Safety, Biodistribution, and Dosimetry Study of Meplazumab, a Potential COVID-19 Therapeutic Drug, with 131I-Labeling and SPECT Imaging.

Coronavirus disease 2019 (COVID-19) is a serious threat to public health and is in urgent need of specific drugs. Meplazumab, a humanized monoclonal antibody targeting CD147, was confirmed to competitively block the binding between the spike of syndrome coronavirus 2 (SARS-CoV-2) and CD147, making meplazumab a promising candidate drug for COVID-19. In this study, biodistribution and dosimetry of 131I-labeled meplazumab were performed to further evaluate its potential as a therapeutic drug for COVID-19. 131I-meplazumab was both safe and tolerant in mice and healthy volunteers. A biodistribution study was performed in normal mice, and blood samples were used for pharmacokinetic analysis. Three healthy volunteers were included and subjected to single-photon-emission computed tomography (SPECT) imaging of 131I-meplazumab within 2 weeks. The distribution in mice and humans was consistent with the in vivo distribution of CD147. Biodistribution and SPECT imaging results exhibited that the liver was the organ with the highest uptake for both mice and humans. Deiodination of 131I-meplazumab can be observed in vivo, and taking Lugol's solution can protect the thyroid gland effectively. The pharmacokinetic characteristics of 131I-meplazumab in mice and humans best fit the two-compartment model. The clearance half-life (T1/2ß) in mice and humans was 117.4 and 223.5 h, respectively. The results indicated that its pharmacokinetic properties in vivo were ideal. The effective dose calculated from healthy volunteers was 0.811 ± 0.260 mSv·MBq-1, which was twice the value calculated from mice. It was safe and feasible to perform human clinical imaging experiments using a diagnostic dose of 131I-meplazumab after thyroid closure by Lugol's solution. This study will provide more experimental basis for advancing the clinical translation of meplazumab and will be valuable in evaluating therapeutic interventions for patients with COVID-19, as well as providing a reference for clinical translation studies of other antibody drugs.

A Simple Kit Formulation for Preparation and Exploratory Human Studies of a Novel 99mTc-Labeled Fibroblast Activation Protein Inhibitor Tracer for Imaging of the Fibroblast Activation Protein in Cancers.

Fibroblast activation protein (FAP) is a potential target for tumor diagnosis and treatment because it is selectively expressed on the cell membrane of cancer-associated fibroblasts in most solid tumor stroma. The aim of this study was to develop a 99mTc-labeled fibroblast activation protein inhibitor (FAPI) tracer, evaluate its imaging efficacy in nude mice, and further explore its biodistribution in healthy volunteers and uptake in tumor patients. An FAPI-derived ligand (DP-FAPI) containing d-proline was designed and synthesized as a linker, and a stable hydrophilic 99mTc-labeled complex ([99mTc]Tc-DP-FAPI) was obtained by kit formulation. In vitro cellular uptake and saturation binding assays were performed in FAP-transfected HT-1080 cells (FAP-HT-1080). The biodistribution was characterized, and micro-single-photon emission computed tomography (SPECT) imaging was performed in BALB/c nude mice bearing U87 MG tumors. Furthermore, a first-in-man application was performed in four healthy volunteers and three patients with gastrointestinal tumors. In vitro, the nanomolar Kd values of [99mTc]Tc-DP-FAPI indicated that it had significantly high target affinity for FAP. Biodistribution and micro-SPECT imaging studies showed that [99mTc]Tc-DP-FAPI exhibited high uptake and high tumor-to-nontargeted ratios. The calculated effective dose for [99mTc]Tc-DP-FAPI was approximately <5 mSv in four healthy volunteers. In three patients with gastrointestinal tumors, [99mTc]Tc-DP-FAPI quantitative SPECT/CT revealed high and reliable uptake. [99mTc]Tc-DP-FAPI exhibited high selectivity and affinity for FAP in vitro. The safety and effectiveness of [99mTc]Tc-DP-FAPI in primary tumor imaging have been confirmed by animal and clinical studies, revealing the potential clinical application value of this tracer.

[Electrocardiogram classification algorithm based on CvT-13 and multimodal image fusion].

