Reliability of MRI-derived measurements of human cerebral cortical thickness: the effects of field strength, scanner upgrade and manufacturer

In vivo MRI-derived measurements of human cerebral cortex thickness are providing novel insights into normal and abnormal neuroanatomy, but little is known about their reliability. We investigated how the reliability of cortical thickness measurements is affected by MRI instrument-related factors, including scanner field strength, manufacturer, upgrade and pulse sequence. Several data processing factors were also studied. Two test-retest data sets were analyzed: 1) 15 healthy older subjects scanned four times at 2-week intervals on three scanners; 2) 5 subjects scanned before and after a major scanner upgrade. Within-scanner variability of global cortical thickness measurements was <0.03 mm, and the point-wise standard deviation of measurement error was approximately 0.12 mm. Variability was 0.15 mm and 0.17 mm in average, respectively, for cross-scanner (Siemens/GE) and cross-field strength (1.5 T/3 T) comparisons. Scanner upgrade did not increase variability nor introduce bias. Measurements across field strength, however, were slightly biased (thicker at 3 T). The number of (single vs. multiple averaged) acquisitions had a negligible effect on reliability, but the use of a different pulse sequence had a larger impact, as did different parameters employed in data processing. Sample size estimates indicate that regional cortical thickness difference of 0.2 mm between two different groups could be identified with as few as 7 subjects per group, and a difference of 0.1 mm could be detected with 26 subjects per group. These results demonstrate that MRI-derived cortical thickness measures are highly reliable when MRI instrument and data processing factors are controlled but that it is important to consider these factors in the design of multi-site or longitudinal studies, such as clinical drug trials.

Structure-based discovery of an organic compound that binds Bcl-2 protein and induces apoptosis of tumor cells

Bcl-2 and related proteins are key regulators of apoptosis or programmed cell death implicated in human disease including cancer. We recently showed that cell-permeable Bcl-2 binding peptides could induce apoptosis of human myeloid leukemia in vitro and suppress its growth in severe combined immunodeficient mice. Here we report the discovery of HA14-1, a small molecule (molecular weight = 409) and nonpeptidic ligand of a Bcl-2 surface pocket, by using a computer screening strategy based on the predicted structure of Bcl-2 protein. In vitro binding studies demonstrated the interaction of HA14-1 with this Bcl-2 surface pocket that is essential for Bcl-2 biological function. HA14-1 effectively induced apoptosis of human acute myeloid leukemia (HL-60) cells overexpressing Bcl-2 protein that was associated with the decrease in mitochondrial membrane potential and activation of caspase-9 followed by caspase-3. Cytokine response modifier A, a potent inhibitor of Fas-mediated apoptosis, did not block apoptosis induced by HA14-1. Whereas HA14-1 strongly induced the death of NIH 3T3 (Apaf-1(+/+)) cells, it had little apoptotic effect on Apaf-1-deficient (Apaf-1(-/-)) mouse embryonic fibroblast cells. These data are consistent with a mechanism by which HA14-1 induces the activation of Apaf-1 and caspases, possibly by binding to Bcl-2 protein and inhibiting its function. The discovery of this cell-permeable molecule provides a chemical probe to study Bcl-2-regulated apoptotic pathways in vivo and could lead to the development of new therapeutic agents.

Recent developments in heterogeneous photocatalytic water treatment using visible light-responsive photocatalysts: a review

This review summarizes the recent progress in the design, fabrication, and application of visible light-responsive photocatalysts.

Near-Infrared-Triggered Photodynamic Therapy with Multitasking Upconversion Nanoparticles in Combination with Checkpoint Blockade for Immunotherapy of Colorectal Cancer

