Absorption cross sections and number densities of electron and hole polarons in congruently melting LiNbO(3).

The number densities and absorption cross sections of both optically generated and reduction-induced small electron and hole polarons in LiNbO(3) are determined by means of time-resolved pump-multiprobe spectroscopy. The data are obtained for free (Nb(Nb)(4+)) and bound (Nb(Li)(4+)) electron polarons, bound Nb(Li)(4+):Nb(Nb)(4+) electron bipolarons, and bound O(-) hole polarons. The peak absorption cross sections are in the range of σ(pol)≈(4-14) × 10(-22) m(2), comparable to that for Fe(2+). In all cases the ratio of occupied to unoccupied polaronic sites is less than 10(-2).

RSA-measured inducible micromotion and interface modeling with finite element methods.

Osteolysis is the main cause of aseptic loosening and stem failure. The mechanism that leads to osteolysis is poorly understood; pressure generation caused by reversible stem micromotion may play an important role. We aimed to determine whether dynamically inducible micromotion occurs in vivo at the prosthesis-cement interface and to use these data to develop and confirm a finite element representation of this interface. Dynamically inducible micromotion was measured using radiostereometric analysis in 21 hips implanted with an Exeter stem, at 3 months and 12 months postoperatively, by changing loading from double-leg stance to single-leg stance. Dynamically inducible micromotion occurred at 3 and 12 months; similar micromotion was observed at both time points. At 3 months the head of the stem was displaced posteriorly (0.10 +/- 0.16 mm) and inferiorly (0.08 +/- 0.12 mm) on loading. A Coulomb friction nonbonded representation of the stem-cement interface was used to fit the clinically measured dynamically inducible micromotion. The final finite element model predicted gap opening and closing between the implant and the mantle. This may be a mechanism for generating pressure and distributing wear debris, which are believed to important contributors to failure.

Nonuniform dynamic gratings in photorefractive media with nonlocal response.

The amplitude of the phase dynamic grating is a nonuniform space distributed in photorefractive crystals with nonlocal response as a result of energy transfer between the interacted waves. The dynamical process of grating formation in the case of transmission two- and four-wave mixing is described by the damped sine-Gordon equation that governs the soliton propagation. A stationary soliton solution for the grating amplitude profile was obtained. Experiments on observation of a nonuniform distribution of the grating amplitude through the crystal volume are presented. It is experimentally shown that the changes of the grating amplitude profile in dependence of input intensity ratio match the solutions of the damped sine-Gordon equation in steady state. The diffraction efficiency of energy transfer is determined by the value of the integral under the grating amplitude profile. The soliton profile is altered with changing input intensity ratio of recorded beams. It provides the effect of diffraction efficiency management by changing the half-width and the position of the soliton. The theory predicts a multisoliton behavior in reversible media with strong amplification gain that leads to auto-oscillations of output wave intensities.

Development and numerical validation of a finite element model of the muscle standardized femur.

The human femur is one of the parts of the musculo-skeletal system most frequently analysed by means of the finite element (FE) method. Most FE studies of the human femur are based on computed tomography data sets of a particular femur. Since the geometry of the chosen sample anatomy influences the computed results, direct comparison across various models is often difficult or impossible. The aim of the present work was to develop and validate a novel three-dimensional FE model of the human femur based on the muscle standardized femur (MuscleSF) geometry. In the new MuscleSF FE model, the femoral attachment of each muscle was meshed separately on the external bone surface. The model was tested under simple load configurations and the results showed good agreement with the converged solution of a former study. In the future, using the validated MuscleSF FE model for numerical studies of the human femur will provide the following benefits: (a) the numerical accuracy of the model is known; (b) muscle attachment areas are incorporated in the model, therefore physiological loading conditions can be easily defined; (c) analyses of the femur under physiological load cases will be replicable; (d) results based on different load configurations could be compared across various studies.

Strain distribution within the human femur due to physiological and simplified loading: finite element analysis using the muscle standardized femur model.

The aim of the current work was to study the effect of simplified loading on strain distribution within the intact femur using the Muscle Standardized Femur finite element model and to investigate whether the interaction between the intact human femur and the muscles which are attached to the bone surface could accurately be represented by concentrated forces, applied through the centroids of their attachment areas. An instant at 10 per cent of the gait cycle during level walking was selected as the reference physiological load case; nine load cases were analysed. Comparison of the calculated results for the physiological load case with muscle forces uniformly distributed over their attachment areas showed good agreement with in vivo measurements of strain values and femoral head displacement in humans. Simplified load cases generated unrealistic displacement results and high strain magnitudes, exceeding the physiological range. It was found that when muscles with large attachment areas are included in the model and the muscle forces are simplified, stress and strain distributions will be affected not only on the external bone surface in the vicinity of the load application node, but also on the internal surface of the cortical bone. However, applying muscle forces as concentrated loads at the centroids of the attachment areas can serve as first indicators of the physiological stress and strain levels, if results from nodes and elements in the vicinity of the load application nodes are discarded. Omitting muscle forces or fixing the femur in mid-shaft leads to large unphysiological strain values.

