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Sex-related functional outcome after periacetabular osteotomy in mild to severe hip dysplasia
(2025)
Aims
Periacetabular osteotomy (PAO) is well established for acetabular reorientation and has shown successful improvement in patient-reported outcome measures (PROMs). Nevertheless, studies focusing on postoperative outcomes related to patient individual factors are still underrepresented. Therefore, this study aimed to analyze the functional outcome and activity level in relation to patient sex with a minimum follow-up of two years after PAO for mild to severe hip dysplasia.
Methods
A single-centre study was conducted, enrolling patients undergoing PAO and completing a preoperative and postoperative radiological and clinical outcome assessment. The PROMs were assessed using the modified Harris Hip Score (mHHS), the Hip disability and Osteoarthritis Outcome Score (HOOS) with the subscales for pain, sport, activities of daily living (ADL), and quality of life (QoL), and the University of California, Los Angeles (UCLA) activity score. Kendall’s tau were calculated for correlation analyses.
Results
In total, 145 patients (28 male, 117 female) were included. The PROMs improved significantly across males and females at the latest follow-up. Female patients had significantly lower preoperative PROMs: mHHS (47 vs 57.4; p = 0.002); HOOS pain (44.9 vs 60; p = 0.003), sport (47 vs 57.4; p = 0.002), ADL (58.9 vs 69.3; p = 0.032), and QoL (26.8 vs 39.3; p = 0.009); and UCLA (5.6 vs 6.7, p = 0.042) scores. Males showed higher postoperative UCLA scores (7.5 vs 6.7; p = 0.03). Kendall’s tau showed significant negative correlation between BMI and UCLA scores in females and males (-0.21 to -0.29; p = 0.002/0.048), while BMI and HOOS sport (-0.16; p = 0.015) and ADL (-0.2; p = 0.003), as well as QoL (-0.14; p = 0.031) and preoperative acetabular inclination (-0.13; p = 0.049) were only significantly negatively correlated in females.
Conclusion
Patient sex affects PROMs before and after PAO. Female patients experience higher improvement in hip function and activity level, due to poorer preoperative PROMs than males. Thus, these data are particularly interesting in providing preoperative guidance regarding postoperative outcome expectations.
Introduction
Mental illness stigma is associated with a range of negative consequences, such as reduced help-seeking for mental health problems. Since stigma affects individual, social, and structural aspects, multilevel interventions such as the Canadian programme The Working Mind have been proven to be the most effective. Given the solid evidence base for The Working Mind, it is our aim to implement and evaluate culturally adapted versions of the programme in German higher education, targeting students, employees and managers.
Methods and analysis
We will evaluate the programme with regard to its effect on mental illness stigma, openness to mental health problems, willingness to seek help, and positive mental health outcomes. Further, we will investigate the programme’s effectiveness dependent on gender and personal values, various mechanisms of change, and factors facilitating and hindering implementation. The study uses a sequential explanatory mixed-methods evaluation design (QUAN → qual) that consists of three steps: (1) quasi-experimental online survey with programme participants, (2) focus groups with programme participants, and (3) qualitative interviews with programme stakeholders. The quantitative data collected in step 1 will be analysed using 2×3 analysis of variances and a parallel multiple mediation analysis. The results will inform the qualitative data to be collected in steps 2 and 3, which will be analysed using qualitative content analysis.
Ethics and dissemination
The study was approved by the local Ethics Committee (Ethics Committee of University Medicine Greifswald; BB 098/23). Participants have to provide written consent before taking part in a focus group or interview. As for the online survey, participants have to give their consent by agreeing to an online data protection form before they can start completing the survey. We will publish central results and the anonymised data in an Open Access Journal. Further, the statistical code will be included as a supplement to the paper(s) documenting the results of the study.
Trial registration number
DRKS00033523.
