Construction of a human cell landscape at single-cell level.

Single-cell analysis is a valuable tool for dissecting cellular heterogeneity in complex systems1. However, a comprehensive single-cell atlas has not been achieved for humans. Here we use single-cell mRNA sequencing to determine the cell-type composition of all major human organs and construct a scheme for the human cell landscape (HCL). We have uncovered a single-cell hierarchy for many tissues that have not been well characterized. We established a 'single-cell HCL analysis' pipeline that helps to define human cell identity. Finally, we performed a single-cell comparative analysis of landscapes from human and mouse to identify conserved genetic networks. We found that stem and progenitor cells exhibit strong transcriptomic stochasticity, whereas differentiated cells are more distinct. Our results provide a useful resource for the study of human biology.

Construction of a cross-species cell landscape at single-cell level.

Individual cells are basic units of life. Despite extensive efforts to characterize the cellular heterogeneity of different organisms, cross-species comparisons of landscape dynamics have not been achieved. Here, we applied single-cell RNA sequencing (scRNA-seq) to map organism-level cell landscapes at multiple life stages for mice, zebrafish and Drosophila. By integrating the comprehensive dataset of > 2.6 million single cells, we constructed a cross-species cell landscape and identified signatures and common pathways that changed throughout the life span. We identified structural inflammation and mitochondrial dysfunction as the most common hallmarks of organism aging, and found that pharmacological activation of mitochondrial metabolism alleviated aging phenotypes in mice. The cross-species cell landscape with other published datasets were stored in an integrated online portal-Cell Landscape. Our work provides a valuable resource for studying lineage development, maturation and aging.

How many cell types are there in nature? How do they change during the life cycle? These are two fundamental questions that researchers have been trying to understand in the area of biology. In this study, single-cell mRNA sequencing data were used to profile over 2.6 million individual cells from mice, zebrafish and Drosophila at different life stages, 1.3 million of which were newly collected. The comprehensive datasets allow investigators to construct a cross-species cell landscape that helps to reveal the conservation and diversity of cell taxonomies at genetic and regulatory levels. The resources in this study are assembled into a publicly available website at http://bis.zju.edu.cn/cellatlas/.

Genetically encoded protein sensors for metal ion detection in biological systems: a review and bibliometric analysis.

Metal ions are indispensable elements in living organisms and are associated with regulating various biological processes. An imbalance in metal ion content can lead to disorders in normal physiological functions of the human body and cause various diseases. Genetically encoded fluorescent protein sensors have the advantages of low biotoxicity, high specificity, and a long imaging time in vivo and have become a powerful tool to visualize or quantify the concentration level of biomolecules in vivo and in vitro, temporal and spatial distribution, and life activity process. This review analyzes the development status and current research hotspots in the field of genetically encoded fluorescent protein sensors by bibliometric analysis. Based on the results of bibliometric analysis, the research progress of genetically encoded fluorescent protein sensors for metal ion detection is reviewed, and the construction strategies, physicochemical properties, and applications of such sensors in biological imaging are summarized.

Larval thermal characteristics of multiple ixodid ticks.

Temperature limits the geographic ranges of several tick species. Little is known about the thermal characteristics of these pests outside of a few studies on survival related to thermal tolerance. In this study, thermal tolerance limits, thermal preference, and the impact of temperature on activity levels and metabolic rate were examined in larvae for six species of ixodid ticks. Tolerance of low temperatures ranged from -15 to -24 °C with Dermacentor andersoni surviving the lowest temperatures. High temperature survival ranged from 41 to 47 °C, with Rhipicephalus sanguineus sensu lato having the highest upper lethal limit. Ixodes scapularis showed the lowest survival at both low and high temperatures. Thermal preference temperatures were tested from 0 to 41 °C. The majority of species preferred temperatures between 17 and 22 °C, while Dermacentor variabilis preferred significantly lower temperatures, near 12 °C. Overall activity was measured across a range of temperatures from 10 to 60 °C, and most tick species had the greatest activity near 30 °C. Metabolic rate was the greatest between 30 and 40 °C for all tick species and was relatively stable from 5 to 20 °C. The optimal temperature for tick larvae is likely near the thermal preference for each species, where oxygen consumption is low and activity occurs that will balance questing and conservation of nutrient reserves. In summary, tick species vary greatly in their thermal characteristics, and our results will be critical to predict distribution of these ectoparasites with changing climates.