Identification of the white blood cell populations responsible for Th1 immunity to trophoblast and the timing of the response in women with recurrent pregnancy loss.

AIM: The purpose of this study was to identify the white blood cell populations responsible for Th1 immunity to trophoblast as evidenced in our in vitro assays following trophoblast activation and the timing of this response. STUDY DESIGN: Peripheral blood mononuclear cells (PBMC) were isolated from 32 nonpregnant women with a history of at least three prior first trimester spontaneous abortions of unknown etiology except their PBMC secreted Th1 embryotoxic cytokines in response to trophoblast stimulation. White blood cell populations were separated from PBMC by magnetic immunobeads and cultured with and without a trophoblast antigen extract. Supernatants from these cultures were added to two cell mouse embryos and after four days of culture assessment of blastocyst development was made to determine the white blood cell population responsible for embryotoxicity. In separate experiments trophoblast-activated PBMC culture supernatants were prepared over seven time points and individual Th1 cytokines (IL-2, INF-gamma, TNF-alpha) were measured by ELISA to determine the timing of the response to trophoblast stimulation. RESULTS: The white blood cell (CD45) populations responsible for embryotoxicity in response to trophoblast were T cells (CD3) and NK (CD56) cells. Levels of IL-2 peaked in the first 24 h of culture followed by TNF-alpha and IFN-gamma levels which peaked at 96 h of culture. CONCLUSIONS: Our data demonstrated that the white blood cell populations responsible for embryotoxicity in our in vitro assays, were both T and NK cells. The kinetics of the cytokine response to trophoblast found in our study parallels the time course of a typical Th1 cytokine response. The profile of secreted cytokines support our hypothesis that trophoblast can produce Th1 immunity in some women with recurrent pregnancy loss that have embryotoxic effects in vitro.

A comparison between automatically generated linear and parabolic tetrahedra when used to mesh a human femur.

Finite element models of bone segments generated from computed tomography data using automatic mesh generation algorithms are becoming common not only in research but also in clinical applications such as computer aided orthopaedic surgery. Especially in the case of the latter application, the models cannot be verified against an experimental measurement, therefore their inherent accuracy should be well known before drawing conclusions based on the calculated results. This study was carried out to assess the performance of tetrahedral solid finite elements with linear and quadratic displacement functions when they are used to mesh the human femur in conjunction with automatic mesh generator methods. Ten-node quadratic tetrahedra (T10) having parabolic displacement functions were compared with four-node linear tetrahedron elements (T4) on the basis of accuracy and central processing unit (CPU) time. From the analyses of 11 finite element meshes, it was concluded that linear tetrahedral elements should be avoided and quadratic tetrahedral elements ought to be chosen for the purposes of finite element analysis of the human femur. When incremental loading and iterative solution is necessary, the coarsest possible T10 mesh compatible with accuracy is needed to minimize computer capacity and CPU time.

Progesterone inhibits in-vitro embryotoxic Th1 cytokine production to trophoblast in women with recurrent pregnancy loss.

A dichotomous T-helper 1 (Th1) versus T-helper 2 (Th2) cytokine response to trophoblast has been proposed to mediate reproductive failure and success, respectively. Progesterone has immunosuppressive properties. In this study, peripheral blood mononuclear cells from women with and without unexplained recurrent pregnancy loss who had and did not have evidence of embryotoxic, Th1 immunity to trophoblast were cultured with progesterone (10(-5) mol/l) or interleukin (IL)-10 (1500 pg/ml) to determine whether these agents were capable of inhibiting embryotoxic, Th1 immunity to trophoblast. The effects of progesterone on Th2 cytokines and transforming growth factor (TGF)-beta secretion were also assessed. Progesterone was found to specifically block Th1 immunity to trophoblast, as was IL-10. Progesterone also appeared to upregulate TGF-beta secretion in response to trophoblast but had no effect on Th2 cytokine secretion. Our data suggest that assaying Th1 cytokines in supernatants of peripheral blood mononuclear cells cultured with a protein extract from trophoblast may identify individuals more likely to benefit from potentially immunosuppressive doses of progesterone. An appropriately designed clinical trial is needed to determine whether therapies modifying Th1 cytokine secretion in response to trophoblast are useful in the clinical management of recurrent pregnancy loss in women producing these cytokines in response to reproductive antigen stimulation.