Skeletal muscle is a dynamic tissue with high plasticity which maintains its functionality by regulating the balance between protein degradation and protein synthesis. In response to injury and other pathological conditions like inflammation and sepsis, a loss in muscle mass (muscle atrophy) and function (metabolic homeostasis, contractility) occurs. Critically ill septic patients often develop intensive care unit-acquired weakness (ICUAW), characterized by muscle weakness and atrophy as well as insulin resistance. Sepsis and inflammation are major risk factors for ICUAW. However, the pathogenesis of this syndrome is poorly understood but a disturbed glucose homeostasis and an enhanced inflammation are implicated. Previous RNA sequencing and quantitative real-time polymerase chain reaction (qRT-PCR) analyses of RNAs isolated from human M. vastus lateralis of critically ill patients and muscles from septic mice revealed an increased expression of the protein tyrosine phosphatases protein tyrosine phosphatase 1 B (PTP1B/PTPN1) and t-cell protein tyrosine phosphatase (TCPTP/PTPN2). In parallel a decreased expression of insulin receptor substrate (IRS) 1 and reduced insulin receptor (INSR) phosphorylation indicative for insulin resistance was observed. Because PTP1B and TCPTP are nodal enzymes in insulin and cytokine signaling in skeletal muscle and immune cells these data suggested their involvement in inflammation-mediated insulin resistance and skeletal muscle atrophy. I hypothesized that PTP1B and TCPTP are major regulators of insulin signaling and inflammation via dephosphorylation of cytokine receptor associated proteins in skeletal muscle. To investigate the mechanism responsible for Ptpn1 and Ptpn2 upregulation during inflammation I treated C2C12 myocytes with the inflammatory cytokine interleukin 6 (IL-6). IL-6 increased the expression of Ptpn1 and Ptpn2. Using small interfering RNA (siRNA) and chemical inhibitors, I found that this effect was mediated by the transmembrane IL-6 receptor glycoprotein 130 (Gp130) and the downstream kinases Janus kinase 2 (JAK2) and Signal transducer and activator of transcription 3 (STAT3). IL-6 facilitates its pro- and anti-inflammatory effects through the transcription factor STAT3, which gets tyrosine phosphorylated, translocates into the nucleus and modulates the expression of IL-6 responsive genes, such as suppressor of cytokine signaling 3 (Socs3). Overexpression of PTP1B and TCPTP attenuated IL-6 mediated STAT3 tyrosine phosphorylation and Socs3 gene expression. Overexpression of PTP1B but not TCPTP inhibited insulin mediated phosphorylation of the insulin receptor beta chain and its downstream targets IRS1, Akt (protein kinase B), and Akt substrate of 160 kDa (AS160) in C2C12 myocytes. To investigate the role of PTP1B and TCPTP in skeletal muscle in vivo, I generated male and female mice devoid of Ptpn1 (Ptpn1 cKO), Ptpn2 (Ptpn2 cKO) and Ptpn1+Ptpn2 (DKO) in myocytes. I subjected these mice to polymicrobial sepsis for 24 hours or 96 hours employing cecal ligation and puncture surgery (CLP). Sham treated male and female KO and wildtype (WT) mice served as controls. Septic DKO mice showed a higher mortality compared to their sham operated littermates and septic WT mice. Morphological and histological analyses showed a higher muscle mass loss and more muscle atrophy, tissue leucocyte infiltration and leucocyte marker gene expression in muscle of septic DKO mice. This was accompanied by an increased pro-inflammatory cytokine signature with increased amounts of interleukin 1 beta (IL-1β/Il1b), tumor necrosis factor alpha (TNFα/Tnfa), interferon gamma (IFNγ/Ifng) and IL-6/Il6 in skeletal muscle and serum of septic DKO mice. Chemokines that are chemo attractants for immune cells, like C-C-motif ligand 2 and 5 (Ccl2, Ccl5) and C-X-C motif ligands 9 and 10 (Cxcl9, Cxcl10) were upregulated on gene expression level in muscle tissue as well as in serum of septic DKO mice compared to septic WT mice. Additionally, I observed an increased NLR family pyrin domain containing 3 (NLRP3) -inflammasome activation in muscle of septic DKO mice. Inflammasomes are multiprotein complexes which facilitate innate immune responses after infection by activation of caspases which cleave and mediate the release pro-inflammatory cytokines like IL-1β and interleukin 18 (IL-18). In addition, using global proteomics analyses I observed a