Preparation and evaluation of oral self-microemulsifying drug delivery system of Chlorophyll.

OBJECTIVE: This study was aimed at improving the water solubility and oral bioavailability of Chl by self-microemulsifying drug delivery system (Chl-SMEDDS). METHODS: Compatibility experiments, pseudo-ternary phase diagram and central composite design were used to optimize the formulation. The selected systems were further evaluated for physical characteristics, including particle size, zeta potential, and appearance. The stability, in vitro dispersion test, and in vivo intestinal perfusion experiments were used to evaluate the SMEDDS. RESULTS: The optimal composition of Chl-SMEDDS included: Labrafil M 1944 CS (35%), kolliphor RH 40 (46%), Transcutol HP (19%) and 60 mg/g Chl. The appearance of water emulsified Chl-SMEDDS was green and transparent. The particle size, ζ-potential, and transmission electron microscopy studies showed that spherical globules of Chl-SMEDDS with a size of about 22.82 ± 1.29 nm and a negative surface charge of -24.21 ± 3.45 mV were obtained. Chl-SMEDDS could remain stable at 25 °C and 4 °C for at least 6 months. The dispersion test showed that Chl-SMEDDS dispersed spontaneously to form microemulsion after disintegration of capsule shell and 90% drug dispersed in just 30 min in pH 1.2 HCl without any drug precipitation during the test period. In vivo intestinal perfusion experiment revealed that the main absorption site for Chl-SMEDDS was duodenum. CONCLUSIONS: This study indicates that SMEDDS formulation could be an effective strategy for the oral administration of Chl.

Revisiting the epidemiology of pertussis in Canada, 1924-2015: a literature review, evidence synthesis, and modeling study.

BACKGROUND: Disease surveillance is central to the public health understanding of pertussis epidemiology. In Canada, public reporting practices have significantly changed over time, creating challenges in accurately characterizing pertussis epidemiology. Debate has emerged over whether pertussis resurged after the introduction of adsorbed pertussis vaccines (1981-1985), and if the incidence fell to its pre-1985 after the introduction of acellular pertussis vaccines (1997-1998). Here, we aim to assemble a unified picture of pertussis disease incidence in Canada. METHODS: Using publicly available pertussis surveillance reports, we collected, analyzed and presented Canadian pertussis data for the period (1924-2015), encompassing the pre-vaccine era, introduction of vaccine, changes to vaccine technology, and the introduction of booster doses. Information on age began to be reported since 1952, but age reporting practices (full, partial or no ages) have evolved over time, and varied across provinces/territories. For those cases reported without age each year, we impute an age distribution by assuming it follows that of the age-reported cases. RESULTS: Below the age of 20 years, the adjusted age-specific incidence from 1969 to 1988 is substantially higher than existing estimates. In children < 1 year, the incidence in some years was comparable to that during the 1988-1999 resurgence. CONCLUSIONS: The results presented here suggest that the surge in the average yearly incidence of pertussis that began in 1988 was weaker than previously inferred, and in contrary to the past findings, below age 5, the average yearly incidence of pertussis from 1999 to 2015 (when the incidence dropped again) has been lower than it was from 1969 to 1988.

Protein nanocages that penetrate airway mucus and tumor tissue.

