Measurement of the Vector and Tensor Asymmetries at Large Missing Momentum in Quasielastic (e[over →],e

We report the measurement of the beam-vector and tensor asymmetries A_{ed}^{V} and A_{d}^{T} in quasielastic (e[over →],e^{'}p) electrodisintegration of the deuteron at the MIT-Bates Linear Accelerator Center up to missing momentum of 500 MeV/c. Data were collected simultaneously over a momentum transfer range 0.1

Expression and identification of recombinant chicken vascular endothelial growth factor in Pichia pastoris and its role in the pathogenesis of tibial dyschondroplasia.

Vascular endothelial growth factor (VEGF) is an essential mediator of angiogenesis and endochondral ossification. To explore the role of VEGF in avian diseases such as tibial dyschondroplasia (TD), a typical disorder of endochondral ossification, we expressed and identified recombinant chicken VEGF (chVEGF) protein in Pichia pastoris and evaluated its effects on thiram-induced TD in broiler chickens. The SDS-PAGE showed that 2 recombinant proteins, with molecular weights of ~46 and ~70 kDa, were obtained. Western blot analysis indicated that the 2 proteins were recognized by rabbit anti-chicken and goat anti-human VEGF polyclonal antibodies. Moreover, the mixture of the proteins significantly stimulated angiogenesis in the chick chorioallantoic membrane. In 21-d-old broilers that had been fed a thiram-enriched diet (100 mg/kg of thiram for 2 d at 8 d old) to induce TD, intramuscular injection of the chVEGF proteins (at a dosage of 10 or 30 µg/kg) significantly reduced the severity of TD but had no effect on TD incidence or BW; decreased serum Ca and P concentrations and tartrate-resistant acid phosphatase activity and elevated serum alkaline phosphatase activity; enhanced the total antioxidant capacity, superoxide dismutase, and glutathione peroxidase activities in the liver and kidney; upregulated the expression of type X collagen, matrix metalloproteinase (MMP)-13, and Runx2; and downregulated the Bcl-2 expression in the growth plates. In thiram-treated broilers at 15 d old, the chVEGF proteins upregulated the expression of MMP-13 and Runx2, and had different effects on type X collagen and Bcl-2 expression at different dosages. Our results indicate that exogenous chVEGF proteins promoted the recovery of TD-affected growth plates by improving the antioxidant capacity in the liver and kidney and by regulating differential expression of genes relating to endochondral ossification at different stages of TD development; VEGF deficiency in the growth plates was involved in the pathogenesis of TD.

Precise measurement of deuteron tensor analyzing powers with BLAST.

We report a precision measurement of the deuteron tensor analyzing powers T(20) and T(21) at the MIT-Bates Linear Accelerator Center. Data were collected simultaneously over a momentum transfer range Q=2.15-4.50 fm(-1) with the Bates Large Acceptance Spectrometer Toroid using a highly polarized deuterium internal gas target. The data are in excellent agreement with calculations in a framework of effective field theory. The deuteron charge monopole and quadrupole form factors G(C) and G(Q) were separated with improved precision, and the location of the first node of G(C) was confirmed at Q=4.19±0.05 fm(-1). The new data provide a strong constraint on theoretical models in a momentum transfer range covering the minimum of T(20) and the first node of G(C).

Letrozole inhibits the osteogenesis of medullary bone in prelay pullets.

This study was performed to investigate the effect of letrozole, an aromatase inhibitor, on osteogenesis of medullary bone in prelay pullets. Three hundred fifteen 95-d-old ISA prelay pullets were used. After 10 d of adaptation in the cages, 15 pullets were selected randomly to collect the serum and bone samples and the rest were randomly assigned to 2 groups with 3 replicates each. One group was control and the other was letrozole-treated, fed 0.5 mg of letrozole per prelay pullet per day for 18 d. The serum and bone samples from these birds were collected during the experiment. Estradiol and testosterone in serum were assayed using commercial RIA kits. The serum alkaline phosphatase (ALP), tartrate-resistant acid phosphatase (TRAP), Ca, and inorganic P were measured by an automatic biochemistry analyzer with commercial kits. The periosteum perimeter, endosteum perimeter, cortical bone index, cortical width, cortical bone area, and cortical area ratios of tibia were measured by transmitted scanner and a computer-assisted image analyzer. Our results showed that relative to the control-fed pullet, letrozole-fed pullets had reduced serum estrogen (57.5%), Ca (33.2%), ALP (33.6%), and TRAP (24.2%) and that values of serum estrogen, Ca, estrogen receptor expression, tibia radiographic density, serum ALP, and TRAP were all reduced (P < 0.05) and the serum P had a degressive trend in letrozole-treated groups. By contrast, the serum androgen and the tibia cortical bone index values were higher in the letrozole-treated group (P < 0.05). No differences were observed in the periosteum perimeter, endosteum perimeter, cortical width, and cortical area ratios of tibia between the 2 groups. The results showed that letrozole can inhibit the development of bone and medullary osteogenesis by inhibiting the synthesis of estrogen and its receptor in prelay pullets.