significantly dysregulated interferon γ (IFNγ) response in TA muscle of septic DKO mice shown by increased IFN stimulated gene (ISG) expression, increased abundancy of interferon regulatory factor 1 (IRF1) transcription factor as well as increased IFN-dependent chemokine expression. Utilizing murine myocytes in vitro and treating them with IFNγ, I reproduced the phenotype seen in mice. These data are indicative for a myocyte specific phenotype. I could also activate the NLRP3 inflammasome in primary myocytes from mice that were differentiated into myotubes. In these cells I show that the release of IL-1β and GSDMD is dependent on PTP1B and TCPTP; further validating the results seen in TA muscle of septic mice. In summary, deficiency of PTP1B and TCPTP caused a hyperinflammatory systemic and skeletal muscle phenotype which was caused by a dysregulated IFNγ and NLRP3 inflammasome response to infection. Furthermore, it pronounces the role of skeletal muscle as a highly immunomodulatory organ, which is crucial in maintaining whole body proteo- and homeostasis. Therefore, inhibition of PTPs should be carefully evaluated in a clinical setting.
Global climate change and biological invasions are reshaping biodiversity worldwide, particularly in semi-enclosed seas like the North Sea, Baltic Sea, and the Arctic Ocean, where rapid warming drives poleward species range shifts. These shifts depend on complex ecological and evolutionary processes, with multiple environmental drivers often interacting unpredictably. This underscores the use of multi-driver studies to unravel the interactive effects of co-occurring environmental drivers and ecologically relevant intraspecific variability. Because sympatric species might react differently to such change, interspecific comparisons are important in predicting potential changes in community composition. In benthic marine invertebrates with complex life cycles, larvae are the main dispersive life stages that can reach and colonise new habitats. Typically, there is a substantial variation in the magnitude of environmental effects between life stages, with larvae forming an important bottleneck in a population's ability to persist in a habitat.
Coastal crabs are key species that play critical roles in food webs, functioning as both predators and prey, as well as ecosystem engineers that shape their habitats. They are also among the most successful marine invasive species. Using larvae of ecologically relevant coastal decapod crustaceans as models, this thesis investigates inter- and intraspecific variability across environmental gradients and elucidates its role in climate-driven range shifts. Using two model systems, (1) the interactive effect of salinity and temperature on larval development in invasive populations of two Hemigrapsus species, H. takanoi and H. sanguineus, along a salinity gradient from the North Sea to the Baltic Sea, and (2) the variability of larval traits like temperature tolerance in C. maenas across a temperature gradient in its native range along the European Atlantic coast were investigated. Based on individual studies on intraspecific variation, comparisons could be drawn among the three species, the native C. maenas and the two non-native species.
Larval rearing experiments in factorial designs assessed survival, duration of development, and growth across environmental treatments, with larvae sourced from multiple populations and females. In the first part (Manuscript 1 & 2), the thesis demonstrates that both Hemigrapsus spp. found in Europe exhibit increased survival, developmental and growth rates compared to the native species at combinations of high temperatures and low salinities. Comparing populations of H. takanoi, a surprising lack of adaptations to low salinities was found in populations from the Baltic Sea. Larvae from the higher salinity areas in the North Sea showed higher survival and faster development than the populations from the Baltic Sea, with the population from the range edge showing poor performance across treatments. Accompanying population genetics analysis revealed no significant genetic separation among populations, indicating persistent connectivity among populations. In combination with the very low survival in the population from the range edge and the low salinity of the area, a source-sink dynamic among populations or complex ontogenetic migration patterns appear likely.