While immunotherapy has become a highly promising paradigm for cancer treatment in recent years, it has long been recognized that photodynamic therapy (PDT) has the ability to trigger antitumor immune responses. However, conventional PDT triggered by visible light has limited penetration depth, and its generated immune responses may not be robust enough to eliminate tumors. Herein, upconversion nanoparticles (UCNPs) are simultaneously loaded with chlorin e6 (Ce6), a photosensitizer, and imiquimod (R837), a Toll-like-receptor-7 agonist. The obtained multitasking UCNP-Ce6-R837 nanoparticles under near-infrared (NIR) irradiation with enhanced tissue penetration depth would enable effective photodynamic destruction of tumors to generate a pool of tumor-associated antigens, which in the presence of those R837-containing nanoparticles as the adjuvant are able to promote strong antitumor immune responses. More significantly, PDT with UCNP-Ce6-R837 in combination with the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) checkpoint blockade not only shows excellent efficacy in eliminating tumors exposed to the NIR laser but also results in strong antitumor immunities to inhibit the growth of distant tumors left behind after PDT treatment. Furthermore, such a cancer immunotherapy strategy has a long-term immune memory function to protect treated mice from tumor cell rechallenge. This work presents an immune-stimulating UCNP-based PDT strategy in combination with CTLA-4 checkpoint blockade to effectively destroy primary tumors under light exposure, inhibit distant tumors that can hardly be reached by light, and prevent tumor reoccurrence via the immune memory effect.

MR-based synthetic CT generation using a deep convolutional neural network method

PURPOSE

Interests have been rapidly growing in the field of radiotherapy to replace CT with magnetic resonance imaging (MRI), due to superior soft tissue contrast offered by MRI and the desire to reduce unnecessary radiation dose. MR-only radiotherapy also simplifies clinical workflow and avoids uncertainties in aligning MR with CT. Methods, however, are needed to derive CT-equivalent representations, often known as synthetic CT (sCT), from patient MR images for dose calculation and DRR-based patient positioning. Synthetic CT estimation is also important for PET attenuation correction in hybrid PET-MR systems. We propose in this work a novel deep convolutional neural network (DCNN) method for sCT generation and evaluate its performance on a set of brain tumor patient images.

METHODS

The proposed method builds upon recent developments of deep learning and convolutional neural networks in the computer vision literature. The proposed DCNN model has 27 convolutional layers interleaved with pooling and unpooling layers and 35 million free parameters, which can be trained to learn a direct end-to-end mapping from MR images to their corresponding CTs. Training such a large model on our limited data is made possible through the principle of transfer learning and by initializing model weights from a pretrained model. Eighteen brain tumor patients with both CT and T1-weighted MR images are used as experimental data and a sixfold cross-validation study is performed. Each sCT generated is compared against the real CT image of the same patient on a voxel-by-voxel basis. Comparison is also made with respect to an atlas-based approach that involves deformable atlas registration and patch-based atlas fusion.

RESULTS

The proposed DCNN method produced a mean absolute error (MAE) below 85 HU for 13 of the 18 test subjects. The overall average MAE was 84.8 ± 17.3 HU for all subjects, which was found to be significantly better than the average MAE of 94.5 ± 17.8 HU for the atlas-based method. The DCNN method also provided significantly better accuracy when being evaluated using two other metrics: the mean squared error (188.6 ± 33.7 versus 198.3 ± 33.0) and the Pearson correlation coefficient(0.906 ± 0.03 versus 0.896 ± 0.03). Although training a DCNN model can be slow, training only need be done once. Applying a trained model to generate a complete sCT volume for each new patient MR image only took 9 s, which was much faster than the atlas-based approach.

CONCLUSIONS

A DCNN model method was developed, and shown to be able to produce highly accurate sCT estimations from conventional, single-sequence MR images in near real time. Quantitative results also showed that the proposed method competed favorably with an atlas-based method, in terms of both accuracy and computation speed at test time. Further validation on dose computation accuracy and on a larger patient cohort is warranted. Extensions of the method are also possible to further improve accuracy or to handle multi-sequence MR images.

MRI-derived measurements of human subcortical, ventricular and intracranial brain volumes: Reliability effects of scan sessions, acquisition sequences, data analyses, scanner upgrade, scanner vendors and field strengths

