Perioperative blood conservation strategies for pediatric scoliosis surgery.

PURPOSE: Many pediatric patients with severe scoliosis requiring surgery have baseline anemia. Pediatric scoliosis fusion surgery is associated with perioperative blood loss requiring transfusion. As such, many patients in this surgical population could benefit from a perioperative blood conservation program. METHODS: Here we present a narrative review of perioperative blood conservation strategies for pediatric scoliosis surgery involving nurses, transfusion medicine physicians, anesthesiologists, surgeons, dieticians, perfusionists and neurophysiologists spanning the pre-, intra- and postoperative phases of care. RESULTS: The review highlights how perioperative blood conservation strategies, have the potential to minimize exposures to exogenous blood products. Further, we describe a relevant example of blood conservation related to the care of a Jehovah's Witness patient undergoing staged scoliosis repair. Lastly, we outline areas which would benefit from clinical studies to further elucidate perioperative blood conservation interventions and their outcomes relevant to pediatric scoliosis surgery patients. CONCLUSION: Interdisciplinary communication and meticulous blood conservation strategies are proving to be a means of reducing if not eliminating the need for allogeneic blood products for surgical correction of pediatric scoliosis.

PlanHab Study: Consequences of combined normobaric hypoxia and bed rest on adenosine kinetics.

Adenosine plays a role in the energy supply of cells and provokes differential, hormone-like functions in circulating cells and various tissues. Its release is importantly regulated by oxygen tension. This renders adenosine and its kinetics interesting to investigate in humans subjected to low oxygen conditions. Especially for space exploration scenarios, hypoxic conditions - together with reduced gravity - represent two foreseen living conditions when planning manned long-duration space missions or planetary habitats. The PlanHab study investigated microgravity through inactivity in bed rest and normobaric hypoxia to examine their independent or combined effect on adenosine and its kinetics. Healthy male subjects (n = 14) completed three 21-day interventions: hypoxic bed rest (HBR); hypoxic ambulatory confinement (HAMB); normoxic bed rest (NBR). The interventions were separated by 4 months. Our hypothesis of a hypoxia-triggered increase in adenosine was confirmed in HAMB but unexpectedly also in NBR. However, the highest adenosine levels were noted following HBR. Furthermore, the percentage of hemolysis was elevated in HBR whereas endothelial integrity markers stayed low in all three interventions. In summary, these data suggest that neocytolysis accounts for these effects while we could reduce evidence for microcirculatory changes.

PlanHab study: assessment of psycho-neuroendocrine function in male subjects during 21 d of normobaric hypoxia and bed rest.

Immobilization and hypoxemia are conditions often seen in patients suffering from severe heart insufficiency or primary pulmonary diseases (e.g. fibrosis, emphysema). In future planned long-duration and exploration class space missions (including habitats on the moon and Mars), healthy individuals will encounter such a combination of reduced physical activity and oxygen tension by way of technical reasons and the reduced gravitational forces. These overall unconventional extraterrestrial conditions can result in yet unknown consequences for the regulation of stress-permissive, psycho-neuroendocrine responses, which warrant appropriate measures in order to mitigate foreseeable risks. The Planetary Habitat Simulation Study (PlanHab) investigated these two space-related conditions: bed rest as model of reduced gravity and normobaric hypoxia, with the aim of examining their influence on psycho-neuroendocrine responses. We hypothesized that both conditions independently increase measures of psychological stress and enhance neuroendocrine markers of stress, and that these effects would be exacerbated by combined treatment. The cross-over study composed of three interventions (NBR, normobaric normoxic horizontal bed rest; HBR, normobaric hypoxic horizontal bed rest; HAMB, normobaric hypoxic ambulatory confinement) with 14 male subjects during three sequential campaigns separated by 4 months. The psychological state was determined through three questionnaires and principal neuroendocrine responses were evaluated by measuring cortisol in saliva, catecholamine in urine, and endocannabinoids in blood. The results revealed no effects after 3 weeks of normobaric hypoxia on psycho-neuroendocrine responses. Conversely, bed rest induced neuroendocrine alterations that were not influenced by hypoxia.

Hubbard U calculations for gap states in dilute magnetic semiconductors.