In the second part (Manuscript 3 & 4), variability in larval traits, such as temperature tolerance was studied along a large latitudinal gradient in C. maenas. a strong increase in the body mass of freshly hatched larvae with latitude was found across 35° latitude of the native distribution range. Further, considerable variations in thermal tolerance across the range of this species were detected. Some variations met expectations based on the biogeography of the species, like the slightly elevated tolerance to chronically high temperatures in populations from southern Spain and the strong increase in tolerance to cold exposure (6 °C) with latitude. However, unexpected features like high survival rates in populations from the northern edge of the distribution range under chronically high temperatures were also found. In temperature ramp experiments, a correlation between the performance in cold ramps and heat ramps was found, indicating that there is no trade-off between these two traits but that they could be a measure of larval quality. The performance in the acute exposure experiments did not correlate with performance under chronic exposure, indicating that each method assesses different aspects of thermal tolerance.
This thesis emphasises the importance of recognising intraspecific variation in response to environmental drivers, as it shapes both the success of invasive species and the adaptability of native species in changing environments. By integrating macrophysiological and multi-driver approaches, this thesis advances the understanding of species responses to environmental change and informs predictions about range shifts under future climates.
Die präklinische Notfall-Versorgung nimmt in Deutschland einen zentralen Stellenwert in der Gesundheitsversorgung ein. Im Rahmen der Arbeit werden einerseits die Entwicklungen der Vergangenheit analysiert, andererseits aber auch die Herausforderungen, die auf die präklinische Notfallversorgung in Zukunft zukommen, betrachtet.
Auf Basis dieser Analysen besteht das Ziel der Arbeit darin, Strategien für eine nachhaltige, flächendeckende und zukunftssichere Versorgungssicherheit in verschiedenen Regionen in Deutschland zu erarbeiten.
Die Rahmenbedingungen inklusive u. a. der rechtlichen Grundlagen, der Organisation und Einbettung des Rettungsdienstes in die präklinische Notfallversorgung, sowie die Finanzierung und das Wirtschaftlichkeitsprinzip sind Faktoren, die in der Bereitstellung des Rettungsdienstes zu berücksichtigen sind.
Daneben wird der Rettungsdienst durch Entwicklungen von außerhalb beeinflusst. Auf der einen Seite steht die im Laufe der Jahre angestiegene Nachfrage nach der Leistung Rettungsdienst. Diese lässt sich auf eine Vielzahl von Veränderungen, die den Rettungs-dienst betreffen, wie u.a. dem medizinischen Fortschritt, dem demografischen Wandel und den damit verbundenen Konsequenzen, den Veränderungen in der ambulanten und stationären medizinischen Versorgung, sowie dem veränderten Inanspruchnahmeverhalten durch die Bevölkerung zurückführen.
Diese Rahmenbedingungen, sowie weitere beeinflussende Faktoren werden im ersten Teil der Arbeit ausführlich auf Basis von Literaturanalysen betrachtet. Anschließend er-folgt, um die Versorgung des Rettungsdienstes tiefgründiger zu verstehen, eine Vorstellung der vorhandenen präklinischen Versorgungsmöglichkeiten mit detaillierter Betrachtung der einzelnen Rettungsmittel. Zudem erfolgt eine Ist-Status-Analyse der präklinischen Versorgungsmöglichkeiten mit ihren Chancen und Risiken im Allgemeinen und Speziellen. In diesem Zusammenhang wird außerdem auf ergänzende Rettungsmittel und First-Responder-Konzepte zum Herztod eingegangen.
Inwieweit sich die aus der Literaturanalyse gewonnenen Ergebnisse in der Praxis anhand von veränderter Einsatznachfrage und veränderten Einsatzzeiten, sowie anhand weiterer ausgewählter Einsatzparameter widerspiegeln, wird im zweiten Teil der Arbeit empirisch untersucht. Dafür stehen 16 Einsatz-Datensätze von realen Leitstellen aus verschiedenen Kommunen in Deutschland überwiegend über einen Zeitraum von zehn Jahren zur Verfügung. Diese Daten werden aufgeteilt nach den drei Regionsgrundtypen einzeln vor dem Hintergrund der in der Literaturanalyse gewonnenen Ergebnisse im ersten Schritt deskriptiv für verschiedene Einsatzparameter und Zeitintervalle untersucht.
