Generalizability of the EAST-AFNET 4 trial: assessing outcomes of early rhythm-control therapy in patients with atrial fibrillation

Background

The Early Treatment of Atrial Fibrillation for Stroke Prevention Trial (EAST-AFNET 4) demonstrated clinical benefit of early rhythm-control therapy in patients with recently diagnosed atrial fibrillation (AF) and concomitant cardiovascular conditions (CHA2DS2-VASc-Score ≥2) compared to the current practice of limited rhythm-control therapy to improve AF-related symptoms.

Purpose

To evaluate the generalizability of the EAST-AFNET 4 trial in routine practice, we assessed the proportion of patients who would have met trial eligibility and examined the association between early rhythm-control and clinical outcomes.

Methods

Using a large US administrative database, we identified 109,739 patients with newly diagnosed AF from July 28th, 2011 to December 30th, 2016, the enrollment period of the EAST-AFNET 4 trial. Eligibility for trial inclusion was assessed based on inclusion criteria. Eligible patients were classified as either receiving early rhythm-control, i.e AF ablation and/or any antiarrhythmic drug therapy, within the first year after AF diagnosis (N=27,106) or patients not receiving early rhythm-control (N=82,633). The date 12 months after the first AF diagnosis was defined as the index date and the start of the follow up period. Propensity score overlap weighting was used to balance patients on 90 baseline characteristics. Cox proportional hazards regression was used to compare early rhythm-control with no early rhythm-control for the primary outcome of a composite end point of all-cause mortality, stroke, or hospitalization with the diagnoses heart failure or myocardial infarction.

Results

Eligible for the trial were 72.9% (82,633/109,739) of all patients with newly diagnosed AF. Early rhythm-control therapy was associated with a reduction in the composite end point in the overall cohort of patients (hazard ratio [HR] 0.85; 95% confidence interval [CI] 0.75–0.97; P=0.015) with largely consistent treatment effects between patients eligible or ineligible for the trial. The reduction of stroke risk associated with early rhythm-control therapy was found in the overall cohort (HR 0.66; 95% CI 0.47–0.93; P=0.017) and in the trial-eligible cohort (HR 0.67; 95% CI 0.45–0.98; P=0.041).

Conclusion

In a large health care data set, the majority of patients with newly diagnosed AF were eligible for the trial. Early rhythm-control therapy was associated with a 15% reduction in the composite end point of all-cause mortality, stroke, or hospitalization with the diagnoses heart failure or myocardial infarction, with the greatest benefit in the reduction of stroke risk. The treatment effect was consistent between patients eligible or ineligible for the trial. Patients in routine practice had higher rates of adverse outcomes than the trial, but the relative risk reduction with early rhythm-control therapy was similar. These data demonstrate the potential of early rhythm-control therapy to reduce outcomes in patients with AF.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): German Heart Foundation (Mit Fördermitteln der Deutschen Herzstiftung e.V.)

Ultrawide field, distortion-corrected ocular shape estimation with MHz optical coherence tomography (OCT)

Ocular deformation may be associated with biomechanical alterations in the structures of the eye, especially the cornea and sclera in conditions such as keratoconus, congenital glaucoma, and pathological myopia. Here, we propose a method to estimate ocular shape using an ultra-wide field MHz swept-source optical coherence tomography (SS-OCT) with a Fourier Domain Mode-Locked (FDML) laser and distortion correction of the images. The ocular biometrics for distortion correction was collected by an IOLMaster 700, and localized Gaussian curvature was proposed to quantify the ocular curvature covering a field-of-view up to 65°×62°. We achieved repeatable curvature shape measurements (intraclass coefficient = 0.88 ± 0.06) and demonstrated its applicability in a pilot study with individuals (N = 11) with various degrees of myopia.