Reports on drug delivery systems capable of overcoming multiple biological barriers are rare. We introduce a nanoparticle-based drug delivery technology capable of rapidly penetrating both lung tumor tissue and the mucus layer that protects airway tissues from nanoscale objects. Specifically, human ferritin heavy-chain nanocages (FTn) were functionalized with polyethylene glycol (PEG) in a unique manner that allows robust control over PEG location (nanoparticle surface only) and surface density. We varied PEG surface density and molecular weight to discover PEGylated FTn that rapidly penetrated both mucus barriers and tumor tissues in vitro and in vivo. Upon inhalation in mice, PEGylated FTn with optimized PEGylation rapidly penetrated the mucus gel layer and thus provided a uniform distribution throughout the airways. Subsequently, PEGylated FTn preferentially penetrated and distributed within orthotopic lung tumor tissue, and selectively entered cancer cells, in a transferrin receptor 1-dependent manner, which is up-regulated in most cancers. To test the potential therapeutic benefits, doxorubicin (DOX) was conjugated to PEGylated FTn via an acid-labile linker to facilitate intracellular release of DOX after cell entry. Inhalation of DOX-loaded PEGylated FTn led to 60% survival, compared with 10% survival in the group that inhaled DOX in solution at the maximally tolerated dose, in a murine model of malignant airway lung cancer. This approach may provide benefits as an adjuvant therapy combined with systemic chemo- or immunotherapy or as a stand-alone therapy for patients with tumors confined to the airways.

Integrated multiomic analysis reveals comprehensive tumour heterogeneity and novel immunophenotypic classification in hepatocellular carcinomas.

OBJECTIVE: Hepatocellular carcinoma (HCC) is heterogeneous, especially in multifocal tumours, which decreases the efficacy of clinical treatments. Understanding tumour heterogeneity is critical when developing novel treatment strategies. However, a comprehensive investigation of tumour heterogeneity in HCC is lacking, and the available evidence regarding tumour heterogeneity has not led to improvements in clinical practice. DESIGN: We harvested 42 samples from eight HCC patients and evaluated tumour heterogeneity using whole-exome sequencing, RNA sequencing, mass spectrometry-based proteomics and metabolomics, cytometry by time-of-flight, and single-cell analysis. Immunohistochemistry and quantitative polymerase chain reactions were performed to confirm the expression levels of genes. Three independent cohorts were further used to validate the findings. RESULTS: Tumour heterogeneity is considerable with regard to the genomes, transcriptomes, proteomes, and metabolomes of lesions and tumours. The immune status of the HCC microenvironment was relatively less heterogenous. Targeting local immunity could be a suitable intervention with balanced precision and practicability. By clustering immune cells in the HCC microenvironment, we identified three distinctive HCC subtypes with immunocompetent, immunodeficient, and immunosuppressive features. We further revealed the specific metabolic features and cytokine/chemokine expression levels of the different subtypes. Determining the expression levels of CD45 and Foxp3 using immunohistochemistry facilitated the correct classification of HCC patients and the prediction of their prognosis. CONCLUSION: There is comprehensive intratumoral and intertumoral heterogeneity in all dimensions of HCC. Based on the results, we propose a novel immunophenotypic classification of HCCs that facilitates prognostic prediction and may support decision making with regard to the choice of therapy.

Effect of Vitamin D Supplementation on Some Inflammatory Biomarkers in Type 2 Diabetes Mellitus Subjects: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND/AIMS: The mechanism, by which vitamin D influences inflammatory biomarkers in type 2 diabetes mellitus (T2DM), is not very well known. Thus, a meta-analysis of randomized controlled trials was conducted to assess the effect of vitamin D supplementation on some inflammatory biomarkers in T2DM subjects. METHODS: We searched randomized controlled trials from PubMed and the Cochrane Library in October 2017 and conducted a meta-analysis to evaluate the effectiveness of vitamin D supplementation on high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). Either a fixed-effects or a random-effects model was used to calculate pooled effects. RESULTS: We identified 13 studies that met our inclusion criteria. The results indicated that the vitamin D supplementation significant decreased the hs-CRP level by 0.45 µg/mL, whereas the vitamin D supplementation did not  influence the TNF-α and IL-6. Subgroup analysis showed that vitamin D significantly lowered hs-CRP by 0.34 µg/mL among trials with a daily vitamin D dose ≤4,000 IU and by 0.31 µg/mL among trials with time of vitamin D supplementation > 12 weeks. CONCLUSIONS: Vitamin D supplementation is beneficial for the reduction of hs-CRP inT2DM subjects but does not have a significant influence on TNF-α and IL-6 in T2DM subjects.

