>1 year) following surgery for PFT continue to present with ataxia. Higher ataxia and lower physical function scores were demonstrated in children with medulloblastoma and midline tumors and those diagnosed with CMS. The high prevalence of ataxia demonstrates the need for further research regarding rehabilitation management in this population.
MicroRNA‐766 promotes cancer progression by targeting NR3C2 in hepatocellular carcinoma
Authors: Yang Chao , Ma Xiang , Guan Ge , Liu Huan , Yang Yuling , Niu Qinghui , Wu Zehua , Jiang Yueping , Bian Cheng , Zang Yunjin , Zhuang Likun
Published: August 2018

MicroRNAs (miRNAs) have been reported to play important roles in tumor progression of various cancers. However, the clinical significance and biologic function of miR‐766 in hepatocellular carcinoma (HCC) remain unknown. In this study, we investigated the roles of miR‐766 in HCC progression using HCC cell lines and a xenograft mouse model. miR‐766 expression in tumor tissues and adjacent nontumorous liver tissues of patients with HCC was evaluated by quantitative RT‐PCR. Our results showed that miR‐766 promoted proliferation and metastasis of HCC cells in vitro and in vivo and that NR3C2 was a direct target of miR‐766 and involved in miR‐766–mediated proliferation and metastasis of HCC cells. We also found that miR‐766 affected the β‐catenin signaling pathway by targeting NR3C2. Furthermore, miR‐766 was significantly up‐regulated in HCC tissues and was correlated with the prognosis of patients with liver cancer. Taken together, our results show that miR‐766 affects HCC progression by modulating NR3C2 expression and is a possible new therapeutic target for patients with HCC.—Yang, C., Ma, X., Guan, G., Liu, H., Yang, Y., Niu, Q., Wu, Z., Jiang, Y., Bian, C., Zang, Y., Zhuang, L. MicroRNA‐766 promotes cancer progression by targeting NR3C2 in hepatocellular carcinoma. FASEB J. 33, 1456–1467 (2019). www.fasebj.org
Effect of Intrathecal Bupivacaine Dose on the Success of External Cephalic Version for Breech Presentation: A Prospective, Randomized, Blinded Clinical Trial
Authors: Chalifoux L.A. , Bauchat J.R. , Higgins N. , Toledo P. , Peralta F.M. , Farrer J. , Gerber S.E. , McCarthy R.J. , Sullivan J.T.
Published: August 2018

(Anesthesiology 2017;127:625–632)

Increased rate of cesarean delivery without measurable improvements in maternal or neonatal outcomes is a major public health problem. Breech presentation is a major contributor to the incidence of cesarean delivery and can be prevented by external cephalic version (ECV). Neuraxial blockade for ECV improves maternal satisfaction and procedural success and decreases maternal pain. Meta-analysis of randomized controlled trials suggests that administering higher doses of local anesthetic (LA) for neuraxial block leads to increased ECV success, although the protocol for providing neuraxial blockade for this procedure has not yet been standardized.
Physical Activity and Preterm Birth: Risk Factor or Benefit?
Authors: Armson B.A.
Published: August 2018

(BJOG 2017;124:1827)

Exercise during pregnancy has been discouraged in the past, for fear that it may contribute to preterm labor. While physically demanding work, including heavy lifting, physical exertion and prolonged standing, has been associated with an increased risk of preterm birth, it has been recently suggested that exercise during pregnancy may reduce the risk of preterm birth. The safety and effectiveness of exercise preventing preterm birth is still controversial.
Maternal and Neonatal Outcomes Following Abnormally Invasive Placenta: A Population-based Record Linkage Study
Authors: Baldwin H.J. , Patterson J.A. , Nippita T.A. , Torvaldsen S. , Ibiebele I. , Simpson J.M. , Ford J.B.
Published: August 2018

(Acta Obstet Gynecol Scand 2017;96:1373–1381)

Abnormally invasive placenta (AIP), which includes placenta accreta, increta, and percreta, is associated with serious complications, especially severe postpartum hemorrhage. Several studies have reported an increased prevalence of this condition in conjunction with the increasing cesarean delivery rates in many countries. Most previous studies of AIP have focused only on maternal morbidity and have been limited by small sample sizes. The aim of this population-based Australian study was to examine both maternal and neonatal outcomes after AIP using data from a 10-year period.
Maternal Near-misses at a Provincial Hospital in Papua New Guinea: A Prospective Observational Study
Authors: Bolnga J.W. , Morris M. , Totona C. , Laman M.
Published: August 2018

