Exploration of reference genes for the development of a diagnostic kit on vascular aging in human saliva

Identifying reliable biomarkers in saliva can be a promising approach to developing a rapid diagnostic kit for detecting vascular aging. This study investigated the most suitable reference gene for polymerase chain reaction (PCR) in saliva that is not affected by vascular aging variables. Whole saliva samples were collected to assess the expression of reference genes: actin beta (ACTB), 18S ribosomal RNA (18S rRNA), beta-2-microglobulin, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The most abundantly expressed gene was 18S rRNA, and the least expressed gene was GAPDH. Four genes were ranked according to their relative stability, as determined by mathematical algorithms, indicating that ACTB and 18S rRNA were stably expressed as reference genes. 18S rRNA was identified as the most promising reference gene for detecting systemic diseases using saliva from patients with vascular aging in these limited experimental conditions.

Comparative performances of seven quantitative Reverse-Transcription Polymerase Chain Reaction assays (RT-qPCR) for detecting SARS-CoV-2 infection in samples from individuals suspected of COVID-19 in São Paulo, Brazil

Introduction

Brazil is the second largest country with COVID-19 positive cases worldwide. Due to the potent spread of the virus and the scarcity of kits and supplies, the Brazilian Ministry of Health has granted authorization for the use of kits available during this emergency, without an accurate evaluation of their performance. This study compared the performance and cost-effectiveness of seven molecular assays/kits available in São Paulo, Brazil, for SARS-CoV-2 diagnosis

Materials and methods

A total of 205 nasopharyngeal/oropharyngeal samples from suspected cases of COVID-19, were tested using the following assays: (i) GeneFinder COVID-19 plus RealAmp kit; (ii) 2019-nCoV RNA PCR-Fluorescence Probing, Da An Gene Co.; (iii) in-house RT-qPCR SARS-CoV-2 IAL; (iv) 2019-nCoV kit, IDT; (v) molecular SARS-CoV-2 (E) kit, Bio-Manguinhos; (vi) Allplex 2019-nCoV modified Assay, Seegene Inc, and (vii) Biomol one-step COVID-19 kit, IBMP. The criteria for determining a SARS-CoV-2 true positive result included the cycle threshold cut-off values, the characteristics of exponential/linear curves, the gene target diversity, and a positive result in at least two assays

Results

The overall sensitivity of the assays listed were GeneFinder 83.6%, Da An Gene 100.0%, IAL 90.4%, IDT 94.6%, Bio-Manguinhos 87.7%, Allplex 97.3%, and IBMP 87.7%. The minor sensitive gene target was RdRP. Although all assays had a Cohen's Kappa index ≥0.893, the best tests used multiplex assays identifying N-gene and/or E-gene targets

Conclusion

All assays tested accurate for diagnosis, but considering cost-effectiveness (cost, time consumption, number of samples tested, and performance), the in-house IAL assay was ideal for COVID-19 diagnosis in São Paulo, Brazil.

Study on the Role of Calreticulin Within Platelet from Adult Patients with Chronic Immune Thrombocytopenic Purpura

To observe the differences in proteins between adult patients with chronic immune thrombocytopenic purpura (ITP) and healthy adults. 30 patients with chronic ITP and 30 healthy controls were enrolled into the study. The platelet total protein was extracted from peripheral venous blood of 10 chronic ITP patients and 10 healthy controls respectively, and subjected to two-dimensional electrophoresis (2-DE) to find the differential protein spot between chronic ITP patients and healthy controls, then the differential protein spots were identified by mass spectrometry. Subsequently, platelets RNA and proteins were isolated from the other 20 chronic ITP patients and 20 healthy controls respectively, and used for confirming the 2-DE and mass spectrometry results by using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and enzyme linked immunosorbent assay (ELISA). 2-DE combined with mass spectrometry revealed that calreticulin (CRT) expressed normally within platelets from healthy controls, while it reduced within platelets from patients with chronic ITP. qPCR and ELISA confirmed that CRT was decreased at both RNA transcription and protein expression levels within platelets from chronic ITP patients compared with healthy controls. Decreased transcription and expression of CRT within platelets may play an important role in the pathogenesis of chronic ITP, which is worthy of further study.