Enhanced oral bioavailability of 10-hydroxycamptothecin through the use of poly (n-butyl cyanoacrylate) nanospheres.

The article describes the preparation, physicochemical characterization, drug release, and in vivo behavior of 10-hydroxycamptothecin-loaded poly (n-butyl cyanoacrylate) (PBCA) nanospheres (HCPT-PBCA-NSs). HCPT-PBCA-NSs were successfully prepared via emulsion polymerization of n-butyl cyanoacrylate (BCA) monomer in acidic medium with the aid of two colloidal stabilizers (Poloxamer 188 and Dextran 70). The influence of pH, the time of polymerization, and the dosage of the drug on particle size and encapsulation efficiency (EE) were studied. HCPT-PBCA-NSs were of spherical shape and uniformly dispersed with a particle size of 135.7 nm, and zeta potential of -18.18 mV. EE, drug loading (DL), and yield of HCPT-PBCA-NSs were 51.52, 0.63, and 88.25%, respectively. FTIR, 1H NMR, and DSC showed complete polymerization of BCA monomer and HCPT existed in the form of molecular or amorphous in NSs. In vitro release of the drug from HCPT-PBCA-NSs exhibited sustained-release behavior with an initial burst release and about 60% of HCPT was released from the formulation within 24 h of dialysis. The pharmacokinetic study in healthy rats after oral administration showed that encapsulation of HCPT into PBCA-NSs increased the Cmax about 3.84 times and increased AUC0-t about 5.40 times compared with that of HCPT suspension. It was concluded that PBCA-NSs could be a promising drug carrier to load HCPT for oral drug delivery if efforts are made in the future to improve its poor DL capacity.

Redox-Sensitive Micelles Based on O,N-Hydroxyethyl Chitosan-Octylamine Conjugates for Triggered Intracellular Delivery of Paclitaxel.

A redox-sensitive micellar system constructed from an O,N-hydroxyethyl chitosan-octylamine (HECS-ss-OA) conjugate with disulfide linkages between the hydrophobic alkyl chains and hydrophilic chitosan backbone was synthesized for triggered intracellular delivery of hydrophobic paclitaxel (PTX). In aqueous environments, conjugates formed micelles with high PTX loading (>30%). Mechanistically, the sensitivity of HECS-ss-OA micelles to reducing environments was investigated using the parameters of in vitro release and particle size. Intracellular release of nile red fluorescence alongside cytotoxicity studies further confirmed the potency of redox-sensitive micelles for intracellular drug delivery compared with redox-insensitive micelles. Additionally, an in vivo study confirmed the efficacy of PTX-loaded micelles in tumor-bearing mice with superior antitumor efficacy and diminished systemic toxicity when compared with the redox-insensitive micelles and a PTX solution. These results demonstrate the potential of redox-sensitive HECS-ss-OA micelles for intracellular trafficking of lipophilic anticancer drugs.

Folic acid attenuates the effects of amyloid ß oligomers on DNA methylation in neuronal cells.

PURPOSE: Alzheimer's disease (AD) is a highly prevalent type of dementia. The epigenetic mechanism of gene methylation provides a putative link between nutrition, one-carbon metabolism, and disease progression because folate deficiency may cause hypomethylation of promoter regions in AD-relevant genes. We hypothesized that folic acid supplementation may protect neuron cells from amyloid ß (Aß) oligomer-induced toxicity by modulating DNA methylation of APP and PS1 in AD models. METHODS: Primary hippocampal neuronal cells and hippocampal HT-22 cells were incubated for 24 h with a combination of folic acid and either Aß oligomers or vehicle and were then incubated for 72 h with various concentrations of folic acid. AD transgenic mice were fed either folate-deficient or control diets and gavaged daily with various doses of folic acid (0 or 600 µg/kg). DNA methyltransferase (DNMT) activity, cell viability, methylation potential of cells, APP and PS1 expression, and the methylation of the respective promoters were determined. RESULTS: Aß oligomers lowered DNMT activity, increased PS1 and APP expression, and decreased cell viability. Folic acid dose-dependently stimulated methylation potential and DNMT activity, altered PS1 and APP promoter methylation, decreased PS1 and APP expression, and partially preserved cell viability. Folic acid increased PS1 and APP promoter methylation in AD transgenic mice. CONCLUSION: These results suggest a mechanism by which folic acid may prevent Aß oligomer-induced neuronal toxicity.

