Expanding the field of acute care surgery: a systematic review of the use of resuscitative endovascular balloon occlusion of the aorta (REBOA) in cases of morbidly adherent placenta.

PURPOSE: Prophylactic placement of endovascular balloon occlusion catheters has grown to be part of the surgical plans to control intraoperative hemorrhage in cases of abnormal placentation. We performed a systematic literature review to investigate the safety and effectiveness of the use of REBOA during cesarean delivery in pregnant woman with morbidly adherent placenta. METHODS: A systematic review was performed. Relevant case reports and nonrandomized studies were identified by the literature search in MEDLINE. We included studies involving pregnant woman with diagnosis of abnormal placentation who underwent cesarean delivery with REBOA placed for hemorrhage control. MINORS' criteria were used to evaluate the risk of bias of included studies. A formal meta-analysis was not performed. RESULTS: Eight studies were included in cumulative results. These studies included a total of 392 patients. Overall, REBOA was deployed in 336 patients. Six studies reported the use of REBOA as an adjunct for prophylactic hemorrhage control in pregnant woman with diagnosis of morbidly adherent placenta undergoing elective cesarean delivery. In two studies, REBOA was deployed in patients already in established hemorrhagic shock at the moment of cesarean delivery. REBOA was deployed primarily by interventional radiologists; however, one study reported a surgeon as the REBOA provider. The results from our qualitative synthesis indicate that the use of REBOA during cesarean delivery resulted in less blood loss with a low rate complications occurrence. CONCLUSION: REBOA is a feasible, safe, and effective means of prophylactic and remedial hemorrhage control in pregnant women with abnormal placentation undergoing cesarean delivery.

Giant cross-magnetic-field steps due to binary collisions between pair particles.

Giant cross-magnetic-field steps can occur as a result of positron-electron collisions. Within a constant magnetic field (e.g., 1 T), a collision between a positron and an electron can result in a correlated drift across the magnetic field for a continuous range of impact parameters. Within this range, drift distances orders of magnitude larger than that associated with like-charge collisions were observed by computer simulation. Outside of this range, the collisional behavior is similar to that for collisions between particles with the same charge. A theoretical analysis of the phenomenon using center-of-mass and relative coordinates provides insights regarding the occurrence of giant cross-magnetic-field steps.

Reprogramming of cassava (Manihot esculenta) microspores towards sporophytic development.

Gametes have the unique potential to enter the sporophytic pathway, called androgenesis. The plants produced are usually haploid and recombinant due to the preceding meiosis and they can double their chromosome number to form doubled haploids, which are completely homozygous. Availability of the doubled haploids facilitates mapping the genes of agronomically important traits, shortening the time of the breeding process required to produce new hybrids and homozygous varieties, and saving the time and cost for inbreeding. This study aimed to test the feasibility of using isolated and in vitro cultured immature cassava (Manihot esculenta) microspores to reprogramme and initiate sporophytic development. Different culture media and different concentrations of two ion components (Cu(2+) and Fe(2+)) were tested in two genotypes of cassava. External structural changes, nuclear divisions and cellular changes during reprogramming were analysed by scanning electron microscopy, by staining with 4',6-diamidino-2-phenylindole, and through classical histology and transmission electron microscopy. In two cassava genotypes, different developmental stages of microspores were found to initiate sporophytic cell divisions, that is, with tetrads of TMS 60444 and with mid or late uni-nucleate microspores of SM 1219-9. In the modified NLN medium (NLNS), microspore enlargements were observed. The medium supplemented with either sodium ferrous ethylene-diamine-tetraacetic acid (NaFeEDTA) or CuSO4·5H2O induced sporophytic cell division in both genotypes. A low frequency of the reprogramming and the presence of non-responsive microspores among the responsive ones in tetrads were found to be related to the viability and exine formation of the microspores. The present study clearly demonstrated that reprogramming occurs much faster in isolated microspore culture than in anther culture. This paves the way for the development of an efficient technique for the production of homozygous lines in cassava. This is the first ever detailed report of microspore reprogramming at the tetrad stage and the first report of microspore embryogenesis induction in cassava with detailed evidence.

A milestone in the doubled haploid pathway of cassava: a milestone in the doubled haploid pathway of cassava (Manihot esculenta Crantz): cellular and molecular assessment of anther-derived structures.

This study was aimed at inducing androgenesis in cultured anthers of cassava (Manihot esculenta Crantz) to develop a protocol for the production of doubled haploids. Microspore reprogramming was induced in cassava by cold or heat stress of anthers. Since the anthers contain both haploid microspores and diploid somatic cells, it was essential to verify the origin of anther-derived calli. The origin of anther-derived calli was assessed by morphological screening followed by histological analysis and flow cytometry (FCM). Additionally, simple sequence repeat (SSR) and amplified fragmented length polymorphism (AFLP) assays were used for the molecular identification of the microspore-derived calli. The study clearly demonstrated the feasibility of producing microspore-derived calli using heat- or cold-pretreated anthers. Histological studies revealed reprogramming of the developmental pathway of microspores by symmetrical division of the nucleus. Flow cytometry analysis revealed different ploidy level cell types including haploids, which confirmed their origin from the microspores. The SSR and AFLP marker assays independently confirmed the histological and FCM results of a haploid origin of the calli at the DNA level. The presence of multicellular microspores in the in vitro system indicated a switch of developmental program, which constitutes a crucial step in the design of protocols for the regeneration of microspore-derived embryos and plants. This is the first detailed report of calli, embryos, and abnormal shoots originated from the haploid cells in cassava, leading to the development of a protocol for the production of doubled haploid plants in cassava.