Automated MRI-derived measurements of in-vivo human brain volumes provide novel insights into normal and abnormal neuroanatomy, but little is known about measurement reliability. Here we assess the impact of image acquisition variables (scan session, MRI sequence, scanner upgrade, vendor and field strengths), FreeSurfer segmentation pre-processing variables (image averaging, B1 field inhomogeneity correction) and segmentation analysis variables (probabilistic atlas) on resultant image segmentation volumes from older (n=15, mean age 69.5) and younger (both n=5, mean ages 34 and 36.5) healthy subjects. The variability between hippocampal, thalamic, caudate, putamen, lateral ventricular and total intracranial volume measures across sessions on the same scanner on different days is less than 4.3% for the older group and less than 2.3% for the younger group. Within-scanner measurements are remarkably reliable across scan sessions, being minimally affected by averaging of multiple acquisitions, B1 correction, acquisition sequence (MPRAGE vs. multi-echo-FLASH), major scanner upgrades (Sonata-Avanto, Trio-TrioTIM), and segmentation atlas (MPRAGE or multi-echo-FLASH). Volume measurements across platforms (Siemens Sonata vs. GE Signa) and field strengths (1.5 T vs. 3 T) result in a volume difference bias but with a comparable variance as that measured within-scanner, implying that multi-site studies may not necessarily require a much larger sample to detect a specific effect. These results suggest that volumes derived from automated segmentation of T1-weighted structural images are reliable measures within the same scanner platform, even after upgrades; however, combining data across platform and across field-strength introduces a bias that should be considered in the design of multi-site studies, such as clinical drug trials. The results derived from the young groups (scanner upgrade effects and B1 inhomogeneity correction effects) should be considered as preliminary and in need for further validation with a larger dataset.

Nanoparticle-Enhanced Radiotherapy to Trigger Robust Cancer Immunotherapy

External radiotherapy is extensively used in clinic to destruct tumors by locally applied ionizing-radiation beams. However, the efficacy of radiotherapy is usually limited by tumor hypoxia-associated radiation resistance. Moreover, as a local treatment technique, radiotherapy can hardly control tumor metastases, the major cause of cancer death. Herein, core-shell nanoparticles based poly(lactic-co-glycolic) acid (PLGA) are fabricate, by encapsulating water-soluble catalase (Cat), an enzyme that can decompose H₂ O₂ to generate O₂ , inside the inner core, and loading hydrophobic imiquimod (R837), a Toll-like-receptor-7 agonist, within the PLGA shell. The formed PLGA-R837@Cat nanoparticles can greatly enhance radiotherapy efficacy by relieving the tumor hypoxia and modulating the immune-suppressive tumor microenvironment. The tumor-associated antigens generated postradiotherapy-induced immunogenic cell death in the presence of such R837-loaded adjuvant nanoparticles will induce strong antitumor immune responses, which together with cytotoxic T-lymphocyte associated protein 4 (CTLA-4) checkpoint blockade will be able to effectively inhibit tumor metastases by a strong abscopal effect. Moreover, a long term immunological memory effect to protect mice from tumor rechallenging is observed post such treatment. This work thus presents a unique nanomedicine approach as a next-generation radiotherapy strategy to enable synergistic whole-body therapeutic responses after local treatment, greatly promising for clinical translation.

Neuregulins promote survival and growth of cardiac myocytes. Persistence of ErbB2 and ErbB4 expression in neonatal and adult ventricular myocytes

Neuregulins (i.e. neuregulin-1 (NRG1), also called neu differentiation factor, heregulin, glial growth factor, and acetylcholine receptor-inducing activity) are known to induce growth and differentiation of epithelial, glial, neuronal, and skeletal muscle cells. Unexpectedly, mice with loss of function mutations of NRG1 or of either of two of their cognate receptors, ErbB2 and ErbB4, die during midembryogenesis due to the aborted development of myocardial trabeculae in ventricular muscle. To examine the role of NRG and their receptors in developing and postnatal myocardium, we studied the ability of a soluble NRG1 (recombinant human glial growth factor 2) to promote proliferation, survival, and growth of isolated neonatal and adult rat cardiac myocytes. Both ErbB2 and ErbB4 receptors were found to be expressed by neonatal and adult ventricular myocytes and activated by rhGGF2. rhGGF2 (30 ng/ml) provoked an approximate 2-fold increase in embryonic cardiac myocyte proliferation. rhGGF2 also promoted survival and inhibited apoptosis of subconfluent, serum-deprived myocyte primary cultures and also induced hypertrophic growth in both neonatal and adult ventricular myocytes, which was accompanied by enhanced expression of prepro-atrial natriuretic factor and skeletal alpha-actin. Moreover, NRG1 mRNA could be detected in coronary microvascular endothelial cell primary cultures prepared from adult rat ventricular muscle. NRG1 expression in these cells was increased by endothelin-1, another locally acting cardiotropic peptide within the heart. The persistent expression of both a neuregulin and its cognate receptors in the postnatal and adult heart suggests a continuing role for neuregulins in the myocardial adaption to physiologic stress or injury.

