Shared Antigen-specific CD8⁺ T cell Responses Against the SARS-COV-2 Spike Protein in HLA A*02:01 COVID-19 Participants

We report here on antigens from the SARS-CoV-2 virus spike protein, that when presented by Class I MHC, can lead to cytotoxic CD8⁺ T cell anti-viral responses in COVID-19 patients. We present a method in which the SARS-CoV-2 spike protein is converted into a library of peptide antigen-Major Histocompatibility Complexes (pMHCs) as single chain trimers that contain the peptide antigen, the MHC HLA allele, and the β-2 microglobulin sub-unit. That library is used to detect the evolution of virus-specific T cell populations from two COVID-19 patients, at two time points over the course of infection. Both patients exhibit similar virus-specific T cell populations, but very different time-trajectories of those populations. These results can be used to track those virus-specific T cell populations over the course of an infection, thus providing deep insight into the variations in immune system trajectories observed in different COVID-19 patients

Perioperative oxygen fraction – effect on surgical site infection and pulmonary complications after abdominal surgery: a randomized clinical trial. Rationale and design of the PROXI-Trial

<p>Abstract</p> <p>Background</p> <p>A high perioperative inspiratory oxygen fraction may reduce the risk of surgical site infections, as bacterial eradication by neutrophils depends on wound oxygen tension. Two trials have shown that a high perioperative inspiratory oxygen fraction (Fi<smcaps>O</smcaps>₂= 0.80) significantly reduced risk of surgical site infections after elective colorectal surgery, but a third trial was stopped early because the frequency of surgical site infections was more than doubled in the group receiving Fi<smcaps>O</smcaps>₂= 0.80. It has not been settled if a high inspiratory oxygen fraction increases the risk of pulmonary complications, such as atelectasis, pneumonia and respiratory failure. The aim of our trial is to assess the potential benefits and harms of a high perioperative oxygen fraction in patients undergoing abdominal surgery.</p> <p>Methods and design</p> <p>The PROXI-Trial is a randomized, patient- and assessor blinded trial of perioperative supplemental oxygen in 1400 patients undergoing acute or elective laparotomy in 14 Danish hospitals. Patients are randomized to receive either 80% oxygen (Fi<smcaps>O</smcaps>₂= 0.80) or 30% oxygen (Fi<smcaps>O</smcaps>₂= 0.30) during surgery and for the first 2 postoperative hours. The primary outcome is surgical site infection within 14 days. The secondary outcomes are: atelectasis, pneumonia, respiratory failure, re-operation, mortality, duration of postoperative hospitalization, and admission to intensive care unit. The sample size allows detection of a 33% relative risk reduction in the primary outcome with 80% power.</p> <p>Discussion</p> <p>This trial assesses benefits and harms of a high inspiratory oxygen fraction, and the trial may be generalizable to a general surgical population undergoing laparotomy.</p> <p>Trial registration</p> <p>ClinicalTrials.gov identifier: NCT00364741.</p

Qualitative analysis of quercetin present in ethanolic leaf extract of Blumea balsamifera L. DC (Sambong) using TLC-bioautography and HPLC-PDA

The objective of the study is to measure the amount of quercetin present in DCM fraction of ethanolic extract of Blumea balsamifera L. leaves using TLC-bioautography and HPLC-PDA. Furthermore, the study compared TLC-bioautography versus HPLC in quantification of quercetin in the plant sample. Powdered B. balsamifera leaves were macerated with 95% ethanol and the filtrate was subjected to liquid-liquid partitioning. The extract was partitioned with an equal amount of n-hexane. Recovered ethanol partition was subjected to rotary evaporation and remaining aqueous fraction was successively partitioned with dichloromethane, chloroform and ethyl acetate. The residue obtained from n-hexane, dichloromethane, chloroform, ethyl acetate and water were screened using Bate-Smith and Metcalf method and Wilstater “cyanidin” test. All fractions tested were negative for Bate-Smith and Metcalf method. Dichloromethane, chloroform and ethyl acetate fractions showed positive results for Wilstate test indicating possible presence of gamma-benzopyrone. Dichloromethane fraction was used for column chromatography because in comparison with ethyl acetate and chloroform fraction, the intensity of color was best. The residue obtained from dichloromethane was purified by column chromatography. Each fraction was spotted in the TLC plate and sprayed with DPPH. All fractions that tested positive for DPPH test were pooled. Thin Layer Chromatography method was developed to carry out the bioautography process utilizing the anti-oxidant property of quercetin. Using the developed method, the amount of quercetin in the DCM fraction was determined. High performance liquid chromatography method was developed to measure the amount of quercetin present in the pooled fractions. The final concentration of quercetin in the pooled fractions for HPLC is 2.022 mg/mL and TLC-bioautography method is 2.25 mg/ mL. Comparison of two methods: Mean: 0.356 mg/mL, variance: 0.000722 mg2/mL2, standard deviation: 0.02687 mg/mL, % relative standard deviation: 7.55%, and the standard error: 0.019 mg/mL. The quantitation of quercetin using TLC-bioautography and HPLC is significantly similar