The Role of Glycoconjugates in Mediating Human Fertilization and Induction of Fetomaternal Tolerance

Using the hemizona assay (HZA), a in vitro sperm-egg binding assay, we show that specific glycoconjugates known to inhibit immune cell interactions mediated by the selectins, potently block human sperm-egg binding. The selectin ligand sialyl Lewisx inhibits sperm binding in the HZA by 60% at a concentration of 1 mg/ml. Our data indicates that glycodelin-A, a endometrial glycoprotein known to block sperm-egg binding in the HZA at low concentrations expresses unusual fucosylated lacdiNAc type glycans. The fucosylated lacdiNAc type sugars have been previously shown to be 15-20 fold more potent ligands of E-selectin. Glycodelin-S a seminal plasma glycoform of glycodelin-A does not express such unusual glycans and is not contraceptive. These results support our hypothesis that human sperm-egg binding may involve a selectin-like event. Periodate oxidation under conditions that affect only the terminal sugar residues results in a 30-40% loss in sperm binding. Treatment of the ZP with neuraminidase and endo-β-galactosidase results in a 2.5 and 4 fold enhancement in sperm binding respectively. However, sequential treatment of the ZP with neuraminidase and periodate results in 80% decrease in sperm binding. These studies strongly indicate that ZP glycans are essential for mediating human gamete binding. Furthermore, efficient initial human sperm egg binding in vivo may require a prior activation event involving desialylation of the gametes. In this study we provide preliminary evidence that human gametes express the bisecting type glycans. Our studies indicate that these glycans potently inhibit natural killer (NK) cells, the predominant cell type expressed in the uterus during pregnancy. Other glycoconjugates like $\alpha$-fetoprotein, expressed in the uterus during pregnancy, also carry the bisecting-type glycans. Based on these observations we propose that glycoconjugates expressed during pregnancy protect are responsible for mediating feto-maternal tolerance. We refer to this model for as the Human Feto-Embryonic Defense System hypothesis. Finally our data suggests that parasites like schistosomes, filarial worms, and the human immunodeficiency virus may be evading the host\u27s immune responses by a similar by expressing immunosuppressive glycoconjugates on their coats

Quasiequilibrium lattice Boltzmann models with tunable bulk viscosity for enhancing stability

Taking advantage of a closed-form generalized Maxwell distribution function [ P. Asinari and I. V. Karlin Phys. Rev. E 79 036703 (2009)] and splitting the relaxation to the equilibrium in two steps, an entropic quasiequilibrium (EQE) kinetic model is proposed for the simulation of low Mach number flows, which enjoys both the H theorem and a free-tunable parameter for controlling the bulk viscosity in such a way as to enhance numerical stability in the incompressible flow limit. Moreover, the proposed model admits a simplification based on a proper expansion in the low Mach number limit (LQE model). The lattice Boltzmann implementation of both the EQE and LQE is as simple as that of the standard lattice Bhatnagar-Gross-Krook (LBGK) method, and practical details are reported. Extensive numerical testing with the lid driven cavity flow in two dimensions is presented in order to verify the enhancement of the stability region. The proposed models achieve the same accuracy as the LBGK method with much rougher meshes, leading to an effective computational speed-up of almost three times for EQE and of more than four times for the LQE. Three-dimensional extension of EQE and LQE is also discussed

Computation of Radiation Heat Transfer in Aeroengine Combustors

In this report the highlights of the research completed for the NASA are summarized. This research has been completed in the form of two Ph.D. theses by Chai (1994) and Parthasarathy (1996). Readers are referred to these theses for a complete details of the work and lists of references. In the following sections, first objectives of this research are introduced, then the finite-volume method for radiation heat transfer is described, and finally computations of radiative heat transfer in non-gray participating media is presented

Aerothermal modeling program, phase 2

The main objectives of the Aerothermal Modeling Program, Phase 2 are: to develop an improved numerical scheme for incorporation in a 3-D combustor flow model; to conduct a benchmark quality experiment to study the interaction of a primary jet with a confined swirling crossflow and to assess current and advanced turbulence and scalar transport models; and to conduct experimental evaluation of the air swirler interaction with fuel injectors, assessments of current two-phase models, and verification the improved spray evaporation/dispersion models

Improved numerical methods for turbulent viscous flows aerothermal modeling program, phase 2

