Recent findings and applications of biomedical engineering for COVID-19 diagnosis: a critical review

COVID-19 is one of the most severe global health crises that humanity has ever faced. Researchers have restlessly focused on developing solutions for monitoring and tracing the viral culprit, SARS-CoV-2, as vital steps to break the chain of infection. Even though biomedical engineering (BME) is considered a rising field of medical sciences, it has demonstrated its pivotal role in nurturing the maturation of COVID-19 diagnostic technologies. Within a very short period of time, BME research applied to COVID-19 diagnosis has advanced with ever-increasing knowledge and inventions, especially in adapting available virus detection technologies into clinical practice and exploiting the power of interdisciplinary research to design novel diagnostic tools or improve the detection efficiency. To assist the development of BME in COVID-19 diagnosis, this review highlights the most recent diagnostic approaches and evaluates the potential of each research direction in the context of the pandemic.

Prevalence, species distribution and antifungal susceptibility of Candida albicans causing vaginal discharge among symptomatic non-pregnant women of reproductive age at a tertiary care hospital, Vietnam

Background

Vaginal candidiasis is frequent in women of reproductive age. Accurate identification Candida provides helpful information for successful therapy and epidemiology study; however, there are very limited data from the Vietnam have been reported. This study was performed to determine the prevalence, species distribution of yeast causing vaginal discharge and antifungal susceptibility patterns of Candida albicans among symptomatic non-pregnant women of reproductive age.

Methods

Vaginal discharge samples were collected from 462 women of reproductive age in Hanoi, Vietnam between Sep 2019 and Oct 2020. Vaginal swabs from these patients were examined by direct microscopic examination (10% KOH). CHROMagar™ Candida medium and Sabouraud dextrose agar supplemented with chloramphenicol (0.5 g/l) were used to isolate yeast, and species identification was performed using morphological tests and molecular tools (PCR and sequencing). Antifungal susceptibility testing was determined according to the Clinical and Laboratory Standards Institute guidelines (M27-A3 and M27-S4).

Results

The prevalence of vaginal yeast colonization in non-pregnant women was 51.3% of 462 participants. Nine different yeast species were identified. Among these isolates, C. albicans (51.37%) was the most frequent, followed by C. parapsilosis (25.88%), C. glabrata (11.37%), C. tropicalis (4.31%), C. krusei (3.92%), C. africana (1.57%), Saccharomyces cerevisiae (0.78%), C. nivariensis (1 isolates, 0.39%), and C. lusitaniae (1 isolates, 0.39%), respectively. Among C. albicans, all 46 isolates were 100% susceptible to micafungin, caspofungin, and miconazole. The susceptibility rates to amphotericine B, 5-flucytosine, fluconazole, itraconazole and voriconazole were 95.65, 91.30, 91.30, 82.61 and 86.95%, respectively.

Conclusions

The prevalence of VVC among symptomatic non-pregnant women of reproductive age in Vietnam was higher than many parts of the world. The high frequency of non-albicans Candida species, which were often more resistant to antifungal agents, was a notable feature. Resistance rates of vaginal C. albicans isolates to antifungal agents was low. Our findings suggest that continued surveillance of changes in species distribution and susceptibility to antifungals should be routinely screened and treated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06192-7.

Serum dioxin concentrations in military workers at three dioxin-contaminated airbases in Vietnam

An estimated 91,998,400 L of herbicides were stocked at three US airbases in Vietnam between 1962 and 1971. These herbicides were contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD). In 2017, we sampled blood from 120 male Vietnamese military workers in the three dioxin-contaminated airbases (Bien Hoa, Da Nang, and Phu Cat) and from 20 workers at an uncontaminated airbase. 2,3,7,8-tetraCDD concentrations were highest in samples from Bien Hoa (18.2 pg/g lipid), followed by samples from Da Nang (9.2 pg/g lipid), Phu Cat (3.7 pg/g lipid), and the reference base (2.1 pg/g lipid). In Bien Hoa, 31 of the 50 subjects had blood 2,3,7,8-tetraCDD levels in the range of 10-100 pg/g lipid and four subjects had 2,3,7,8-tetraCDD levels that exceeded 100 pg/g lipid. In Da Nang, almost half of the subjects had blood 2,3,7,8-tetraCDD concentrations in the range of 10-100 pg/g lipid. These findings suggest that military workers at contaminated bases are the population most vulnerable to dioxin exposure, especially at Bien Hoa.

Isolation and Differentiation of Amniotic Membrane Stem Cells Into Keratinocytes

The human amniotic membrane is a highly abundant and readily available tissue that may be useful for regenerative medicine and cell therapy. The amniotic membrane stem cells can differentiate into multiple cell lineages; they have low immunogenicity and anti-inflammatory functions. This research aims to examine the protocols for the isolation of human amniotic membrane stem cells, including their phenotypic characterization and in vitro potential for differentiation toward keratinocytes. Human placentas were obtained from selected cesarean-sectioned births. We isolated amniotic stem cells by trypsin and collagenase B digestion and centrifuged with Percoll. After monolayer expansion of adherent cells, the cells were characterized by immunocytology with octamer-binding transcription factor 4 and differentiated into keratinocytes by treating the cells with insulin, hydrocortisone, BMP-4, and vitamin C. Protocol for isolation of stem cells from amniotic membrane has high efficiency. Differentiation markers of stem cells into keratinocytes, such as vimentin, cytokeratin (CK) 14, and CK19, were determined by reverse transcription-polymerase chain reaction increase over time in culture. Stem cells isolated from the amniotic membrane can differentiate into keratinocytes. It has opened the prospect of using stem cells to regenerate skin and clinical applications.