Immune interferon gamma inhibits translational mobility of a plasma membrane protein in preimplantation stage mouse embryos: a T-helper 1 mechanism for immunologic reproductive failure.

OBJECTIVE: Immune interferon gamma adversely affects mouse embryo development and has been proposed as a mediator of reproductive failure involving T-helper 1 immunity. We hypothesized that one mechanism by which interferon gamma could exert an adverse effect on embryos was by altering plasma membrane organization and transmembrane protein mobility. STUDY DESIGN: The fluorescence photobleaching recovery technique was used to measure the effect of the T-helper 1 cytokine interferon gamma on the translational mobility of a specific embryonic surface glycoprotein recognized by the monoclonal antibody S75. RESULTS: Compared with controls interferon gamma significantly decreased the fractional mobility of fluorescein isothiocyanate S75 in one- and two-cell mouse embryos. CONCLUSION: Interferon gamma may alter plasma membrane domains or cytoskeletal organization in early-stage embryos. By restricting plasma membrane protein mobility interferon gamma could effect T-helper 1-mediated reproductive failure.

T-helper 1-type immunity to trophoblast in women with recurrent spontaneous abortion.

OBJECTIVE: To test the hypothesis that peripheral blood mononuclear cells in women with unexplained recurrent abortion (URA) produce T-helper 1 (TH1)-type cytokines in response to trophoblast antigens. DESIGN: Cohort study. SETTING: Medical center. PARTICIPANTS: A total of 244 women with URA, 13 reproductively normal parous control women, and 10 men. MAIN OUTCOME MEASURES: Supernatants from trophoblast-activated peripheral blood mononuclear cells from all participants were tested for toxic effects on mouse embryos and by enzyme-linked immunosorbent assay (ELISA) for interferon gamma (IFN-gamma). Supernatants from 20 URA patients with embryotoxic activity and IFN-gamma, 13 reproductively normal parous women, and 10 men were further tested by ELISA for other TH1-type cytokines (interleukin-2 [IL-2], tumor necrosis factor-beta [TNF-beta]), TH2-type cytokines (IL-4, IL-10), and TNF-alpha. RESULTS: Embryotoxic activity was detected in supernatants from 160 of 244 URA patients and in none of the controls. Interferon gamma was detected in supernatants from 125 of 244 URA patients and was significantly associated with embryotoxicity (121 of 160 supernatants with embryotoxicity vs four of 84 supernatants without embryotoxicity [P < .001]). Of 20 supernatants from patients chosen for further study, all were positive for TNF-alpha, 17 for TNF-beta, two for IL-10, and one for IL-4. No cytokines were detected in supernatants from unstimulated or red blood cell membrane-activated cells of women with URA. In contrast, trophoblast-activated lymphocyte supernatants from reproductively normal women and men neither were embryotoxic nor contained TH1-type cytokines, but most contained the TH2-type cytokine IL-10. Three supernatants from reproductively normal women also contained IL-4. CONCLUSION: Whereas TH1-type immunity to trophoblast is associated with URA and may play a role in reproductive failure, TH2-type immunity may be a natural response to trophoblast contributing to successful pregnancy.

Seminal white blood cells and recurrent abortion.

The incidence of leukocytospermia (> 1 million white blood cells/ml semen) and concentrations of white blood cell populations in semen from men whose partners experience unexplained recurrent spontaneous abortion by conventional testing criteria are described and compared to those of men whose partners have normal reproductive histories. Comparable seminal granulocyte and total white blood cell concentrations between groups suggest that couples with unexplained recurrent abortion do not have an abnormally high incidence of subclinical genital tract infections for which leukocytospermia could serve as a marker. However, a significantly higher prevalence of elevated CD4+ and CD8+ T lymphocyte concentrations in semen from men whose partners have cellular immunity to sperm antigens (i.e. produce embryotoxic factors in response to sperm antigen stimulation) warrants further investigation.

Cell-mediated immunity to trophoblast antigens in women with recurrent spontaneous abortion.