On the basis of constrained density functional theory, we present ab initio calculations for the Hubbard U parameter of transition metal impurities in dilute magnetic semiconductors, choosing Mn in GaN as an example. The calculations are performed by two methods: (i) the Korringa-Kohn-Rostoker (KKR) Green function method for a single Mn impurity in GaN and (ii) the full-potential linearized augmented plane-wave (FLAPW) method for a large supercell of GaN with a single Mn impurity in each cell. By changing the occupancy of the majority t2 gap state of Mn, we determine the U parameter either from the total energy differences E(N + 1) and E(N - 1) of the (N ± 1)-electron excited states with respect to the ground state energy E(N), or by using the single-particle energies for n(0) ± 1/2 occupancies around the charge-neutral occupancy n0 (Janak's transition state model). The two methods give nearly identical results. Moreover the values calculated by the supercell method agree quite well with the Green function values. We point out an important difference between the 'global' U parameter calculated using Janak's theorem and the 'local' U of the Hubbard model.

Role of vacancies in metal-insulator transitions of crystalline phase-change materials.

The study of metal-insulator transitions (MITs) in crystalline solids is a subject of paramount importance, both from the fundamental point of view and for its relevance to the transport properties of materials. Recently, a MIT governed by disorder was observed in crystalline phase-change materials. Here we report on calculations employing density functional theory, which identify the microscopic mechanism that localizes the wavefunctions and is driving this transition. We show that, in the insulating phase, the electronic states responsible for charge transport are localized inside regions having large vacancy concentrations. The transition to the metallic state is driven by the dissolution of these vacancy clusters and the formation of ordered vacancy layers. These results provide important insights on controlling the wavefunction localization, which should help to develop conceptually new devices based on multiple resistance states.

[Preclinical evaluation of coated knee implants for allergic patients]. / Präklinische Ergebnisse beschichteter Knieimplantate für Allergiker.

BACKGROUND: 10-15% of the population show allergic reactions against skin contact to metals as nickel, cobalt or chromium and have thus a risk of not tolerating implants containing those materials. The relationship between periimplantary hypersensivity reaction and given cutaneous contact allergy is currently unknown. A new developed multilayer coating system is supposed to prevent long-term allergic reactions that may result from uncoated implants. METHODS: Stability and function (concerning bonding durability, wear and ion release to the serum) of the multilayer coating system has been examined in a test series. RESULTS: The specific architecture of the multilayer coating system evidences a very good bonding durability. The results of the test in the simulator show a reduction of wear of approximately 60% compared to the uncoated implants. Ion concentrations within the serum of the wear tests were by magnitudes lower than those measured in reference tests on uncoated components. CONCLUSION: The results of the preclinical evaluation prove that the durability and function of the multilayer coating system are as intended.

Changes in soft tissue composition are the primary predictors of 4-year bone mineral density changes in postmenopausal women.

UNLABELLED: Changes in body weight influence bone mineral density, but the role of body composition is not clear in postmenopausal women. Body weight and soft tissue composition predicted bone changes independent of calcium supplementation and exercise frequency, indicating that soft tissue composition should be measured in clinical trials. INTRODUCTION: The purpose of this study was to examine the relationship between changes in body weight and composition and changes in 4-year bone mineral density (BMD) after accounting for age, 4-year exercise frequency (EX), and 4-year calcium supplement intake (CA) in postmenopausal women with and without hormone therapy (HT). METHODS: Postmenopausal women (aged 40-65 years) either using HT (for 1-3.9 years) or not using HT (for > or =1 year) were recruited to the study. EX and CA was monitored throughout the study and 167 women completed 4 years. BMD and soft tissue composition measurements were made using dual-energy X-ray absorptiometry. Regression was used to predict 4-year BMD changes from EX, CA, age, baseline and 4-year changes in body weight and composition. HT users (n = 115, 55.3 +/- 4.3 years) and non-users (n = 52, 57.5 +/- 4.7 years) were analyzed separately. RESULTS: The models predicting regional BMD changes that included soft tissue composition changes explained the most variation compared with those with body weight or EX and CA alone. Larger amounts of variation in BMD changes were explained in the no HT group. CONCLUSION: Body composition changes are important positive predictors of BMD changes independent of EX and CA supplementation, but their contribution varies according to bone site and with HT use.

Electrical conductivity measurement: a new technique to detect iatrogenic initial pedicle perforation.