Multiparametric Magnetic Resonance Imaging in the Diagnosis of Clinically Significant Prostate Cancer: an Updated Systematic Review

There has been growing utilisation of multiparametric magnetic resonance imaging (MPMRI) as a non-invasive tool to diagnose and localise clinically significant prostate cancer (CSPCa). This updated systematic review examines the use of MPMRI in patients with an elevated risk of CSPCa who have had a prior negative transrectal ultrasound systematic biopsy (TRUS-SB) and who were biopsy naïve. MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews were searched for existing systematic reviews published up to September 2020. The literature search of the electronic databases combined disease-specific terms (prostate cancer, prostate carcinoma, etc.) and treatment-specific terms (magnetic resonance, etc.). Studies were included if they were randomised controlled trials (RCTs) comparing MPMRI to template transperineal mapping biopsy (TPMB) or to TRUS-SB. Thirty-six RCTs were eligible. For biopsy-naïve men, accuracy of diagnosis of CSPCa showed sensitivities from 87 to 96% and specificities ranging from 29 to 45%. Meta-analyses for CSPCa showed increased detection favouring MPMRI-targeted biopsy over TRUS-SB by 3% (95% confidence interval 0-7%, P = 0.03) and decreased detection of clinically insignificant prostate cancer (CISPCa) favouring MPMRI by 8% (95% confidence interval -11 to 5%, P < 0.00001). Accuracy of MPMRI for men with prior negative biopsy showed sensitivities of 78-100% and specificities of 30-100%. Meta-analyses comparing MPMRI to TRUS-SB showed increased detection of 5% (95% confidence interval 3-7%, P < 0.0001) with a reduction of CISPCa detection of 7% (95% confidence interval 4-9%, P < 0.00001). The growing acceptance of MPMRI utilisation internationally and the recent publication of several RCTs regarding MPMRI in reducing CISPCa detection rates, particularly in biopsy-naïve men, without loss of sensitivity for CSPCa necessitates the synthesis of updated evidence examining MPMRI in the diagnosis of CSPCa.

The efficacy and safety of dupilumab in Chinese patients with moderate-to-severe atopic dermatitis: a randomized, double-blind, placebo-controlled study

BACKGROUND

Dupilumab is an antibody against interleukin 4 receptor α, used in treating atopic dermatitis (AD).

OBJECTIVES

To evaluate the efficacy and safety of dupilumab in adult Chinese patients with moderate-to-severe AD.

METHODS

In this randomized, double-blind, placebo-controlled, parallel-group, phase III study, conducted between December 2018 and February 2020, patients with AD received dupilumab (300mg) or placebo once every 2 weeks for 16 weeks, and were followed up for 12 weeks. The primary efficacy endpoint was the proportion of patients with both Investigator's Global Assessment (IGA) score of 0-1 and a reduction from baseline of ≥2 points at week 16.

RESULTS

Overall, 165 patients (mean age: 30.6 years; 71.5% male) were randomized: 82 to dupilumab and 83 to placebo. At week 16, 26.8% of patients in the dupilumab group and 4.8% of patients in the placebo group achieved the primary endpoint (difference, 22.0%; 95% confidence interval [CI], 11.37-32.65%; p<0.0001). Compared with placebo, higher proportions of patients in the dupilumab group achieved ≥75% reduction in the Eczema Area and Severity Index score (57.3% vs 14.5%; difference, 42.9%; 95% CI, 29.75-55.97%; p<0.0001) and had ≥3-point (52.4% vs 9.6%; difference, 42.8%; 95% CI, 30.26-55.34%; p<0.0001) and ≥4-point (39.0% vs 4.8%; difference, 34.2%; 95% CI, 22.69-45.72%; p<0.0001) reductions in weekly average daily peak daily pruritus numerical rating scale scores. The incidence of TEAEs during the treatment period was similar in the two groups. The incidence of conjunctivitis, allergic conjunctivitis, and injection site reaction was higher in the dupilumab group than in the placebo group.

CONCLUSIONS

In adult Chinese patients, dupilumab was effective in improving the signs and symptoms of AD and demonstrated a favorable safety profile.