Electrocardiogram (ECG) signal is an important basis for the diagnosis of arrhythmia and myocardial infarction. In order to further improve the classification effect of arrhythmia and myocardial infarction, an ECG classification algorithm based on Convolutional vision Transformer (CvT) and multimodal image fusion was proposed. Through Gramian summation angular field (GASF), Gramian difference angular field (GADF) and recurrence plot (RP), the one-dimensional ECG signal was converted into three different modes of two-dimensional images, and fused into a multimodal fusion image containing more features. The CvT-13 model could take into account local and global information when processing the fused image, thus effectively improving the classification performance. On the MIT-BIH arrhythmia dataset and the PTB myocardial infarction dataset, the algorithm achieved a combined accuracy of 99.9% for the classification of five arrhythmias and 99.8% for the classification of myocardial infarction. The experiments show that the high-precision computer-assisted intelligent classification method is superior and can effectively improve the diagnostic efficiency of arrhythmia as well as myocardial infarction and other cardiac diseases.

18F-FDG PET imaging-monitored anti-inflammatory therapy for acute myocardial infarction: Exploring the role of MCC950 in murine model.

BACKGROUND: MCC950 is a novel NLRP3 inflammasome inhibitor that possesses potent anti-inflammatory properties in acute myocardial infarction (AMI). However, the lack of noninvasive monitoring methods limits its potential clinical translation. Thus, we sought to investigate whether 18F-FDG PET imaging can monitor the therapeutic effects of MCC950 in an AMI murine model. METHODS: C57BL/6 mice were used to generate an AMI model. MCC950 or sterile saline was intraperitoneally administered 1 hour after surgery and then daily for 7 consecutive days. 18F-FDG PET (inflammation) imaging was used to monitor inflammatory changes on days 3 and 5. Immunohistochemistry and Western blot were used to detect inflammatory markers and to confirm the PET imaging results. 18F-FDG PET (viability) imaging was used to quantitate the viability defect expansion on days 7 and 28. Cardiac ultrasound and survival analyses were performed to evaluate the cardiac function and survival rate. Adverse remodeling was determined by Wheat Germ Agglutinin (WGA) and Masson trichrome staining. RESULTS: The FDG-PET (inflammation) imaging revealed that MCC950 treatment led to lower 18F-FDG inflammatory uptakes, at the infarct region, on days 3 and 5 when compared to the MI group. The decreased M1 macrophages and neutrophils infiltration and the remission of the NLRP3/IL-1ß pathway, confirmed the FDG-PET (inflammation) imaging results. The FDG-PET (viability) imaging revealed that MCC950 significantly decreased the expansion of the viability defect, demonstrating its myocardial preservation effects. The acute FDG-PET (inflammation) signal positively correlated with the late viability defect and with the reduction in the left ventricular ejection fraction (LVEF). Additionally, the alleviated adverse remodeling and the improved survival rate further support the anti-inflammatory efficiency of MCC950 in AMI. CONCLUSION: Using 18F-FDG PET imaging, we noninvasively demonstrated the therapeutic effects of MCC950 in AMI and showed that 18F-FDG PET imaging holds promising application potentials in MCC950's clinical translation.

Using the Diaphragm as a Tracking Surrogate in CyberKnife Synchrony Treatment.

BACKGROUND In this study, we assessed the usefulness of diaphragm surrogate tracking in the design of a respiratory model for CyberKnife Synchrony treatment of lung tumors. MATERIAL AND METHODS Twenty-four patients with lung cancer who underwent stereotactic body radiotherapy with CyberKnife between April and November 2019 were enrolled. Simulation plans for each patient were designed using Xsight lung tracking (XLT) and diaphragm tracking (DT) methods, and tumor visualization tests were performed. The offset consistency at each respiratory phase was analyzed. The relative distance along the alignment center of the superior-inferior (SI) axis in the 2 projections (dxAB), uncertainty (%), and average standard error (AvgStdErr)/maximum standard error (MAXStdErr) were also analyzed. RESULTS Bland-Altman analyses revealed that the average differences±standard deviation (SD) between XLT and DT tracking methods were 0.4±2.9 mm, 0.3±4.35 mm, and -1.8±6.8 mm for the SI, left-right (LR), and anterior-posterior (AP) directions, respectively. These results indicated high consistency in the SI and LR directions and poor consistency in the AP direction. Uncertainty differed significantly between XLT and DT (22.813±5.721% vs 9.384±3.799%; t=-5.236; P=0.0008), but we found no significant differences in dxAB, AvgStdErr, or MAXStdErr. CONCLUSIONS In the majority of cases, motion tracking by XLT and DT was consistent and synchronized in the SI directions, but not in the LR and AP directions. With a boundary margin of 0.3±4.35 mm and 1.8±6.8 mm for the LR and AP directions, DT may contribute to better implementation of CyberKnife Synchrony treatment in patients with lung tumors near the diaphragm that cannot be seen in tumor visualization tests.