Pedicle screw fixation has achieved significant popularity amongst spinal surgeons for both single and multi-level spinal fusion. Misplacement and pedicle cortical violation occurs in over 20% of screw placement and can result in potential complications such as dysthesia, paraparesis or paraplegia. There have been many advances in techniques available for navigating through the pedicle; however, these techniques are not without drawbacks. A new electrical conductivity-measuring device, previously evaluated on the porcine model to detect the pedicle violation, was evaluated amongst nine European Hospitals to be used in conjunction with the methods currently used in that centre. This new device is based on two original principles; the device is integrated in the drilling or screwing tool. The technology allows real-time detection of perforation through two independent parameters, impedance variation and evoked muscle contractions. Data was collected twofold. Initially, the surgeon was given the device and a comparison was made between the devices ability to detect a breech and the surgeon's ability to detect one using his traditional methods of pedicle preparation. In the second module of the study, the surgeon was limited to using the electrical conductivity detection device as their sole guide to detect pedicle breaches. A comparison was made between the detection ability of the device and the other detection possibilities. Post-operative fine cut CT scanning was used to detect the pedicle breaches. Overall, the 11 trial surgeons performed a total of 521 pedicle drillings on 97 patients. Initially there were 147 drillings with 23 breaches detected. The detection rate of these breaches were 22/23 for the device compared to 10/23 by the surgeon. Over both parts of the study 64 breaches (12.3%) were confirmed on post-operative CT imaging. The electrical conductivity detection device detected 63 of the 64 breaches (98.4%). There was one false negative and four false positives. This gives the device an overall sensitivity of 98% and specificity of 99% for detecting a pedicle breach. The negative predictive value was 99.8%, with a positive predictive value of 94%. No adverse event was noted with the use of the electrical conductivity device. Electrical conductivity monitoring may provide a simple, safe and sensitive method of detecting pedicle breech during routine perforation of the pedicle, in the course of pedicle screw placement.

Factors influencing nurses' judgements about self-neglect cases.

From the perspective of the practising nurse self-neglect may best be understood in terms of a set of complex and often poorly defined clinical problems in which two key clinical issues are "how do I judge whether this person has the capacity to make decisions about their lifestyle?" and "do we need to treat this person using mental health legislation?" These are taxing questions as judging if a patient has the capacity to make decisions about their lifestyle choices is difficult for even the most experienced clinicians. Such determinations require nurses to form a judgement as to mental capacity of the patient. We do not know what patient characteristics and in what combination nurses use these when making these judgements. This factorial survey aimed to identify which patient characteristics influenced Registered Nurses' judgements on decision-making capacity and decisions on the use of interventions which require statutory interventions in cases of self-neglect. Judgements on decision-making capacity were overwhelmingly predicted by information of the patients' mental health status. Nurses place patients in one of three broad categories of no mental illness, minor mental illness and severe mental illness. This categorization appears to operate as a fast and frugal heuristic indicating that nurses may use mental status as a cognitive screen to work from in judging self-neglect. Although there is a correlation between the severity of mental illness and the capacity for making decisions they are not the same. This study shows the continued work that needs done in educating nurses not only about self-neglect but also about the role a patient's mental status may have in assessment of problems.

[Orthopedic treatment of spinal deformities in infancy and early childhood]. / Le traitement orthopédique dans la pathologie vertébrale du petit enfant.

Surgical treatment of spinal deformities in infancy and early childhood (before age 6) is often very useful if the lesion is localized and curable by one unique surgery, such as hemivertebra resection and fusion. On the contrary, if the lesion, whether idiopathic or paralytic, is extended to a large part of the spine, early surgical treatment in infancy gives very disappointing results and often worsens the status of the child, especially respiratory function if the lesion is mainly thoracic. The goal of this paper is to explain in detail indications and management of non-surgical treatment of such lesions. These are variable according to localization, etiology, and associated anomalies, and are mainly based on proper casting (often repeated), bracing (often intermittent between casting) and proper respiratory equipment. From time to time, a surgical treatment is locally indicated, but most of the time results are disappointing and the best is to repeat non-surgical treatment until proper definitive arthrodesis can be performed. This approach is not very rewarding for the child and family, but is clearly better than sudden extensive surgery in early childhood with very severe and disastrous results in adulthood. It is our hope that the recommendations and thoughts presented in this paper will help readers to manage young children using the most efficient, non-aggressive, but long-lasting therapy.

