Carbohydrate compositional effects on tissue distribution of chicken riboflavin-binding protein

Riboflavin-binding proteins (RBP) purified from chicken egg white, yolk and the serum of laying hens differ in their carbohydrate compositions reflecting tissue-specific modifications of a single gene product. All three are complex glycoproteins having more than twice as many N-acetylglucosamine residues (>12) as mannose residues (approx. 6). Egg white RBP is distinctive in having only one sialic acid and two galactose residues. Serum RBP contains approx. five sialic acid and seven galactose residues. In addition there is one residue of fucose. The carbohydrate composition of yolk RBP indicates the hydrolysis, respectively, of one, one, two and 3 residues of sialic acid, fucose, galactose, and N-acetylglucosamine from its precursor, serum RBP. The effect of these differing levels of glycosylation on plasma clearance, ovarian uptake and tissue distribution of ¹²⁵I-labeled riboflavin-binding proteins in laying hens were compared. 2 h after intravenous injection, 19% of the egg white RBP, 29% of the yolk RBP, and 37% of the serum RBP remained in circulation. The kinetics of plasma clearance was distinctly biphasic for each of the radioiodinated proteins. The initial rapid-turnover component ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{=13}\text{min}$) ranged from 27% of the serum RBP sample to 48% of the egg white RBP sample. The remaining slow-turnover components were cleared with half-lives fo 81 min (egg white RBP), 101 min (yokl RBP), and 121 min (serum RBP). 16 h after injection, only 4% of the egg white RBP was deposited in the yolk of developing oocytes while about 12% of the serum RBP and yolk RBP was deposited. This higly significant difference is apparently due to preferential, carbohydrate-dependent clearance of egg white RBP by the liver rather than preferential uptake of serum and yolk RBP by the ovarian follicle. We find no evidence for carbohydrate-directed uptake of riboflavin-binding protein by the ovarian follicle.     

The TMEM16A chloride channel as an alternative therapeutic target in cystic fibrosis

Cystic fibrosis (CF), a multiorgan genetic disease, is caused by loss of function of CFTR, a cAMP-regulated anion channel. In CF airway epithelia, defective Cl⁻ and bicarbonate secretion impairs mucociliary clearance and other innate defense mechanisms, favoring the colonization of the lungs by highly virulent bacteria. The airway epithelium expresses TMEM16A, a second type of Cl⁻ channel that is activated by cytosolic Ca²⁺. TMEM16A is particularly expressed in goblet cells. This specific localization could be important in the release and hydration of mucins. Activation of TMEM16A with pharmacological agents could circumvent the primary defect in CF. This strategy needs to be carefully designed and tested to avoid possible undesired effects due to the expression of TMEM16A in other cell types such as bronchial smooth muscle cells.This article is part of a Directed Issue entitled: Cystic Fibrosis: From o-mics to cell biology, physiology, and therapeutic advances.     

Effect of antigen-dependent clearance on pharmacokinetics of anti-heparin-binding EGF-like growth factor (HB-EGF) monoclonal antibody

Heparin-binding EGF-like growth factor (HB-EGF) is a member of the EGF family and is an important therapeutic target in some types of human cancers. KM3566 is a mouse anti-HB-EGF monoclonal antibody that neutralizes HB-EGF activity by inhibiting the binding of HB-EGF to its receptors. Based on the results of our pharmacokinetics study, a humanized derivative antibody, KHK2866, is rapidly cleared from serum and shows nonlinear pharmacokinetics in cynomolgus monkeys. In this study, we examined the antigen-dependent clearance of an anti-HB-EGF monoclonal antibody in vivo and in vitro in order to pharmacokinetically explain the rapid elimination of KHK2866. We revealed tumor size-dependent clearance of KM3566 in in vivo studies and obtained good fits between the observed and simulated concentrations of KM3566 based on the two-compartment with a saturable route of clearance model. Furthermore, in vivo imaging analyses demonstrated tumor-specific distribution of KM3566. We then confirmed rapid internalization and distribution to lysosome of KM3566 at a cellular level. Moreover, we revealed that the amounts of HB-EGF on cell surface membrane were maintained even while HB-EGF was internalized with KM3566. Recycled or newly synthesized HB-EGF, therefore, may contribute to a consecutive clearance of KM3566, which could explain a rapid clearance from serum. These data suggested that the rapid elimination in pharmacokinetics of KM3566 is due to antigen-dependent clearance. Given that its antigen is expressed in a wide range of normal tissue, it is estimated that the rapid elimination of KHK2866 from cynomolgus monkey serum is caused by antigen-dependent clearance.     

Altered clearance of human α2-macroglobulin complexes following reaction with cis-dichlorodiamineplatinum(II)

Clearance studies were performed in mice using α₂-macroglobulin (α₂M), α₂M-trypsin comlex and α₂M-CH₃NH₂ complex. All three species were incubated with cis-dichlorodiamine platinum(II) (cis-DDPt) at concentrations between 9.0 μM and 1.67 mM for 4 h and then dialyzed. The clearance rate of native α₂M was unchanged following incubation with cis-DDPt. α₂M-trypsin and α₂M-CH₃NH₂ cleared rapidly from the ciruculation; however, reaction with cis-DDPt significantly decreased the plasma elimination rate of both complexes. Non-denaturing gel electrophoresis and α₂M activity assays demonstrated relative stability following incubations with cis-DDPt which markedly altered clearance. Evidence for cis-DDPt crosslinking of α₂M subunits was obtained: however, whether this crosslinking is involved in altered clearance remains undetermined. Iodoacetamide treatment of α₂M did not duplicate the effect of cis-DDPton α₂M clearance, nor did it inhibit the effect of cis-DDPt on α₂M clearance. Plasma elimination of α₂M complex was also unaltered by pretreatment of mice with intravenous free cis-DDPt.     

