Clinical performance testing of the automated haematology analyzer XN-31 prototype using whole blood samples from patients with imported malaria in Japan.

BACKGROUND: The automated haematology analyzer XN-31 prototype (XN-31p) is a new flow cytometry-based device developed to measure the number and the ratio of malaria-infected red blood cells (MI-RBC) with a complete blood count (CBC). The XN-31p can provide results in about one minute and also can simultaneously provide information on the malaria parasite (Plasmodium) species. In this study, clinical testing of the XN-31p was performed using blood samples from patients with imported malaria in Japan. METHODS: Blood samples were collected from 80 patients who visited the hospital of the National Center for Global Health and Medicine, Tokyo, Japan, for malaria diagnosis from January 2017 to January 2019. The test results by the XN-31p were compared with those by other standard methods, such as microscopic observation, rapid diagnostic tests and the nested PCR. RESULTS: Thirty-three patients were diagnosed by the nested PCR as being malaria positive (28 Plasmodium falciparum, 2 Plasmodium vivax, 1 Plasmodium knowlesi, 1 mixed infection of P. falciparum and Plasmodium malariae, and 1 mixed infection of P. falciparum and Plasmodium ovale), and the other 47 were negative. The XN-31p detected 32 patients as "MI-RBC positive", which almost matched the results by the nested PCR and, in fact, completely matched with the microscopic observations. The ratio of RBCs infected with malaria parasites as determined by the XN-31p showed a high correlation coefficient of more than 0.99 with the parasitaemia counted under microscopic observation. The XN-31p can analyse the size and nucleic acid contents of each cell, and the results were visualized on a two-dimensional cytogram termed the "M scattergram". Information on species and developmental stages of the parasites could also be predicted from the patterns visualized in the M scattergrams. The XN-31p showed a positive coincidence rate of 0.848 with the nested PCR in discriminating P. falciparum from the other species. CONCLUSIONS: The XN-31p could rapidly provide instructive information on the ratio of MI-RBC and the infecting Plasmodium species. It was regarded to be of great help for the clinical diagnosis of malaria.

Robust calibration models to predict antipyrine content in various kinds of packaged hospital powder preparations by using near-infrared spectroscopy.

The purpose of this study was to evaluate drug content of hospital powder preparations using non-destructive, non-contact, short-term measurements with near-infrared spectroscopy (NIR). Antipyrine (0-50%) was mixed with additive powder, and packed with semi-transparent (SP) or transparent (TP) paper to obtain single packaged samples (SPP and TPP). Double packaged samples were obtained by packing TPP with TP. NIR spectra of the packaged samples were recorded using a NIR spectrometer with a fiber-optic probe. The best calibration model was determined to minimize the standard error of cross-validation (SEP) by the leave-out-one method in principal component regression (PCR). The calibration models for SPP and TPP were calculated to be the minimum SEP based on one- and four-PC models by the PCR method, respectively. Plots of predicted and actual drug contents for SPP and TPP showed a straight line with a slope of 0.946 and 0.948, and γ of 0.965 and 0.980, respectively. On the other hand, the calibration model for the single and double TPP was obtained based on a three-PC model, and the plot of predicted and actual drug content showed a straight line with a slope of 0.942 and γ of 0.977.