Giant magnetic anisotropy of single cobalt atoms and nanoparticles.

The isotropic magnetic moment of a free atom is shown to develop giant magnetic anisotropy energy due to symmetry reduction at an atomically ordered surface. Single cobalt atoms deposited onto platinum (111) are found to have a magnetic anisotropy energy of 9 millielectron volts per atom arising from the combination of unquenched orbital moments (1.1 Bohr magnetons) and strong spin-orbit coupling induced by the platinum substrate. By assembling cobalt nanoparticles containing up to 40 atoms, the magnetic anisotropy energy is further shown to be dependent on single-atom coordination changes. These results confirm theoretical predictions and are of fundamental value to understanding how magnetic anisotropy develops in finite-sized magnetic particles.

FGF signalling is required for differentiation-induced cytoskeletal reorganisation and formation of actin-based processes by podocytes.

To examine the potential role of fibroblast growth factor (FGF) signalling during cell differentiation, we used conditionally immortalised podocyte cells isolated from kidneys of Fgf2 mutant and wild-type mice. Wild-type mouse podocyte cells upregulate FGF2 expression when differentiating in culture, as do maturing podocytes in vivo. Differentiating wild-type mouse podocyte cells undergo an epithelial to mesenchymal-like transition, reorganise their actin cytoskeleton and extend actin-based cellular processes; all of these activities are similar to the activity of podocytes in vivo. Molecular analysis of Fgf2 mutant mouse podocyte cells reveals a general disruption of FGF signalling as expression of Fgf7 and Fgf10 are also downregulated. These FGF mutant mouse podocyte cells in culture fail to activate mesenchymal markers and their post-mitotic differentiation is blocked. Furthermore, mutant mouse podocyte cells in culture fail to reorganise their actin cytoskeleton and form actin-based cellular processes. These studies show that FGF signalling is required by cultured podocytes to undergo the epithelial to mesenchymal-like changes necessary for terminal differentiation. Together with other studies, these results point to a general role for FGF signalling in regulating cell differentiation and formation of actin-based cellular processes during morphogenesis.

Burn wound itch control using H1 and H2 antagonists.

This study investigated the use of a combination of H1 and H2 antagonists and topical medications to control burn wound itch. Graeco-Latin square assignment provided an oral combination of 1) cetirizine and cimetidine or 2) diphenhydramine and placebo in four divided doses. The study protocol lasted 16 days divided into 4-day intervals, scoring itch before the initial dose of medication and at 1-hour, 6-hour, and 12-hour intervals after the first medication. A significant difference between mean itch scores across the four times was observed (Wilks' Lambda F = 26.52, df = 3, P <.0005). A three-way nested repeated measures interaction effect (Wilks' Lambda F = 9.85, df = 9, P <.0005) was observed representing a significantly different pattern on days 1 to 4 of the study compared with the remaining days. Controlling for the effect of topical medications, the cetirizine/cimetidine combination demonstrated a dramatic improvement at 1 and 6 hours, and a moderate improvement at 12 hours after initial medication for the day when compared with the diphenhydramine/placebo combination.

Strongly enhanced orbital moments and anisotropies of adatoms on the Ag(001) surface.

We present ab initio calculations for orbital moments and anisotropy energies of 3d and 5d adatoms on the Ag(001) surface, based on density functional theory, including Brooks' orbital polarization (OP) term, and applying a fully relativistic Korringa-Kohn-Rostoker-Green's function method. In general, we find unusually large orbital moments and anisotropy energies, e.g., in the 3d series, 2.57 mu(B) and +74 meV for Co, and, in the 5d series, 1.78 mu(B) and +42 meV for Os. These magnetic properties are determined mainly by the OP and even exist without spin-orbit coupling.

The factorial survey: an experimental method to replicate real world problems.

