On the analysis of nucleon-nucleon scattering experiments

A method of perturbation calculation, especially adapted to nucleon-nucleon scattering problems, is described. Any contribution to the energy of the system which is relatively small where the nuclear potential is large may be treated as the perturbation. Two principal examples are discussed. (1) Energy as the perturbation: An expansion of the phase shifts in powers of the energy is written down which extends earlier results of Schwinger, Blatt, and Jackson. (2) The Coulomb field as the perturbation in the proton-proton problem: Expansions are given which relate the nuclear phase shifts in a combined nuclear and Coulomb field to the corresponding phase shifts for a purely nuclear problem. Attention is confined to central forces throughout

Adaptation of Plasmodium falciparum in human RBC supplemented NSG mice

Human chimeric mouse models, also known as humanized mice, are powerful tools to study human obligate pathogens such as Plasmodium falciparum. In our chimeric mouse model, human RBC supplemented NSG mice, static in vitro cultured P. falciparum require adaptation to become competent to thrive in the mice. During the adaptation process, variant surface antigens (VSAs), known to play a major role in virulence and antigenic variation are upregulated. These VSAs belong to large multigenic families such as P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1) and Repetitive Interspersed Family proteins (RIFINs) that have been shown to immune modulate effector function of host immune cells. Adapted parasite upregulates VAR2CSA PfEMP1, a known immune modulator of macrophages. Using an in vivo conditional knockdown of P. falciparum membrane-associated histidine rich protein 1 (MAHRP1), surface expression of PfEMP1 was affected and diminished in adapted P. falciparum. This led to reduced competency of adapted parasites in the huRBC-NSG mice. In vitro phagocytosis assay also showed that adapted parasites are less recognized and phagocytosed by mouse and human macrophages compared to non-adapted parasites. MAHRP1 knockdown of adapted parasites also resulted in increased macrophage recognition and phagocytosis. We utilized the phagocytosis assay to screen known macrophage-polarizing compounds for increased phagocytosis of adapted parasites. Three compounds that polarize macrophages towards M1-like and three towards M2-like macrophages were able to increase phagocytosis of adapted parasites after 24-hour treatment of M0 human primary macrophages. Adapted parasites also upregulate A-type RIFINs that have been shown recently to ligate host immune inhibitory receptor, leucocyte immunoglobulin-like receptor B1 (LILRB1). Adapted parasites are less controlled by primary responder NK cell compared to non-adapted parasites. Moreover, anti-LILRB1 blocking antibody partially restores NK cell control of adapted parasites, indicating that LILRB1 is involved in the reduction of NK cell control of adapted parasites. Therefore, adapted P. falciparum infection in huRBC-NSG mice provides a powerful tool to elucidate host immune modulatory mechanisms of P. falciparum and provides new approaches for therapy and treatment.Doctor of Philosoph

On the analysis of nucleon-nucleon scattering experiements /

Administrative - General."Issued January 15, 1949"Bibliography: p. 20.Sponsored by U.S. Atomic Energy CommissionMode of access: Internet

Risk awareness during operation of analytical flow cytometers and implications throughout the COVID-19 pandemic

The COVID-19 pandemic has brought biosafety to the forefront of many life sciences. The outbreak has compelled research institutions to re-evaluate biosafety practices and potential at-risk areas within research laboratories and more specifically within Shared Resource Laboratories (SRLs). In flow cytometry facilities, biological safety assessment encompasses known hazards based on the biological sample and associated risk group, as well as potential or unknown hazards, such as aerosol generation and instrument “failure modes.” Cell sorting procedures undergo clearly defined biological safety assessments and adhere to well-established biosafety guidelines that help to protect SRL staff and users against aerosol exposure. Conversely, benchtop analyzers are considered low risk due to their low sample pressure and enclosed fluidic systems, although there is little empirical evidence to support this assumption of low risk. To investigate this, we evaluated several regions on analyzers using the Cyclex-d microsphere assay, a recently established method for cell sorter aerosol containment testing. We found that aerosol and/or droplet hazards were detected on all benchtop analyzers predominantly during operation in “failure modes.” These results indicate that benchtop analytical cytometers present a more complicated set of risks than are commonly appreciated

A Randomized, Masked, Crossover Trial of Acetazolamide for Cystoid Macular Edema in Patients with Uveitis

Purpose: To study the effect of acetazolamide on cystoid macular edema in patients with uveitis. Methods: Forty patients with chronic intermediate, posterior, or panuveitis associated cystoid macular edema were randomized into a masked, cross-over trial comparing acetazolamide versus placebo. Patients received an initial 4-week course of either acetazolamide or placebo (course A) followed by a 4-week washout period. They then received a 4-week course of the opposite study medication (course B). Primary endpoints included area of cystoid macular edema measured on late-phase views of fluorescein angiography and visual acuity. Results: Thirty-seven patients completed the trial and were available for analysis; 17 (46%) were randomized to receive acetazolamide and 20 (54%) to receive placebo during course A. Acetazolamide resulted in a 0.5-disc area (25%) decrease in cystoid macular edema over that of placebo (P = 0.01; estimated treatment effect = -0.5 disc areas; 95% confidence interval, -0.9 to -0.1 ). However, there was no statistically significant effect of acetazolamide on visual acuity (P = 0.61; estimated treatment effect = 0.6 letters; 95% confidence interval, -2 to 3). Conclusions: A 4-week course of acetazolamide therapy results in a statistically significant but small decrease in cystoid macular edema in patients with chronic uveitis, and does not improve visual acuity. In contrast to previous studies in the literature, acetazolamide may have a more limited clinical benefit in patients with long-standing cystoid macular edema associated with chronic uveitis