Association between leukocyte telomere length and COVID-19 severity.

Background: Inter-individual variations in the clinical manifestations of SARS-CoV-2 infection are among the challenging features of COVID-19. The known role of telomeres in cell proliferation and immune competency highlights their possible function in infectious diseases. Variability in telomere length is an invaluable parameter in the heterogeneity of the clinical presentation of diseases. Result: In this study, our aim was to investigate the possible association between leukocyte telomere length (LTL) and COVID-19 severity. LTL was measured in 100 patients with moderate and severe forms of COVID-19 using the quantitative PCR (q-PCR) method. Statistical analysis confirmed a strong inverse correlation between relative LTL and COVID-19 severity. Conclusions: These findings suggest that LTL can be a useful parameter for predicting disease severity in patients, as individuals with short telomeres may have a higher risk of developing severe COVID-19. Supplementary Information: The online version contains supplementary material available at 10.1186/s43042-023-00415-z.

Effects of Desilication in NaOH/Piperidine Medium and Phosphorus Modification on the Catalytic Activity of HZSM-5 Catalyst in Methanol to Propylene Conversion.

BACKGROUND: Propylene is one of the main petrochemical building blocks applied as a feedstock for various chemical and polymer intermediates. The methanol-to-propylene (MTP) processes are reliable options for propylene production from non-petroleum resources. The highsilica ZSM-5 zeolite is found to be a reliable candidate for the methanol to propylene catalysis. OBJECTIVE: In this study, the mesoporosity was first introduced into a high silica ZSM-5 zeolite via an alkaline treatment by NaOH solution with piperidine to decrease the diffusion limitation, and then the structure of zeolite was stabilized by phosphorus modification to improve the acidic properties and to enhance the catalyst stability. METHODS: High-silica H-ZSM-5 catalysts (Si/Al = 200) were successfully prepared through microwave-assisted hydrothermal technique in the presence of tetrapropyl ammonium hydroxide (TPAOH) structure-directing agent. The mesoporosity was efficiently introduced into the ZSM-5 crystals via desilication derived from alkaline NaOH/piperidine solution. Then, the acidity of the desilicated ZSM-5 samples was improved using phosphorus modification. The catalysts were subjected to XRD, ICP-OES, FE-SEM, BET, TGA, FT-IR and NH3-TPD analysis. RESULTS: The catalytic performance of the prepared catalysts in the methanol to propylene (MTP) reaction was examined in a fixed-bed reactor at 475 °C, atmospheric pressure and methanol WHSV of 0.9 h-1. The results showed that the alkaline treatment in NaOH/piperidine solution created uniform mesoporosity with no severe damage in the crystal structure. Similarly, phosphorus modification developed the acidic features and led to the optimal catalytic efficiency in terms of the maximum propylene selectivity (49.16%) and P/E ratio (5.97) as well as the catalyst lifetime. CONCLUSION: The results showed an excellent catalytic activity in terms of 99.21% methanol conversion, good propylene selectivity up to 49.16%, a high ratio of P/E of 5.97 and a low selectivity to C5 + hydrocarbons of 11.57% for ZS-D-PI-P sample.

Preparation of a novel magnetic Pd(II) ion-imprinted polymer for the fast and selective adsorption of palladium ions from aqueous solutions.

A novel magnetic ion-imprinted polymer with high accessibility to palladium ions was synthesized via co-precipitation polymerization. Accordingly, a ternary complex composed of PdCl2 as an imprinting ion, 8-aminoquinoline (AQ) as a ligand, and 4-vinyl pyridine (4-VP) as a complexing monomer was applied to Fe3O4@SiO2 as magnetic core, followed by precipitation polymerization using 2-hydroxyethyl methacrylate (2-HEMA) as a co-monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, and 2,2-azobisisobutyronitrile (AIBN) as an initiator in the presence of 2-methoxyethanol as a solvent. The palladium ions were leached out by a solution containing 50% (v/v) HCl. The synthesized polymer was characterized physically and morphologically using different techniques. In order to assess the conditions required for adsorption, as well as the selectivity and reusability, batch adsorption experiments were carried out. The experiments exhibited that the maximum adsorption capacity was about 65.75 mg g-1 at 25 °C, while the pH solution and the adsorbent dose were 4 and 1 g L-1, respectively. Kinetic studies of experimental data demonstrated that they correspond very much to the pseudo-second-order kinetic model. The development of the Langmuir and Freundlich isothermal models on the equilibrium data proved to correspond well to the Langmuir isotherm model. Interferences studies of the magnetic polymer demonstrated higher affinity and discernment for palladium ions than other co-existing ions in the solutions. Spontaneous (ΔG < 0) and exothermic (ΔH < 0) behavior of the adsorption process is confirmed by thermodynamic studies. In addition, the affinity of the spent polymer has not been dramatically reduced over at least five regeneration cycles.

Ventilator-associated pneumonia in patients admitted to intensive care units, using open or closed endotracheal suctioning.

BACKGROUND: Critically ill patients under mechanical ventilation require frequent suctioning of airway secretion. Closed suction permits suctioning without disconnection from ventilator; so it might decrease hypoxemia and infection rate. OBJECTIVES: This study aimed to evaluate the effect of closed tracheal suction system (CTSS) versus open tracheal suction system (OTSS). PATIENTS AND METHODS: This is a prospective randomized study, which was carried on 100 patients in surgical Intensive Care Unit requiring mechanical ventilation for more than 48 hours from June 2012 to November 2013. In two groups, suction was performed based on the patients' need as well as physician's or nurses' decision on tracheal secretions. Patients randomly allocated into two groups (50 patients each): CTSS group and OTSS group. Patients were monitored for developing ventilator-associated pneumonia (VAP) during the study. Throat samples were taken on admission and two times per week from each patient. Tracheal samples were performed during endotracheal intubation, two times per week during mechanical ventilation and during extubation. RESULTS: Drainage of subglottic secretions decreased the incidence of VAP (P < 0.05). Also type of the pharmacologic medicine for stress ulcer prophylaxis has significant effect on VAP incidence. Among the patients in OTSS and CTSS groups, 20% and 12% developed VAP, respectively. Use of CTSS compared with OTSS did not show statistically significant effect on VAP incidence in multivariate analysis; however, OR (odds ratio) tended to identify OTSS as an exposure factor for the development of VAP (OR = 1.92; CI = 0.45-8.30; = 0.38) compared with the CTSS. Higher levels of APACHE II score, sinusitis and tracheostomy put the patients at the risk of VAP. However, using heat and moisture exchanger (HME) instead of humidifier decreased this risk. CONCLUSIONS: Based on the results obtained from our study, impact of suctioning is similar between CTSS and OTSS regarding the occurrence of VAP. It seems that physicians must consider many factors such as duration of mechanical ventilation, comorbidities, oxygenation parameters, number of required suctioning, and the cost prior to using each type of tracheal suction system.