BACKGROUND: Vignettes are used by nurse researchers use to determine how clinical judgments about patient care situations are made. However, when vignettes are designed there is often a restriction on the number of characteristics studied, which oversimplifies the richness and complexity of real world healthcare situations. OBJECTIVES: The purpose of this article is to describe a factorial survey. Its multilevel design of independent variables allows for real world complexity in a way not tested by a sample set of four to six identical vignettes. Nurses' judgments about patients' confusion and the application of restraints are used to illustrate the method. METHOD: The factorial survey is an experimental design that can be developed in three steps: (a) identifying and using the variables, (b) writing a coherent vignette, and (c) randomly generating the vignettes. RESULTS: The unit of analysis is the vignette and Ordinary Least Squares (OLS) regression is used for analyses. In the example provided on confusion recognition and restraint use, patient characteristics accounted for the majority of explained variance in confusion recognition of (40%, R2 = 0.40) and restraint intervention for (43%, R2 = 0.43). The results for both models were strikingly similar as the same patient characteristics all were significant predictors for confusion recognition and restraint use. CONCLUSIONS: The versatility of the factorial survey lies in the researcher's ability to use it to test judgments in a variety of complex clinical simulations, to aid in concept development, and to identify consensus and disagreement among nurses. The multilevel design of the independent variables allows for real world complexity in a way not tested by a sample set of four to six identical vignettes.

Fixation, embedding, and sectioning of tissues, embryos, and single cells.

This unit describes selected methods for fixing and sectioning various forms of biological materials ranging from tissues to single cells. Sections prepared according to these protocols can then be used to examine cell and tissue morphology and in studies involving in situ hybridization, immunohistochemistry, and enzyme histochemistry. The basic protocol describes how tissues and embryos can be prepared for sectioning by fixing in paraformaldehyde followed by embedding in wax, while the alternate protocol describes fixation of suspended or cultured cells. Two support protocols cover preserving and fixing organs by perfusion of whole animals with paraformaldehyde and a procedure for sectioning wax blocks of fixed tissue, plus the subsequent mounting of sections onto prepared or "subbed" glass slides.

In situ hybridization to cellular RNA.

In situ hybridization to cellular RNA is used to determine the cellular localization of specific messages within complex cell populations and tissues. In this unit, protocols are described for hybridizing slide-mounted paraffin sections or cryosections with labeled probes. Support protocols describe synthesis of 35S-labeled riboprobes and dsDNA probes, which are then detected using film autoradiography or emulsion autoradiography. Another support protocol describes synthesis of digoxigenin-labeled RNA probes, which are non-radioactive and thus have several advantages. They are easily synthesized in large quantities, they are stable for several months, and they can be reused up to three times. An additional advantage of RNA versus DNA probes is that they result in cleaner signals because nonspecifically bound probe is removed during ribonuclease treatment.

Counterstaining and mounting of autoradiographed in situ hybridization slides.

The morphology of specimen sections and the identity of specific areas are defined by lightly counterstaining sections. After staining, slides are dehydrated, mounted with coverslips, hardened, and cleaned for examination under the microscope. In the protocols provided in this unit, Giemsa stains predominantly the nuclei, hematoxylin/eosin stain differentiates both the nuclei and cytoplasm, toluidine blue staining is a simpler procedure that lightly stains both nuclei and cytoplasm, and Hoechst staining of nuclei provides a fast, easy, and effective way to simultaneously view the entire tissue and the regions of hybridization.

Fixation, embedding, and sectioning of tissues, embryos, and single cells.

This unit describes selected methods for fixing and sectioning various forms of biological materials ranging from tissues to single cells. Sections prepared according to these protocols can then be used to examine cell and tissue morphology and in studies involving in situ hybridization, immunohistochemistry, and enzyme histochemistry. The basic protocol describes how tissues and embryos can be prepared for sectioning by fixing in paraformaldehyde followed by embedding in wax, while an alternate protocol describes fixation of suspended or cultured cells. Two support protocols cover preserving and fixing organs by perfusion of whole animals with paraformaldehyde and a procedure for sectioning wax blocks of fixed tissue, plus the subsequent mounting of sections onto prepared or "subbed" glass slides.

In situ hybridization to cellular RNA.

In situ hybridization to cellular RNA is used to determine the cellular localization of specific messages within complex cell populations and tissues. Tissues may either be embedded in paraffin and sectioned on a microtome (see Hybridization Using Paraffin Sections and Cells), or frozen and sectioned in a cryostat (see Hybridization Using Cryosections). RNA contained in the specimens is hybridized to a specific radiolabeled probe (see Synthesis of (35)S-Labled Riboprobes and Synthesis of (35)S-Labled Double-Stranded DNA Probes), which is then detected using film autoradiography or emulsion autoradiography (Chapter 8).