Can treatment increase the epidemic size?

Antiviral treatment is one of the key pharmacological interventions against many infectious diseases. This is particularly important in the absence of preventive measures such as vaccination. However, the evolution of drug-resistance in treated patients and its subsequent spread to the population pose significant impediments to the containment of disease epidemics using treatment. Previous models of population dynamics of influenza infection have shown that in the presence of drug-resistance, the epidemic final size (i.e., the total number of infections throughout the epidemic) is affected by the treatment rate. These models, through simulation experiments, illustrate the existence of an optimal treatment rate, not necessarily the highest possible rate, for minimizing the epidemic final size. However, the conditions for the existence of such an optimal treatment rate have never been found. Here, we provide these conditions for a class of models covered in the literature previously, and investigate the combination effect of treatment and transmissibility of the drug-resistant pathogen strain on the epidemic final size. For the first time, we obtain the final size relations for an epidemic model with two strains of a pathogen (i.e., drug-sensitive and drug-resistant). We also discuss this model with specific functional forms of de novo resistance emergence, and illustrate the theoretical findings with numerical simulations.

Lactoferrin-modified poly(ethylene glycol)-grafted BSA nanoparticles as a dual-targeting carrier for treating brain gliomas.

In this study, a dual-targeting drug delivery system based on bovine serum albumin nanoparticles (BSA-NPs) modified with both lactoferrin (Lf) and mPEG2000 loading doxorubicin (DOX) was designed, and its blood-brain barrier (BBB) penetration and brain glioma cells targeting properties were explored. BSA-NPs were prepared by a desolvation technique, and mPEG2000 was incorporated onto the surface of BSA-NPs by reacting with the free amino-group of BSA to form mPEG2000-modified BSA-NPs (P2000-NPs). Finally, Lf-modified P2000-NPs (Lf-NPs) was obtained by absorbing Lf onto the surface of P2000-NPs via the positive and negative charges interaction at physiological pH. Three levels of mPEG2000 and Lf-modified NPs were prepared and characterized, respectively. The uptake and potential cytotoxicity of different DOX preparations in vitro by the primary brain capillary endothelial cells (BCECs) and glioma cells (C6) were investigated. The dual-targeting effects were studied on the BBB model in vitro, BCECs/C6 glioma coculture model in vitro, and C6 glioma-bearing rats in vivo, respectively. The results exhibited that, with the increase of the amount of both mPEG2000 and Lf, the particle size of NPs increased and its zeta potential decreased. The in vivo pharmacokinetics study in healthy rats exhibited that P2000-NPs with a high level of mPEG2000 (P2000H-NPs) had longer circulation time in vivo. Compared to other NPs, Lf-NPs with high level of both Lf and mPEG2000 (LfH-NPs) showed the strongest cytotoxicity and the highest effectiveness in the uptake both in BCECs and C6 as well as improved the dual-targeting effects. Body distribution of DOX in different formulations revealed that LfH-NPs could significantly increase the accumulation of DOX in the brain, especially at 2 h postinjection (P < 0.05). In conclusion, Lf-NPs were a prospective dual-targeting drug delivery system for effective targeting therapy of brain gliomas.

Transmission dynamics for vector-borne diseases in a patchy environment.