Effect of positron space charge on operation of an antihydrogen trap.

Experimental conditions have recently been reported [G. Andresen, Phys. Rev. Lett. 98, 023402 (2007)] that are relevant to the prospect of trapping antihydrogen atoms. An analysis of the experimental conditions indicates that positron space charge can have an important effect. The fraction of antiprotons that have an energy suitable for antihydrogen trapping can be reduced by drifts caused by the presence of positron space charge.

Adiabatic formation of quasibound states of antihydrogen.

The classical trajectory of an initially unbound positron within the electric field of an antiproton and a uniform magnetic field is simulated in three dimensions. Several simulations are run incorporating experimental parameters used for antihydrogen production, which has been achieved by two different groups [M. Amoretti, Nature (London) 419, 456 (2002); G. Gabrielse, Phys. Rev. Lett. 89, 213401 (2002)]. The simulations indicate that temporary bound states of antihydrogen can form at positive energies, where the energy of the system is defined to be zero when the positron and antiproton are at rest with infinite separation. Such quasibound states, which form only when the magnetic field is present, are typically smaller than in a dimension perpendicular to the magnetic field. An analytical model is developed for a formation cross section, and it is found that quasibound states may form more frequently than stable Rydberg states.

Plasma two-temperature equilibration rate.

A theory is developed that is suitable for describing a two-species thermalization process in a plasma with parameters suitable for recombination to take place. Recombining plasmas have recently been produced using positrons and antiprotons [M. Amoretti et al., Nature (London) 419, 456 (2002); G. Gabrielse et al., Phys. Rev. Lett. 89, 213401 (2002)]. The theory is not restricted to large Coulomb logarithm values, and correspondence with prior theory is shown in the limit of large Coulomb logarithm values. The theory applies for two plasma species, each having a Maxwellian velocity distribution and being weakly correlated.

Fully and partially non-neutral plasma equilibria in a variable-electrode-radius Malmberg-Penning trap.

Two types of plasma equilibria are self-consistently computed for a three-electrode Malmberg-Penning trap that has an increase in the radius of a section of the center electrode. When a single species, fully non-neutral plasma is confined within the trap, equilibria are predicted in which the plasma produces a three-dimensional electric potential well. Partially non-neutral plasma equilibria are predicted to be possible by confining a second, oppositely signed plasma species within the three-dimensional well produced by the first plasma species. Conditions that are necessary for partially non-neutral plasma equilibria to be self-consistently possible are reported. A partially non-neutral plasma formed of electrons and singly charged xenon ions is then specifically considered, first with the ions confined within a three-dimensional well produced by the electrons and next with the electrons confined within a three-dimensional well produced by the ions.

Growth of the conceptus in alpacas.

OBJECTIVE: To determine growth of the alpaca conceptus during early gestation, using ultrasonography. ANIMALS: 40 pregnant alpacas (20 multiparous, 20 nulliparous). PROCEDURE: Transrectal ultrasonography with a 5-MHz probe was performed 3 times weekly from days 7 through 45 after copulation (day of copulation = day 0). Blood samples were collected for progesterone assay on days of ultrasonography. RESULTS: Forty embryonic vesicles and embryos were identified and measured. Embryonic vesicles were first detected on day 12 after copulation and appeared spherical. Cumulative percentage of embryonic vesicles detected was 50, 82.5, and 100% on days 12, 14, and 16, respectively. Embryos were first detected by day 22 and heartbeats by day 24. Similarly, cumulative percentage of embryos detected was 17.5, 82.5 and 100% for 22, 24, and 26 days after copulation, respectively. Embryonic vesicles occupied both uterine horns beginning on day 19. A positive correlation existed between length and width of embryonic vesicles. Size of embryonic vesicles and embryos and progesterone concentrations did not differ between multiparous and nulliparous females. Five sets of twins were detected from days 21 through 33 after copulation, but the conceptus identified in the right uterine horn became nondetectable between days 28 and 33. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasonography was useful in detecting the earliest appearance of alpaca embryonic vesicles and determining the changes in growth from days 12 through 45 after copulation. Embryos were first detected by day 22. Transrectal ultrasonography was not harmful to animals and did not provoke embryonic death in this study.

Confinement physics for thermal, neutral, high-charge-state plasmas in nested-well solenoidal traps.

A theoretical study is presented which indicates that it is possible to confine a neutral plasma using static electric and solenoidal magnetic fields. The plasma consists of equal temperature electrons and highly stripped ions. The solenoidal magnetic field provides radial confinement, while the electric field, which produces an axial nested-well potential profile, provides axial confinement. A self-consistent, multidimensional numerical solution for the electric potential is obtained, and a fully kinetic theoretical treatment on axial transport is used to determine an axial confinement time scale. The effect on confinement of the presence of a radial electric field is explored with the use of ion trajectory calculations. A thermal, neutral, high-charge-state plasma confined in a nested-well trap opens new possibilities for fundamental studies on plasma recombination and cross-field transport processes under highly controlled conditions.