Functions of Vti1a and Vti1b in the Development of the Mouse Nervous System: Evidence from Double Knockout Mice

Um die Homöostase aufrecht zu erhalten und adäquate Signalkaskaden in eukaryotischen Zellen zu ermöglichen, müssen Moleküle zu ihren korrekten intrazellulären Zielen transportiert werden, ohne dabei die strukturelle Integrität zellulärer Kompartimente zu beeinträchtigen. Dazu knospen Transportvesikel von intrazellulären Donororganellen ab, bewegen sich in Richtung einer Akzeptororganelle, docken an diese an und fusionieren schließlich mit ihr. SNARE (Soluble NSF attachment protein receptor)-Proteinen wurde eine zentrale Rolle bei der Steuerung der intrazellulären Lokalisationprozesse für die Membran zugeschrieben. Die SNAREs vti1a und vti1b stimmen zu 30% in ihrer Aminosäuresequenz überein und sind eindeutig aber dabei überlappend subzellulär lokalisiert. Vti1a wurde mit endosomaler Fusion und Recycling-Prozessen nach der Endozytose in Verbindung gebracht, während Vti1b mit später endosomaler Fusion und lysosomalen Abbauprozessen im Zusammenhang steht. Vti1a- und Vti1b-defiziente Mäuse, denen also beide endosomale SNARE-Proteine fehlen, sterben intrauterin kurz vor der Geburt, während Einzelknockouts und dreiallelige Mäuse überleben und ohne Probleme ein normales Alter erreichen. Diese Knockout-Mäuse zeigen Veränderungen im zentralen (ZNS) wie auch peripheren (PNS) Nervensystem. Im ZNS weisen sie geweitete Ventrikel und bestimmte Nervenfaserbahnen fehlen, unter ihnen die vordere Kommissur, die hippocampale Kommissur und mammilothalamische, spinotrigeminale, kortikospinale und pyramidale Bahnen. Die Dicke des Corpus callosum ist stark reduziert und thalamokortikale Axone können die pallio-subpalliale Grenze nicht überwinden. Andererseits erreichen nur wenige kortikothalamische Axone den Thalamus. Insgesamt weisen die Daten auf ein Defizit der Membranreorganisation hin, welches zu einem gestörten Axonwachstum führt. Zusätzlich weisen die KO-Mäuse Veränderungen des kortikalen Schichtungsmusters auf. Neurone der Schicht 5 fehlen ganz und Schicht 6 ist erweitert. Dies könnte an einer veränderten Zell Produktion der Ventrikularzone während der Entwicklung der kortikalen Schichten liegen. Die veränderte Produktivität könnte auf Störungen der Zellpolarität, dem Ausfall früher Schritte der abstammungsspezifischen Differenzierung aus neuralen Vorläufern oder beliebigen Veränderungen von Signalmolekülen, die solche Konsequenzen hervorrufen können, beruhen. Andererseits entwickeln die KO-Mäuse unterschiedlichste Ausprägungen einer Neurodegeneration verschiedener Typen von Ganglien im PNS. Trigeminale (TG), spinale (DRG) und nodosal-petrosale Ganglien weisen eine schwere Neurodegeneration (bis zu 98%) auf, während vestibuläre und cochleäre Ganglien nur 15-25% Degeneration zeigen. Diese Neurodegeneration könnte durch mangelnde Absicherung des retrograden Transports während der Entwicklung dieser Ganglien oder durch fehlende Bereitstellung einer effizienten Plasmamembran entstehen, die während der Ausbildung des axonalen Wachstumkegels benötigt wird. Das unterschiedliche Ausmaβ der Neurodegeneration in diesen Ganglien könnte durch die Distanz zwischen den Ganglien und ihren Zielgebieten erklärt werden. Im Vergleich zu TG und DRG besitzen vestibuläre und cochleäre Ganglien nahe gelegene Zielgebiete und könnten deshalb überleben. Der Gesamtphänotyp impliziert, dass vti1a- und vti1b-bezogene endosomale Funktionen kritisch für die Entwicklung des zentralen wie auch des peripheren Nervensystems sind

The overlap of accessory virulence factors and multidrug resistance among clinical and surveillance Klebsiella pneumoniae isolates from a neonatal intensive care unit in Nepal: a single-centre experience in a resource-limited setting

