General structure-activity/selectivity relationship patterns for the inhibitors of the chemokine receptors (CCR1/CCR2/CCR4/CCR5) with application for virtual screening of PubChem database

CC chemokine receptors (CCRs) form a crucial subfamily of G protein-linked receptors that play a distinct role in the onset and progression of various life-threatening diseases. The main aim of this research is to derive general structure-activity relationship (SAR) patterns to describe the selectivity and activity of CCR inhibitors. To this end, a total of 7332 molecules related to the inhibition of CCR1, CCR2, CCR4, and CCR5 were collected from the Binding Database and analyzed using machine learning techniques. A diverse set of 450 molecular descriptors was calculated for each molecule, and the molecules were classified based on their therapeutic targets and activities. The variable importance in the projection (VIP) approach was used to select discriminatory molecular features, and classification models were developed using supervised Kohonen networks (SKN) and counter-propagation artificial neural networks (CPANN). The reliability and predictability of the models were estimated using 10-fold cross-validation, an external validation set, and an applicability domain approach. We were able to identify different sets of molecular descriptors for discriminating between active and inactive molecules and model the selectivity of inhibitors towards different CCRs. The sensitivities of the predictions for the external test set for the SKN models ranged from 0.827-0.873. Finally, the developed classification models were used to screen approximately 2 million random molecules from the PubChem database, with average values for areas under the receiver operating characteristic curves ranging from 0.78-0.96 for SKN models and 0.75-0.89 for CPANN models.Communicated by Ramaswamy H. Sarma.

CO2 Levels Behind and in Front of Different Protective Mask Types

Objectives

Many individuals have difficulty adapting to face mask use and report symptoms while using masks. Our primary objective was to determine whether continuous mask-wearing causes elevated levels of carbon dioxide (CO₂) behind the facemasks.

Methods

CO₂ concentrations were measured behind 3 different types of face masks and were compared to CO₂ concentrations at the mask front in 261 subjects who continuously wore masks for at least 5 minutes. These CO₂ concentrations were also measured in several randomly selected subjects after a 5-minute walk.

Results

There were significantly higher CO₂ concentrations behind the mask (3176 ppm) compared to the front (843 ppm) with an average of 49 minutes of continuous mask use. Of all the subjects, 76.6% had a behind-the-mask CO₂ concentration of more than 2000 ppm (the threshold for clinical symptoms), and 12.2% had a CO₂ concentration of at least 5000 ppm (occupational health exposure limit). The CO₂ level behind the N-95 masks was highest (especially after exertion) and was lowest behind cloth masks. The combination of warm ambient temperature, an N-95 mask, exercise, and young age appeared to induce exceedingly high CO₂ levels that should be avoided.

Discussion

Although masks might be necessary for healthcare workers or to lessen the spread of airborne disease, we found that elevated CO₂ concentrations were present while wearing them. Elevated CO₂ concentrations have historically caused symptoms of CO₂ toxicity. Periodic mask breaks in designated areas may be needed to avoid adverse effects.

Conclusion

The use of masks increased the CO₂ concentration in the air behind them to levels historically associated with toxicity.

SARS-CoV-2 Antibody Positivity and Prevalence in an Outpatient Medical Setting in Las Vegas, NV

Background

SARS-CoV-2 antibody testing shows the prevalence of COVID-19 disease in different communities and has epidemiological significance.

Methods

SARS-CoV-2 IgM and IgG were tested in 319 patients, staff and visitors of a primary care clinic in Las Vegas, NV on a continuous as-requested basis.

Results

Prevalence of SARS-CoV-2 antibodies was 3.76% in a primary care office in Las Vegas, NV. Positivity of IgM was 0.31% and IgG 3.44%. The most common symptoms reported amongst those who tested positive were cough, shortness of breath and loss of smell and taste. The most common comorbidities included hypertension, chronic lung disease, seasonal allergies, and type 2 diabetes mellitus, in that order.

Conclusion

Prevalence was 2.3% in Washoe County, NV in June 2020 and 3.76% in Clark County, NV in April-June 2020. This has important implications for heavily populated urban areas.

Bacillary angiomatosis associated with myositis in a patient infected with human immunodeficiency virus

A man with AIDS presented with a deep soft-tissue mass involving the right thigh. Biopsy of a skin lesion on the back and culture of a specimen from this lesion showed bacillary angiomatosis due to Bartonella (formerly Rochalimaea) quintana. Magnetic resonance imaging revealed a large heterogeneous mass involving the vastus medialis and intermedius muscles. Therapy with erythromycin caused rapid resolution of both the cutaneous lesion and the muscle lesion. Bartonella infection is proposed as an additional cause of bacterial myositis and expands the spectrum of presentation of bacillary angiomatosis.