Metal–organic frameworks (MOFs), which are a unique class of hybrid porous materials built from metal ions and organic linkers, have attracted significant research interest in recent years. Compared ...with conventional porous materials, MOFs exhibit a variety of advantages, including a large surface area, a tunable pore size and shape, an adjustable composition and structure, biodegradability, and versatile functionalities, which enable MOFs to perform as promising platforms for drug delivery, molecular imaging, and theranostic applications. In this article, the recent research progress related to nanoscale metal–organic frameworks (NMOFs) is summarized with a focus on synthesis strategies and drug delivery, molecular imaging, and theranostic applications. The future challenges and opportunities of NMOFs are also discussed in the context of translational medical research. More effort is warranted to develop clinically translatable NMOFs for various applications in nanomedicine.
Nanoscale metal‐organic frameworks (NMOFs) are reviewed with a focus on the synthesis strategies and drug delivery, molecular imaging, and theranostic applications. The future challenges and opportunities of NMOFs in the context of translational medical research are systematically discussed.
Abstract Diagnosis of Alzheimer's disease (AD) can be performed with the assistance of amyloid imaging. The current method relies on positron emission tomography (PET), which is expensive and exposes ...people to radiation, undesirable features for a population screening method. Magnetic resonance imaging (MRI) is cheaper and is not radioactive. Our approach uses magnetic nanoparticles (MNPs) made of superparamagnetic iron oxide (SPIO) conjugated with curcumin, a natural compound that specifically binds to amyloid plaques. Coating of curcumin-conjugated MNPs with polyethylene glycol-polylactic acid block copolymer and polyvinylpyrrolidone by antisolvent precipitation in a multi-inlet vortex mixer produces stable and biocompatible curcumin magnetic nanoparticles (Cur-MNPs) with mean diameter <100 nm. These nanoparticles were visualized by transmission electron microscopy and atomic force microscopy, and their structure and chemistry were further characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and Fourier transform infrared spectroscopy. Cur-MNPs exhibited no cytotoxicity in either Madin–Darby canine kidney (MDCK) or differentiated human neuroblastoma cells (SH-SY5Y). The Papp of Cur-MNPs was 1.03 × 10−6 cm/s in an in vitro blood–brain barrier (BBB) model. Amyloid plaques could be visualized in ex vivo T2*-weighted magnetic resonance imaging (MRI) of Tg2576 mouse brains after injection of Cur–MNPs, and no plaques could be found in non-transgenic mice. Immunohistochemical examination of the mouse brains revealed that Cur-MNPs were co-localized with amyloid plaques. Thus, Cur–MNPs have the potential for non-invasive diagnosis of AD using MRI.
Photoluminescent carbon dots (CDs) have received ever-increasing attention in the application of optical bioimaging because of their low toxicity, tunable fluorescent properties, and ultracompact ...size. We report for the first time on enhanced photoluminescence (PL) performance influenced by structure effects among the various types of nitrogen doped (N-doped) PL CDs. These CDs were facilely synthesized from condensation carbonization of linear polyethylenic amine (PEA) analogues and citric acid (CA) of different ratios. Detailed structural and property studies demonstrated that either the structures or the molar ratio of PEAs altered the PL properties of the CDs. The content of conjugated π-domains with CN in the carbon backbone was correlated with their PL Quantum Yield (QY) (up to 69%). The hybridization between the surface/molecule state and the carbon backbone synergistically affected the chemical/physical properties. Also, long-chain polyethylenic amine (PEA) molecule-doped CDs exhibit increasing photostability, but at the expense of PL efficiency, proving that the PL emission of high QY CDs arise not only from the sp2/sp3 carbon core and surface passivation of CDs, but also from the molecular fluorophores integrated in the CDs. In vitro and in vivo bioimaging of these N-doped CDs showed strong photoluminescence signals. Good biocompatibility demonstrates their potential feasibility for bioimaging applications. In addition, the overall size profile of the as-prepared CDs is comparable to the average size of capillary pores in normal living tissues (∼5 nm). Our study provides valuable insights into the effects of the PEA doping ratios on photoluminescence efficiency, biocompatibility, cellular uptake, and optical bioimaging of CDs.
Intranasal administration of phospholipid-based gelatin nanoparticles (GNP) was prepared to investigate the neuro-recovery effects of neuropeptide Substance P (SP) on hemiparkinsonian rats.
The ...SP-loaded gelatin nanoparticles (SP-GNP) were prepared by a water-in-water emulsion method and possessed high stability, encapsulating efficiency and loading capacity. PC-12 cells were used to examine the growth enhancement of SP-GNP in vitro by MTT assays and flow cytometry (FCM). The therapeutic effects of SP-GNP on 6-hydroxydopamine (6-OHDA) induced hemiparkinsonian rats were assessed by quantifying rotational behavior and the levels of tyrosine hydroxylase (TH), phosphorylated c-Jun protein (p-c-Jun) and Caspase-3 (Cas-3) expressed in substantia nigra (SN) region of hemiparkinsonian rats.
