Contamination of personal protective equipment during COVID-19 autopsies.

Confronted with an emerging infectious disease at the beginning of the COVID-19 pandemic, the medical community faced concerns regarding the safety of autopsies on those who died of the disease. This attitude has changed, and autopsies are now recognized as indispensable tools for understanding COVID-19, but the true risk of infection to autopsy staff is nevertheless still debated. To clarify the rate of SARS-CoV-2 contamination in personal protective equipment (PPE), swabs were taken at nine points in the PPE of one physician and one assistant after each of 11 full autopsies performed at four centers. Swabs were also obtained from three minimally invasive autopsies (MIAs) conducted at a fifth center. Lung/bronchus swabs of the deceased served as positive controls, and SARS-CoV-2 RNA was detected by real-time RT-PCR. In 9 of 11 full autopsies, PPE samples tested RNA positive through PCR, accounting for 41 of the 198 PPE samples taken (21%). The main contaminated items of the PPE were gloves (64% positive), aprons (50% positive), and the tops of shoes (36% positive) while the fronts of safety goggles, for example, were positive in only 4.5% of the samples, and all the face masks were negative. In MIAs, viral RNA was observed in one sample from a glove but not in other swabs. Infectious virus isolation in cell culture was performed on RNA-positive swabs from the full autopsies. Of all the RNA-positive PPE samples, 21% of the glove samples, taken in 3 of 11 full autopsies, tested positive for infectious virus. In conclusion, PPE was contaminated with viral RNA in 82% of autopsies. In 27% of autopsies, PPE was found to be contaminated even with infectious virus, representing a potential risk of infection to autopsy staff. Adequate PPE and hygiene measures, including appropriate waste deposition, are therefore essential to ensure a safe work environment.

Self-Organisation, Thermotropic and Lyotropic Properties of Glycolipids Related to their Biological Implications.

Glycolipids are amphiphilic molecules which bear an oligo- or polysaccharide as hydrophilic head group and hydrocarbon chains in varying numbers and lengths as hydrophobic part. They play an important role in life science as well as in material science. Their biological and physiological functions are quite diverse, ranging from mediators of cell-cell recognition processes, constituents of membrane domains or as membrane-forming units. Glycolipids form an exceptional class of liquid-crystal mesophases due to the fact that their self-organisation obeys more complex rules as compared to classical monophilic liquid-crystals. Like other amphiphiles, the supra-molecular structures formed by glycolipids are driven by their chemical structure; however, the details of this process are still hardly understood. Based on the synthesis of specific glycolipids with a clearly defined chemical structure, e.g., type and length of the sugar head group, acyl chain linkage, substitution pattern, hydrocarbon chain lengths and saturation, combined with a profound physico-chemical characterisation of the formed mesophases, the principles of the organisation in different aggregate structures of the glycolipids can be obtained. The importance of the observed and formed phases and their properties are discussed with respect to their biological and physiological relevance. The presented data describe briefly the strategies used for the synthesis of the used glycolipids. The main focus, however, lies on the thermotropic as well as lyotropic characterisation of the self-organised structures and formed phases based on physico-chemical and biophysical methods linked to their potential biological implications and relevance.

Structural polymorphism of hydrated monoacylated maltose glycolipids.

The physico-chemical properties of three fully hydrated monoacyl maltoside glycolipids were investigated with Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS). The different synthesized maltoside glycoconjugates vary in the length and saturation of the fatty acid moiety, whereas the constant head group region contains a beta-linked maltose with a OC(2)-NH spacer. The compounds with saturated acyl chains showed a complex pattern of temperature-dependent behaviour, regarding the adopted three-dimensional aggregate structure of the molecules and the main phase transition from the gel to liquid crystalline phase of the acyl chains. A substitution of the saturated acyl chain with an unsaturated acyl chain led to a complete change of the structural preferences, from a high ordered stacking of the bilayers to an unilamellar arrangement of completely disordered and fluid membranes. The presence of the NH group in the spacer, compared to the compounds lacking the NH group allows the formation of a hydrogen bonding network, which influences the observed phase properties. The results of these studies of the hydrated monoacylated maltose glycolipids are discussed in relation to the thermotropic phase properties of the pure compounds in the absence of water.

Self-assembly properties of alkyloxyethyl beta-glycosides with different types of carbohydrate headgroups.

