Evaluation of serum total sialic acid in moderate COVID-19 patients with and without gastrointestinal tract manifestations.

BACKGROUND: It is known that SARS-CoV-2 mostly infects the respiratory system causing pneumonia; although it can also affect the gastrointestinal tract (GIT), which covered with a bi-layer of mucus rich in glycosylated proteins that terminated by sialic acid. Therefore; this study aimed to evaluate serum total sialic acid (TSA) in moderate COVID-19 patients with and without GIT manifestations. METHODS: A total of 161 moderate COVID-19 patients without and with GIT manifestations and 50 controls were enrolled into our study. Serum electrolytes levels were measured by using colorimetric or turbidmetric commercial assay kits, while the level of serum TSA was measured by using a commercial ELISA kit. RESULTS: Our results showed that serum TSA level was highly significantly increased in moderate COVID-19 patients with GIT manifestations (81.43 ± 8.91) when compared with controls (61.24 ± 6.41) or even moderate COVID-19 patients without GIT manifestations (69.46 ± 7.03). ROC curve analysis showed that AUC for TSA is 0.84 with 76.2 % sensitivity and 73.7 % specificity in discrimination between moderate COVID-19 patients with and without GIT manifestations. Serum potassium and sodium levels were highly significantly decreased in moderate COVID-19 patients with GIT manifestations when compared with controls or even moderate COVID-19 patients without GIT manifestations; while serum calcium level was found to be significantly decreased in moderate COVID-19 patients with GIT manifestations when compared with controls. CONCLUSION: Finally, we can conclude that SA plays a crucial role in the pathogenesis of GIT complications associated with COVID-19 and could be a potential biomarker for the COVID-19 gastrointestinal complications.

Simulated sunlight decreases the viability of SARS-CoV-2 in mucus.

The novel coronavirus, SARS-CoV-2, has spread into a pandemic since its emergence in Wuhan, China in December of 2019. This has been facilitated by its high transmissibility within the human population and its ability to remain viable on inanimate surfaces for an extended period. To address the latter, we examined the effect of simulated sunlight on the viability of SARS-CoV-2 spiked into tissue culture medium or mucus. The study revealed that inactivation took 37 minutes in medium and 107 minutes in mucus. These times-to-inactivation were unexpected since they are longer than have been observed in other studies. From this work, we demonstrate that sunlight represents an effective decontamination method but the speed of decontamination is variable based on the underlying matrix. This information has an important impact on the development of infection prevention and control protocols to reduce the spread of this deadly pathogen.

Exhaled aerosol increases with COVID-19 infection, age, and obesity.

COVID-19 transmits by droplets generated from surfaces of airway mucus during processes of respiration within hosts infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. We studied respiratory droplet generation and exhalation in human and nonhuman primate subjects with and without COVID-19 infection to explore whether SARS-CoV-2 infection, and other changes in physiological state, translate into observable evolution of numbers and sizes of exhaled respiratory droplets in healthy and diseased subjects. In our observational cohort study of the exhaled breath particles of 194 healthy human subjects, and in our experimental infection study of eight nonhuman primates infected, by aerosol, with SARS-CoV-2, we found that exhaled aerosol particles vary between subjects by three orders of magnitude, with exhaled respiratory droplet number increasing with degree of COVID-19 infection and elevated BMI-years. We observed that 18% of human subjects (35) accounted for 80% of the exhaled bioaerosol of the group (194), reflecting a superspreader distribution of bioaerosol analogous to a classical 20:80 superspreader of infection distribution. These findings suggest that quantitative assessment and control of exhaled aerosol may be critical to slowing the airborne spread of COVID-19 in the absence of an effective and widely disseminated vaccine.

Transmission risk of viruses in large mucosalivary droplets on the surface of objects: A time-based analysis.

The novel human coronavirus SARS-CoV-2 has been responsible for a worldwide pandemic. Although media transmission through contaminated surfaces is one of the most recognized ways of transmission, the study on the number and viability of viruses surviving on a surface after leaving the host represents a "blind spot" in current research. In this paper we have reviewed studies on the physical process of droplet evaporation on media surfaces, and analyzed the recent literature related to experiments on the decay of the viral concentration and infectious activity of SARS-CoV-2 and other viruses on those surface and in the air. The huge differences in the risk of media transmission of large saliva and sputum droplets were analyzed in terms of time elapsed. Due to the rapid decrease of water content in the evaporated droplets and the increased concentration of each component, the living environment of the virus tended to deteriorate sharply, and virus concentration plummeted within a few minutes. Although a virus can be detected in a matter of hours, tens of hours, or days, the risk of transmission is negligible compared to when it first left the host. This study suggests that the key to prevention and control is to start from the source, the earlier the better. It is extremely important to develop good public health habits, wear masks, and wash hands frequently. That said, excessive disinfection and sterilization of surfaces during a later period may have adverse effects.

The proteomic characteristics of airway mucus from critical ill COVID-19 patients.

BACKGROUND: The pandemic of the coronavirus disease 2019 (COVID-19) has brought a global public health crisis. However, the pathogenesis underlying COVID-19 are barely understood. METHODS: In this study, we performed proteomic analyses of airway mucus obtained by bronchoscopy from severe COVID-19 patients. In total, 2351 and 2073 proteins were identified and quantified in COVID-19 patients and healthy controls, respectively. RESULTS: Among them, 92 differentiated expressed proteins (DEPs) (46 up-regulated and 46 down-regulated) were found with a fold change >1.5 or <0.67 and a p-value <0.05, and 375 proteins were uniquely present in airway mucus from COVID-19 patients. Pathway and network enrichment analyses revealed that the 92 DEPs were mostly associated with metabolic, complement and coagulation cascades, lysosome, and cholesterol metabolism pathways, and the 375 COVID-19 only proteins were mainly enriched in amino acid degradation (Valine, Leucine and Isoleucine degradation), amino acid metabolism (beta-Alanine, Tryptophan, Cysteine and Methionine metabolism), oxidative phosphorylation, phagosome, and cholesterol metabolism pathways. CONCLUSIONS: This study aims to provide fundamental data for elucidating proteomic changes of COVID-19, which may implicate further investigation of molecular targets directing at specific therapy.

Soft matter science and the COVID-19 pandemic.

Much of the science underpinning the global response to the COVID-19 pandemic lies in the soft matter domain. Coronaviruses are composite particles with a core of nucleic acids complexed to proteins surrounded by a protein-studded lipid bilayer shell. A dominant route for transmission is via air-borne aerosols and droplets. Viral interaction with polymeric body fluids, particularly mucus, and cell membranes controls their infectivity, while their interaction with skin and artificial surfaces underpins cleaning and disinfection and the efficacy of masks and other personal protective equipment. The global response to COVID-19 has highlighted gaps in the soft matter knowledge base. We survey these gaps, especially as pertaining to the transmission of the disease, and suggest questions that can (and need to) be tackled, both in response to COVID-19 and to better prepare for future viral pandemics.

Effect of Environmental Conditions on SARS-CoV-2 Stability in Human Nasal Mucus and Sputum.

We found that environmental conditions affect the stability of severe acute respiratory syndrome coronavirus 2 in nasal mucus and sputum. The virus is more stable at low-temperature and low-humidity conditions, whereas warmer temperature and higher humidity shortened half-life. Although infectious virus was undetectable after 48 hours, viral RNA remained detectable for 7 days.