(Aust N Z J Obstet Gynaecol 2017;57:624–629)

Life-threatening pregnancy-related adverse outcomes and maternal deaths are high in developing countries due to health care systems that are weak and resources that are limited. As laboratory facilities with the capacity to undertake postmortem examinations in order to determine causes of maternal deaths are limited in less developed countries, maternal near-miss cases are increasingly being used as a proxy with the goal of understanding factors associated with maternal mortality as well as morbidity. Even within a developing country, the maternal mortality ratio (MMR) tends to be significantly higher in rural areas than urban areas as there is better access to health care facilities in the urban regions. This prospective observational study aimed to determine the near-miss ratio and MMR as well as understand the contributing factors of maternal near-misses and mortality in a provincial level hospital in the Madang Province in Papua New Guinea (PNG). The majority of women living in this province are underprivileged and reside in rural areas.
Nonmedically Indicated Induction in Morbidly Obese Women is Not Associated With an Increased Risk of Cesarean Delivery
Authors: Kawakita T. , Iqbal S.N. , Huang C.C. , Reddy U.M.
Published: August 2018

(Am J Obstet Gynecol. 2017;217:451.e1–e8)

Morbid obesity is associated with an increased risk of cesarean delivery and maternal comorbidities compared with normal-weight women, hence the high prevalence of class II and class III obesity in women is concerning. Obesity is also a risk factor for stillbirth, especially at >39 weeks gestation. Data regarding the rate of cesarean delivery associated with nonmedically indicated induction of labor compared with expectant management in morbidly obese women are very limited. This retrospective cohort study aimed to evaluate the rate of cesarean delivery associated with nonmedically indicated induction of labor compared with expectant management in morbidly obese women without other comorbidities at term. Secondary outcomes were severe maternal and neonatal outcomes.
Pregnant Trauma Victims Experience Nearly 2-Fold Higher Mortality Compared With their Nonpregnant Counterparts
Authors: Deshpande N.A. , Kucirka L.M. , Smith R.N. , Oxford C.M.
Published: August 2018

(Am J Obstet Gynecol 2017;217:590.e1–e9)

Among all women of reproductive age (14 to 49 y), the leading nonobstetric cause of death is trauma, which affects 1 in 12 pregnancies. Trauma in pregnant women presents unique challenges, such as altered anatomy and hemodynamics and a lack of formal guidelines for treating pregnant women affected by trauma. This study aimed to categorize types of traumatic injuries in pregnant women compared with their nonpregnant counterparts and determine whether pregnancy is an independent risk factor for death among women experiencing trauma. The study also aimed to identify risk factors for death in pregnant women affected by trauma.
Trauma in Pregnancy: An Underappreciated Cause of Maternal Death
Authors: Kilpatrick S.J.
Published: August 2018

(Am J Obstet Gynecol 2017;217:499–500)

While the maternal mortality ratio (MMR) drastically decreased from 1917 to 1980, the MMR in the United States has been steadily on the rise since 1980. Increased obesity, high maternal age, higher cesarean section rate and other factors may contribute to this increase. Currently, deaths from trauma in pregnant women are not counted in the MMR or pregnancy-related maternal death statistics and therefore many deaths are not captured.
Antenatal Corticosteroids: It’s All about Timing
Authors: Gyamfi-Bannerman C.
Published: August 2018

(BJOG 2017;124:1575)

The important effect of timing of corticosteroid administration on the likelihood of benefit has been known for a decade. Subsequent studies have examined possible adverse neonatal outcomes after inappropriately timed antenatal corticosteroids, finding evidence of increased likelihood of ventilator support for infants delivered >14 days following steroids.
Spontaneous and Indicated Preterm Delivery Risk is Increased Among Overweight and Obese Women Without Pregnancy Chronic Disease
Authors: Kim S.S. , Mendola P. , Zhu Y. , Hwang B.S. , Grantza K.L.
Published: August 2018

(BJOG 2017;124:1708–1716)