Continuous Solvent/Detergent Virus Inactivation Using a Packed‐Bed Reactor

Continuous virus inactivation (VI) remains one of the missing pieces while the biopharma industry moves toward continuous manufacturing. The challenges of adapting VI to the continuous operation are two‐fold: 1) achieving fluid homogeneity and 2) a narrow residence time distribution (RTD) for fluid incubation. To address these challenges, a dynamic active in‐line mixer and a packed‐bed continuous virus inactivation reactor (CVIR) are implemented, which act as a narrow RTD incubation chamber. The developed concept is applied using solvent/detergent (S/D) treatment for inactivation of two commonly used model viruses. The in‐line mixer is characterized and enables mixing of the viscous S/D chemicals to ±1.0% of the target concentration in a small dead volume. The reactor's RTD is characterized and additional control experiments confirm that the VI is due to the S/D action and not induced by system components. The CVIR setup achieves steady state rapidly before two reactor volumes and the logarithmic reduction values of the continuous inactivation process are identical to those obtained by the traditional batch operation. The packed‐bed reactor for continuous VI unites fully continuous processing with very low‐pressure drop and scalability.     

The NAD-Booster Nicotinamide Riboside Potently Stimulates Hematopoiesis through Increased Mitochondrial Clearance

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Analysis of the volume of fluid (VOF) method for the simulation of the mucus clearance process with CFD

The clearance of mucus through coughing is a complex, multiphase process, which is affected principally by mucus viscosity and airflow velocity; however, it is also critically affected by the thickness of the two layers of mucus—the serous and gel layers—and oscillation level. The present study examines the effects of the latter parameters more closely. To do so, the mucus clearance process is simulated with a transient 3D volume of fluid (VOF) multiphase model in ANSYS Fluent. The model includes mucus’ bilayer properties and a wide range of boundary conditions were tested. The model was analysed in both a straight tube and a realistic trachea. Ultimately, the model was able to both capture air-mucus interface wave evolution and predict the overall behaviour of the clearance process. The results were consistent with experimental clearance data and numerical airflow simulations, which indicates our methodology is appropriate for future studies. Ultimately, the mere presence of the serous layer was found to increase mucus clearance by more than 15 percent. An oscillating flow enhanced clearance by up to 5 percent. Interestingly, interface wave steepness was found to be inversely correlated with mucus thickness, but directly with mucus velocity, which suggests it will be an interesting parameter for further study.     

颅内动脉瘤开颅术后患者肺部感染的危险因素分析

目的:探讨颅内动脉瘤开颅术后发生肺部感染的危险因素。方法:回顾性分析在我院接受开颅手术治疗的211例颅内动脉瘤患者的性别、年龄、吸烟史、糖尿病史、高血压病史、Hunt-Hess分级、动脉瘤部位、动脉瘤直径、手术时机及术后肺部感染的情况,对可能导致肺感染的因素行X2检验及Logistic回归分析。结果:单因素分析显示影响颅内动脉瘤患者术后肺感染的因素主要包括年龄、吸烟、糖尿病、Hunt-Hess分级(P0.05)。多因素Logistic回归分析结果显示影响颅内动脉瘤患者开颅术后发生肺部感染的因素为吸烟和Hunt-Hess分级。结论:吸烟、高Hunt-Hess分级是影响颅内动脉瘤开颅术后发生肺部感染的独立危险因素。     

P301L tau expression affects glutamate release and clearance in the hippocampal trisynaptic pathway

Individuals at risk of developing Alzheimer's disease (AD) often exhibit hippocampal hyperexcitability. A growing body of evidence suggests that perturbations in the glutamatergic tripartite synapse may underlie this hyperexcitability. Here, we used a tau mouse model of AD (rTg(TauP301L)4510) to examine the effects of tau pathology on hippocampal glutamate regulation. We found a 40% increase in hippocampal vesicular glutamate transporter, which packages glutamate into vesicles, and has previously been shown to influence glutamate release, and a 40% decrease in hippocampal glutamate transporter 1, the major glutamate transporter responsible for removing glutamate from the extracellular space. To determine whether these alterations affected glutamate regulation in vivo, we measured tonic glutamate levels, potassium‐evoked glutamate release, and glutamate uptake/clearance in the dentate gyrus, cornu ammonis 3(CA3), and cornu ammonis 1(CA1) regions of the hippocampus. P301L tau expression resulted in a 4‐ and 7‐fold increase in potassium‐evoked glutamate release in the dentate gyrus and CA3, respectively, and significantly decreased glutamate clearance in all three regions. Both release and clearance correlated with memory performance in the hippocampal‐dependent Barnes maze task. Alterations in mice expressing P301L were observed at a time when tau pathology was subtle and before readily detectable neuron loss. These data suggest novel mechanisms by which tau may mediate hyperexcitability.