Regulation of p38MAPK-mediated dendritic cell functions by the deubiquitylase otubain 1

Dendritic cells (DCs) are professional antigen presenting cells (APCs) that represent the essential link between innate and acquired immunity. Otubain (OTUB) 1 is shown to deubiquitinate TRAFs to suppress virus-induced inflammatory response. MAPK, a downstream molecule of TRAFs, is involved in regulating LPS-induced immune reactions and its activation is sensitive to the presence of OTUB1. Little is known about contributions of OTUB1 to changes in biological properties of DCs. The present study, therefore, explored whether DC functions are influenced by OTUB1. To this end, DCs were isolated and cultured with GM-CSF to attain bone marrow-derived DCs (BMDCs) and followed by treatment with lipopolysaccharide (LPS) in the presence or absence of OTUB1 siRNA. Expression of markers of cellular maturation and proliferation were analyzed by flow cytometry, and secretion of inflammatory cytokines and ability to stimulate CD4⁺ T-cells in allogenic mixed leukocyte reaction (allo-MLR) by ELISA, cell migration by a transwell migration assay and phagocytic capacity by FITC-dextran uptake measurement. As a result, treatment of the cells with OTUB1 siRNA prolonged activation of p38MAPK, increased CD54 expression and IL-6 release and reduced FITC-dextran uptake. Moreover, cytokine release produced from CD4⁺ T-cells in allo-MLR was different. The enhanced level of IFN-γ, but not other cytokine production was observed in the presence of siRNA OTUB1. All the effects were completely abolished when the cells were exposed with p38MAPK inhibitor SB203580. In conclusion, OTUB1 prevents the prolonged activation of p38MAPK, which in turn compromises DC functions.

Association of dioxin exposure and reproductive hormone levels in men living near the Bien Hoa airbase, Vietnam

Dioxins are endocrine-disrupting chemicals, and their effects on reproductive functions are well-documented. The aim of the present study was to measure the levels of reproductive hormones in 42 men residing near a dioxin-contaminated area in Vietnam. We measured levels of 17 2,3,7,8-substituted congeners of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) and four non-ortho polychlorinated biphenyls (PCBs) in blood. Levels of follicle-stimulating hormone, luteinizing hormone, progesterone, prolactin, estradiol, and total testosterone were measured in serum. Blood dioxin levels were elevated; the levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin was 7.3pg/g fat. Seven of the men had testosterone levels below 250ng/dL, and nine men had prolactin levels above 9.7ng/mL. Four PCDD congeners, two PCDF congeners, one PCB congener, and the sum TEQ of PCDDs, PCDDs/Fs, and PCDDs/Fs/PCBs were positively and significantly correlated with prolactin levels. Two PCDD congeners, six PCDF congeners, two PCB congeners, and the TEQs of PCDFs and PCBs were negatively and significantly correlated with testosterone levels. There were no significant correlations between dioxin congeners and follicle-stimulating hormone, luteinizing hormone, or progesterone levels.

Allelopathic Responses of Rice Seedlings under Some Different Stresses

The objective of this study was to evaluate the allelopathic responses of rice seedlings under submergence stress at different temperatures (10, 25, 32, and 37 °. The results showed that a wide range of allelopathic responses of rice seedlings depended on varieties and stress conditions, with temperature was being a key factor. It showed that the extracts of rice seedlings induced significant suppression on lettuce and radish seedling germination, but had negligible allelopathic effects on growth of barnyardgrass, whilst the emergence and growth of natural weeds was stimulated. In contrast, the root exudates of Koshihikari rice seedlings (K32) at 32 °C reduced the number of total weeds by ≈60.0% and the total dry weight of weeds by 93.0%; i.e., to a greater extent than other root exudates. Among the 13 identified phenolic acids, p-hydroxybenzoic, vanillic, syringic, sinapic and benzoic acids—at concentrations of 0.360, 0.045, 3.052, 1.309 and 5.543 μg/mL might be involved in allelopathic responses of K32, inhibiting the growth of barnyardgrass and natural weeds. Findings of the present study may provide useful information on allelopathic responses of rice under environmental stresses and thus further understand of the competitive relationships between rice and weeds under natural conditions.

Klotho sensitive regulation of dendritic cell functions by vitamin E

Background

Dendritic cells (DCs) are the most potent professional antigen-presenting cells for naive T cells to link innate and acquired immunity. Klotho, an anti-aging protein, participates in the regulation of Ca²⁺ dependent migration in DCs. Vitamin E (VitE) is an essential antioxidant to protect cells from damage and elicits its inhibitory effects on NF-κB-mediated inflammatory response. However, the roles of VitE on mouse DC functions and the contribution of klotho to those effects both are unknown. The present study explored the effects of VitE on klotho expression, maturation, ROS production and migration in DCs.

Methods

The mouse bone marrow cells were isolated and cultured with GM-CSF to attain bone marrow-derived DCs (BMDCs). Cells were stimulated with LPS (100 ng/ml) in the presence or absence of VitE (500 µM). RT-PCR and immunoprecipitation methods were employed to determine klotho expression, ELISA to determine cytokine release, flow cytometry to analyze number of CD86⁺CD11c⁺ cells, the intracellular expression of cytokines and reactive oxygen species (ROS) production and a transwell migration assay to trace migration.

Results

Klotho transcript level and this hormone secretion in DC supernatant were enhanced by VitE treatment and further increased in the presence of NF-κB inhibitor Bay 11-7082 (10 µM). Moreover, VitE treatment inhibited IL-12p70 protein expression of, ROS accumulation in and CCL21-dependent migration of LPS-triggered mature DCs, these effects were reversed following klotho silencing.

Conclusion

The up-regulation of klotho by VitE could contribute to the inhibitory effects of VitE on NF-κB-mediated DC functional maturation. The events might contribute to immunotherapeutic effect of VitE on the pathophysiology of klotho-related disease.