An update on the status of COVID-19: a comprehensive review.

The last two decades have witnessed two large-scale pandemics caused by coronaviruses, including severe acute respiratory syndrome (SARS) and the Middle East respiratory syndrome (MERS). At the end of 2019, another novel coronavirus, designated as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), hit Wuhan, a city in the center of China, and subsequently spread rapidly to the whole world. Latest reports revealed that more than 800 thousand people in over 200 countries are involved in the epidemic disease by SARS-CoV-2. Due to the high mortality rate and the lack of optimum therapeutics, it is crucial to understand the biological characteristics of the virus and its possible pathogenesis to respond to the SARS-CoV-2. Rapid diagnostics and effective therapeutics are also important interventions for the management of infection control. However, the rapid evolution of SARS-CoV-2 exerted tremendous challenges on its diagnostics and therapeutics. Therefore, there is an urgent need to summarize the existing research results to guide decision-making on the prioritization of resources for research and development. In this review, we focus on our current understanding of epidemiology, pathogenesis, diagnostics and therapeutics of coronavirus disease 2019 (COVID-19).

Effects of Gushukang, a Chinese herbal medicine, on bone characteristics and osteoporosis in laying hens.

In this study, we evaluated the effects of the herb medicine formula Gushukang (GSK) on bone characteristics and osteoporosis in end-of-lay hens. One thousand 55-wk-old ISA caged layers were allotted randomly to 2 groups. The control group was given the basal diet, and the GSK group was given the basal diet supplemented with additional GSK (1 g/kg) for 10 wk. Egg production, shell quality, bone radiographic density, and biochemical markers of bone turnover were determined. The results showed that GSK significantly increased the egg laying rate and decreased the percentage of cracked eggs (P < 0.05).The serum calcium, phosphate, and alkaline phosphatase were decreased (P < 0.05) in the GSK-treated group compared with the control group, whereas bone characteristics were significantly improved (P < 0.05). The results suggested that GSK can improve egg production and prevent bone loss by inhibiting bone turnover.

Chicken receptor activator of nuclear factor-kappaB ligand induces formation of chicken osteoclasts from bone marrow cells and also directly activates mature osteoclasts.

Receptor activator of nuclear factor-kappaB ligand (RANKL), which functions as a major determinant of osteoclast differentiation and activation, is a type II transmembrane protein and is expressed in osteoblasts-stromal cells. The aim of this study was to clarify the role of chicken RANKL (chRANKL) in chicken osteoclast differentiation and to determine its effect on mature chicken osteoclasts. In the present study, chRANKL protein was first cloned and expressed in Escherichia coli. We then treated chicken bone marrow cells with chRANKL protein and found that it induced the formation of chicken osteoclast-like multinucleated cells in a dose-dependent manner in the presence of human macrophage colony-stimulating factor. Moreover, the addition of chicken osteoprotegerin could block the effect of chRANKL with regard to osteoclast-like multi-nucleated cell formation and bone resorption. Using primary cultures of chicken osteoclasts on bone slices, we also found that bone resorption pits per cell increased with chRANKL concentration in a dose-dependent manner. The chRANKL-treated hens exhibited increased blood Ca(++) levels within 2 h after injection, showing that chRANKL also activates osteoclasts in vivo. These results clearly indicate that the expressed protein is functional and may also be a critical factor for chicken osteoclastogenesis and bone resorption.

Rapid increase of carbonate in cortical bones of hens during laying period.

The incorporation of carbonate has been recognized as an evident change in bone mineral (bioapatite) during aging. Laying hens (Gushi layer) at 4 stages of age (8 hens each stage) were studied by Raman spectroscopy and X-ray radiography to investigate the mineralogical changes and bone density, respectively. Cortical bones of the humerus and femur show a rapid increase of carbonate (∼1.9 wt.%) from sexual maturity to the peak of hens' laying period, while the densities of the cortical bones are relatively stable. Before sexual maturity, the density of the cortical bones increases considerably during aging. However, after the peak of the laying period, only femoral density continues elevating. Carbonate contents in the cortical bones reach the maximum at the peak of the laying period. Two pathways (halted growth of density and Ca-release due to the CO3 incorporation) could both contribute to the intense Ca requirement for egg laying. Crystallization, however, has no significant changes during aging and the laying period. This study could shed light on the mechanism of mineral losses due to CO3 incorporation, and also shows the advantages of Raman spectroscopy in tracking mineral loss in poultry bone.