Erweiternd dazu ist eine Umfrage unter Rettungsdienstfachpersonal durchgeführt worden, aus welcher die gewichteten Nutzwerte auf Basis von der Bewertung verschiedener Kriterien für die einzelnen primären Rettungsdienstmittel und der Ergänzungen für jeden Regionsgrundtyp einzeln gewonnen worden sind. Zudem sind die Nutzwerte für verschiedene First-Responder-Konzepte beim plötzlichen Herztod gewonnen worden. Dieses er-folgte analog der Analyse der realen Einsatzdaten für die drei unterschiedlichen Regionsgrundtypen. Diese Daten sind einerseits erneut deskriptiv, andererseits inferenzstatistisch mit Hilfe von verschiedenen Signifikanztests ausgewertet worden. U. a. im Hinblick auf regionale Unterschiede, aber auch im Hinblick auf Unterschiede zwischen den Rettungs-mitteln bzw. Teilkonzepten beim plötzlichen Herztod. Im Ergebnis zeigt sich eine historisch gewachsene und systembedingte Entwicklung der präklinischen Versorgung. Im Laufe der Zeit hat sich die präklinische Versorgung einerseits hinsichtlich des Einsatzspektrums und verschiedener Rahmenbedingungen verändert. Andererseits hat die Einsatznachfrage in vielen Regionen zugenommen und verschiedene Zeitintervalle, wie z. B. die Zeitdauer von der Alarmierung bis zum Erreichen des Einsatzortes, haben sich über den Betrachtungszeitraum in den einzelnen Regionen im unterschiedlichen Ausmaß überwiegend verlängert, sodass auch mehr Fahrzeug bereitzustellen sind. Weiterhin wird im Rahmen der Arbeit gezeigt, dass das NEF in allen Regionsgrundtypen mit dem höchsten Nutzwert bedacht worden ist, gefolgt vom RTW und RTH.
Auf Basis dieser Ergebnisse gilt es schlussendlich, die präklinischen Notfallversorgung zukunftssicher zu gestalten. Auf Grund der gewonnenen Erkenntnisse wird deutlich, dass dieses potentiell eine Herausforderung sein wird. Da die Nachfrage über den Zeitverlauf in vielen Regionen zugenommen hat, dass Angebot jedoch zum einen nicht unbegrenzt zur Verfügung steht und zum anderen nicht vorproduziert werden kann, gilt es u. a. die Nachfrage zu steuern. Es muss in Zukunft u. a. verhindert werden, dass der Rettungs-dienst unberechtigt in Anspruch genommen wird und der Bürger muss Wissen darüber erlangen, wann der Rettungsdienst zu alarmieren ist und wann andere Versorgungssäulen in Anspruch genommen werden. Zeitgleich müssen die präklinischen Berufsbilder attraktiv genug erscheinen, damit in Zeiten des Fachkräftemangels der Rettungsdienst überhaupt in ausreichendem Maße aufrechterhalten werden kann, um die notwendige präklinische Versorgung sicherzustellen.