PC-12 cells under SP-GNP treatment showed better cell viability and lower degree of apoptosis than those under SP solution treatment. Hemiparkinsonian rats under intranasal SP-GNP administration demonstrated better behavioral improvement, higher level of TH in SN along with much lower extent of p-c-Jun and Cas-3 than those under intranasal SP solution administration and intravenous SP-GNP administration.
With the advantages of GNP and nose-to-brain pathway, SP can be effectively delivered into the damaged SN region and exhibit its neuro-recovery function through the inhibition on JNK pathway and dopaminergic neuron apoptosis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study was aimed to determine whether pure molecular-based diffusion coefficient (D) and perfusion-related diffusion parameters (perfusion fraction f, perfusion-related diffusion coefficient D*) ...differ in healthy livers and fibrotic livers through intra-voxel incoherent motion (IVIM) MR imaging.
17 healthy volunteers and 34 patients with histopathologically confirmed liver fibrosis patients (stage 1 = 14, stage 2 = 8, stage 3 & 4 = 12, METAVIR grading) were included. Liver MR imaging was performed at 1.5-T. IVIM diffusion weighted imaging sequence was based on standard single-shot DW spin echo-planar imaging, with ten b values of 10, 20, 40, 60, 80, 100, 150, 200, 400, 800 sec/mm2 respectively. Pixel-wise realization and regions-of-interest based quantification of IVIM parameters were performed.
D, f, and D* in healthy volunteer livers and patient livers were 1.096±0.155 vs 0.917±0.152 (10(-3) mm2/s, p = 0.0015), 0.164±0.021 vs 0.123±0.029 (p<0.0001), and 13.085±2.943 vs 9.423±1.737 (10(-3) mm2/s, p<0.0001) respectively, all significantly lower in fibrotic livers. As the fibrosis severity progressed, D, f, and D* values decreased, with a trend significant for f and D*.
Fibrotic liver is associated with lower pure molecular diffusion, lower perfusion volume fraction, and lower perfusion-related diffusion. The decrease of f and D* in the liver is significantly associated liver fibrosis severity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Female sex hormones play an important role in the etiology and pathophysiology of a variety of musculoskeletal degenerative diseases. Postmenopausal women show accelerated disc degeneration due to ...relative estrogen deficiency. This literature review aims to validate or falsify this hypothesis, i.e., while overall females have higher prevalence of low back pain (LBP) across all age groups, this male vs. female difference in LBP prevalence further increases after female menopause age. The literature search was performed on PubMed on January 2, 2016. The search word combination was (low back pain) AND prevalence AND (males OR men) AND (females OR women). The following criteria were taken to include the papers for synthetic analysis: (I) only English primary literatures on nonspecific pain; (II) only prospective studies on general population, but not population with occupational LBP causes, of both males and female subjects studied using the same LBP criterion, ages-specific information available, and males and female subjects were age-matched; (III) studies without major quality flaws. In total 98 studies with 772,927 subjects were analyzed. According to the information in the literature, participant subjects were divided into four age groups: (I) school age children group: 6-19 years; (II) young and middle aged group: 20-50 years; (III) mixed age group: data from studies did not differentiate age groups; (IV) elderly group: ≥50 years old. When individual studies were not weighted by participant number and each individual study is represented as one entry regardless of their sample size, the median LBP prevalence ratio of female vs. males was 1.310, 1.140, 1.220, and 1.270 respectively for the four age groups. When individual studies were weighted by participant number, the LBP prevalence ratio of female vs. males was 1.360, 1.127, 1.185, and 1.280 respectively for the four groups. The higher LBP prevalence in school age girls than in school age boys is likely due to psychological factors, female hormone fluctuation, and menstruation. Compared with young and middle aged subjects, a further increased LBP prevalence in females than in males was noted after menopause age.
The importance of identifying osteoporotic vertebral endplate or/and cortex fracture (ECF), which primarily includes endplate fracture (EPF) and vertebral anterior cortex buckling, has been ...recognized. However, some old traumatic ECFs with healing process in the elderly may be mistaken as osteoporotic. This study analyzes the radiological features of traumatic EPF.
This was a retrospective analysis of 194 spine trauma patients with 263 vertebral fractures (mean age: 42.11 ± 9.82 years, 118 males and 76 females). All patients had traumatic EPF identified by X-ray/CT/MRI.
The involved vertebra was mostly L1 (29.7%), followed by T12 and L2. Except EPFs involved both superior and inferior endplates (12.6%), only 1.9% involved inferior endplate alone, with the majority involved superior endplate. If each endplate was divided into five segments of equal lengths (from anterior to posterior: a1, a2, m, p2, p1), the most depressed point of superior EPFs was mostly at segment-a2 (approximately 45%), followed by segment-a1 (approximately 20%) or segment-m (approximately 20%), and very rarely at segment-p1. The upper 1/3 of anterior vertebral wall was more likely to fracture, followed by middle 1/3 of anterior wall. For posterior vertebral wall fracture, 68.5% broke the bony wall surrounding the basivertebral vain. 58.6%, 30.0%, and 11.4% of vertebral fractures had <1/5, 1/5-1/3, and >1/3 vertebral body height loss. As the extent of vertebral height loss increased, the chance of having both superior and inferior EPFs also increased; however, the chance of having inferior EPF alone did not increase.