Integrating manual diagnosis into radiomics for reducing the false positive rate of 18F-FDG PET/CT diagnosis in patients with suspected lung cancer.

PURPOSE: The high false positive rate (FPR) of 18F-FDG PET/CT in lung cancer screening represents a severe challenge for clinical decision-making. This study aimed to develop a clinical-translatable radiomics nomogram for reducing the FPR of PET/CT in lung cancer diagnosis, and to determine the impact of integrating manual diagnosis to the performance of the radiomics nomogram. METHODS: Among 3,947 18F-FDG PET/CT-screened patients with lung lesion, 157 malignant and 111 benign patients were retrospectively enrolled and divided into training and test cohorts. The data of manual diagnosis were recorded. A total of 4,338 features were extracted from CT, thin-section CT, PET and PET/CT, and the four radiomics signatures (RS) were then generated by LASSO method. Radiomics prediction nomogram integrating imaging-based RS and manual diagnosis was developed using multivariable logistic regression. The performances of RS and prediction nomograms were independently validated through key discrimination index and clinical benefit. RESULTS: The FPR of manual diagnosis was found to be 30.6%. Among the four RS, PET/CT RS exhibited the best performance. By integrating manual diagnosis, the hybrid nomogram integrating PET/CT RS and manual diagnosis demonstrated lowest FPR and highest area under curve (AUC) and Youden index (YI) in both training and test cohorts (FPR: 5.4% and 9.1%, AUC: 0.98 and 0.92, YI: 85.8% and 75.5%, respectively). This hybrid nomogram respectively corrected 78.6% and 37.5% among FPR cases produced by PET/CT RS, without significantly sacrificing its sensitivity. The net benefit of hybrid nomogram appeared highest at <85% threshold probability. CONCLUSION: The established hybrid nomogram integrating PET/CT RS and manual diagnosis can significantly reduce FPR, improve diagnostic accuracy and enhance clinical benefit compared to manual diagnosis. By integrating manual diagnosis, the performance of this hybrid nomogram is superior to PET/CT RS, indicating the importance of clinicians' judgement as an essential information source for improving radiomics diagnostic approaches.

Robust Rate Maximization for Heterogeneous Wireless Networks under Channel Uncertainties.

Heterogeneous wireless networks are a promising technology in next generation wireless communication networks, which has been shown to efficiently reduce the blind area of mobile communication and improve network coverage compared with the traditional wireless communication networks. In this paper, a robust power allocation problem for a two-tier heterogeneous wireless networks is formulated based on orthogonal frequency-division multiplexing technology. Under the consideration of imperfect channel state information (CSI), the robust sum-rate maximization problem is built while avoiding sever cross-tier interference to macrocell user and maintaining the minimum rate requirement of each femtocell user. To be practical, both of channel estimation errors from the femtocells to the macrocell and link uncertainties of each femtocell user are simultaneously considered in terms of outage probabilities of users. The optimization problem is analyzed under no CSI feedback with some cumulative distribution function and partial CSI with Gaussian distribution of channel estimation error. The robust optimization problem is converted into the convex optimization problem which is solved by using Lagrange dual theory and subgradient algorithm. Simulation results demonstrate the effectiveness of the proposed algorithm by the impact of channel uncertainties on the system performance.

Indoor Positioning Algorithm Based on the Improved RSSI Distance Model.

The Global Navigation Satellite System (GNSS) cannot achieve accurate positioning and navigation in the indoor environment. Therefore, efficient indoor positioning technology has become a very active research topic. Bluetooth beacon positioning is one of the most widely used technologies. Because of the time-varying characteristics of the Bluetooth received signal strength indication (RSSI), traditional positioning algorithms have large ranging errors because they use fixed path loss models. In this paper, we propose an RSSI real-time correction method based on Bluetooth gateway which is used to detect the RSSI fluctuations of surrounding Bluetooth nodes and upload them to the cloud server. The terminal to be located collects the RSSIs of surrounding Bluetooth nodes, and then adjusts them by the RSSI fluctuation information stored on the server in real-time. The adjusted RSSIs can be used for calculation and achieve smaller positioning error. Moreover, it is difficult to accurately fit the RSSI distance model with the logarithmic distance loss model due to the complex electromagnetic environment in the room. Therefore, the back propagation neural network optimized by particle swarm optimization (PSO-BPNN) is used to train the RSSI distance model to reduce the positioning error. The experiment shows that the proposed method has better positioning accuracy than the traditional method.

Inter-heterogeneity and intra-heterogeneity of αvß3 in non-small cell lung cancer and small cell lung cancer patients as revealed by 68Ga-RGD2 PET imaging.