ProLuCID: An improved SEQUEST-like algorithm with enhanced sensitivity and specificity

ProLuCID, a new algorithm for peptide identification using tandem mass spectrometry and protein sequence databases has been developed. This algorithm uses a three tier scoring scheme. First, a binomial probability is used as a preliminary scoring scheme to select candidate peptides. The binomial probability scores generated by ProLuCID minimize molecular weight bias and are independent of database size. A modified cross-correlation score is calculated for each candidate peptide identified by the binomial probability. This cross-correlation scoring function models the isotopic distributions of fragment ions of candidate peptides which ultimately results in higher sensitivity and specificity than that obtained with the SEQUEST XCorr. Finally, ProLuCID uses the distribution of XCorr values for all of the selected candidate peptides to compute a Z score for the peptide hit with the highest XCorr. The ProLuCID Z score combines the discriminative power of XCorr and DeltaCN, the standard parameters for assessing the quality of the peptide identification using SEQUEST, and displays significant improvement in specificity over ProLuCID XCorr alone. ProLuCID is also able to take advantage of high resolution MS/MS spectra leading to further improvements in specificity when compared to low resolution tandem MS data. A comparison of filtered data searched with SEQUEST and ProLuCID using the same false discovery rate as estimated by a target-decoy database strategy, shows that ProLuCID was able to identify as many as 25% more proteins than SEQUEST. ProLuCID is implemented in Java and can be easily installed on a single computer or a computer cluster. This article is part of a Special Issue entitled: Computational Proteomics.

Plasmalogen deficiency in early Alzheimer's disease subjects and in animal models: molecular characterization using electrospray ionization mass spectrometry

To explore the hypothesis that alterations in ethanolamine plasmalogen may be directly related to the severity of dementia in Alzheimer's disease (AD), we performed a systematic examination of plasmalogen content in cellular membranes of gray and white matter from different regions of human subjects with a spectrum of AD clinical dementia ratings (CDR) using electrospray ionization mass spectrometry (ESI/MS). The results demonstrate: (1) a dramatic decrease in plasmalogen content (up to 40 mol% of total plasmalogen) in white matter at a very early stage of AD (i.e. CDR 0.5); (2) a correlation of the deficiency in gray matter plasmalogen content with the AD CDR (i.e. approximately 10 mol% of deficiency at CDR 0.5 (very mild dementia) to approximately 30 mol% of deficiency at CDR 3 (severe dementia); (3) an absence of alterations of plasmalogen content and molecular species in cerebellar gray matter at any CDR despite dramatic alterations of plasmalogen content in cerebellar white matter. Alterations of ethanolamine plasmalogen content in two mouse models of AD, APP(V717F) and APPsw, were also examined by ESI/MS. A plasmalogen deficiency was present (up to 10 mol% of total plasmalogen at the age of 18 months) in cerebral cortices, but was absent in cerebella from both animal models. These results suggest plasmalogen deficiency may play an important role in the AD pathogenesis, particularly in the white matter, and suggest that altered plasmalogen content may contribute to neurodegeneration, synapse loss and synaptic dysfunction in AD.

Membrane structure and fusion-triggering conformational change of the fusion domain from influenza hemagglutinin

The N-terminal domain of the influenza hemagglutinin (HA) is the only portion of the molecule that inserts deeply into membranes of infected cells to mediate the viral and the host cell membrane fusion. This domain constitutes an autonomous folding unit in the membrane, causes hemolysis of red blood cells and catalyzes lipid exchange between juxtaposed membranes in a pH-dependent manner. Combining NMR structures determined at pHs 7.4 and 5 with EPR distance constraints, we have deduced the structures of the N-terminal domain of HA in the lipid bilayer. At both pHs, the domain is a kinked, predominantly helical amphipathic structure. At the fusogenic pH 5, however, the domain has a sharper bend, an additional 3(10)-helix and a twist, resulting in the repositioning of Glu 15 and Asp 19 relative to that at the nonfusogenic pH 7.4. Rotation of these charged residues out of the membrane plane creates a hydrophobic pocket that allows a deeper insertion of the fusion domain into the core of the lipid bilayer. Such an insertion mode could perturb lipid packing and facilitate lipid mixing between juxtaposed membranes.

