The sensitivity of SARS-CoV-2 antigen tests in the view of large-scale testing.

OBJECTIVES: Antigen tests have emerged as an alternative to SARS-CoV-2 diagnostic PCR, thought to be valuable especially for the screening of bigger communities. To check appropriateness of the antigen based testing, we determined sensitivity of two point-of-care antigen tests when applied to a cohort of COVID-19 symptomatic, COVID-19 asymptomatic and healthy persons. METHODS: We examined nasopharyngeal swabs with antigen test 1 (Panbio Covid-19 Ag Rapid Test, Abbott) and antigen test 2 (Standard F Covid-19 Ag FIA, SD Biosensor). An additional nasopharyngeal and oropharyngeal swab of the same individual was checked with PCR (Allplex SARS-nCoV-2, Seegene). Within a 4-day period in October 2020, we collected specimens from 591 subjects. Of them, 290 had COVID-19 associated symptoms. RESULTS: While PCR positivity was detected in 223 cases, antigen test 1 and antigen test 2 were found positive in 148 (sensitivity 0.664, 95%CI 0.599, 0.722) and 141 (sensitivity 0.623, 95%CI 0.558, 0.684) patients, respectively. When only symptomatic patients were analysed, sensitivity increased to 0.738 (95%CI 0.667, 0.799) for the antigen test 1 and to 0.685 (95%CI 0.611, 0.750) for the antigen test 2. The substantial drop in sensitivity to 12.9% (95%CI 0.067, 0.234) was observed for samples with the PCR threshold cycle above > 30. CONCLUSIONS: Low sensitivity of antigen tests leads to the considerable risk of false negativity. It is advisable to implement repeated testing with high enough frequency if the antigen test is used as a frontline screening tool, and to follow with PCR if it is applied to vulnerable populations.

Effects of sinusoidal magnetic field on adherence inhibition of leucocytes: preliminary results.

The leucocyte surface properties manifest the cell-mediated immunity. The response of the cell-mediated immunity to external magnetic field was examined by observing leucocyte adherence to solid state surfaces. In the presence of antigen, leucocytes taken from cancer patients exhibit decreased adherence in contrast with adherence of leucocytes from healthy humans. After 1 h exposure to a sinusoidal magnetic field of 50 Hz and of 1 mT or 10 mT, adherence of leucocytes taken from cancer patients is strongly increased. The 1 mT magnetic field has stronger effect than the 10 mT field.

Effects of magnetic field exposure on the development of lung fibrosis elicited by industrial pollutants.

Lung injury elicited by a single intratracheal instillation of fibrogenic (quartz) and nuisance (anatase) dusts and/or weekly repeated instillation of CdCl2 solution combined with sinusoidal (50 Hz, 10 mT) magnetic field (MF) exposure was studied in male rats. Combined effects in bronchoalveolar lavage (BAL), rat lungs and regional lymph nodes after 4 months of MF exposure (1 h/5 days per week) were evaluated biochemically and by cytological and histopathological examination. Damage of cell membranes in the cell part of BAL due to MF exposure was not observed in the examined animal groups. Following MF exposure, decreased synthesis of collagen proteins (incorporation of [14C]proline) was demonstrated in lungs with quartz dust burden. Histological examination revealed differences in the lung tissue reaction suggesting the modification of the repair process due to MF exposure following experimental injury in both quartz and cadmium groups.

Sodium bis(hydroxyethyl)dithiocarbamate reduces acute lung tissue damage induced by cadmium in rats.

The protective effect of three dithiocarbamates against lung tissue damage induced by a single intratracheal instillation of cadmium chloride was examined in rats. The relative efficacy of these compounds was tested by comparing characteristic features of lung tissue damage: the increase of lung weight, and the changes in the synthesis and content of structural proteins. Of three compounds administered intraperitoneally at a dose of 2.46 mmol/kg body weight, the most effective in suppressing lung damage was sodium bis(hydroxyethyl)dithiocarbamate (DEDTC). Its efficacy was dependent on the time interval between administration of cadmium chloride and the DEDTC. The parameters of lung tissue damage which were examined approached control values when DEDTC and cadmium chloride were administered simultaneously.

Sulfated glycosaminoglycans in rat bronchopulmonary lavage: detection after in vivo labelling.

Sulfated macromolecules occurring in bronchoalveolar lavage fluid supernatant were radiolabelled in vivo by 35SO4, that was insufflated via trachea. DEAE-Sephacel chromatography dissociated sulfated glycoproteins, presumably of tracheobronchial mucus origin, from a minor, but heavily labelled component. Degradative analysis and acetyl cellulose electrophoresis identified this component as a mixture of heparan sulfate and chondroitin sulfate proteoglycans.

Ethics in health sciences librarianship.

Against a background of discussion about drafting of an ethical code for librarians and a review of articles confronting ethical issues in librarianship, the authors surveyed the 150 institutional members of the Health Science Librarians of Illinois (HSLI) regarding their perceptions of ethical concerns. Among the issues addressed in the survey are library organization, personnel policies, and professional competency, along with the traditional concerns of professional versus personal values, privacy and confidentiality, access to materials, and materials selection criteria in a health sciences context. Based on a 60% response rate, survey results indicate widespread agreement on some issues and a conspicuous lack of consensus on others. Further research is suggested in order to assess the need for a separate ethical code for health sciences librarians.