Framework for quantitative three-dimensional choroidal vasculature analysis using optical coherence tomography

Choroidal vasculature plays an important role in the pathogenesis of retinal diseases, such as myopic maculopathy, age-related macular degeneration, diabetic retinopathy, central serous chorioretinopathy, and ocular inflammatory diseases. Current optical coherence tomography (OCT) technology provides three-dimensional visualization of the choroidal angioarchitecture; however, quantitative measures remain challenging. Here, we propose and validate a framework to segment and quantify the choroidal vasculature from a prototype swept-source OCT (PLEX Elite 9000, Carl Zeiss Meditec, USA) using a 3×3 mm scan protocol centered on the macula. Enface images referenced from the retinal pigment epithelium were reconstructed from the volumetric data. The boundaries of the choroidal volume were automatically identified by tracking the choroidal vessel feature structure over the depth, and a selective sliding window was applied for segmenting the vessels adaptively from attenuation-corrected enface images. We achieved a segmentation accuracy of 96% ± 1% as compared with manual annotation, and a dice coefficient of 0.83 ± 0.04 for repeatability. Using this framework on both control (0.00 D to -2.00 D) and highly myopic (-8.00 D to -11.00 D) eyes, we report a decrease in choroidal vessel volume (p<0.001) in eyes with high myopia.

Bacterial adhesion inhibitor prevents infection in a rodent surgical incision model

Surgical site infection risk continues to increase due to lack of efficacy in current standard of care drugs. New methods to treat or prevent antibiotic-resistant bacterial infections are needed. Multivalent Adhesion Molecules (MAM) are bacterial adhesins required for virulence. We developed a bacterial adhesion inhibitor using recombinant MAM fragment bound to polymer scaffold, mimicking MAM7 display on the bacterial surface. Here, we test MAM7 inhibitor efficacy to prevent Gram-positive and Gram-negative infections. Using a rodent model of surgical infection, incision sites were infected with antibiotic-resistant bioluminescent strains of Staphylococcus aureus or Pseudomonas aeruginosa. Infections were treated with MAM7 inhibitor or control suspension. Bacterial abundance was quantified for nine days post infection. Inflammatory responses and histology were characterized using fixed tissue sections. MAM7 inhibitor treatment decreased burden of S. aureus and P. aeruginosa below detection threshold. Bacterial load of groups treated with control were significantly higher than MAM7 inhibitor-treated groups. Treatment with inhibitor reduced colonization of clinically-relevant pathogens in an in vivo model of surgical infection. Use of MAM7 inhibitor to block initial adhesion of bacteria to tissue in surgical incisions may reduce infection rates, presenting a strategy to mitigate overuse of antibiotics to prevent surgical site infections.

Taraxasterol inhibits TGF-β1-induced epithelial-to-mesenchymal transition in papillary thyroid cancer cells through regulating the Wnt/β-catenin signaling

Taraxasterol (TAR) is a kind of active compound extracted from dandelion and its molecular structure resembles steroid hormones. Recently, TAR has been reported to show an anti-tumor activity. However, the specific role of TAR in papillary thyroid cancer (PTC) has not been clarified. In this study, we investigated the effect of TAR on PTC cell migration, invasion and epithelial-to-mesenchymal transition (EMT) induced by TGF-β1. PTC cells were exposed to TGF-β1 (5 ng/mL) and then treated with different concentrations of TAR. We found that TAR showed no obvious cytotoxicity below 10 μg/mL but notably reduced migration and invasion of TGF-β1-treated PTC cells. Moreover, TAR treatment decreased MMP-2 and MMP-9 levels, and obviously affected the expression of EMT markers. We also observed that Wnt3a and β-catenin levels were significantly increased in TGF-β1-treated PTC cells while TAR inhibited these effects in a concentration-dependent manner. Additionally, activation of the Wnt pathway by LiCl attenuated the suppressive effect of TAR on TGF-β1-induced migration, invasion and EMT in PTC cells. Taken together, we highlighted that TAR could significantly suppress TGF-β1-regulated migration and invasion by reversing the EMT process via the Wnt/β-catenin pathway, suggesting that TAR may be a potential anti-cancer agent for PTC treatment.

Full circumferential morphological analysis of Schlemm's canal in human eyes using megahertz swept source OCT

We performed full circumferential imaging of the Schlemm's canal (SC) of two human eyes using a Fourier domain mode-lock laser (FDML) based 1.66-MHz SS-OCT prototype at 1060 nm. Eight volumes with overlapping margins were acquired around the limbal area with customized raster scanning patterns designed to fully cover the SC while minimizing motion artifacts. The SC was segmented from the volumes using a semi-automated active contour segmentation algorithm, whose mean dice similarity coefficient was 0.76 compared to the manual segmentation results. We also reconstructed three-dimensional (3D) renderings of the 360° SC by stitching the segmented SCs from the volumetric datasets. Quantitative metrics of the full circumferential SC were provided, including the mean and standard deviation (SD) of the cross-sectional area (CSA), the maximum CSA, the minimum and maximum SC opening width, and the number of collector channels (CC) stemming from the SC.