A close anatomical and physiological relationship is known between the senses of hearing and balance, while an additional pathophysiological interaction is supposed. The mechanisms underlying this association are not yet fully understood, especially in individuals without a known specific otologic disorder. In particular, only scarce information on the combined occurrence of audiovestibular sensory impairment is available so far. Therefore, this study aims to provide further insight into the prevalence and co-prevalence of the audiovestibular symptoms hearing loss, tinnitus and dizziness. Additionally, the influence of potential risk factors from lifestyle habits as well as cardiovascular and metabolic conditions on the development of those symptoms is studied. Data was analyzed from 8134 individuals from the population-based Study of Health in Pomerania (SHIP). SHIP pursues a broad and comprehensive examination program in chronologically separated cohorts with longitudinal follow-up. Cohorts are sampled from Western Pomerania, a rural region of north-eastern Germany. The study population represents a cross-sectional analysis from the cohorts SHIP-START (recruited 1997–2001) and SHIP-TREND (recruited 2008–2012), sampled for baseline investigations (SHIP-START-0 and SHIP-TREND-0) at the age of 20–79 years. Audiovestibular symptoms as outcome variables were assessed by structured questionnaires. Additionally, individuals were comprehensively characterized regarding modifiable lifestyle factors as well as cardiovascular and metabolic disorders, allowing the assessment of their role as exposure variables. We calculated a weighted prevalence of 14.2% for hearing loss, 9.7% for tinnitus, and 13.5% for dizziness in the population. Prevalence increased with age and differed among the sexes. A considerable share of 28.0% of the investigated individuals reported more than one symptom at once. The prevalence of hearing loss as well as tinnitus increased between the two cohorts. A moderate positive correlation was found between the occurrence of hearing loss and tinnitus (phi-coefficient 0.318). In multivariable regression analyses, education was identified as a significant protective factor while only smoking was significantly associated with all three symptoms. Furthermore, several cardiovascular risk factors contributed to both hearing loss and dizziness. In conclusion, audiovestibular symptoms are highly prevalent in the investigated population. A considerable but complex influence of risk factors points towards a relation with neuronal as well as cardiovascular disease processes. To clarify the underlying mechanisms, the interaction between the senses of hearing and balance as well as the mode of action of the risk factors should be evaluated in more detail in the future.
Individual use of self-medication and other remedies in COVID-19 outpatients in Western-Pomerania
(2024)
We analyzed data from positively tested COVID-19 outpatients to describe self-medication with OTC drugs and use of other remedies against symptoms of SARS-CoV-2 infection. We specifically considered their type and frequency, as well as associations with patient characteristics, and reasons for use. Data were collected between May 1, 2020 and February 22, 2021 with two questionnaires in an observational cohort study with PCR-confirmed SARS-CoV-2-positive adult outpatients in the district of Western Pomerania in Germany. 523 out of 710 outpatients (74%; 340 women and 183 men) reported using drugs and other remedies to relieve COVID-19-symptoms. Overall, participants reported utilization of 1282 finished dosage products or remedies, including 213 different ingredients. In the population of 710 outpatients, utilization of ibuprofen (26%), acetaminophen (21%), metamizole (14%), and acetylsalicylic acid (10%) was most commonly reported. Phytopharmaceuticals, herbal and animal products as well as vitamins and minerals were also frequently reported. Among the 523 participants who used drugs and other remedies, most commonly mentioned reasons for use were headache (40%), other kinds of pain (e.g. myalgia; 37%), fever (24%) and cough (16%). Our analysis showed that a majority of the participants tried to alleviate COVID-19-symptoms using drugs and other remedies. Especially analgesic and antipyretic agents, followed by herbal medicines, were used very frequently. Trial registration: German Register for Clinical Studies DRKS00021672, first registration on December 1st, 2020.
Background
Dyslipidemia has been associated with reduced bone mineral density and osteoporotic fractures, but the relation between lipid and bone metabolism remains poorly understood. Analysing the effects of lipoprotein subclasses on bone turnover may provide valuable insights into this association. We therefore examined whether lipoprotein subclasses, measured by proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy, are associated with bone turnover markers (BTMs) and with the ultrasound-based bone stiffness index.
Methods
Data from 1.349 men and 1.123 women, who participated in the population-based Study of Health in Pomerania-TREND were analysed. Serum intact amino-terminal propeptide of type I procollagen (P1NP, bone formation) and carboxy-terminal telopeptide of type I collagen (CTX, bone resorption) concentrations were measured. Associations between the lipoprotein data and the BTMs or the stiffness index were investigated using linear regression models.
Results
The triglyceride or cholesterol content in very-low-density lipoprotein and intermediate-density lipoprotein particles was inversely associated with both BTMs, with effect estimates being slightly higher for CTX than for P1NP. The triglyceride content in low-density lipoprotein and high-density lipoprotein particles and the Apo-A2 content in high-density lipoprotein particles was further inversely associated with the BTMs. Associations with the ultrasound-based bone stiffness index were absent.