Premature delivery is the leading cause of infant death in the United States. The relationship between preterm delivery and maternal obesity is not clear, as previous studies have treated factors such as gestational age, parity, and indicated versus spontaneous delivery in varying ways. This study used data from the Consortium on Safe Labor, a large, contemporary US cohort, to investigate preterm delivery risk associated with prepregnancy body mass index in women without chronic diseases by parity, etiological category, and gestational age.
Delivery Parameters, Neonatal Parameters and Incidence of Urinary Incontinence 6 Months Postpartum: A Cohort Study
Authors: Wesnes S.L. , Hannestad Y. , Rortveit G.
Published: August 2018

(Acta Obstet Gynecol Scand 2017;96:1214–1222)

Research on postpartum urinary incontinence (UI) has yielded contradictory results regarding delivery parameters as risk factors for developing this condition. Clear identification of risk factors could be useful for understanding the mechanisms by which UI develops postpartum as well as potentially decreasing the risk of UI if modifiable risk factors are found. The current study used data from a large population-based cohort study to investigate the association between both single risk factors and combinations of risk factors and the development of UI.
Intrapartum and Neonatal Outcomes in Singleton Pregnancies Following Conception by Assisted Reproduction Techniques
Authors: Rozdarz K.M. , Flatley C.J. , Kumar S.
Published: August 2018

(Aust N Z J Obstet Gynaecol 2017;57:588–592)

With the expansion of medically assisted reproductive techniques, including assisted reproductive technologies (ART) and non-ART treatments, a large number of successful pregnancies and births have been achieved in couples affected by infertility. For prospective parents seeking such treatments, awareness regarding intrapartum and perinatal outcomes associated with medically assisted reproductive techniques is essential. Therefore, the current retrospective study was undertaken.
Intravenous Dexmedetomidine for Cesarean Delivery and Its Concentration in Colostrum
Authors: Yoshimura M. , Kunisawa T. , Suno M. , Sugawara A. , Kurosawa A. , Nakanishi R. , Aoki K. , Toriumia T.
Published: August 2018

(Int J Obstet Anesth 2017;32:28–32)

Dexmedetomidine (DEX) has been reported to be useful for reducing postoperative pain after cesarean delivery under spinal anesthesia. The transfer of DEX into the colostrum in humans has not previously been investigated. This study aimed to measure postoperative DEX concentrations in blood and colostrum after elective cesarean delivery performed under spinal-epidural anesthesia in which a DEX infusion was administered during surgery.
Effects on Adult Cognitive Function after Neonatal Exposure to Clinically Relevant Doses of Ionising Radiation and Ketamine in Mice
Authors: Buratovic S. , Stenerlow B. , Sundell-Bergman S. , Fredricksson A. , Viberg H. , Gordh T. , Eriksson P.
Published: August 2018

(Br J Anaesth. 2018;120:546–554)

The “brain growth spurt” (BGS) during fetal development is a vulnerable period characterized by synaptogenesis, dendritic arborization, extensive myelination, and chemical changes. Exposure to ionizing radiation (IR) may have detrimental effects on this period of development. In experimental rodent models, a single neonatal IR dose of 0 to 100 mGy during the BGS period induced modification in behavior of the mice, with a proposed developmental neurotoxicity at 350 mGy, and alteration in cerebral cortex tau levels at 500 mGy. In addition, rodent neonatal exposure to ketamine has been shown to cause acute apoptotic neurodegeneration, alterations of essential neuroproteins, induction of hyperactive phenotype, and cognitive impairment. As pediatric patients often undergo radiotherapy or sedation/anesthesia before or during radiologic procedures, the authors of the present study explored whether IR doses in the range of exposure associated with computerized tomography (CT) scans could interact with low doses of ketamine to induce neurotoxicity in the developing mouse brain.
The Effects of Gestational Use of Antidepressants and Antipsychotics on Neonatal Outcomes for Women With Severe Mental Illness
Authors: Frayne J. , Nguyen T. , Bennett K. , Allen S. , Hauck Y. , Liira H.
Published: August 2018

(Aust N Z J Obstet Gynaecol 2017;57:526–532)

Approximately 4% to 7.6% of fetuses are exposed to psychotropic medications in pregnant women with mental illness. Negative neonatal outcomes and poor neonatal adaptation syndrome are strongly associated with selective serotonin reuptake inhibitor exposure in pregnancy. High rates of special care nursery (SCN) admission appear to be greater in fetuses of women with severe mental illness (SMI). This study aimed to analyze the association between psychotropic medication use and the rates of SCN admission in a cohort of women with SMI and to also examine the neonatal outcomes associated with third trimester exposure to antidepressant medication alone, antipsychotic medication alone, or a combination of both.
Postoperative Antimicrobial Prophylaxis Following Cesarean Delivery in Obese Women: An Exception to the Rule?
Authors: Calfee D.P. , Grünebaum A.
Published: August 2018