PURPOSE: Integrin αvß3 is the therapeutic target of the anti-angiogenic drug cilengitide. The objective of this study was to compare αvß3 levels in non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) patients, by using the positron emission tomography (PET) tracer 68Ga-labeled dimerized-RGD (68Ga-RGD2). METHODS: Thirty-one patients with pathologically confirmed lung cancer were enrolled (21 were NSCLC and 10 were SCLC). PET/CT images were acquired using 68Ga-RGD2.18F-FDG PET/CT images were also acquired on the consecutive day as reference. The standard uptake values (SUV) and the tumor/nontarget (T/NT) values were quantitatively compared. Expression of the angiogenesis marker αvß3 in NSCLC and SCLC lesions was analyzed by immunohistochemistry. RESULTS: The 18F-FDG SUVmax and the SUVmean were not significantly different between NSCLC and SCLC patients. The 68Ga-RGD2 uptake of SCLC patients was at background levels in both SUV and T/NT measurements and was significantly lower than that of NSCLC patients. The range value of 68Ga-RGD2 SUVmean was 4.5 in the NSCLC group and 2.2 in the SCLC group, while the variation coefficient was 36.2% and 39.3% in NSCLC and SCLC primary lesions, respectively. Heterogeneity between primary lesions and putative distant metastases was also observed in some NSCLC cases. Immunostaining showed that αvß3 integrin was expressed in the cells and neovasculature of NSCLC lesions, while SCLC samples had negative expression. CONCLUSIONS: The uptake of 68Ga-RGD2 in SCLC patients is significantly lower than that in NSCLC patients, indicating a lower αvß3 target level for cilengitide in SCLC. Apparent intra-tumor heterogeneities of αvß3 also exist in both NSCLC and SCLC. Such inter- and intra-heterogeneity of αvß3 may potentially improve current applications of αvß3-targeted therapy and diagnostic imaging in lung cancer.

Elucidating and Regulating the Acetoin Production Role of Microbial Functional Groups in Multispecies Acetic Acid Fermentation.

UNLABELLED: Acetoin (3-hydroxy-2-butanone) formation in vinegar microbiota is crucial for the flavor quality of Zhenjiang aromatic vinegar, a traditional vinegar produced from cereals. However, the specific microorganisms responsible for acetoin formation in this centuries-long repeated batch fermentation have not yet been clearly identified. Here, the microbial distribution discrepancy in the diacetyl/acetoin metabolic pathway of vinegar microbiota was revealed at the species level by a combination of metagenomic sequencing and clone library analysis. The results showed that Acetobacter pasteurianus and 4 Lactobacillus species (Lactobacillus buchneri, Lactobacillus reuteri, Lactobacillus fermentum, and Lactobacillus brevis) might be functional producers of acetoin from 2-acetolactate in vinegar microbiota. Furthermore, A. pasteurianus G3-2, L. brevis 4-22, L. fermentum M10-3, and L. buchneri F2-5 were isolated from vinegar microbiota by a culture-dependent method. The acetoin concentrations in two cocultures (L. brevis 4-22 plus A. pasteurianus G3-2 and L. fermentum M10-3 plus A. pasteurianus G3-2) were obviously higher than those in monocultures of lactic acid bacteria (LAB), while L. buchneri F2-5 did not produce more acetoin when coinoculated with A. pasteurianus G3-2. Last, the acetoin-producing function of vinegar microbiota was regulated in situ via augmentation with functional species in vinegar Pei After 72 h of fermentation, augmentation with A. pasteurianus G3-2 plus L. brevis 4-22, L. fermentum M10-3, or L. buchneri F2-5 significantly increased the acetoin content in vinegar Pei compared with the control group. This study provides a perspective on elucidating and manipulating different metabolic roles of microbes during flavor formation in vinegar microbiota. IMPORTANCE: Acetoin (3-hydroxy-2-butanone) formation in vinegar microbiota is crucial for the flavor quality of Zhenjiang aromatic vinegar, a traditional vinegar produced from cereals. Thus, it is of interest to understand which microbes are driving the formation of acetoin to elucidate the microbial distribution discrepancy in the acetoin metabolic pathway and to regulate the metabolic function of functional microbial groups in vinegar microbiota. Our study provides a perspective on elucidating and manipulating different metabolic roles of microbes during flavor formation in vinegar microbiota.

Evaluation of 68Ga-labeled iNGR peptide with tumor-penetrating motif for microPET imaging of CD13-positive tumor xenografts.