Traumatic EPF features are characterized, which may help the differentiation of traumatic and osteoporotic EPFs.
The aim of this study was to establish reference values for middle‐aged subjects and to investigate the age and gender dependence of liver diffusion MRI parameters. The IVIM type of liver diffusion ...scan was based on a single‐shot spin‐echo–type echo‐planar sequence using a 1.5 T magnet with 16 b‐values. Diffusion‐derived vessel density (DDVD)(b0b2) or DDVD(b0b10) was the signal difference between b = 0 and b = 2 (or b = 10) s/mm2 images after removing visible vessels. IVIM analysis was performed with full fitting and segmented fitting, and with a threshold b‐value of 60 or 200 s/mm2, and fitting started from b = 2 s/mm2. Thirty‐one men (age range: 25‐71 years) and 26 men (age: 22‐69 years) had DDVD and IVIM analysis, respectively, while 37 women (age: 20‐71 years) and 36 women (age: 20‐71 years) had DDVD and IVIM analysis, respectively. DDVD results showed a significant age‐related reduction for women. IVIM results for full fitting showed excellent agreement with those for segmented fitting using a threshold b of 60 s/mm2, but this was less good for results with a threshold b of 200 s/mm2. As age increased, female subjects' Dslow measure showed a significant reduction, while their PF and Dfast measures showed a significant increase. For the age group of 40‐55 years, DDVD(b0b2), DDVD(b0b10), Dslow, PF and Dfast were 12.26 ± 3.90 au/pixel, 16.95 ± 5.45 au/pixel, 1.072 ± 0.067 (10−3 mm2/s), 0.141 ± 0.025 and 61.0 ± 14.0 (10−3 mm2/s) for men, and 13.35 ± 3.6 au/pixel, 17.20 ± 3.62 au/pixel, 1.069 ± 0.074 (10−3 mm2/s), 0.119 ± 0.014 and 57.1 ± 13.2 (10−3 mm2/s) for women, respectively. DDVD measure of this study suggest that aging is associated with a reduction in liver perfusion. There is a possibility that a lower Dslow measure is associated with artificially higher PF and Dfast measures, and that IVIM modeling of the perfusion component is constrained by the diffusion component.
1. Diffusion‐weighted imaging measures show that liver parenchyma has an age‐dependent decrease of micro‐vessel density in women.
2. IVIM results with full fitting are very similar to the results of segmented fitting with a threshold b of 60 s/mm2, while they differ substantially from the results of segmented fitting with a threshold b of 200 s/mm2.
3. As age increases, female subjects' diffusion measure show a significant reduction, and this may lead to an artificial increase in perfusion measures.
The U.S. National Library of Medicine has made two datasets of postero-anterior (PA) chest radiographs available to foster research in computer-aided diagnosis of pulmonary diseases with a special ...focus on pulmonary tuberculosis (TB). The radiographs were acquired from the Department of Health and Human Services, Montgomery County, Maryland, USA and Shenzhen No. 3 People's Hospital in China. Both datasets contain normal and abnormal chest X-rays with manifestations of TB and include associated radiologist readings.
Purpose
This study seeks to explore whether chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) can detect liver composition changes between after-meal and over-night-fast ...statuses.
Procedures
Fifteen healthy volunteers were scanned on a 3.0-T human MRI scanner in the evening 1.5–2 h after dinner and in the morning after over-night (12-h) fasting. Among them, seven volunteers were scanned twice to assess the scan–rescan reproducibility. Images were acquired at offsets (
n
= 41, increment = 0.25 ppm) from −5 to 5 ppm using a turbo spin echo (TSE) sequence with a continuous rectangular saturation pulse. Amide proton transfer-weighted (APTw) and GlycoCEST signals were quantified with the asymmetric magnetization transfer ratio (MTR
asym
) at 3.5 ppm and the total MTR
asym
integrated from 0.5 to 1.5 ppm from the corrected Z-spectrum, respectively. To explore scan time reduction, CEST images were reconstructed using 31 offsets (with 20 % time reduction) and 21 offsets (with 40 % time reduction), respectively.
Results
For reproducibility, GlycoCEST measurements in 41 offsets showed the smallest scan-rescan mean measurements variability, indicated by the lowest mean difference of −0.049 % (95 % limits of agreement, −0.209 to 0.111 %); for APTw, the smallest mean difference was found to be 0.112 % (95 % limits of agreement, −0.698 to 0.921 %) in 41 offsets. Compared with after-meal, both GlycoCEST measurement and APTw measurement under different offset number decreased after 12-h fasting. However, as the offsets number decreased (41 offsets vs. 31 offsets vs. 21 offsets), GlycoCEST map and APTw map became more heterogeneous and noisier.
Conclusion
Our results show that CEST liver imaging at 3.0 T has high sensitivity for fasting.
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