In this paper, a mathematical model is derived to describe the transmission and spread of vector-borne diseases over a patchy environment. The model incorporates into the classic Ross-MacDonald model two factors: disease latencies in both hosts and vectors, and dispersal of hosts between patches. The basic reproduction number R(0) is identified by the theory of the next generation operator for structured disease models. The dynamics of the model is investigated in terms of R(0). It is shown that the disease free equilibrium is asymptotically stable if R(0) > 1, and it is unstable if R(0) > 1; in the latter case, the disease is endemic in the sense that the variables for the infected compartments are uniformly persistent. For the case of two patches, more explicit formulas for R(0) are derived by which, impacts of the dispersal rates on disease dynamics are also explored. Some numerical computations for R(0) in terms of dispersal rates are performed which show visually that the impacts could be very complicated: in certain range of the parameters, R(0) is increasing with respect to a dispersal rate while in some other range, it can be decreasing with respect to the same dispersal rate. The results can be useful to health organizations at various levels for setting guidelines or making policies for travels, as far as malaria epidemics is concerned.

Effect of enrichment conditions of secondary feeding on the synthesis of polyhydroxyalkanoates (PHAs) by activated sludge.

Polyhydroxyalkanoates (PHAs) are biodegradable plastics with great performance and development prospects. However, their traditional anaerobic/aerobic enrichment process requires a high concentration of dissolved oxygen (DO), resulting in high energy consumption. In this study, an anaerobic/oxygen-limited with secondary feeding enrichment mode was used to enhance the synthesis of PHAs while reducing energy consumption. The enrichment process of PHAs-synthesizing bacteria lasted up to 100 days, and the experiment was conducted to investigate the change of the PHAs synthesizing ability of the system in this mode by detecting the PHAs content and community distribution of the activated sludge under different stages. Under these conditions, the system enriched two major genera of PHAs-synthesizing bacteria, Thauera (30.21%) and Thiothrix (21.30%). The content of PHAs in the sludge increased from 4.51% to 30.87% and was able to achieve a concomitant increase in poly(3-hydroxyvalerate) (PHV) monomer content. After nitrogen limitation (C/N = 150) treatment, the content of PHAs reached 63.05%. The results showed that the enrichment mode of anaerobic/oxygen-limited with secondary feeding could enrich more PHAs-synthesizing bacteria and significantly increase the synthesis amount of PHAs, which revealed the great potential of this mode in solid waste value-added and reduce the production cost of PHAs and could provide a theoretical basis for the production of PHAs from activated sludge.

Dissecting the immune discrepancies in mouse liver allograft tolerance and heart/kidney allograft rejection.

The liver is the most tolerogenic of transplanted organs. However, the mechanisms underlying liver transplant tolerance are not well understood. The comparison between liver transplantation tolerance and heart/kidney transplantation rejection will deepen our understanding of tolerance and rejection in solid organs. Here, we built a mouse model of liver, heart and kidney allograft and performed single-cell RNA sequencing of 66,393 cells to describe the cell composition and immune cell interactions at the early stage of tolerance or rejection. We also performed bulk RNA-seq of mouse liver allografts from Day 7 to Day 60 post-transplantation to map the dynamic transcriptional variation in spontaneous tolerance. The transcriptome of lymphocytes and myeloid cells were characterized and compared in three types of organ allografts. Cell-cell interaction networks reveal the coordinated function of Kupffer cells, macrophages and their associated metabolic processes, including insulin receptor signalling and oxidative phosphorylation in tolerance induction. Cd11b+ dendritic cells (DCs) in liver allografts were found to inhibit cytotoxic T cells by secreting anti-inflammatory cytokines such as Il10. In summary, we profiled single-cell transcriptome analysis of mouse solid organ allografts. We characterized the immune microenvironment of mouse organ allografts in the acute rejection state (heart, kidney) and tolerance state (liver).

Multiple bouts of blood feeding in mosquitoes allow prolonged survival and are predicted to increase viral transmission during drought.