The aim of the study is to evaluate the efficacy of 68Ga-labeled iNGR, containing Asn-Gly-Arg (NGR) homing sequence and CendR (R/KXXR/K) penetrating motif, as a new molecular probe for microPET imaging of CD13-positive xenografts. The synthesized iNGR and NGR peptides were conjugated with DOTA and then labeled with 68Ga. 68Ga-iNGR and 68Ga-NGR were compared in the performance of the in vitro stability, partition coefficient, binding affinity, cell uptake analysis, in vivo microPET imaging, and biodistribution studies in CD13-positive HT-1080 and CD13-negative HT-29 cell lines. The in vitro results revealed that both probes exhibited high radiochemical purity and stability, and no significant difference between two probes was observed in terms of the binding affinity to CD13. In vivo microPET/CT imaging showed that the uptake of 68Ga-iNGR in HT-1080 tumor was significantly higher than that of 68Ga-NGR. Moreover, tumor 68Ga-iNGR uptake could be completely blocked by cold NGR and partially blocked by neutralizing NRP-1 antibody. We concluded that 68Ga-iNGR has a higher tumor uptake and better tumor retention than 68Ga-NGR through NRP-1, indicating that CendR motif modification is a promising method for improving NGR peptide performance.

Batch-to-batch uniformity of bacterial community succession and flavor formation in the fermentation of Zhenjiang aromatic vinegar.

Solid-state fermentation of traditional Chinese vinegar is a mixed-culture refreshment process that proceeds for many centuries without spoilage. Here, we investigated bacterial community succession and flavor formation in three batches of Zhenjiang aromatic vinegar using pyrosequencing and metabolomics approaches. Temporal patterns of bacterial succession in the Pei (solid-state vinegar culture) showed no significant difference (P > 0.05) among three batches of fermentation. In all the batches investigated, the average number of community operational taxonomic units (OTUs) decreased dramatically from 119 ± 11 on day 1 to 48 ± 16 on day 3, and then maintained in the range of 61 ± 9 from day 5 to the end of fermentation. We confirmed that, within a batch of fermentation process, the patterns of bacterial diversity between the starter (took from the last batch of vinegar culture on day 7) and the Pei on day 7 were similar (90%). The relative abundance dynamics of two dominant members, Lactobacillus and Acetobacter, showed high correlation (coefficient as 0.90 and 0.98 respectively) among different batches. Furthermore, statistical analysis revealed dynamics of 16 main flavor metabolites were stable among different batches. The findings validate the batch-to-batch uniformity of bacterial community succession and flavor formation accounts for the quality of Zhenjiang aromatic vinegar. Based on our understanding, this is the first study helps to explain the rationality of age-old artistry from a scientific perspective.

Near-infrared fluorescence imaging of CD13 receptor expression using a novel Cy5.5-labeled dimeric NGR peptide.

In this study, we synthesized a novel Cy5.5-labeled dimeric NGR peptide (Cy5.5-NGR2) via bioorthogonal click chemistry, and evaluated the utility of Cy5.5-NGR2 for near-infrared fluorescence imaging of CD13 receptor expression in vivo. The dimeric NGR peptide (NGR2) was conjugated with an alkyne-containing PEG unit followed by mixing with an azide-terminated Cy5.5 fluorophore (Cy5.5-N3) to afford Cy5.5-NGR2. The probe was subject to in vitro and in vivo evaluations. The bioorthogonal click chemistry provided a rapid conjugation of the alkyne-containing NGR2 with Cy5.5-N3 in a quantitative yield within 15 min. The laser confocal microscopy revealed that binding of Cy5.5-NGR2 to CD13 receptor is target-specific as demonstrated in CD13-positive HT-1080 cells, CD13-negative MCF-7 cells, and a blocking study in HT-1080 cells. For in vivo optical imaging, Cy5.5-NGR2 exhibited rapid HT-1080 tumor targeting at 0.5 h postinjection (pi), and highest tumor-to-background contrast at 2 h pi. The CD13-specific tumor accumulation of Cy5.5-NGR2 was accomplished by a blocking study with unlabeled NGR peptide in HT-1080 tumor bearing mice. The tumor-to-muscle ratio of Cy5.5-NGR2 at 2 h pi reached 2.65 ± 0.13 in the non-blocking group vs. 1.05 ± 0.06 in the blocking group. The results from ex vivo imaging were consistent with the in vivo findings. We concluded that Cy5.5-NGR2 constructed by bioorthogonal click chemistry is a promising molecular probe, not only allowing the NIR optical imaging of CD13 overexpressed tumors, but also having the potential to facilitate noninvasive monitoring of CD13-targeted tumor therapy.

