A rapid multiplex assay of human malaria parasites by digital PCR.

BACKGROUND: Blood smear examination through traditional optical microscopy is the gold standard for malaria diagnosis. However, it imposes strict requirements for operational staff and its sensitivity cannot perfectly satisfy the needs of clinical requirements. More sensitive and accurate modern technologies should be applied to this field. Digital PCR (dPCR), as an absolute quantification detection method, can serve as an effective tool to facilitate the diagnosis and classification of different malaria species. OBJECTIVE: We aimed to establish a new multiplex dPCR detection system for four main Plasmodium species: P. vivax, P. falciparum, P. ovale and P. malariae, which can distinguish exact species of malaria by one PCR reaction. METHODS: A total of 39 patients were identified as malaria-positive by microscopic examination in Huashan Hospital from 2016 to 2021; seventy blood samples from these patients were collected. Additionally, 20 healthy individuals, 20 patients with fever and 6 patients with other types of blood parasites infection were also included in this study. Each blood sample was subjected to examination by both blood smears and dPCR. By optimizing four different fluorescence-labeled probes in one reaction system, dPCR permitted the performance of accurate quantitation and working out the exact number of copies of malaria DNA per microliter in whole blood. Rapid diagnostic tests were also conducted to verify part of the results obtained by dPCR. RESULTS: The dPCR system was able to make rapid diagnosis and quantification of malaria DNA samples. The analytical sensitivity of multiplex dPCR was as low as 0.557 copies/µL (95% CI 0.521 to 0.607), and it had a sensitivity of 98.0% and a specificity of 100% in clinical samples. Additionally, three multiple malaria co-infection samples have been detected by this dPCR system, including one triple malaria infection case. By testing consecutive daily blood samples of Patient 39, dPCR facilitated monitoring the efficacy of drug treatment. It showed that the DNA concentrations of P. falciparum ranged from 5474 copies/µL to 0 copies/µL, which can reflect the efficacy of antimalarials in real time. This study also found that haemocyte samples (plasma removed) rather than whole blood had higher malaria detection capability and an enhanced positive rate. CONCLUSION: The multiplex dPCR system newly established here made a substantial contribution in detecting malaria infection at low concentrations. It is suitable for mixed-infection diagnosis and multi-sample continuous monitoring, and presents a promising candidate as an absolute quantitative tool in clinical practice.

Interferents of Automated Reticulocyte Analysis Integrated with Relevant Clinical Cases.

BACKGROUND: Reticulocyte count (RET) has been used for many years to estimate the erythropoietic activity of the bone marrow. Fully automated methods not only provide enhanced precision and accuracy, but also enable reliable measurements of mRNA content and cellular indices. However, problems still exist, such as interference. The aim of the present study was to investigate the interferents of Sysmex XN 9000 reticulocyte analysis and ensure the accuracy of the results. METHODS: We collected a total of 510 specimens from normal control patients and patients with various diseases including anemias, leukemias, infectious diseases, immune diseases, kidney disease, etc. Correlation of the agreement for reticulocytes between the new methylene blue (NMB) visual microscopy method and automated reticulocyte counting was evaluated by paired sample method according to the CLSI-ICSH document H44-A2-Methods for Reticulocyte Count. Blood smear microscopic examination was carried out on the disturbed samples, and the interferents were analyzed with the medical history, flagging algorithms, the warning information, and the microscopic examination. RESULTS: A total of 44 (8.6%) cases exhibited interference. The main interferents of spuriously high reticulocyte count were caused by parasites, such as malaria, as well as suspicious autofluorescence due to drugs, while the main interferents of spuriously low reticulocyte count were caused by RBC fragments. CONCLUSIONS: Detection of potential interferences may be accomplished through alarm information and flagging algorithms incorporated into the instrument and by examination of a blood film to ensure absence of relevant interferences.

MnB2 nanosheet and nanotube: stability, electronic structures, novel functionalization and application for Li-ion batteries.

In this paper, two kinds of two-dimensional manganese boride monolayers, h-MnB2 and t-MnB2, are predicted to be stable metallic nanosheets, which exhibit favorable mechanical and thermal properties. The Young's moduli of h-MnB2 and t-MnB2 are 77.73 N m-1 and 59.59 N m-1, respectively. Ab initio molecular dynamics results show that h-MnB2 and t-MnB2 can sustain up to 500 K and 1000 K, respectively. The magnetic property of h-MnB2 is frustrated antiferromagnetic with a Néel temperature of about 25 K, and the magnetic property of t-MnB2 is collinear antiferromagnetic with a Néel temperature of about 317 K. In addition, the electronic structure of the h-MnB2 monolayer can be tuned by passivation to exhibit Dirac states. h-MnB2 can also self-assemble to form nanotubes, and is thus very promising for application as the anode for Li-ion batteries because of its high capacity (about 875 mA h g-1), low diffusion barrier (about 0.03 eV) and strong stability.

Human African Trypanosomiasis in Emigrant Returning to China from Gabon, 2017.

Human African trypanosomiasis is endemic to parts of sub-Saharan Africa and should be considered in the differential diagnosis of patients who have visited or lived in Africa. We report a 2017 case of stage 2 Trypanosoma brucei gambiense disease in an emigrant who returned to China from Gabon.

Soy Protein Isolate-Alginate Microspheres for Encapsulation ofEnterococcus faecalis HZNU P2

ABSTRACTIn this work, the mixture of alginate and soy protein isolate used as a wall material was developed to encapsulateEnterococcus faecalis HZNU P2 (E. faecalis HZNU P2). The survival ability in the simulated gastric fluid (SGF) and bile salt solution, storage stability at different temperatures and release properties in the simulated intestinal fluid (SIF) of encapsulated cells were assessed. The results showed that encapsulation could offer sufficient protection toE. faecalis HZNU P2. The viability of encapsulatedE. faecalis HZNU P2 did not decrease in SGF at pH 2.5 or 2.0 after 2 h incubation, while free cells were reduced from 11 to 9.85 log CFU/mL in SGF (pH 2.5) at the same exposure time. Only minor viability of encapsulatedE. faecalis HZNU P2 lost in 1.0 or 2.0% bile salt solution for 1 or 2 h exposure, compared with no survival of freeE. faecalis HZNU P2 under the same conditions. EncapsulatedE. faecalis HZNU P2 was completely released from the microspheres in SIF within 1 h. The viability of encapsulatedE. faecalisHZNU P2 stored for two weeks at 4°C was fully retained. Viabilities of encapsulatedE. faecalis HZNU P2, 9.6 and 9.0 Log CFU/g were obtained at 25 and 37°C after 21 days storage, respectively. However, around 1.0 log CFU/mL of free cells was reduced after two weeks storage at 4°C. EncapsulatedE. faecalis HZNU P2 using soy protein isolate and alginate as wall materials could play an important role in food applications.