OBJECTIVES: The purpose of this study was to determine whether trophoblast antigens activate cell-mediated immune responses in women with recurrent abortion of unknown cause by inducing lymphocyte proliferation and to correlate this with embryotoxic factor production. STUDY DESIGN: Mononuclear cells were isolated from 57 nonpregnant women with recurrent abortion of unknown cause and from 10 fertile controls with normal reproductive histories. Lymphocyte proliferation assays were performed with trophoblast antigen extracts from the human choriocarcinoma cell lines Jeg-3 and JAR, fractionated trophoblast antigens, and for control, red blood cell membrane antigens. A stimulation index > 3 was considered significant stimulation. Trophoblast-stimulated culture supernatants were also tested for embryotoxic activity. RESULTS: Thirty (52.6%) women with recurrent abortion of unknown cause responded to trophoblast antigen stimulation with a stimulation index > 3, whereas none of the control group responded. Neither patients with recurrent abortion nor women with normal reproductive histories responded to red blood cell membrane antigen. The mean stimulation index in the trophoblast antigen lymphocyte proliferation assay was significantly higher in women with recurrent abortion than in women with normal reproductive histories (3.99 +/- 2.82 vs 1.64 +/- 0.34, p < 0.01). Antigen extracts from the cytosol and membrane fractions of Jeg-3 provided the strongest stimulation. Lymphocyte proliferation correlated with embryotoxic factor production; 90.0% of women with a stimulation index > 3 and none of the controls produced embryotoxic factors after stimulation with trophoblast antigens. CONCLUSION: In this study 52.6% of women with recurrent abortion of unknown cause compared with none in controls exhibited in vitro evidence of T-cell immunity to trophoblast antigen stimulation. Further work is needed to determine whether T-cell immunity to trophoblast is involved in the pathogenesis of recurrent spontaneous abortion.

Use of the translational mobility of a plasma membrane protein to assess fertilization of mouse oocytes and viability of mouse zygotes and two-cell embryos.

The fluorescence photobleaching recovery (FPR) technique was used to measure the translational mobility of a glycoprotein recognized by the monoclonal antibody (mAb) S75 in plasma membranes of mouse oocytes, zygotes, and two-cell embryos. Glycoprotein fractional mobility (f) was significantly decreased in membranes of unfertilized oocytes compared to zygotes or two-cell embryos (f values, 46 +/- 2 and 65 +/- 2%, respectively; p < 0.0001). Reduced apparent glycoprotein mobility was also observed in morphologically degenerated zygotes and two-cell embryos compared to viable zygotes and two-cell embryos (f values, 8 +/- 1 and 60 +/- 3%, respectively; p < 0.0001). These results indicate that the FPR technique can be used to assess oocyte fertilization and preimplantation embryonic viability. This method may be useful in the evaluation of embryonic viability following in vitro fertilization and in the detection of toxic effects of novel compounds on embryonic development.

The effects of cytokines on human chorionic gonadotropin (hCG) production by a trophoblast cell line.

The present study was conducted to investigate the effects of cytokines on human chorionic gonadotropin (hCG) and its alpha- and beta-subunit release as well as protein synthesis in a trophoblast cell line. The human choriocarcinoma cell line, Jar, was used as a trophoblast model. Jar cells were incubated for 24 h with varying concentrations (5 x 10(-4)-40 micrograms/ml) of the following cytokines: Il-1, Il-2, Il-3, Il-4, Il-5, Il-6, IFN-gamma, tumor necrosis factor (TNF)-alpha, M-CSF and GM-CSF. Supernatants were assayed for hCG and its alpha- and beta-subunits by immunoradiometric methods. Cytotoxic effects were assessed by trypan blue staining. Protein synthesis was measured by [3H]leucine incorporation. The cytokines Il-1 and TNF-alpha significantly stimulated hCG release. The other cytokines had no significant effect on hCG production. Protein synthesis by the Jar cells was not significantly affected by either Il-1 or TNF-alpha. However, IFN-gamma (40 micrograms/ml) significantly suppressed protein synthesis by the Jar cells. Trophoblast viability in the presence of TNF-alpha (10 micrograms/ml) and IFN-gamma (40 micrograms/ml) was only 40% and 50%, respectively. These results suggest that cytokines may be important regulators of trophoblast function. Il-I appears to have a stimulatory effect on trophoblast hCG release, while TNF-alpha and IFN-gamma appear to have cytotoxic effects on trophoblast cells.

Evidence of embryo- and trophoblast-toxic cellular immune response(s) in women with recurrent spontaneous abortion.