Amplification of Tumor Oxidative Stresses with Liposomal Fenton Catalyst and Glutathione Inhibitor for Enhanced Cancer Chemotherapy and Radiotherapy

Amplification of intracellular oxidative stress has been found to be an effective strategy to induce cancer cell death. To this end, we prepare a unique type of ultrasmall gallic acid-ferrous (GA-Fe(II)) nanocomplexes as the catalyst of Fenton reaction to enable persistent conversion of H₂O₂ to highly cytotoxic hydroxyl radicals (•OH). Then, both GA-Fe(II) and l-buthionine sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, are coencapsulated within a stealth liposomal nanocarrier. Interestingly, the obtained BSO/GA-Fe(II)@liposome is able to efficiently amplify intracellular oxidative stress via increasing •OH generation and reducing GSH biosynthesis. After chelating with ^99mTc⁴⁺ radioisotope, such BSO/GA-Fe(II)@liposome could be tracked under in vivo single-photon-emission-computed-tomography (SPECT) imaging, which illustrates the time-dependent tumor homing of such liposomal nanoparticles after intravenous injection. With GA-Fe(II)-mediated •OH production and BSO-mediated GSH depletion, treatment with such BSO/GA-Fe(II)@liposome would lead to dramatically enhanced intratumoral oxidative stresses, which then result in remarkably improved therapeutic efficacies of concurrently applied chemotherapy or radiotherapy. This work thus presents the concise fabrication of biocompatible BSO/GA-Fe(II)@liposome as an effective adjuvant nanomedicine to promote clinically used conventional cancer chemotherapy and radiotherapy, by greatly amplifying the intratumoral oxidative stress.

Electrospray ionization mass spectroscopic analysis of human erythrocyte plasma membrane phospholipids

Electrospray ionization mass spectrometry (ESI-MS) was utilized for the structural determination and quantitative analysis of individual phospholipid molecular species from subpicomole amounts of human erythrocyte plasma membrane phospholipids. The sensitivity of ESI-MS was 2-3 orders of magnitude greater than that achievable with fast-atom bombardment mass spectrometry (FAB-MS). Phospholipid structure determination and quantitative analysis with ESI-MS can be performed directly from chloroform extracts of biologic samples, obviating the need for prior chromatographic separation of phospholipid classes which has been necessary in FAB-MS phospholipid analyses. Furthermore, ESI-MS is uncomplicated by differential fragmentation of molecular ions and idiosyncratic surface desorption, allowing the quantitation of phospholipids with coefficients of determination (r2) > 0.99 and accuracies > 95%. More than 50 human erythrocyte plasma membrane phospholipid constituents were identified by direct ESI-MS analysis of chloroform extracts of plasma membranes derived from the equivalent of < 1 microliter of whole blood. The major ethanolamine glycerophospholipid subclass in erythrocyte plasma membranes was plasmenylethanolamine that was highly enriched in polyunsaturated fatty acids at the sn-2 position. Collectively, these results demonstrate that ESI-MS of phospholipids is an enabling strategy for the direct structural determination and quantitative analysis of subpicomole amounts of phospholipids from biologic samples.

Targeting the Thioredoxin System for Cancer Therapy

Thioredoxin (Trx) and thioredoxin reductase (TrxR) are essential components of the Trx system which plays pivotal roles in regulating multiple cellular redox signaling pathways. In recent years TrxR/Trx have been increasingly recognized as an important modulator of tumor development, and hence targeting TrxR/Trx is a promising strategy for cancer treatment. In this review we first discuss the structural details of TrxR, the functions of the Trx system, and the rational of targeting TrxR/Trx for cancer treatment. We also highlight small-molecule TrxR/Trx inhibitors that have potential anticancer activity and review their mechanisms of action. Finally, we examine the challenges of developing TrxR/Trx inhibitors as anticancer agents and perspectives for selectively targeting TrxR/Trx.