Stimulation of alveolar macrophages by mineral dusts in vitro: luminol-dependent chemiluminescence study.

Luminol-dependent chemiluminescence (CL) of normal (nonactivated) rabbit alveolar macrophages (AMs) was measured in suspension upon stimulation by various size fractions of one quartz dust sample or by various mineral dusts (quartz, corundum, anatas, and chrysotile asbestos as an example of fibrous dust). The CL-triggering capacity of the tested dusts was inhibited by their preincubation with autologous serum. The intensity of luminol-dependent CL induced by particulate dusts upon their action on AMs depended on the kind of dust, on the dust particle sizes, and on the ratio of the number of particles to the number of cells in a given suspension. The cytotoxicity and/or fibrogenicity of the dust and its capacity to trigger the luminol-dependent CL of nonadherent AMs were not directly correlated.

Sulfated glycosaminoglycans in rat lung tissue during experimental silicotic fibrosis.

The biosynthesis of sulfated glycosaminoglycans (GAG) was studied in healthy and fibrotic lung tissue (experimental silicosis). Male rats received a single intratracheal instillation of 25 mg quartz dust (DQ 12) in 0.7 ml saline and were sacrificed at days 15, 30, 90, 150 and 240 after the insult. GAGs were labeled in vivo by i.p. (intraperitoneal) administration of [35S] sulfate. The concentration of GAGs in delipidated dry tissue was unaffected, however, the uptake of [35S] sulfate into silicotic lung tissue was significantly higher than in controls. Identification of sulfated GAGs isolated from pooled samples by DEAE-cellulose chromatography was achieved by electrophoresis and chondroitinase digestion. The most marked change in the label distribution among individual GAGs occurred with regard to dermatan sulfate. The fraction of label in dermatan sulfate was elevated in silicotic lung.

Changes in pulmonary connective tissue proteins after a single intratracheal instillation of cadmium chloride in the rat.

Changes of soluble and insoluble fractions of pulmonary connective tissue proteins were studied in rats for 2-84 days following a single intratracheal instillation of cadmium chloride (10 micrograms Cd2+/lung). A transient decrease in body weight and an immediate increase in lung wet weight (200% of control value, P less than 0.01) were observed. Incorporation of [14C]proline and its conversion to [14C]hydroxyproline in vivo into different soluble and insoluble fractions of connective tissue revealed an increased metabolic turnover elicited by cadmium intoxication. A lag in the maturation of collagen into higher functional forms in the early phase of the process was demonstrated. A striking decrease in elastin was found in first 7 days (40-50%). However, this acute damage of pulmonary connective tissue was followed by a permanent increase of collagen and elastin concentration in the later phase of recovery. Histopathologic examination 14-84 days after cadmium instillation confirmed the presence of lesions in pulmonary tissue with an initial inflammation followed by reparatory changes.

Analysis of the renal tissue of a woman chronically exposed to cadmium.

In a 61-year-old woman, who had been exposed for 20 years to cadmium in the production of Ni-Cd batteries, nephrectomy of the contracted kidney was performed. The removed kidney was examined histologically and the cadmium concentration was determined in the cortex (44.97 micrograms g-1) and in the medulla (7.71 micrograms g-1). The homogenates of the renal cortex and medulla were subjected to gel filtration on Sephadex G-75. In the cortex, as well as the medulla, cadmium was predominantly found in the low-molecular (metallothionein) fraction, but in the cortex, Cd content in this fraction was six times higher than in the medulla. The determination of SH groups and proteins in high- and low-molecular fractions indicates an induction of the metallothionein formation primarily in the renal cortex.

The chemiluminescence of rabbit alveolar macrophages induced by quartz dust particles.

Quartz dust particles (respirable fraction) triggered luminol-dependent chemiluminescence (CL) when added to unstimulated rabbit alveolar macrophages (AM). It was shown by increasing the dust dose added to the same amount of cells, and conversely, that the intensity of chemiluminescent reaction depended on the ratio cells:dust particles. The ratio giving maximum CL yield was estimated.

Changes in pulmonary connective tissue after a single intratracheal instillation of papain in the rat.

The effect of a single intratracheal instillation of 2 mg of papain on metabolic changes of collagen and elastin in lungs was studied in rats labeled with [14C]proline in vivo. The total amount, concentration, specific and total radioactivity of both proteins were examined during the 28 days after papain administration. In the early period (1 to 3 days) a loss of elastin content (about 50% of control; p less than 0.01) was found, whereas collagen content increased (p less than 0.05). Simultaneously, the specific as well as the total radioactivity of both proteins was enhanced (p less than 0.01) which indicated an accelerated biosynthesis and metabolic turnover. This fact was reflected in the increased amounts of both collagen and elastin in the lungs 14 and 28 days after instillation of the enzyme. The changes in connective tissue proteins accompanied a large increase in lung weight (200% that of the control rats; p less than 0.01) immediately after the exposure. Toward the end of the 28-day period, the increase was smaller. The enzymatic damage probably induced the formation of nonfunctional elastin and fibrous scars as a consequence of the healing process.