The details of a study to develop accurate and efficient numerical schemes to predict complex flows are described. In this program, several discretization schemes were evaluated using simple test cases. This assessment led to the selection of three schemes for an in-depth evaluation based on two-dimensional flows. The scheme with the superior overall performance was incorporated in a computer program for three-dimensional flows. To improve the computational efficiency, the selected discretization scheme was combined with a direct solution approach in which the fluid flow equations are solved simultaneously rather than sequentially

Screening effects in flow through rough channels

A surprising similarity is found between the distribution of hydrodynamic stress on the wall of an irregular channel and the distribution of flux from a purely Laplacian field on the same geometry. This finding is a direct outcome from numerical simulations of the Navier-Stokes equations for flow at low Reynolds numbers in two-dimensional channels with rough walls presenting either deterministic or random self-similar geometries. For high Reynolds numbers, when inertial effects become relevant, the distribution of wall stresses on deterministic and random fractal rough channels becomes substantially dependent on the microscopic details of the walls geometry. In addition, we find that, while the permeability of the random channel follows the usual decrease with Reynolds, our results indicate an unexpected permeability increase for the deterministic case, i.e., ``the rougher the better''. We show that this complex behavior is closely related with the presence and relative intensity of recirculation zones in the reentrant regions of the rough channel.Comment: 4 pages, 5 figure

Partnership of obstetrician and neonatologist to improve neonatal outcome in peri-viable and premature babies: a cross sectional survey

Background: Collaboration between obstetricians and paediatricians/Neonatologists provides the best quality care to infants and their mothers. Present study was conducted to evaluate the practices of obstetricians and neonatologists’ partnership to improve neonatal outcome.Methods: Present cross-sectional, observational study was conducted on 50 Obstetricians and 50 paediatricians/ neonatologists during October 2021 to evaluate the practices of obstetricians and neonatologists’ partnership to improve neonatal outcome.Results: In present study, among 50 obstetricians and 50 pediatricians/ neonatologists, all i.e., 100 (100%) feel that partnership of obstetrician and neonatologist in managing pre-viable pregnancy improves neonatal outcome. Among 50 obstetricians, all i.e., 50 (100%) said that they will explain the need for caesarean section and if necessary classical caesarean section. All said they will explain the need and advantages of steroids. Among 50 pediatricians/ neonatologists, majority i.e., 44 (88%) said that they will explain the need for caesarean section and if necessary classical caesarean section. All said they will explain the need and advantages of steroids. Among 50 obstetricians, majority i.e., 45 (90%) said that they will explain thoroughly the risk to the baby, survival, short term complications and disability, 30 (60%) each said that they will explain thoroughly the risk of RDS, need of resuscitation, need of NICU for baby, uncertainty of hospital stay and outcome. Among 50 pediatricians/ neonatologists, all i.e., 50 (100%) each said that they will explain thoroughly the risk to the baby, survival, short term complications and disability, the risk of RDS, need of resuscitation, need of NICU for baby, uncertainty of hospital stay and outcome. Expressions of pediatricians/ neonatologists were significantly different on counselling aspects of mother and baby.Conclusions: In present study, majority of obstetricians and pediatricians/ neonatologists were of opinion that partnership between them surely improves neonatal outcome in peri viable and preterm babies. 

Analysis of plasma instabilities and verification of the BOUT code for the Large Plasma Device

The properties of linear instabilities in the Large Plasma Device [W. Gekelman et al., Rev. Sci. Inst., 62, 2875 (1991)] are studied both through analytic calculations and solving numerically a system of linearized collisional plasma fluid equations using the 3D fluid code BOUT [M. Umansky et al., Contrib. Plasma Phys. 180, 887 (2009)], which has been successfully modified to treat cylindrical geometry. Instability drive from plasma pressure gradients and flows is considered, focusing on resistive drift waves, the Kelvin-Helmholtz and rotational interchange instabilities. A general linear dispersion relation for partially ionized collisional plasmas including these modes is derived and analyzed. For LAPD relevant profiles including strongly driven flows it is found that all three modes can have comparable growth rates and frequencies. Detailed comparison with solutions of the analytic dispersion relation demonstrates that BOUT accurately reproduces all characteristics of linear modes in this system.Comment: Published in Physics of Plasmas, 17, 102107 (2010