(JAMA 2017;318(11):1012–1013)

Cesarean delivery represents approximately a third of all US births and is the most important risk factor for postpartum infection. Obesity is one of the most common risk factors for postcesarean surgical site infection (SSI).
Tenofovir Versus Placebo to Prevent Perinatal Transmission of Hepatitis B
Authors: Jourdain G. , Ngo-Giang-Huong N. , Harrison L. , Decker L. , Khamduang W. , Tierney C. , Salvadori N. , Cressey T.R. , Sirirungsi W. , Achalapong J. , Yuthavisuthi P. , Kanjanavikai P. , Ayudhaya O.P. Na , Siriwachirachai T. , Prommas S. , Sabsanong P. , Limtrakul A. , Varadisai S. , Putiyanun C. , Suriyachai P. , Liampongsabuddhi P. , Sangsawang S. , Matanasarawut W. , Buranabanjasatean S. , Puernngooluerm P. , Bowonwatanuwong C. , Puthanakit T. , Klinbuayaem V. , Thongsawat S. , Thanprasertsuk S. , Siberry G.K. , Watts D.H. , Chakhtoura N. , Murphy T.V. , Nelson N.P. , Chung R.T. , Pol S. , Chotivanich N.
Published: August 2018

(N Engl J Med 2018;378:911–923)

Despite vaccination and administration of hepatitis B immune globulin at birth, mother-to-child transmission of hepatitis B virus (HBV) can still occur, specifically in infants born to women who test positive of hepatitis B e antigen (HBeAg), have a high HBV viral load (>200,000 IU/mL), or have a mutant HBV strain that escapes the vaccine or immune globulin. Antiviral agents like lamivudine, tenofovir disoproxil fumarate (TDF), and telbivudine have been used prophylactically in pregnant women with high HBV viral loads. However, the evidence on the relative benefits or harm of this intervention are limited or of low quality. Therefore, these authors present the results of a clinical trial, in which they assessed the efficacy and safety of TDF in the prevention of mother-to-child HBV transmission in pregnant women positive for HBeAg.
Fetal Survival in Second-trimester Termination of Pregnancy Without Feticide
Authors: Springer S. , Gorczyca M.E. , Arzt J. , Pils S. , Bettelheim D. , Ott J.
Published: August 2018

(Obstet Gynecol 2018;131:575–579)

The recommendations of the Society of Family Planning and guidelines of the Royal College of Obstetricians and Gynaecologists are that, in cases of late termination of pregnancy, feticide should be offered beyond 22 weeks of gestation to ensure stillbirth. However, data on live birth rates and survival times after pregnancy between 20 0/7 and 24 0/7 weeks of gestation are scarce and contradictory. In the present study, the authors reported on their own experience with termination of pregnancy procedures between 20 0/7 and 24 0/7 weeks of gestation not preceded by feticide; they evaluated the live birth rate and in cases of live birth, the duration of neonatal survival.
Patients Undergoing Cesarean Delivery After Exposure to Oxytocin During Labor Require Higher Postpartum Oxytocin Doses
Authors: Foley A. , Gunter A. , Nunes K.J. , Shahul S. , Scavone B.M.
Published: August 2018

(Anesth Analg. 2018;126:920–924)

The effective dose in 90% of patients (ED90) of oxytocin infusion after cesarean delivery (CD) without labor has been reported to be 17.4 IU/h. A recent study has demonstrated an increased ED90 of 44.2 IU/h for patients who were exposed to oxytocin during labor and then progressed to CD. The University of Chicago Family Birth Center protocol for oxytocin administration in the third stage of labor calls for administration of 18 IU/h of oxytocin, with the option for doubling the infusion rate to 36 IU/h in cases of inadequate response. In this retrospective study, the authors determined the clinical relevance of increased dosing requirements for third-stage oxytocin among those patients who were exposed to oxytocin before CD versus those who were not, with the hypothesis that patients exposed to oxytocin before CD would require a higher infusion rate than called for in the protocol.
Onset of Labour Epidural Analgesia With Low-dose Bupivacaine and Different Doses of Fentanyl
Authors: Vedagiri Sai R. , Singh S.I. , Qasem F. , Nguyen D. , Dhir S. , Marmai K. , Adam R. , Jones P.M.
Published: August 2018