[Swertiamarin alleviates diabetic peripheral neuropathy in rats by suppressing NOXS/ ROS/NLRP3 signal pathway]

OBJECTIVE

To observe the therapeutic effect of swertiamarin on diabetic peripheral neuropathy (DPN) in rats and explore the molecular mechanism in light of the NOXS/ROS/NLRP3 signal pathway.

OBJECTIVE

Thirty-two SD rats were randomly divided into control group, DPN model group (treated with saline), swertiamarin (5 mg/kg) treatment group and NOXS inhibitor (10 mL/kg DPI) treatment group. Rat models of DPN were established in the latter 3 groups by intraperitoneal injections of STZ, and the treatments were administered on days 1, 7 and 14 after modeling. Tactile hypersensitivity of the rats was evaluated 30 min after the treatment. The expressions of NOXS, ROS, NLRP3 and inflammatory factors in the spinal cord tissue were detected using ELISA, and the protein expressions of NOXS, ROS, and NLRP3 were also detected with Western blotting.

OBJECTIVE

Compared with those in the control group, the rats in DPN group showed significant hyperalgesia (P < 0.001), increased expressions of TNF-α (P < 0.001) and IL-6 (P < 0.001), decreased expressions of TGF-β (P < 0.001), and increased expressions of NOXS/ROS/NLRP3 signal pathway (P < 0.001). Compared with those in DPN model group, the rats with swertiamarin treatment showed improved hyperalgesia (P < 0.001), decreased expressions of TNF-α (P=0.03) and IL-6 (P=0.002), increased expressions of TGF-β (P=0.04), and decreased expressions of NOXS (P < 0.001), ROS (P < 0.001) and NLRP3 (P=0.002). Treatment with swertiamarin and the NOXS inhibitor produced similar effects on the expressions of the inflammatory factors in the rat models (P>0.05).

OBJECTIVE

DPN effectively relieves hyperalgesia in rat models of DPN by restoring the balance in the expressions of the inflammatory factors by suppressing NOXs/ROS/NLRP3 signaling pathway.

Focal Structure-Function Relationships in Primary Open-Angle Glaucoma Using OCT and OCT-A Measurements

Purpose

To evaluate the focal structure-function associations among visual field (VF) loss, optical coherence tomography angiography (OCT-A) vascular measurements, and optical coherence tomography (OCT) structural measurements in glaucoma.

Methods

In this cross-sectional study, subjects underwent standard automated perimetry, OCT-based nerve fiber thickness measurements, and OCT-A imaging. Mappings of focal VF test locations with OCT and OCT-A measurements were defined using anatomically adjusted nerve fiber trajectories and were studied using multivariate mixed-effects analysis. Segmented regression analysis was used to determine the presence of breakpoints in the structure-function associations.

Results

The study included 119 eyes from 86 Chinese subjects with primary open-angle glaucoma (POAG). VF mean deviation was significantly associated with global capillary perfusion density (β = 0.13 ± 0.08) and global retinal nerve fiber layer thickness (β = 0.09 ± 0.02). Focal capillary density (FCD) was significantly associated with VF losses at 34 VF test locations (66.7% of 24-2 VF), with 24 of the 34 locations being within 20° of retinal eccentricity. Focal nerve layer (FNL) thickness was significantly associated with 16 VF test locations (31.4% of 24-2 VF; eight locations within 20° eccentricity). For VF test locations in the central 10° VF, VF losses below the breakpoint were significantly associated with FCD (slope, 0.89 ± 0.12, P < 0.001), but not with FNL thickness (slope, 0.57 ± 0.39, P = 0.15).

Conclusions

Focal capillary densities were significantly associated with a wider range of visual field losses and in a larger proportion of the visual field compared to nerve fiber thickness.