In vivo NIRF imaging-guided delivery of a novel NGR-VEGI fusion protein for targeting tumor vasculature.

Pathological angiogenesis is crucial in tumor growth, invasion and metastasis. Previous studies demonstrated that the vascular endothelial growth inhibitor (VEGI), a member of the tumor necrosis factor superfamily, can be used as a potent endogenous inhibitor of tumor angiogenesis. Molecular probes containing the asparagine-glycine-arginine (NGR) sequence can specifically bind to CD13 receptor which is overexpressed on neovasculature and several tumor cells. Near-infrared fluorescence (NIRF) optical imaging for targeting tumor vasculature offers a noninvasive method for early detection of tumor angiogenesis and efficient monitoring of response to anti-tumor vasculature therapy. The aim of this study was to develop a new NIRF imaging probe on the basis of an NGR-VEGI protein for the visualization of tumor vasculature. The NGR-VEGI fusion protein was prepared from prokaryotic expression, and its function was characterized in vitro. The NGR-VEGI protein was then labeled with a Cy5.5 fluorophore to afford Cy5.5-NGR-VEGI probe. Using the NIRF imaging technique, we visualized and quantified the specific delivery of Cy5.5-NGR-VEGI protein to subcutaneous HT-1080 fibrosarcoma tumors in mouse xenografts. The Cy5.5-NGR-VEGI probe exhibited rapid HT-1080 tumor targeting, and highest tumor-to-background contrast at 8 h post-injection (pi). Tumor specificity of Cy5.5-NGR-VEGI was confirmed by effective blocking of tumor uptake in the presence of unlabeled NGR-VEGI (20 mg/kg). Ex vivo NIRF imaging further confirmed in vivo imaging findings, demonstrating that Cy5.5-NGR-VEGI displayed an excellent tumor-to-muscle ratio (18.93 ± 2.88) at 8 h pi for the non-blocking group and significantly reduced ratio (4.92 ± 0.75) for the blocking group. In conclusion, Cy5.5-NGR-VEGI provided highly sensitive, target-specific, and longitudinal imaging of HT-1080 tumors. As a novel theranostic protein, Cy5.5-NGR-VEGI has the potential to improve cancer treatment by targeting tumor vasculature.

MicroPET imaging of CD13 expression using a (64)Cu-labeled dimeric NGR peptide based on sarcophagine cage.

CD13 receptor as a tumor vasculature biomarker has attracted great attention in cancer research. Through phage display screening, NGR-containing peptides have been characterized as specific ligands binding to CD13 receptor. In this study, a (64)Cu-labeled dimeric NGR peptide based on sarcophagine cage was synthesized and evaluated for micropositron emission tomography (PET) imaging of CD13 expression in vivo. Macrocyclic chelating agent (sarcophagine cage) was conjugated with two azide moieties, followed by mixing with an alkyne-containing NGR peptide to rapidly provide the Sar-NGR2 peptide by click chemistry. Radiolabeling of Sar-NGR2 with (64)Cu was achieved in >90% decay-corrected yield with radiochemical purity of >99%. The cell uptake study showed that (64)Cu-Sar-NGR2 binds to CD13-positive HT-1080 cells, but not to CD13-negative MCF-7 cells. MicroPET imaging results revealed that (64)Cu-Sar-NGR2 exhibits good tumor uptake in CD13-positive HT-1080 xenografts and significantly lower tumor uptake in CD13-negative MCF-7 xenografts. The CD13-specific binding of (64)Cu-Sar-NGR2 was further verified by significant reduction of tumor uptake in HT-1080 tumor xenografts with coinjection of a nonradiolabeled NGR peptide. The biodistribution results demonstrated good tumor/muscle ratio (8.28 ± 0.37) of (64)Cu-Sar-NGR2 at 24 h pi in HT-1080 tumor xenografts, which is in agreement with the quantitative analysis of microPET imaging. In conclusion, sarcophagine cage has been successfully applied to the construction of a (64)Cu-labeled dimeric NGR-containing peptide. In vitro and in vivo studies demonstrated that (64)Cu-Sar-NGR2 is a promising PET probe for imaging CD13 expression in living mice.

Prevalence, molecular characterization and zoonotic potential of Cryptosporidium spp. in goats in Henan and Chongqing, China.

