The pandemic of the coronavirus disease (COVID-19) caused by SARS-CoV-2 affects millions of people worldwide. There are still many unknown aspects to this infection which affects the whole world. In addition, the potential impacts caused by this infection are still unclear. Amino acid metabolism, in particular, contains significant clues in terms of the development and prevention of many diseases. Therefore, this study aimed to compare amino acid profile of COVID-19 and healthy subject. In this study, the amino acid profiles of patients with asymptomatic, mild, moderate, and severe/critical SARS-CoV-2 infection were scanned with LC–MS/MS. The amino acid profile encompassing 30 amino acids in 142 people including 30 control and 112 COVID-19 patients was examined. 20 amino acids showed significant differences when compared to the control group in COVID-19 patient groups with different levels of severity in the statistical analyses conducted. It was detected that the branched-chain amino acids (BCAAs) changed in correlation with one another, and l -2-aminobutyric acid and l -phenylalanine had biomarker potential for COVID-19. Moreover, it was concluded that l -2-aminobutyric acid could provide prognostic information about the course of the disease. We believe that a new viewpoint will develop regarding the diagnosis, treatment, and prognosis as a result of the evaluation of the serum amino acid profiles of COVID-19 patients. Determining l -phenylalanine and l -2-aminobutyric levels can be used in laboratories as a COVID-19-biomarker. Also, supplementing COVID patients with taurine and BCAAs can be beneficial for treatment protocols. Supplementary Information The online version contains supplementary material available at 10.1007/s00726-021-03081-w.

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While the COVID-19 disease progresses mildly or asymptomatically in some people, its progression is severe and symptomatic in others, and it is an issue that requires a scientific response regarding the disease. The present study includes 60 people infected with COVID-19, and the cases were divided into the following groups: asymptomatic, mild, moderate, and severe. Serum Zn, Se, and Cu levels of these groups were analyzed by ICP-MS. All measurements in the patients were compared with those of 32 healthy individuals. When the patient group is compared with the control group, the serum Zn and Se concentrations were statistically low ( p < 0.001) in the patient group. Serum Zn level decreased significantly in 4 different patient groups compared to the control group. Although the serum Se level decreased in all four patient groups compared to the control group, the change in Se level was statistically significant only in the severe and mild patient groups. This study examined serum Zn, Se concentrations, and biochemical parameters in patients with different severity of COVID-19, compared them with healthy individuals, and revealed new targets for diagnosis and treatment by revealing those data that may be important.

A new spectrofluorimetric method to determine losartan potassium (LP) in rabbit plasma is described. The method was based on measuring the native fluorescence of LP in acidic medium. Optimum excitation and emission wavelengths were found to be 248 nm and 410 nm, respectively, in methanol that was diluted with a sulfurous acid solution LP was extracted from rabbit plasma by methyl-tertiary-butyl-ether in acidic media and then back extracted with NaOH. The calibration curves were linear between 0.025 and 0.5 µg/mL with a lower limit of detection 0.004 µg/mL. Precision and accuracy values of the method were calculated as lower than 4.97% and ± 5.68, respectively and the recovery of LP from rabbit plasma was higher than 91.1%. In addition, stability studies of LP in rabbit plasma were carried out and demonstrated its good stability at - 20 °C and at room temperature. The developed and validated method was successfully applied for estimating the pharmacokinetic parameters of LP following oral administrations of a single 10 mg LP/kg to rabbits and it could be concluded that the method can be applied to clinical trials.

Invasive ductal carcinoma (IDC) is the most common type of breast cancer. In this study, matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS)-based analyses were conducted for determining differential N-glycosylation patterns of IDC.

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Olanzapine is an atypical antipsychotic drug from the thienobenzodiazepine family which displays efficacy in patients with schizophrenia and related psychoses. A novel LC/MS method was developed and validated for determination of olanzapine in schizophrenia patients' plasma. A liquid–liquid extraction procedure was carried out using 5 mL diethyl ether–diisopropyl ether mixture (1:1, v/v). Average recovery of the extraction procedure was 94.8%. Chromatographic separation was performed on reversed‐phase C18 column (250 × 2.0 mm, 5 μm) using mixture of deionized water (trifluoro acetic acid 0.1%)–acetonitrile (20:80, v/v) as mobile phase at a flow rate of 1 mL/min. Irbesartan was used as internal standart and total run time was 2.5 min. Mass spectrometric analysis were carried out in selective‐ion montoring mode, and detected olanzapine at m/z 313.1 and IS at m/z 429.4 in all forms of the ions. The calibration curve of olanzapine was linear in the range 2–300 ng/mL (r2 > 0.9993). The interday and intraday precisions (RSD) were <7.55%, and accuracy was >7.59% (n = 6). The proposed study was successfully validated with respect to the US Food and Drug Administration guidelines.

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