[Clinical study of transjugular intrahepatic portosystemic shunt with Viatorr stent in 43 cases]

Objective: To investigate the clinical efficacy and safety of transjugular intrahepatic portosystemic shunt (TIPS) with the use of Viator stent in the treatment of cirrhotic portal hypertension. Methods: 43 cases with cirrhotic portal hypertension were implanted with Viatorr stent during TIPS procedure from March 2016 to August 2018. Serological indicators, color Doppler ultrasound, gastroscopy, rebleeding, ascites and hepatic encephalopathy were regularly followed up. Portal venous pressure, liver and kidney function, coagulation indexes were compared by t-test. Stent patency rate, hepatic encephalopathy incidence, rebleeding rate and survival rate were calculated by Kaplan-Meier curve. Results: TIPS procedure success rate was 100% in all patients. Portal pressure gradient was decreased from (25.57 ± 5.50) mmHg to (9.76 ± 2.92) mmHg before and after operation. Alanine aminotransferase (ALT) was significantly higher at 1 month after operation than before operation, but there was no significant difference between 3 and 6 months after and before operation. Total bilirubin, serum ammonia and prothrombin time at 1, 3, and 6 months after operation were higher than before operation. Albumin had no significant change compared with before operation, and creatinine and urea nitrogen were lower than before operation. The cumulative rebleeding rates at 12 and 24 months after operation was 0% and 9%, respectively. Of the 26 patients with ascites, 22 cases (84.6%) had complete disappearance of ascites and 3 (11.5%) had significant decrease of ascites. The cumulative incidence of hepatic encephalopathy at 3, 6, 12 and 24 months after surgery was 11.6%, 17.3%, 21.9% and 21.9%, respectively. The cumulative incidence of stent dysfunction at 12 and 24 months after surgery was 5.6% and 23.7%, respectively. The cumulative survival rate at 12 months and 24 months after surgery was 91.9%. Conclusion: TIPS procedure with Viatorr stent can effectively reduce portal pressure and rebleeding rate, improve intrahepatic shunt patency rate, and will not increase the risk of postoperative hepatic encephalopathy, and has a higher cumulative survival rate.

Inoculation of Bacillus megaterium strain A14 alleviates cadmium accumulation in peanut: effects and underlying mechanisms

AIMS

A cadmium (Cd)-tolerant Bacillus megaterium strain A14 was used to investigate the effects and mechanisms of bacterial inoculation on peanut growth, Cd accumulation in grains and Cd fixation in Cd-contaminated soil.

METHODS AND RESULTS

Spectroscopic analysis showed that A14 has many functional groups (-OH, -NH2 and -COO et al.) distributed on its surface. The pot experiment indicated that compared to the Cd-contaminated soil alone treatment, inoculation with strain A14 increased shoot and root biomass by 59·93 and 58·31% respectively. The accumulation of Cd in grains decreased by 48·14%, while the proportion of exchangeable Cd in soil decreased from 40 to 26% in A14 inoculated soil.

CONCLUSIONS

Inoculation with B. megaterium A14 improved peanut plant growth via (i) adsorbing Cd²⁺ through functional groups on cell surface, (ii) immobilization of Cd in soil through extracellular secretions, (iii) scavenging the reactive oxygen species through production of antioxidant enzymes, and (iv) by reducing the phytoavailable Cd through regulation of Cd transport gene expression.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provided a new sight on microbial approach for the chemical composition transformation of soil Cd and associated food safety production, which pointed out an efficient way to improve peanut cultivation.

Longitudinal Structural and Microvascular Observation in RCS Rat Eyes Using Optical Coherence Tomography Angiography

Purpose

To evaluate the change of retinal thickness and ocular microvasculature in a rat model of retinitis pigmentosa using swept source optical coherence tomography angiography (SS-OCTA)

Methods

Three-weeks-old Royal College of Surgeons (RCS) rats (n = 8) and age-matched control rats (n = 14) were imaged by a prototype SS-OCTA system. Follow-up measurements occurred every three weeks on six RCS rats until week 18, and cross-sectional measurements were conducted on control rats. Thicknesses of different retinal layers and the total retina were measured. The enface angiograms from superficial vascular plexiform (SVP) and deep capillary plexiform (DCP) were analyzed, and the image sharpness was also extracted from the choroidal angiograms. Immunohistochemical analysis was done in the RCS rats after week 18, as well as in three-week-old RCS rats and age-matched controls.