To estimate the prevalence and public health significance of cryptosporidiosis in goats in China, 1265 fecal samples from seven farms in Henan province and Chongqing city were examined for Cryptosporidium oocysts. The overall infection rate of Cryptosporidium spp. was 3.48% (44/1256). Significant difference was observed among age groups, with the post weaned kids having the highest infection rate (4.58%; ρ<0.01). Cryptosporidium spp. were characterized by PCR-restriction fragment length polymorphism (RFLP) analysis and DNA sequence analysis of the small subunit (SSU) rRNA gene. The SSU rRNA-based PCR identified three Cryptosporidium species, including Cryptosporidium ubiquitum (24/44) in Henan and Chongqing, and Cryptosporidium andersoni (16/44) and Cryptosporidium xiaoi (4/44) in Henan. Among which, the C. ubiquitum and C. andersoni were first identified in goats thus far and were found in all age groups except no C. andersoni being found in the postparturition nannies, whereas the C. xiaoi was detected in pre-weaned kids and pregnant nannies. Subtyping C. ubiquitum by DNA sequence analysis of the 60 kDa glycoprotein (gp60) gene suggested the isolates identified all belonged to zoonotic XIIa subtype 2. Thus, the dominant C. ubiquitum found in this study and the XIIa subtype 2 has been found in humans indicated goats are a potential source for zoonotic infections with the C. ubiquitum. More studies are needed for better understanding of differences in the transmission and public health significance of cryptosporidiosis in goats.

Comparison of diagnostic efficacy between 99mTc-methylene diphosphate SPECT/CT and MRI for bone and joint infections: a multicenter retrospective analysis.

Objective: There is currently no non-invasive examination that can fully determine the diagnosis of osteomyelitis. SPECT/CT tomographic fusion imaging can provide both local metabolic activity and anatomical information to determine the condition and location. This study evaluates the diagnostic efficacy of 99mTc-MDP SPECT/CT in bone infections, compared to MRI. Methods: In this multicenter retrospective study, 363 patients with suspected bone and joint infections or osteomyelitis were included. Participants underwent 99mTc-MDP SPECT/CT and/or MRI examinations, supplemented by pathogenic bacterial cultures and histopathological analysis. Results: Only SPECT/CT was tested in 169 patients, and only MRI was used in 116. 78 people have implemented both inspections and have detailed information. The diagnostic sensitivity and specificity of SPECT/CT for infection were 96% and 92% respectively, with an accuracy of 96%. For MRI, these figures were 88%, 84%, and 87% respectively. Conclusion: This represents the largest global study to date evaluating osteomyelitis and bone infection diagnosis using 99mTc-MDP SPECT/CT tomographic fusion imaging. The findings indicate that 99mTc-MDP SPECT/CT fusion imaging offers superior diagnostic accuracy compared to MRI. This is particularly evident in cases involving metallic implants and chronic infections. 99mTc-MDP SPECT/CT fusion imaging emerges as a highly suitable non-invasive diagnostic modality, facilitating enhanced clinical follow-up and treatment.

Imaging and therapy of hSSTR2-transfected tumors using radiolabeled somatostatin analogs.

The aim of this study was to introduce human somatostatin receptors subtype-2 (hsstr2) gene into A549 lung carcinoma cells in order to investigate the role of these receptors, and to observe the lethal effect of (131)I-RC-160 (RC-160, vapreotide, an analog of somatostatin) on transfected cells through tumor scintigraphy. Clones overexpressing SSTR2 were selected for radioligand-receptor binding assay and assessment of (125)I-RC-160 internalization. The methylthiazolyl tetrazolium test was used to observe the lethal effect of (131)I-RC-160, Na(131)I, and RC-160 on hSSTR2-transfected A549 cells (A549-hSSTR2). Planar imaging was performed with a gamma camera equipped with pinhole collimator in nude mice bearing both A549-hSSTR2 tumors overexpressing SSTR2 and A549-pcDNA3 (pcDNA3-transfected A549 cells) tumors as control. Images were obtained at 0.5, 6, and 24 h after injection of 3.7 × 10(6) Bq (99m)Tc-RC-160 via the tail vein. The inhibitory effects of (131)I-RC-160, RC-160, and Na(131)I on the tumors were recorded by measuring the tumor volumes. At the end of the study, the tumors were excised and HE staining was performed. The binding radioactivity (sum of membrane-bound and internalized radioligand) of A549-hSSTR2 cells was 18.24 ± 1.9 % of total counts added after 1 h of incubation, and was higher than that of A549-pcDNA3 cells 5.7 ± 1.4 % (P < 0.05). The inhibition ratio of A549-hSSTR2 cells was 78.8 ± 5.9 %. Clear images of tumor lesions in nude mice were achieved at 0.5 h post injection. In the A549-hSSTR2 xenograft tumor group, the growth of the tumors treated with (131)I-RC-160 was significantly inhibited as compared to tumors in the group treated with RC-160 (P < 0.01). This study demonstrated that it was possible to introduce hsstr2 to non-expressing tumor cell lines and treat tumors with radiolabeled somatostatin analogs.