Background: There is a lack of data on the characteristics of overlap between acquired antimicrobial resistance and virulence factors in Klebsiella pneumoniae in high-risk settings, especially with the inclusion of surveillance isolates along with the clinical. We investigated K. pneumoniae isolates, from a neonatal intensive care unit (NICU) in Nepal, for the presence of both accessory virulence factors and acquired antimicrobial resistance. Methods: Thirty-eight clinical and nineteen surveillance K. pneumoniae isolates obtained between January 2017 and August 2022 in the NICU of Siddhi Memorial Hospital, Bhaktapur, Nepal were investigated with antimicrobial susceptibility testing, PCR-based detection of β-lactamases and virulence factors, and genetic similarity by ERIC–PCR. Results: K. pneumoniae was found positive in 37/85 (43.5%) blood culture-positive neonatal bloodstream infections, 34/954 (3.6%) patient surveillance cultures, and 15/451 (3.3%) environmental surveillance samples. Among 57 isolates analyzed in this study, we detected multidrug resistance in 37/57 (64.9%), which was combined with at least one accessory virulence factor in 21/37 (56.8%). This overlap was mostly among β-lactamase producing isolates with accessory mechanisms of iron acquisition. These isolates displayed heterogenous ERIC–PCR patterns suggesting genetic diversity. Conclusions: The clinical significance of this overlap between acquired antimicrobial resistance and accessory virulence genes in K. pneumoniae needs further investigation. Better resource allocation is necessary to strengthen infection prevention and control interventions in resource-limited settings

Sisters

I wish to express my sincere gratitude to my supervisor Prof. Dr. Kerstin Krieglstein (head of the Neuroanatomy department, faculty of medicine) for her excellent guidance and many insightful conversations during the development of the ideas in this thesis work. I am honored to have such a great personality as my mentor and I thank her for helpful comments, continuous support, fruitful scientific discussion / suggestions during my whole PhD period. I truly worship her for providing me an opportunity to learn and practice science in her lab. Her input in the early stages of my scientific career has helped me a lot to enhance my knowledge in neuroscience. My sincere thanks go to Dr. M. Rickmann for his generous support and useful guidance during my PhD work and critical reading of the thesis. I am really impressed on his knowledge about electron microscopy and neuroanatomy which also helped me to learn many things in those aspects. My deepest sincere thanks are presented to the members of the thesis committee, Prof. Dr. Ernst Wimmer for his helpful discussion during my PhD study and critical readin

Status of gastrointestinal parasites in red panda of Nepal

Red pandas are known to be highly susceptible to endoparasites, which can have a prominent impact on the population dynamics of this endangered species. There are very limited published reports on prevalence and risk of parasites in wild populations of red panda, especially localized reports. This study attempts to provide an in- depth insight of the status of endoparasites in red pandas, which is critical for strengthening conservation efforts. A total of 272 fecal samples were collected through systematic sampling across the red panda distribution range in Nepal and coprological examination was completed using standard techniques. It was followed by an estimation of prevalence and mean intensity of parasites, as well as statistical analysis, which was carried out using R statistical software. Parasite prevalence was documented in 90.80% (n=247) out of 272 samples examined which includes seven different species along with three genera of parasites belonging to Protozoans (3 species), Cestodes (1 genus, 1 species) and Nematodes (2 genera, 3 species). Nematodes predominated in all infected samples (87.62%). Prevalence of Ancyclostoma duodenale (n=227, 70.06%), having a mean intensity of 3.45 ± 2.88 individuals per sample, was observed, followed by Ascaris lumbricoides (n=19, 5.86%) and Entamoeba histolytica (n=24, 7.41%). Eight variables for assessing the determinants of infestation were tested: protected areas; non-protected areas; aspect; elevation; slope; and distance to water sources, herding stations, and settlements. Only the settlement displayed significant association (β=-1534e-04, t=-2.192, p=0.0293) though each parasite species displayed dissimilar association with different variables. This study indicates the urgent need of improving existing herding practice through habitat zonation, rotational grazing, medication of livestock, and prohibition of open defecation within and around red panda habitat

Advantage of neuroeducation in managing mass psychogenic illness among rural school children in Nepal

Introduction: Mass psychogenic illness (MPI), also known as mass hysteria (MH), is a mental health disorder that frequently occurs in Nepal. It primarily affects female students in government high schools and occurs during the course of the school day over a few days without corresponding organic causes. Purpose of the study: This study set out to evaluate and give neuroeducation with the goal of preventing and/or managing MPI after documenting the existing state of knowledge regarding MPI. Materials and methods: A total of 234 female students in grades 6 through 10 who attended MH-affected schools (SMH, n = 119) and schools without a mass hysteria history (SNOMH, n = 114) participated in this mass hysteria awareness study. Participants received written pre- and posttests formatted as questionnaires before and after receiving neuroeducation by watching a drama, viewing a human brainspinal cord model demonstration, and attending an instructive lecture on the human neurological system, stress, and mass hysteria. Results: Our neuroeducation awareness study on mass hysteria was found to be effective among all of the participants from both SMH and SNOMH. The results indicated that the aforementioned neuroeducation tools are more effective in improving knowledge about mental stress differently in different grades of SMH and SNOMH students. The basic understanding of the human neurological system was not improved by the neuroeducation tool, according to our findings. Conclusion: Our study suggests that using day-structured neuroeducational tools might be an efficient way to treat mass psychogenic illness in Nepal