(Anaesthesia 2017;72:1371–1378)

While low-concentration local anesthetic solutions combined with opioids have been shown to decrease motor block without affecting the quality of labor analgesia, the onset of analgesia may be delayed when using these solutions. Previous studies have suggested that the onset of labor analgesia may be improved by the addition of a fentanyl bolus to the initial epidural dose. However, previous studies that evaluated the onset of time of epidural labor analgesia used higher concentrations of local anesthetics than are commonly used in current practice. This dose-comparison study aimed to evaluate the onset of epidural labor analgesia with different doses of fentanyl (20, 50, and 100 μg) administered with a low-concentration bupivacaine (0.08%) solution.
Labor Epidural Analgesia and Breastfeeding
Authors: Chestnut D.H.
Published: August 2018

(Anesthesiology 2017;V:127)

Breastfeeding is paramount for both maternal and neonatal well-being and incurs substantial long-term and short-term health benefits to the infant and the mother. A previous randomized controlled study observed that women receiving high-dose fentanyl labor epidural analgesia (cumulative dose >150 µg) were more likely to stop breastfeeding 6 weeks postpartum compared with women receiving less fentanyl or no fentanyl. In addition, the 24-hour neonatal neurobehavioral scores were also lowest in the neonates of women receiving high-dose epidural fentanyl. A systematic review of 23 studies found the evidence substantiating the association between labor epidural analgesia and breastfeeding success to be inconclusive.
Patients’ Preferences for Labor Analgesic Counseling: A Qualitative Analysis
Authors: Toledo P. , Pumarino J. , Grobman W.A. , Wong C.A. , Holl J.L. , Hasnain-Wynia R.
Published: August 2018

(Birth 2017;44:345–351)

Women’s decisions to use or not use neuraxial analgesia for labor may be influenced by fears and concerns about the neuraxial procedure. The aim of this qualitative study was to evaluate patients’ information sources, the timing and content of antepartum labor analgesia counseling, and patients’ preferences for counseling. An interview guide was developed and focused on the sources used for obtaining information about neuraxial analgesia, communication with practitioners about analgesia, perceptions of analgesia counseling received during labor, and preferences for analgesia counseling.
Intrathecal Clonidine as an Adjuvant for Neuraxial Anaesthesia During Cesarean Delivery: A Systematic Review and Meta-Analysis of Randomized Trials
Authors: Crespo S. , Dangelser G. , Haller G.
Published: August 2018

(Int J Obstet Anesth 2017;32:64–76)

Several adjuvants are commonly used with spinal anesthesia, including fentanyl, sufentanil, morphine, epinephrine, and clonidine, in an attempt to decrease the required dose of local anesthetic. While the benefits of intrathecal clonidine administration for acute and postoperative pain control have been confirmed by various studies, there is limited knowledge about any potential harmful effects. Just one systematic review has been published addressing the risk-benefit ratio of spinal clonidine, and that review included only one obstetric study. In fact, regulatory agencies in several countries, including the US Food and Drug Administration, have not yet approved clonidine for intrathecal use so it is currently being used “off-label.” This current systematic review and meta-analysis aimed to identify the risks and benefits associated with intrathecal clonidine used as an adjuvant to spinal local anesthesia for cesarean delivery.
A Random-allocation Graded Dose-Response Study of Norepinephrine and Phenylephrine for Treating Hypotension During Spinal Anesthesia for Cesarean Delivery
Authors: Ngan Kee W.D.
Published: August 2018

(Anesthesiology 2017;127:934–941)

While phenylephrine is the established preferred vasopressor for maintaining blood pressure during spinal anesthesia for cesarean delivery, it is often associated with decreased heart rate and cardiac output. Both norepinephrine and phenylephrine are potent α-adrenergic agonists, yet norepinephrine also possesses weak β-adrenergic agonist activity. Recent studies have compared phenylephrine with norepinephrine; however, the doses of norepinephrine have varied. This random-allocation, graded dose-response study aimed to determine the relative potencies of norepinephrine and phenylephrine in treatment of hypotension during spinal anesthesia for cesarean delivery.
Strategies for Prevention of Spinal-associated Hypotension During Cesarean Delivery: Are We Paying Attention?
Authors: Uppal V. , McKeen D.M.
Published: August 2018