Measuring zinc in living cells. A new generation of sensitive and selective fluorescent probes.

New fluorescent indicators with nanomolar to micromolar affinities for Zn(2+) have been synthesized in wavelengths from UV to the far red. The UV light-excited indicators are ratiometric. The visible wavelength indicators are non-ratiometric and exhibit large and pH-independent fluorescence increases with increasing zinc concentrations, with little to no sensitivity to physiologically relevant Ca(2+) concentrations. Experiments in neuronal and non-neuronal cell cultures show the new indicators to retain their sensitivity to and selectivity for zinc after conversion to cell-permeable forms.

Measurements of the generalized electric and magnetic polarizabilities of the proton at low Q2 using the virtual-compton-scattering reaction.

The mean square polarizability radii of the proton have been measured for the first time in a virtual-Compton-scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities obtained from a dispersion analysis of the data at Q2 = 0.057 GeV2/c2 are in agreement with O(p3) heavy baryon chiral perturbation theory. The data support the dominance of mesonic effects in the polarizabilities.

Investigation of the conjectured nucleon deformation at low momentum transfer.

We report new precise H(e,e(')p)pi(0) measurements at the Delta(1232) resonance at Q(2)=0.127 (GeV/c)(2) obtained at the MIT-Bates out-of-plane scattering facility which are particularly sensitive to the transverse electric amplitude (E2) of the gamma(*)N-->Delta transition. The new data have been analyzed together with those of earlier measurements to yield precise quadrupole to dipole amplitude ratios: Re(E(3/2)(1+)/M(3/2)(1+))=(-2.3+/-0.3(stat+syst)+/-0.6(model))% and Re(S(3/2)(1+)/M(3/2)(1+))=(-6.1+/-0.2(stat+syst)+/-0.5(model))% for M(3/2)(1+)=(41.4+/-0.3(stat+syst)+/-0.4(model))(10(-3)/m(pi(+))). The derived amplitudes give credence to the conjecture of deformation in hadrons favoring, at low Q2, the dominance of mesonic effects.

Spin-dependent electron-proton scattering in the Delta-excitation region.

We report on measurements of the cross section and provide first data on spin correlation parameters A(TT') and A(TL') in inclusive scattering of longitudinally polarized electrons from nuclear-polarized hydrogen. Polarized electrons were injected into an electron storage ring operated at a beam energy of 720 MeV. Polarized hydrogen was produced by an atomic beam source and injected into an open-ended cylindrical cell, located in the electron storage ring. The four-momentum transfer squared ranged from Q2 = 0.2 GeV(2)/c(2) at the elastic scattering peak to Q2 = 0.11 GeV(2)/c(2) at the Delta(1232) resonance. The data provide a stringent test of pion electroproduction models.

Spin-momentum correlations in quasielastic electron scattering from deuterium.

The spin-momentum correlation parameter A(V)(ed) was measured for the 2H-->(e-->,e'p)n reaction for missing momenta up to 350 MeV/c at Q2 = 0.21 (GeV/c)(2) for quasielastic scattering of polarized electrons from vector-polarized deuterium. The data give detailed information about the deuteron spin structure and are in good agreement with the results of microscopic calculations based on realistic nucleon-nucleon potentials and including various spin-dependent reaction mechanism effects. The experiment reveals in a most direct manner the effects of the D state in the deuteron ground-state wave function and shows the importance of isobar configurations for this reaction.

Measurement of the exclusive 3He(e,e'p) reaction below the quasielastic peak.

New, high-precision measurements of the 3He(e,e(')p) reaction using the A1 Collaboration spectrometers at the Mainz microtron MAMI are presented. These were performed in antiparallel kinematics at energy transfers below the quasielastic peak, and at a central momentum transfer of 685 MeV/c. Cross sections and distorted momentum distributions were extracted and compared to theoretical predictions and existing data. The longitudinal and transverse behavior of the cross section was also studied. Sizable differences in the cross-section behavior from theoretical predictions based on the plane wave impulse approximation were observed in both the two- and three-body breakup channels. Full Faddeev-type calculations account for some of the observed excess cross-section, but significant differences remain.