Evaluation of registration methods on thoracic CT: the EMPIRE10 challenge

EMPIRE10 (Evaluation of Methods for Pulmonary Image REgistration 2010) is a public platform for fair and meaningful comparison of registration algorithms which are applied to a database of intrapatient thoracic CT image pairs. Evaluation of nonrigid registration techniques is a nontrivial task. This is compounded by the fact that researchers typically test only on their own data, which varies widely. For this reason, reliable assessment and comparison of different registration algorithms has been virtually impossible in the past. In this work we present the results of the launch phase of EMPIRE10, which comprised the comprehensive evaluation and comparison of 20 individual algorithms from leading academic and industrial research groups. All algorithms are applied to the same set of 30 thoracic CT pairs. Algorithm settings and parameters are chosen by researchers expert in the configuration of their own method and the evaluation is independent, using the same criteria for all participants. All results are published on the EMPIRE10 website (http://empire10.isi.uu.nl). The challenge remains ongoing and open to new participants. Full results from 24 algorithms have been published at the time of writing. This paper details the organization of the challenge, the data and evaluation methods and the outcome of the initial launch with 20 algorithms. The gain in knowledge and future work are discussed.

The surveillance complex interacts with the translation release factors to enhance termination and degrade aberrant mRNAs

The nonsense-mediated mRNA decay pathway is an example of an evolutionarily conserved surveillance pathway that rids the cell of transcripts that contain nonsense mutations. The product of the UPF1 gene is a necessary component of the putative surveillance complex that recognizes and degrades aberrant mRNAs. Recent results indicate that the Upf1p also enhances translation termination at a nonsense codon. The results presented here demonstrate that the yeast and human forms of the Upf1p interact with both eukaryotic translation termination factors eRF1 and eRF3. Consistent with Upf1p interacting with the eRFs, the Upf1p is found in the prion-like aggregates that contain eRF1 and eRF3 observed in yeast [PSI+] strains. These results suggest that interaction of the Upf1p with the peptidyl release factors may be a key event in the assembly of the putative surveillance complex that enhances translation termination, monitors whether termination has occurred prematurely, and promotes degradation of aberrant transcripts.

Signaling Crosstalk between Salicylic Acid and Ethylene/Jasmonate in Plant Defense: Do We Understand What They Are Whispering?

During their lifetime, plants encounter numerous biotic and abiotic stresses with diverse modes of attack. Phytohormones, including salicylic acid (SA), ethylene (ET), jasmonate (JA), abscisic acid (ABA), auxin (AUX), brassinosteroid (BR), gibberellic acid (GA), cytokinin (CK) and the recently identified strigolactones (SLs), orchestrate effective defense responses by activating defense gene expression. Genetic analysis of the model plant Arabidopsis thaliana has advanced our understanding of the function of these hormones. The SA- and ET/JA-mediated signaling pathways were thought to be the backbone of plant immune responses against biotic invaders, whereas ABA, auxin, BR, GA, CK and SL were considered to be involved in the plant immune response through modulating the SA-ET/JA signaling pathways. In general, the SA-mediated defense response plays a central role in local and systemic-acquired resistance (SAR) against biotrophic pathogens, such as Pseudomonas syringae, which colonize between the host cells by producing nutrient-absorbing structures while keeping the host alive. The ET/JA-mediated response contributes to the defense against necrotrophic pathogens, such as Botrytis cinerea, which invade and kill hosts to extract their nutrients. Increasing evidence indicates that the SA- and ET/JA-mediated defense response pathways are mutually antagonistic.

Transcriptional Regulation of the Warburg Effect in Cancer by SIX1

Aerobic glycolysis (the Warburg effect) facilitates tumor growth, and drugs targeting aerobic glycolysis are being developed. However, how the Warburg effect is directly regulated is largely unknown. Here we show that transcription factor SIX1 directly increases the expression of many glycolytic genes, promoting the Warburg effect and tumor growth in vitro and in vivo. SIX1 regulates glycolysis through HBO1 and AIB1 histone acetyltransferases. Cancer-related SIX1 mutation increases its ability to promote aerobic glycolysis and tumor growth. SIX1 glycolytic function is directly repressed by microRNA-548a-3p, which is downregulated, inversely correlates with SIX1, and is a good predictor of prognosis in breast cancer patients. Thus, the microRNA-548a-3p/SIX1 axis strongly links aerobic glycolysis to carcinogenesis and may become a promising cancer therapeutic target.