(Can J Anaesth 2017;64:991–996)

Spinal anesthesia (SA)-induced hypotension is a common complication during cesarean delivery (CD) and can cause a wide range of adverse maternal and neonatal outcomes if untreated. Moore et al’s clinical trial aimed at assessing the median seated time to prevent hypotension in 50% of parturients undergoing elective CD after SA using an up-down sequential methodology. The participants were randomized to receive either 11.25 or 15 mg hyperbaric bupivacaine along with fentanyl 15 µg and morphine 150 µg. It was noted that the median seated time in the 11.25 mg bupivacaine group was a little more than 2 minutes whereas in the 15 mg bupivacaine group the median seated time was approximately 8 minutes, suggesting that extended seated time after SA could prevent hypotension in CD. Further studies elucidating the association of extended seated time and hypotension are essential to design effective prevention strategies for hypotension in CD. The current study was only powered to detect the intervention that prevented hypotension in 50% of patients, which questions its clinical relevance. Disadvantages of the prolonged seated strategy include a delay in surgical start time, reduced operating room efficiency, and shorter duration of anesthesia.
A Prospective Study of Post-cesarean Delivery Hypoxia After Spinal Anesthesia With Intrathecal Morphine 150 μg
Authors: Ladha K.S. , Kato R. , Tsen L.C. , Bateman B.T. , Okutomi T.
Published: August 2018

(Int J Obstet Anesth. 2017;32:48–53)

Neuraxial morphine is one of the most common postoperative analgesia techniques for women who have undergone cesarean delivery. Delayed respiratory depression is a concerning side effect of intrathecal morphine (ITM), as it can potentially increase morbidity and mortality. While the incidence of bradypnea associated with ITM has been reported to be 0.25% or lower, this rate may not account for all cases of ITM-induced respiratory depression because respiratory rate was not continuously monitored in the studies from which these rate were calculated. In addition, patients may develop hypoxia or hypercarbia without the presence of bradypnea. This study aimed to analyze the incidence and timing of hypoxic events in patients receiving post-cesarean analgesia in the form of ITM 150 μg, in order to better define populations at risk of developing hypoxia following ITM.
A Randomized, Controlled Trial of Rectus Sheath Bupivacaine and Intrathecal Bupivacaine, Without or With Intrathecal Morphine, versus Intrathecal Bupivacaine and Morphine After Caesarean Section
Authors: Lui M.W. , Li T.K.T. , Lui F. , Ong C.Y.T.
Published: August 2018

(Anaesthesia 2017;72:1225–1229)

Adequate analgesia after cesarean delivery plays a role in earlier mobilization after surgery and discharge from the hospital. Intrathecal morphine is one of the most common forms of analgesia used for postcesarean analgesia. It is associated with bothersome side effects of pruritus and nausea/vomiting, however. The rectus sheath block has been found to decrease opioid requirements after many types of surgeries, including cesarean delivery without intrathecal morphine. This study sought to determine the efficacy and side-effects of intrathecal morphine, rectus sheath block with bupivacaine, and their combination for women undergoing elective cesarean deliveries.
Intrathecal Hematoma and Arachnoiditis Mimicking Bacterial Meningitis After an Epidural Blood Patch
Authors: Roy-Gash F. , Engrand N. , Lecarpentier E. , Bonneta M.P.
Published: August 2018

(Int J Obstet Anesth 2017;32:77–78)

Epidural blood patch (EBP) is the most effective method to treat postdural puncture headache and has a low rate of complications. However, severe complications such as cauda equina syndrome and seizures have rarely been reported. This case report describes a woman who underwent an EBP and later presented with symptoms concerning for meningitis, but was ultimately found to have arachnoiditis from an intrathecal hematoma.
Pneumocephalus and Seizures Following Combined Spinal-epidural for Labor
Authors: Jones J.M. , Gouveia J.P. , Rodrigues N.M.
Published: August 2018

(J Clin Anesth. 2018;44:123–124)

