Study on the additive protective effect of PGLYRP3 and Bifidobacterium adolescentis Reuter 1963 on severity of DSS-induced colitis in Pglyrp3 knockout (Pglyrp3 −/−) and wild-type (WT) mice

Background and AimsPglyrp3 is a bactericidal innate immunity protein known to sustain the habitual gut microbiome and protect against experimental colitis. Intestinal inflammation and metaflammation are commonly associated with a marked reduction of commensal bifidobacteria. Whether Pglyrp3 and bifidobacteria interact synergistically or additively to alleviate metaflammation is unknown. We investigated the extent to which Pglyrp3 and bifidobacteria regulate metaflammation and gut bacterial dysbiosis in DSS-induced mouse models of intestinal inflammation.Material & Methods8–10 weeks old male mice were used. In both WT and Pglyrp3 ?/? experiments, the mice were randomly divided into three groups of 16 mice per group: (1) a control group receiving sterile tap water, (2) an experimental group receiving sterile tap water supplemented with only 5% DSS, and (3) an experimental group receiving sterile tap water supplemented with 5% DSS and 1 × 10⁹ CFU/ml of Bifidobacterium adolescentis (B.a.) for 7 days. Wild-type (WT) littermates of the respective gene (i.e. Pglyrp3) were used as controls throughout the study. Clinical signs of general health and inflammation were monitored daily. Faecal pellet samples were analysed by qRT-PCR for microbial composition. Histology of relevant organs was carried out on day 8. Metabolic parameters and liver inflammation were determined in serum samples.ResultsIntestinal inflammation in mice of group 2 were significantly increased compared to those of control group 1. There was a significant difference in mean scores for inflammation severity between DSS-treated WT and DSS-treated Pglyrp3 ?/? mice. Buildup of key serum metabolic markers (cholesterol, triglyceride and glucose) was set off by colonic inflammation. qRT-PCR quantification showed that DSS significantly decreased the Clostridium coccoides and Bifidobacterium cell counts while increasing those of Bacteroides group in both WT and Pglyrp3 ?/? mice. These manifestations of DSS-induced dysbiosis were significantly attenuated by feeding B.a. Both the local and systemic ill-being of the mice alleviated when they received B.a.DiscussionThis study shows that Pglyrp3 facilitates recognition of bifidobacterial cell wall-derived peptidoglycan, thus leading additively to a reduction of metaflammation through an increase in the number of bifidobacteria, which were able to mitigate intestinal immunopathology in the context of Pglyrp3 blockade.     

Gastric mucosa lesions induced by duodenogastric reflux increase penetration of N-[3H]-methyl-N-nitro-N-nitrosoguanidine into corpus mucosa of rats

The mucosal changes by which duodenogastric reflux may predispose to gastric cancer have not been fully clarified. In this study in rats, duodenal fluid was directed into the stomach through a gastroenterostomy (jejunal reflux, N = 29) or through the pylorus (pyloric reflux, N = 30) and compared with 30 controls. Twenty-four weeks later the stomach was exposed to N-[³H]methyl-N-nitro-N-nitrosoguanidine ([³H]MNNG). The corpus mucosa was examined for proliferating cells (bromodeoxyuridine labeled) and cells at risk of methyl-N-nitro-N-nitrosoguanidine-induced carcinogenesis (cells labeled with bromodeoxyuridine and [³H]MNNG). The number of double-labeled cells increased from 0.8 ± 0.1/mm mucosa in the control group to 5.2 ± 0.9 in the jejunal reflux group (P < 0.05) and 2.7 ± 0.5 in the pyloric reflux group (P < 0.05). An erosion or ulcer appeared at the gastroenterostomy in 52% of animals with jejunal reflux and 17% of those with pyloric reflux (P < 0.006). Within erosions the mean number of double-labeled cells was 9.6 ± 2.2 in the jejunal reflux group and 7.7 ± 4.8 in the pyloric reflux group, and significantly higher than in the nonlesion area of the mucosa (0.6 ± 0.2 and 0.8 ± 0.3). In erosions the distance between the gastric lumen and the proliferating cells was significantly shorter and the cell proliferation significantly higher than in the nonlesion area of the mucosa. We conclude that duodenogastric reflux increases the penetration of [³H]MNNG into the corpus mucosa of rats and also induces mucosa lesions, which further increase the penetration of [³H]MNNG into the corpus mucosa.     

Method to quantify accuracy of position feedback signals of a three-dimensional two-photon laser-scanning microscope

Two-photon laser-scanning microscopy enables to record neuronal network activity in three-dimensional space while maintaining single-cellular resolution. One of the proposed approaches combines galvanometric x-y scanning with piezo-driven objective movements and employs hardware feedback signals for position monitoring. However, readily applicable methods to quantify the accuracy of those feedback signals are currently lacking. Here we provide techniques based on contact-free laser reflection and laser triangulation for the quantification of positioning accuracy of each spatial axis. We found that the lateral feedback signals are sufficiently accurate (defined as <2.5 µm) for a wide range of scan trajectories and frequencies. We further show that axial positioning accuracy does not only depend on objective acceleration and mass but also its geometry. We conclude that the introduced methods allow a reliable quantification of position feedback signals in a cost-efficient, easy-to-install manner and should be applicable for a wide range of two-photon laser scanning microscopes.OCIS codes: (180.6900) Three-dimensional microscopy, (180.4315) Nonlinear microscopy, (170.0180) Microscopy, (170.2520) Fluorescence microscopy, (180.2520) Fluorescence microscopy     

From the Cover: COVID-19 lockdown induces disease-mitigating structural changes in mobility networks

In the wake of the COVID-19 pandemic many countries implemented containment measures to reduce disease transmission. Studies using digital data sources show that the mobility of individuals was effectively reduced in multiple countries. However, it remains unclear whether these reductions caused deeper structural changes in mobility networks and how such changes may affect dynamic processes on the network. Here we use movement data of mobile phone users to show that mobility in Germany has not only been reduced considerably: Lockdown measures caused substantial and long-lasting structural changes in the mobility network. We find that long-distance travel was reduced disproportionately strongly. The trimming of long-range network connectivity leads to a more local, clustered network and a moderation of the “small-world” effect. We demonstrate that these structural changes have a considerable effect on epidemic spreading processes by “flattening” the epidemic curve and delaying the spread to geographically distant regions.