Nitric oxide-dependent parasympathetic signaling is due to activation of constitutive endothelial (type III) nitric oxide synthase in cardiac myocytes

Nitric oxide synthase (NOS) isoforms are discovered in an increasing variety of cell types with different roles in signaling. The inducible NOS (i.e. iNOS or NOS II) is expressed in cardiac myocytes in response to specific cytokines. Independent of iNOS induction, however, receptor-dependent signaling is modulated by a constitutive nitric oxide (NO) synthase isoform in these cells (Balligand, J. L., Kelly, R.A., Marsden, P.A., Smith, T. W., and Michel, T. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 347-351). We now show that cardiac myocytes constitutively express the endothelial isoform of NO synthase (ecNOS or NOS III). Transcripts for NOS III were detected by Northern blot in myocyte extracts using as a probe a polymerase chain reaction-generated cDNA amplified with isoform and species-specific primers. In subcellular fractionation experiments, a calcium-sensitive NO synthase activity was present primarily in the particulate fraction, coinciding with the distribution of NOS III analyzed by protein immunoblotting. The localization of NOS III within cardiac myocytes was further demonstrated by immunohistochemistry. The functional role of NOS III was explored by analyzing the effects of NOS inhibitors on single myocyte L-type calcium current and contractility. Inhibition of NOS blocked the attenuation by carbamylcholine of the increases in both parameters induced by beta-adrenergic stimulation. We conclude that NO-dependent parasympathetic signaling is mediated by NOS III in cardiac myocytes.

Alveolar macrophage dysfunction and cytokine storm in the pathogenesis of two severe COVID-19 patients

BACKGROUND

The novel coronavirus pneumonia COVID-19 caused by SARS-CoV-2 infection could lead to a series of clinical symptoms and severe illnesses, including acute respiratory distress syndrome (ARDS) and fatal organ failure. We report the fundamental pathological investigation in the lungs and other organs of fatal cases for the mechanistic understanding of severe COVID-19 and the development of specific therapy in these cases.

METHODS

The autopsy and pathological investigations of specimens were performed on bodies of two deceased cases with COVID-19. Gross anatomy and histological investigation by Hematoxylin and eosin (HE) stained were reviewed on each patient. Alcian blue/periodic acid-Schiff (AB-PAS) staining and Masson staining were performed for the examinations of mucus, fibrin and collagen fiber in lung tissues. Immunohistochemical staining was performed on the slides of lung tissues from two patients. Real-time PCR was performed to detect the infection of SARS-CoV-2. Flow cytometry analyses were performed to detect the direct binding of S protein and the expression of ACE2 on the cell surface of macrophages.

FINDINGS

The main pathological features in lungs included extensive impairment of type I alveolar epithelial cells and atypical hyperplasia of type II alveolar cells, with formation of hyaline membrane, focal hemorrhage, exudation and pulmonary edema, and pulmonary consolidation. The mucous plug with fibrinous exudate in the alveoli and the dysfunction of alveolar macrophages were characteristic abnormalities. The type II alveolar epithelial cells and macrophages in alveoli and pulmonary hilum lymphoid tissue were infected by SARS-CoV-2. S protein of SARS-CoV-2 directly bound to the macrophage via the S-protein-ACE2 interaction.

INTERPRETATION

Infection of alveolar macrophage by SARS-CoV-2 might be drivers of the "cytokine storm", which might result in damages in pulmonary tissues, heart and lung, and lead to the failure of multiple organs .

FUNDING

Shanghai Guangci Translational Medical Research Development Foundation, Shanghai, China.