OBJECTIVE: The purpose of this study was to determine whether reproductive antigens stimulate lymphocytes and macrophages from women with recurrent abortion to secrete factors that are toxic to preimplantation embryos or trophoblast cells in vitro. STUDY DESIGN: Mononuclear cells were isolated from 30 fertile controls and 300 nonpregnant women being evaluated for recurrent abortion. Supernatants generated from these cells after separate culture with sperm and trophoblast antigen extracts were added to two-cell mouse embryo cultures and trophoblast proliferation assays. Toxicity was assumed when the median percentage of embryos developing to blastocysts or trophoblast proliferation was less than or equal to 50% of control values. Both parametric and nonparametric statistical methods were used where appropriate. RESULTS: Mouse embryo development and/or trophoblast proliferation were significantly inhibited by supernatants from trophoblast and/or sperm antigen-activated peripheral blood leukocyte cultures from a majority of 300 women with recurrent abortion but not from 30 women with normal reproductive histories. The mouse blastocyst development assay was more sensitive than the trophoblast proliferation assay in determining toxic factor production. Embryo-toxic factors were produced by activated leukocyte cultures from 90% of 180 women with a history of recurrent abortion of unexplained etiology, whereas trophoblast-inhibitory factors were detected in 50% of women from the same group. The embryo-toxic factor(s) was heat labile, had a molecular weight(s) between 10 and 30 kd, and was absorbed out by passage through affinity columns containing anti-interferon gamma beads. CONCLUSION: We conclude that recurrent abortion in some women is associated with embryo- and/or trophoblast-toxic factor production in response to stimulation by sperm or trophoblast antigens and that the principal factor may involve the 18 kd, heat-labile, T-lymphocyte cytokine interferon gamma. This study suggests a new cause of recurrent abortion.

Modulation of dopamine-induced hypermotility following injection of various opioids into the nucleus accumbens.

The aim of the present work was to obtain some data on the eventual role of nucleus accumbens in the antidopamine action of some opioids. Classical neuroleptics are known to inhibit the dopamine-elicited hypermotility when injecting them into the nucleus accumbens of rats pretreated with MAO inhibitors. In the present study the effects of some opioids have been examined in this model. The opioids examined were morphine, a mu-selective classical opiate, D-Ala2, Nle5-enkephalin sulphonic acid (ES), a delta selective opioid peptide and D-Met2, Pro5-enkephalinamide (EA), a non-selective opioid peptide. Haloperidol and chlorpromazine have been used for comparison. EA and morphine, especially the former, potently antagonized the dopamine-induced hyperactivity, similarly to haloperidol and chlorpromazine. ES exerted biphasic effect, the initial inhibition was followed by potentiation of the dopamine-elicited excitation. Thus the order of potency was: EA greater than haloperidol approximately equal to morphine greater than chlorpromazine greater than EA. The data indicate that the antidopamine action of opioids might be mediated, at least in part, by mu-receptors in the nucleus accumbens.

Characterization of rapidly adhering amniotic fluid cells by combined immunofluorescence and phagocytosis assays.

Culture of human amniotic-fluid cells from cases of fetal neural tube defects produces a population of rapidly adhering cells that were initially thought to be macrophages and later interpreted to be of neural origin. In this study double and triple labeling systems for the simultaneous detection of glial and macrophage differentiation marker antigens have been used to demonstrate that rapidly adhering cells cannot be considered a homogeneous population but instead represent two distinct cell types. One of these cell populations is of glial origin and shows specific staining for glial fibrillary acidic protein, while the other population is monocyte-derived macrophages which express marker antigens recognized by Leu M3, KiM7, and Dako antimacrophage monoclonal antibodies.

Neutral-red uptake and expression of monocytic antigens in amniotic-fluid mononuclear phagocytes: evaluation of a novel approach for prenatal diagnosis of neural-tube defects.

In cases of fetal neural-tube defects macrophages are present in the amniotic fluid. We found that these viable phagocytic cells take up neutral-red and are easily identified as "red cells" by microscopic examination. This method is suitable for the rapid identification and counting of amniotic-fluid macrophages in suspension. We have studied 298 amniotic fluid samples. In the 226 normal cases studied, 0 to 1,200 macrophages per milliliter amniotic fluid have been found. In contrast, we found 1,250 to 99,000 macrophages per milliliter amniotic fluid in our 70 open neural tube defect (ONTD) cases. Statistical evaluation was performed to estimate the normal and pathologic ranges. Specificity and sensitivity of the neutral-red test and predictive value of positive and negative results have been calculated and presented in comparison with alpha-fetoprotein (AFP) determinations and ultrasonic methods. In 5 cases of anencephaly and 7 normal cases amniotic fluid cells were studied by immunocytochemistry: mononuclear cells present in the abnormal cases showed intense immunoreactivity for the Mo1 and Mo2 surface antigens of the phagocytic cell lineage.