Survival through periods of drought is critical for mosquitoes to reside in semi-arid regions with humans, but water sources may be limited. Previous studies have shown that dehydrated mosquitoes will increase blood feeding propensity, but how this would occur over extended dry periods is unknown. Following a bloodmeal, prolonged exposure to dry conditions increased secondary blood feeding in mosquitoes by nearly two-fold, and chronic blood feeding allowed mosquitoes to survive twenty days without access to water sources. This refeeding did not alter the number of eggs generated, suggesting this refeeding is for hydration and nutrient replenishment. Exposure to desiccating conditions following a bloodmeal resulted in increased activity, decreased sleep levels, and prompted a return of CO2 sensing before egg deposition. The increased blood feeding during the vitellogenic stage and higher survival during dry periods are predicted to increase pathogen transmission and explain the elevated levels of specific arbovirus cases during dry conditions. These results solidify our understanding of the role of dry periods on mosquito blood feeding and how mosquito dehydration contributes to vectorial capacity and disease transmission dynamics.

Multistep targeted nano drug delivery system aiming at leukemic stem cells and minimal residual disease.

Refractory leukemia remains the most common therapeutic problem in clinical treatment of leukemia. The key therapy of refractory leukemia is to kill, thoroughly, the minimal residual disease and leukemia stem cells in the highly vascularized red marrow areas. In this study, two new conjugates, alendronate-polyethylene glycol (100) monostearate and folate-polyethylene glycol (100) monostearate, were synthesized to develop a multistep targeting nanostructured lipid carriers by enhancing drug transport to the high bone turnover areas adjacent to the red marrow and targeting the minimal residual disease and leukemia stem cells. This dual targeting system demonstrated a great binding affinity to hydroxyapatite, a model component of bone minerals, and higher cell uptake (in the form of carriers but not drug) and cytotoxicity in the K562 cell line, a leukemia cell line with overexpressed folate receptors, were observed in vitro compared to unmodified carriers, especially when the cells were pretreated and the receptors were up-regulated by all-trans retinoic acid. The comodel test of K562 cells and HA showed that this dual targeting system could desorb from bone surface and be taken up by leukemia cells. For the in vivo study, this dual targeting system exhibited a significant increase in plasma half-life and could specifically accumulate in the bone tissue of rats or mice after intravenous injection. Ex vivo imaging of mice femurs and confocal laser scanning microscope imaging of mice femur slices further confirmed that this dual targeting system could favorably deposit to the osteoblast-enriched areas of high bone turnover in regions of trabecular bone surrounded by red marrow. In vivo antitumor activity in K562/BALB/c-nu leukemia mice showed that the treatment of this dual targeting system significantly reduced the white blood cell (WBC) number in peripheral blood and bone marrow to the normal level. In conclusion, this dual targeting system could precisely target to the regions where the minimal residual disease and leukemia stem cells are located and then be specifically uptaken in large amounts, which is a valuable target for refractory leukemia therapy.

Impact of viral drift on vaccination dynamics and patterns of seasonal influenza.

BACKGROUND: Much research has been devoted to the determination of optimal vaccination strategies for seasonal influenza epidemics. However, less attention has been paid to whether this optimization can be achieved within the context of viral drift. METHODS: We developed a mathematical model that links different intra-seasonal dynamics of vaccination and infection to investigate the effect of viral drift on optimal vaccination for minimizing the total number of infections. The model was computationally implemented using a seasonal force of infection, with estimated parameters from the published literature. RESULTS: Simulation results show that the pattern of large seasonal epidemics is strongly correlated with the duration of specific cross-protection immunity induced by natural infection. Considering a random vaccination, our simulations suggest that the effect of vaccination on epidemic patterns is largely influenced by the duration of protection induced by strain-specific vaccination. We found that the protection efficacy (i.e., reduction of susceptibility to infection) of vaccine is a parameter that could influence these patterns, particularly when the duration of vaccine-induced cross-protection is lengthened. CONCLUSIONS: Given the uncertainty in the timing and nature of antigenically drifted variants, the findings highlight the difficulty in determining optimal vaccination dynamics for seasonal epidemics. Our study suggests that the short- and long-term impacts of vaccination on seasonal epidemics should be evaluated within the context of population-pathogen landscape for influenza evolution.