Results

In RCS rats, the thicknesses of the ganglion cell complex, the nuclear layer, the debris/photoreceptor layer and the total retina decreased over the weeks (P < 0.001). The SVP metrics remained unchanged whereas the DCP metrics decreased significantly over the weeks (P < 0.001). The immunohistochemical analysis confirmed our OCTA findings of capillary dropout in the DCP. The choroidal plexus appeared indistinct initially due to scattering of light at the intact retinal pigment epithelium (RPE) and became more visible after week nine probably due to RPE degeneration. Loss of choriocapillaris was visualized at week 18. In control rats, no vascular change was detected, but nuclear layers, photoreceptor layers and total retina showed slight thinning with age (P < 0.001).

Conclusions

Photoreceptor degeneration in RCS rats was associated with the loss of capillaries in DCP, but not in SVP. The OCTA imaging allows for the characterization of structural and angiographic changes in rodent models.

[Early mortality and risk analysis in adult patients with maintenance hemodialysis]

Objective: To retrospectively analyze the early mortality and related risk factors in adult patients with maintenance hemodialysis (MHD). Methods: Adult MHD patients from 2008 to 2018 were enrolled and divided into training data group and validation data group. In training data group, multivariate logistic regression was used to analyze the risk factors of early death within 120 days after hemodialysis and establish a prediction model. The receiver operating characteristic (ROC) curve was applied to evaluate the prediction ability of the model. Results: A total of 4 885 patients were included. The cumulative mortality within 120 days was 20.97/100 person years, and that within 365 days was 12.25/100 person years. A total of 3 603 patients in the training data group were analyzed. The following risk factors were correlated with early mortality (all P<0.05), including age at start of dialysis over 60 years old (OR=1.792), non-chronic glomerulonephritis (OR=2.214), cardio-cerebrovascular disease (OR=2.695), plasma albumin less than 35 g/L (OR=1.358), platelet count less than 120×10⁹/L (OR=2.194), serum creatinine less than 600 μmol/L (OR=1.652), blood urea nitrogen over 30 mmol/L (OR=1.887), blood phosphorus less than 1.13 mmol/L (OR=1.783), pulse pressure over 55 mmHg(1 mmHg=0.133 kPa) (OR=1.656), low density lipoprotein less than 1.5 mmol/L (OR=1.873), and blood calcium over 2.5 mmol/L (OR=1.876). Risk prediction model was established. The other 1 282 cases in the validation data group were verified. The area under ROC curve was 0.810, with sensitivity 85.7%, and specificity 62.5%. Conclusion: The mortality rate of adult MHD patients within 120 days after dialysis is high. The established prediction model can effectively predict the risk of early death.

Retinal microvasculature dysfunction is associated with Alzheimer's disease and mild cognitive impairment

Background

The retina and brain share many neuronal and vasculature characteristics. We investigated the retinal microvasculature in Alzheimer’s disease (AD) and mild cognitive impairment (MCI) using optical coherence tomography angiography (OCTA).

Methods

In this cross-sectional study, 24 AD participants, 37 MCI participants, and 29 controls were diagnosed according to internationally accepted criteria. OCTA images of the superficial and deep capillary plexus (SCP, DCP) of the retinal microvasculature were obtained using a commercial OCTA system (Zeiss Cirrus HD-5000 with AngioPlex, Carl Zeiss Meditec, Dublin, CA). The main outcome measures were vessel density (VD) and fractal dimension (FD) in the SCP and DCP within a 2.5-mm ring around the fovea which were compared between groups. Perfusion density of large vessels and foveal avascular zone (FAZ) area were additional outcome parameters.

Results

Age, gender, and race did not differ among groups. However, there was a significant difference in diabetes status (P = 0.039) and systolic blood pressure (P = 0.008) among the groups. After adjusting for confounders, AD participants showed significantly decreased VD in SCP and DCP (P = 0.006 and P = 0.015, respectively) and decreased FD in SCP (P = 0.006), compared to controls. MCI participants showed significantly decreased VD and FD only in SCP (P = 0.006 and P < 0.001, respectively) and not the DCP (P > 0.05) compared with controls. There was no difference in the OCTA variables between AD and MCI (P > 0.05). Perfusion density of large vessels and FAZ area did not differ significantly between groups (P > 0.05).