The effect of alkyl chain length on micelle formation in aqueous solutions of synthetic alkyloxyethyl glycosides containing an ethyl spacer with different conformations of the disaccharide headgroups was investigated. The molecular shape was systematically changed from a wedge-shaped to a rodlike geometry by changing the type of carbohydrate headgroup. The lipophilic part consists of dodecyl or tetradecyl chains. The adsorption at the liquid-air interface was investigated by surface tension measurements. The micellar phase region (L1) was studied using small-angle neutron scattering. We have observed a strong influence of the linkage between the sugar moieties in the disaccharide headgroup and the ethyl spacer on the micellar structure: the transformation from spherical to disklike aggregates was observed for compounds with a rodlike shape, but only spherical aggregates were formed by the wedge-shaped molecules.

Structural preferences of dioleoyl glycolipids with mono- and disaccharide head groups.

The structural preferences of 1,2-dioleoyl-sn-glycerol glycolipids with glucose, galactose, maltose, and cellobiose as sugar head group were investigated under near physiological conditions with Fourier-transform infrared spectroscopy (FT-IR) and synchrotron radiation small-angle X-ray scattering (SAXS). Whereas all glycolipids have a very high fluidity at temperatures above 0 degrees C, the mono- and disaccharide compounds differ considerably in their aggregate structures. The monosaccharide compounds adopt only inverted hexagonal (H(II)) structures in the temperature range 5-70 degrees C, while the disaccharide compounds adopt only multilamellar structures. Since these and similar glycolipids are frequently found in nature, these data should be of relevance for the function of their host cell membranes.

Mixed micelles formed by SDS and a bolaamphiphile with carbohydrate headgroups.

The formation of micelles in aqueous mixtures of a carbohydrate-based bolaamphiphile and sodium dodecyl sulfate (SDS) is investigated by surface tension and small-angle neutron scattering. The obtained values of critical micelle concentration (CMC) are analyzed within the framework of regular solution theory. Synergetic interactions between the bolaamphiphile and SDS are observed (parameter beta is negative; a minimum in the plot CMC vs composition). SANS data are collected for mixtures containing protonated and deuterated SDS. This gives us the possibility to conclude that mixed micelles with a homogeneous distribution of surfactant molecules within the micelle are formed. The shape of the micelles is found to be slightly oblate.

Synthesis and mesomorphic properties of glycosyl dialkyl- and diacyl-glycerols bearing saturated, unsaturated and methyl branched fatty acid and fatty alcohol chains. Part I. Synthesis.

Glycosyl dialkyl- and diacyl-glycerols bearing saturated, unsaturated or chiral methyl branched chains in the tail and disaccharide and trisaccharide carbohydrate headgroups were synthesised. Standard procedures were used for the preparation of the educts and the glyco lipids: trichloracetimidate procedure for the preparation of long-chained compounds, glycosylation using the beta-peracetate and boron trifluoride etherate was successful for the preparation of lipids with a medium-alkyl chain length. Preparation of the ester was afforded in a multi-step synthesis according to published procedures. Thus, several lipids were synthesised in a few synthetic steps in good yields. The introduction of unsaturated or methyl branched chains lead to liquid crystallinity at ambient temperature, because these compounds will be used as model compounds for biological systems. The biophysical properties of these compounds will be reported in a following paper.

Synthesis and mesomorphic properties of glycosyl dialkyl- and diacyl-glycerols bearing saturated, unsaturated and methyl branched fatty acid and fatty alcohol chains. Part II. Mesomorphic properties.

The biophysical properties of a series of glycosyl dialkyl- and diacyl-glycerols bearing unsaturated or chiral methyl branched chains in the tail, and di- and trisaccharide carbohydrate headgroups are described. Thermotropism was investigated by polarising microscopy, the lyotropism was investigated by small angle X-ray diffraction and by the contact preparation method, and the gel to liquid crystalline phase transition by FT-IR-spectroscopy. The compounds displayed thermotropic Smectic A (SmA), cubic and columnar phases, whereas in the lyotropic phase diagram lamellar, hexagonal and cubic phases are found. The introduction of unsaturated or methyl branched chains leads to liquid crystallinity at ambient temperature. The difference between the 1,3-oleyl-glycerol maltoside and the corresponding 1,2-oleoyl-glycerol maltoside is small.