(99m)Tc-labeled monomeric and dimeric NGR peptides for SPECT imaging of CD13 receptor in tumor-bearing mice.

CD13 receptor plays a critical role in tumor angiogenesis and metastasis. We therefore aimed to develop (99m)Tc-labeled monomeric and dimeric NGR-containing peptides, namely, NGR1 and NGR2, for SPECT imaging of CD13 expression in HepG2 hepatoma xenografts. Both NGR-containing monomer and dimer were synthesized and labeled with (99m)Tc. In vivo receptor specificity was demonstrated by successful blocking of tumor uptake of (99m)Tc-NGR dimer in the presence of 20 mg/kg NGR2 peptide. Western blot and immunofluorescence staining confirmed the CD13 expression in HepG2 cells. The NGR dimer showed higher binding affinity and cell uptake in vitro than the NGR-containing monomer, presumably due to a multivalency effect. (99m)Tc-Labeled monomeric and dimeric NGR-containing peptides were subjected to SPECT imaging and biodistribution studies. SPECT scans were performed in HepG2 tumor-bearing mice at 1, 4, 12, and 24 h post-injection of ~7.4 MBq tracers. The metabolism of tracers was determined in major organs at different time points after injection which demonstrated rapid, significant tumor uptake and slow tumor washout for both traces. Predominant clearance from renal and hepatic system was also observed in (99m)Tc-NGR1 and (99m)Tc-NGR2. In conclusion, monomeric and dimeric NGR peptide were developed and labeled with (99m)Tc successfully, while the high integrin avidity and long retention in tumor make (99m)Tc-NGR dimer a promising agent for tumor angiogenesis imaging.

Synthesis and evaluation of 64Cu-labeled monomeric and dimeric NGR peptides for MicroPET imaging of CD13 receptor expression.

The NGR-containing peptides have been shown to bind specifically to CD13/aminopeptidase N (APN) receptor, one of the attractive tumor vasculature biomarkers. In this study, we evaluated (64)Cu-labeled monomeric and dimeric NGR peptides for microPET imaging of CD13 receptor expression in vivo. Western blot analysis and immunofluorescence staining were performed to identify CD13-positive and CD13-negative cell lines. NGR-containing peptides were conjugated with 1,4,7,10-tetraazadodecane-N,N',N″,N‴-tetraacetic acid (DOTA) and labeled with (64)Cu (t(1/2) = 12.7 h) in ammonium acetate buffer. The resulting monomeric ((64)Cu-DOTA-NGR1) and dimeric ((64)Cu-DOTA-NGR2) peptides were then subjected to in vitro stability, cell uptake and efflux, small animal micorPET, and biodistribution studies. In vitro studies demonstrated that CD13 receptors are overexpressed in human fibrosarcoma HT-1080 cells and negative in human colon adenocarcinoma HT-29 cells. The binding affinity of (64)Cu-DOTA-NGR2 to HT-1080 cells was measured to be within low nanomolar range and about 2-fold higher than that of (64)Cu-DOTA-NGR1. For small animal microPET studies, (64)Cu-DOTA-NGR2 displayed more favorable in vivo performance in terms of higher tumor uptake and slower tumor washout in CD13-positive HT-1080 tumor xenografts as compared to (64)Cu-DOTA-NGR1. As expected, significantly lower tumor uptake and poorer tumor/normal organ contrast were observed for both (64)Cu-DOTA-NGR1 and (64)Cu-DOTA-NGR2 in CD13-negative HT-29 tumor xenografts in comparison with those in the HT-1080 tumor xenografts. The CD13-specific tumor activity accumulation of both (64)Cu-DOTA-NGR1 and (64)Cu-DOTA-NGR2 was further demonstrated by significant reduction of tumor uptake in HT-1080 tumor xenografts with a coinjected blocking dose of cyclic NGR peptide [c(CNGRC)]. The biodistribution results were consistent with the quantitative analysis of microPET imaging. We concluded that both (64)Cu-DOTA-NGR1 and (64)Cu-DOTA-NGR2 have good and specific tumor uptake in CD13-positive HT-1080 tumor xenografts. (64)Cu-DOTA-NGR2 showed higher tumor uptake and better tumor retention than (64)Cu-DOTA-NGR1, presumably due to bivalency effect and increase in apparent molecular size. (64)Cu-DOTA-NGR2 is a promising PET probe for noninvasive detection of CD13 receptor expression in vivo.