Chlorin e6 Conjugated Poly(dopamine) Nanospheres as PDT/PTT Dual-Modal Therapeutic Agents for Enhanced Cancer Therapy

Photodynamic therapy (PDT), using a combination of chemical photosensitizers (PS) and light, has been successfully applied as a noninvasive therapeutic procedure to treat tumors by inducing apoptosis or necrosis of cancer cells. However, most current clinically used PS have suffered from the instability in physiological conditions which lead to low photodynamic therapy efficacy. Herein, a highly biocompatible poly(dopamine) (PDA) nanoparticle conjugated with Chlorin e6 (referenced as the PDA-Ce6 nanosphere) was designed as a nanotherapeutic agent to achieve simultaneous photodynamic/photothermal therapy (PDT/PTT). Compared to the free Ce6, the PDA-Ce6 nanosphere exhibited significantly higher PDT efficacy against tumor cells, because of the enhanced cellular uptake and subsequently greater reactive oxygen species (ROS) production upon laser irradiation at 670 nm. Meanwhile, the PDA-Ce6 nanosphere could be also used as a photoabsorbing agent for PTT, because of the excellent photothermal conversion ability of PDA nanoparticle under laser irradiation at 808 nm. Moreover, our prepared nanosphere had extremely low dark toxicity, while excellent phototoxicity under the combination laser irradiation of 670 and 808 nm, both in vitro and in vivo, compared to any single laser irradiation alone. Therefore, our prepared PDA-Ce6 nanosphere could be applied as a very promising dual-modal phototherapeutic agent for enhanced cancer therapy in future clinical applications.

Transformable hybrid semiconducting polymer nanozyme for second near-infrared photothermal ferrotherapy

Despite its growing promise in cancer treatment, ferrotherapy has low therapeutic efficacy due to compromised Fenton catalytic efficiency in tumor milieu. We herein report a hybrid semiconducting nanozyme (HSN) with high photothermal conversion efficiency for photoacoustic (PA) imaging-guided second near-infrared photothermal ferrotherapy. HSN comprises an amphiphilic semiconducting polymer as photothermal converter, PA emitter and iron-chelating Fenton catalyst. Upon photoirradiation, HSN generates heat not only to induce cytotoxicity but also to enhance Fenton reaction. The increased ·OH generation promotes both ferroptosis and apoptosis, oxidizes HSN (42 nm) and transforms it into tiny segments (1.7 nm) with elevated intratumoral permeability. The non-invasive seamless synergism leads to amplified therapeutic effects including a deep ablation depth (9 mm), reduced expression of metastasis-related proteins and inhibition of metastasis from primary tumor to distant organs. Thereby, our study provides a generalized nanozyme strategy to compensate both ferrotherapy and phototherapeutics for complete tumor regression.

Due to tumour microenvironment, Fenton reactions have low therapeutic efficiency. Here the authors report on the application of NIR-II hybrid semiconducting nanozymes for combined photothermal therapy and enhanced ferrotherapy with photoacoustic imaging and show application in vivo in tumour models.

Quantitative analysis and molecular species fingerprinting of triacylglyceride molecular species directly from lipid extracts of biological samples by electrospray ionization tandem mass spectrometry

Herein we describe a rapid, simple, and reliable method for the quantitative analysis and molecular species fingerprinting of triacylglycerides (TAG) directly from chloroform extracts of biological samples. Previous attempts at direct TAG quantitation by positive-ion electrospray ionization mass spectrometry (ESI/MS) were confounded by the presence of overlapping peaks from choline glycerophospholipids requiring chromatographic separation of lipid extracts prior to ESI/MS analyses. By exploiting the rapid loss of phosphocholine from choline glycerophospholipids, in conjunction with neutral-loss scanning for individual fatty acids, overlapping peaks in the ESI mass spectrum were deconvoluted generating a detailed molecular species fingerprint of individual TAG molecular species directly from chloroform extracts of biological samples. This method readily detects as little as 0.1 pmol of each TAG molecular species from chloroform extracts and is linear over a 1000-fold dynamic range. The sensitivity of individual TAG molecular species to ESI/MS/MS analyses correlated with the unsaturation index and inversely correlated with total aliphatic chain length of TAG. An algorithm was developed which identifies sensitivity factors, thereby allowing the rapid quantitation and molecular species fingerprinting of TAG molecular species directly from chloroform extracts of biological samples.