Conclusions and relevance

Eyes of patients with AD have significantly reduced macular VD in both plexuses whereas MCI participants only showed reduction in the superficial plexus. Changes in the retinal microvasculature and capillary network may offer a valuable insight on the brain in AD.

Supplementary information

The online version contains supplementary material available at 10.1186/s13195-020-00724-0.

Effect of spectral leakage on the image formation of Fourier-domain optical coherence tomography

We report on the investigation of spectral leakage's impact on the reconstruction of Fourier-domain optical coherence tomography (FD-OCT). We discuss the shift-variant nature introduced by the spectral leakage and develop a novel spatial-domain FD-OCT image formation model. A proof-of-concept phantom experiment is conducted to validate our model. Compared with previous models, the proposed framework could better describe the image formation process, especially when the fineness of the axial structure approaches the theoretical resolution limit.

[Immune characteristics of Plasmodium reinfections in mice following chloroquine cure of primary Plasmodium infections]

OBJECTIVE

To investigate the disease progression and immunoprotective characteristics in mice re-infected with homogeneous/heterogeneous Plasmodium strains following cure of Plasmodium infections with chloroquine at the peak of parasitemia.

METHODS

C57BL/6 mice were infected with the non-lethal P. yoelii 17XNL strain, and half of mice were given treatment with chloroquine at the peak of parasitemia (9 days post-infection), while the other mice were self-cured naturally. Then, all cured mice were re-infected with the equivalent lethal P. yoelii 17XL or P. berghei ANKA strain 90 days following primary Plasmodium infections. The parasitemia levels during primary infections and reinfections were measured by microscopic examinations of Giemsa-stained thin blood films, and the levels of the IgG antibody in sera and the percentages of memory T cell subsets in spleen cells were detected in mice using ELISA and flow cytometry before and after parasite reinfections, respectively.

RESULTS

Following primary infections with the P. yoelii 17XNL strain, the serum IgG antibody levels were (5.047 ± 0.924) pg/mL in the selfcured mice and (4.429 ± 0.624) pg/mL in the chloroquine-treated mice, respectively (t = 0.437, P > 0.05), which were both significantly higher than that in the uninfected mice (1.624 pg/mL ± 0.280 pg/mL) (F = 22.522, P < 0.01). There was no significant difference in the serum IgG antibody level among self-cured and chloroquine-treated mice re-infected with the P. yoelii 17XL strain or the P. berghei ANKA strain (F = 0.542, P > 0.05); however, the serum IgG antibody levels were all significantly higher in selfcured and chloroquine-treated mice re-infected with the P. yoelii 17XLstrain[(15.487±1.173)pg/mLand(15.965±1.150)pg/mL] or the P. berghei ANKA strain [(14.644 ± 1.523) pg/mL and (15.185 ± 1.333) pg/mL] relative to primary infections (F = 67.383, P < 0.01). There was no significant difference in the proportion of CD4⁺ [(34.208 ± 2.106), (32.820 ± 1.930), (34.023 ± 2.289), (35.608 ± 1.779) pg/mL] or CD8⁺ T memory cells [(17.935 ± 2.092), (18.918 ± 2.823), (17.103 ± 1.627), (17.873 ± 1.425) pg/mL] in self-cured and chloroquine-treated mice with primary infections with the P. yoelii 17XNL strain followed by re-infections with the P. yoelii 17XL strain or the P. berghei ANKA strain (F = 0.944 and 0.390, both P > 0.05); however, the proportions of the CD4⁺ or CD8⁺ T memory cells were significantly greater in self-cured and chloroquine-treated mice with primary infections with the P. yoelii 17XNL strain followed by re-infections with the P. yoelii 17XL strain or the P. berghei ANKA strain than in mice with primary infections (F = 50.532 and 21.751, both P < 0.01).

CONCLUSIONS

The cure of murine Plasmodium infections with chloroquine does not affect the production of effective immune protections in mice during parasite re-infections. Following a primary infection, mice show a protection against re-infections with either homogeneous or heterogeneous Plasmodium strains, and a higher-level resistance to re-infections with homogeneous parasite strains is found than with heterogeneous strains.