Pulsatility Index as a Novel Parameter for Perfusion in Mouse Model of Hindlimb Ischemia

Background/Aims: In clinical settings, the pulsatility index (PI) has become a widely used tool for monitoring obstetrics or other vascular diseases. It is based on the maximum Doppler shift waveform derived from ultrasonography. However, it remains unclear whether the PI levels are correctly predicted from the perfusion in mouse model of hindlimb ischemia. Methods: To explore the relationship between PI and perfusion, we generated a unilateral hindlimb ischemia model in 8-week-old C57BL/6 male mice by ligation of the right common iliac artery and femoral artery. These mice were monitored with laser Doppler perfusion imaging (LDPI) and an ultrasound system (Vevo2100). Vessel densities in ischemic skeletal muscles were measured with vWF staining, which functions as a marker for endothelial cells. In order to further verify PI evaluation in other conditions, we performed therapeutic experiments using hindlimb ischemic mouse with PBS or FGF2 treatment. Results: In the mouse model of hindlimb ischemia, the PI levels were continuously elevated and were accompanied by an increased ratio of perfusion to blood flow. 1 and 4 weeks after ischemia, the densities of vWF staining were correlated with PI values. Moreover, the PI index exactly reflected the perfusion in hindlimb ischemic mice after FGF2 treatment, while it indicated the condition of angiogenesis after therapeutic treatment based on the association between PI values and the number of vWF-positive stained cells in muscles. Conclusion: This study confirms the utility of a noninvasive and reproducible ultrasound index for a rapid evaluation of perfusion and blood recovery after hindlimb ischemia in vivo. PI, as one stable and comparable parameter, is correlated with angiogenesis in hindlimb ischemic mouse. Moreover, PI can exactly reflect perfusion and angiogenesis in therapeutic hindlimb ischemic mouse models. This study suggested that PI can serve as a novel index for relatively reproducible and repeatable blood flow recovery in the evaluation of emerging ischemic therapies and disease development in mouse models of hindlimb ischemia

Recombinant proteins A29L, M1R, A35R, and B6R vaccination protects mice from mpox virus challenge

Since May 2022, mutant strains of mpox (formerly monkeypox) virus (MPXV) have been rapidly spreading among individuals who have not traveled to endemic areas in multiple locations, including Europe and the United States. Both intracellular and extracellular forms of mpox virus have multiple outer membrane proteins that can stimulate immune response. Here, we investigated the immunogenicity of MPXV structural proteins such as A29L, M1R, A35R, and B6R as a combination vaccine, and the protective effect against the 2022 mpox mutant strain was also evaluated in BALB/c mice. After mixed 15 μg QS-21 adjuvant, all four virus structural proteins were administered subcutaneously to mice. Antibody titers in mouse sera rose sharply after the initial boost, along with an increased capacity of immune cells to produce IFN-γ alongside an elevated level of cellular immunity mediated by Th1 cells. The vaccine-induced neutralizing antibodies significantly inhibited the replication of MPXV in mice and reduced the pathological damage of organs. This study demonstrates the feasibility of a multiple recombinant vaccine for MPXV variant strains

Heterologous boost with mRNA vaccines against SARS-CoV-2 Delta/Omicron variants following an inactivated whole-virus vaccine.

The coronavirus SARS-CoV-2 has mutated quickly and caused significant global damage. This study characterizes two mRNA vaccines ZSVG-02 (Delta) and ZSVG-02-O (Omicron BA.1), and associating heterologous prime-boost strategy following the prime of a most widely administrated inactivated whole-virus vaccine (BBIBP-CorV). The ZSVG-02-O induces neutralizing antibodies that effectively cross-react with Omicron subvariants. In naïve animals, ZSVG-02 or ZSVG-02-O induce humoral responses skewed to the vaccines targeting strains, but cellular immune responses cross-react to all variants of concern (VOCs) tested. Following heterologous prime-boost regimes, animals present comparable neutralizing antibody levels and superior protection against Delta and Omicron BA.1variants. Single-boost only generated ancestral and omicron dual-responsive antibodies, probably by recall and reshape the prime immunity. New Omicron-specific antibody populations, however, appeared only following the second boost with ZSVG-02-O. Overall, our results support a heterologous boost with ZSVG-02-O, providing the best protection against current VOCs in inactivated virus vaccine-primed populations

Theoretical modeling and experimental demonstration of surface plasmon resonance based sensing using phase detection

This report presents a simplified theoretical modeling and experimental demonstration of surface plasmon resonance based sensing. Two groups of simulation were carried out based on two different configurations using phase shift between p and s polarizations. In order to achieve system optimization, effects of different experimental parameters including gold film thickness, linker layer thickness, sample thickness, incident angle and different gold film permittivity were investigated. Results suggest that the gold thickness should be within 45nm to 50nm to achieve optimize refractive index (RI) resolution of 2.416 x 10-6 unit (RIU), while linker layer and sample thickness greater than 200nm does not affect the sensing. However narrow abrupt phase shift range is a limitation. Experiment was then done based on the optimized theoretical model. Chloride solution was used as sample, obvious phase shift was observed as sample concentration increased. Additional experiment on SPR based imaging was also demonstrated.Bachelor of Engineering (Materials Engineering

Absorbance detection in aqueous solutions using mPOF

Conventionally, aqueous solution absorbance detection is carried out using cuvette as container. Here we demonstrated a novel axial absorbance detection method, using microstructured polymer optical fibers (mPOFs) holding an array of air holes along the fiber to replace cuvette in the experiment set-up. [Peer Assessment Review

Monte Carlo study of the effective electron beam shape in scanning electron microscopic imaging

Theoretical analysis of dimensional measurements made using a scanning electron microscope (SEM) requires a raw image to be corrected for the probe shape of the incident electron beam. In this paper, an effective electron beam shape (EEBS), which differs from the Gaussian profile conventionally assumed in SEM image analysis, was studied using a Monte Carlo simulation method. A model of a focusing electron beam with finite width due to aberration was used in simulating the SEM image of gold particles on a carbon substrate. It was found that the EEBS is local to the electron beam landing position and deviates significantly from the Gaussian profile; it is strongly dependent on both the sample topography and the electron beam focusing condition

Surface and bulk plasmon excitations of silver by electron impact

We present an analysis of electron incident angle-dependent reflected electron energy loss spectroscopy spectra of silver by using a Monte Carlo simulation method with which the separated contributions from surface and bulk excitations can be identified. The simulations were performed at several different incident electron energies and with various incident angles with respect to the surface normal. We found that the surface plasmon excitation plays a dominant role in the loss peak at around 3.7 and 7.5 eV