During the first phase of the coronavirus disease 2019 (COVID-19) pandemic, countries around the world implemented a host of containment policies aimed at mitigating the spread of the disease (1–4). Many policies restricted human mobility, intending to reduce close-proximity contacts, the major driver of the disease’s spread (5). In Germany, these policies included border closures, travel bans, and restrictions of public activity (school and business closures), paired with appeals by the government to avoid trips voluntarily whenever possible (6). We refer to these policies as “lockdown” measures for brevity.Based on various digital data sources such as mobile phone data or social media data, several studies show that mobility significantly changed during lockdowns (7). Most studies focused on general mobility trends and confirmed an overall reduction in mobility in various countries (8–12). Other research focused on the relation between mobility and disease transmission: For instance, it has been argued that mobility reduction is likely instrumental in reducing the effective reproduction number in many countries (13–17), in agreement with theoretical models and simulations, which have shown that containment can effectively slow down disease transmission (18–20).However, it remains an open question whether the mobility restrictions promoted deeper structural changes in mobility networks and how these changes impact epidemic spreading mediated by these networks. Recently, Galeazzi et al. (21) found increased geographical fragmentation of the mobility network. A thorough understanding of how structural mobility network changes impact epidemic spreading is needed to correctly assess the consequences of mobility restrictions not only for the current COVID-19 pandemic, but also for similar scenarios in the future.Here, we analyze structural changes in mobility patterns in Germany during the COVID-19 pandemic. We analyze movements recorded from mobile phones of 43.6 million individuals in Germany. Beyond a general reduction in mobility, we find considerable structural changes in the mobility network. Due to the reduction of long-distance travel, the network becomes more local and lattice-like. Most importantly, we find a changed scaling relation between path lengths and geographic distance: During lockdown, the effective distance (and arrival time in spreading processes) to a destination continually grows with geographic distance. This shows a marked reduction of the “small-world” characteristic, where geographic distance is usually of lesser importance in determining path lengths (22, 23). Using simulations of a commuter-based susceptible-infected-removed (SIR) model, we demonstrate that these changes have considerable practical implications as they suppress (or “flatten”) the curve of an epidemic remarkably and delay the disease’s arrival between distant regions.     

Total leisure noise exposure and its association with hearing loss among adolescents

Objective: To investigate total leisure noise exposure among adolescents and to assess its association with hearing. Design: Based on self-reported time spent on 19 leisure activities and associated mean sound pressure levels reported in the literature, total leisure noise exposure was evaluated and compared to noise at work limits (> 85 dB(A) = hazardous) in a cross-sectional survey. Tympanometry and pure-tone audiometry was performed in sound isolated rooms. Study sample: The study sample consists of 2143 pupils attending grade nine in any school in a German city 2009–2011 (mean age: 15.4 years; range: 13–19 years). Audiometric data were available for 1837 (85.8%) pupils (53.9% girls). Results: 41.9% of the 2143 adolescents who had provided self-reported data on leisure activities associated with noise exposure were estimated to be hazardously exposed to leisure time noise. The interaction of gender with total leisure time noise exposure was not significant. No association between leisure time noise exposure and audiometric notches could be detected. Conclusion: While hearing loss seems seldom in this age group, a high proportion of adolescents aged 15–16 years are exposed to noise levels during leisure time bearing long-term risks of hearing loss.     

A new silent germline mutation of the TSH receptor: coexpression in a hyperthyroid family member with a second activating somatic mutation.

BACKGROUND: Up to date, three thyroid-stimulating hormone receptor (TSHR) germline variants have been reported for which no functional consequences have been detected by in vitro characterizations. However, familial nonautoimmune hyperthyroidism and hot nodules are clearly associated with constitutively activating TSHR germline mutations. We describe a family with a new TSHR germline mutation that is associated with euthyroidism in 13 family members and hyperthyroidism in 1 family member. METHODS: Mutation analysis of the TSHR gene was performed by denaturing gradient gel electrophoresis. TSHR constructs were characterized by determination of cell surface expression, 3'-5'-cyclic adenosine monophosphate (cAMP) accumulation, and constitutive cAMP activity. RESULTS: A novel TSHR germline mutation (N372T) was found in a man who presented with thyrotoxicosis. The mutation was also detected in 13 family members, all of whom were euthyroid. Interestingly, an additional constitutively active somatic mutation (S281N) was identified on the second parental TSHR allele of the hyperthyroid index patient. Linear regression analysis showed a lack of constitutive activity for N372T. Moreover, coexpression studies of N372T with S281N did not reveal any evidence for a functional influence of N372T on the constitutively active mutation (CAM). CONCLUSIONS: N372T is unlikely to cause altered thyroid function. This is consistent with the finding that only the index patient with the additional somatic mutation S281N was hyperthyroid.