In this correspondence, the authors described a patient who presented with simultaneous pneumocephalus and cavernoma after receiving combined spinal-epidural analgesia for labor. However, unlike most cases of combined spinal-epidural analgesia for labor, which use loss of resistance to air to identify the epidural space, the authors used loss of resistance to saline. To the author’s knowledge, there are no published reports of the use of loss of resistance to saline for this purpose. Identification of the epidural space was successful upon the fourth attempt with the patient in a sitting position. Upon injection of local anesthetic, the patient immediately complained of a severe headache, that was unremitting with postural changes and continued into the postpartum period. On postpartum day 2, the patient presented with a tonic-clonic seizure. Magnetic resonance imaging showed intraventricular pneumocephalus and cavernoma in the right frontal region, and electroencephalogram showed abundant epileptic activity. Oxygen was added to the patient’s therapy with clinical improvement; complete reabsorption of air on radiologic examination was seen on the sixth day and the asymptomatic patient was discharged.
Moving Toward Individualized Medicine for Uterine Leiomyomas
Authors: Laughlin-Tommaso Shannon K. , Stewart Elizabeth A.
Published: August 2018

Uterine leiomyomas are common and life-altering for many women. Despite a wide range of symptoms, varying characteristics of the uterus and the leiomyomas themselves, and many alternatives, hysterectomy accounts for almost three fourths of all surgical therapy, yet there is increasing evidence for a variety of procedural therapies for symptomatic leiomyomas and a new generation of medical therapies under development. With increasing evidence of long-term risk from hysterectomy and new data regarding leiomyoma biology, individualized medical approaches to leiomyomas are likely in the near future. Key biological attributes that influence this disease process are common driver mutations and the new appreciation of the interaction of smooth muscle cells and fibroblasts. Additionally, the interaction between cell types and steroid hormone responsiveness likely plays a role in pathogenesis that can be leveraged in individualized therapy. However, given the independent clonal nature of leiomyomas within the same uterus, moving in the direction of biopsies for individual leiomyomas to understand the biology is unlikely to be fruitful. Use of advanced imaging will likely continue to evolve not only to accurately predict malignant disease, including sarcomas, but to predict leiomyoma subtypes, response to therapy, or both. We predict the continued evolution of therapy from excisional or interventional therapies to medical therapies and ultimately prediction of at-risk individuals. Ideally, individualized therapies will offer primary prevention for women at high risk of leiomyomas and secondary prevention after initial treatment.
Improving Obstetric Hypertensive Emergency Treatment in a Tertiary Care Women's Emergency Department
Authors: Froehlich Rosemary J. , Maggio Lindsay , Has Phinnara , Vrees Roxanne , Hughes Brenna L.
Published: August 2018

OBJECTIVE:

To assess treatment outcomes associated with an obstetric hypertensive emergency quality improvement intervention instituted in a tertiary care women's emergency department.

METHODS:

We conducted a cohort study of pregnant (20 weeks of gestation or greater) and postpartum (6 weeks of gestation or less) women treated for hypertensive emergency (systolic blood pressure [BP] 160 mm Hg or greater, diastolic 110 mm Hg or greater, or both) before and after a quality improvement intervention. A multidisciplinary task force revised clinical guidelines and nursing policy, updated electronic order sets, and provided staff education and clinical management aids. Data were collected by electronic chart review. The primary outcome was achieving goal BP (systolic 150 mm Hg or less and diastolic 100 mm Hg or less) within an hour of initial therapy. Secondary outcomes included time from first severe BP to 1) first antihypertensive treatment and 2) goal BP.

RESULTS:

There were no significant differences in baseline characteristics in the preintervention (n=173; September 2014 to September 2015) and postintervention (n=173; December 2015 to November 2016) groups, including gestational age, days postpartum, maternal age, race–ethnicity, or comorbidities. We found no significant difference in primary outcome frequency: 41% achieved goal BP within 60 minutes preintervention vs 47% postintervention (P=.28). Median time from first severe BP to first treatment was unchanged (30 minutes preintervention vs 29 minutes postintervention, P=.058); however, median time from first severe BP to goal BP decreased significantly (122 vs 95 minutes, P=.04). Confirmation of hypertensive emergency within 15 minutes (recommended) was only achieved in approximately 20% of women in either group. More women initially received intravenous antihypertensive treatment after the intervention (52% preintervention vs 80% postintervention, P<.001).

CONCLUSION:

A quality improvement initiative was not associated with more women achieving BP control within an hour of obstetric hypertensive emergency treatment, but was associated with decreased time to achieve control. This suggests improved clinical practice after the intervention.