Conclusions
Consistent inverse associations of triglycerides with bone turnover were observed, which argue for a protective effect on bone health, at least in the normal range. Yet, the presented associations did not translate into effects on the ultrasound-based bone stiffness. Further, there was no relevant gain of information by assessing the lipoprotein subclasses. Nevertheless, our study highlights the close relations between lipid and bone metabolism in the general population.
Background
The gut is an environment in which the immune system closely interacts with a vast number of foreign antigens, both inert such as food and alive, from the viral, bacterial, fungal and protozoal microbiota. Within this environment, germinal centres, which are microanatomical structures where B cells affinity-mature, are chronically present and active.
Main Body
The functional mechanism by which gut-associated germinal centres contribute to gut homeostasis is not well understood. Additionally, the role of T cells in class switching to immunoglobulin A and the importance of B cell affinity maturation in homeostasis remains elusive. Here, we provide a brief overview of the dynamics of gut-associated germinal centres, T cell dependency in Immunoglobulin A class switching, and the current state of research regarding the role of B cell selection in germinal centres in the gut under steady-state conditions in gnotobiotic mouse models and complex microbiota, as well as in response to immunization and microbial colonization. Furthermore, we briefly link those processes to immune system maturation and relevant diseases.
Conclusion
B cell response at mucosal surfaces consists of a delicate interplay of many dynamic factors, including the microbiota and continuous B cell influx. The rapid turnover within gut-associated germinal centres and potential influences of an early-life window of immune system imprinting complicate B cell dynamics in the gut.
The detection and discrimination of chemical signals are fundamental across the animal kingdom, and chemical senses like olfaction, gustation and chemoreception are key mechanisms for processing these cues. Although the olfactory sense organs and their associated neurons exhibit morphological variation, certain patterns are indicative of arthropod olfactory systems. Olfactory sensory neurons are associated with specialized sensory organs, the sensilla, and project their axons into the brain, where they form synapse-dense regions with inter- and projection neurons, called olfactory glomeruli due to their spherical shape. A notable feature of olfactory systems is the convergence of numerous olfactory sensory neurons onto fewer inter- and projection neurons, forming a smaller number of olfactory glomeruli. These connectivity patterns of cells with the same function point towards homology. However, differences in the olfactory pathway exist across pancrustacean groups. Insects evolved from a crustacean-like ancestor and with malacostracan crustaceans form the group of Pancrustacea. Insect olfactory systems have apomorphies like metabotropic receptor molecules in the olfactory sensory neurons in addition to the more ancient ionotropic receptor molecules, as well as differences in the number and connectivity of the involved cells and glomeruli. Within Pancrustacea, the olfactory systems of insects are well-studied, particularly Drosophila species. Therefore, analysing the olfactory system of malacostracan crustaceans and comparing it to the olfactory system of insects offers a multitude of insights into patterns of convergence, divergence, and the evolution of olfactory systems. The most detailed analysis of an olfactory system of malacostracan crustaceans comes from the group of Decapoda (“ten-footed” crustaceans), whereas comparatively little data is available for peracarid crustaceans (“crustaceans with a pouch” for offspring development). In addition to being an understudied crustacean group, peracarid crustaceans are likely closer to the stem line than the highly derived Decapoda. The similar body size of Peracarid and Hexapoda makes their olfactory systems more comparable, as they are likely to be faced with similar energy constrains, a selective pressure on neural tissue. Therefore, two members of Peracarida were analysed in this thesis: the amphipod Parhyale hawaiensis, and the mysid Neomysis interger. Within this thesis, a high level of neurochemical diversity was demonstrated in the olfactory pathway of both species. Contrary to decapods or insects, peracarid crustaceans develop without a larval stage. For P. hawaiensis, the morphology of the olfactory pathway and the neurotransmitter pattern in hatchlings mirrored the morphology of adults, indicating that the complexity of the olfactory system is established early in ontogeny and reflects their environment. In N. integer, a sexual dimorphism in the olfactory pathway was observed in the presence of male and female-specific sensilla and the male-specific neuropil. Within both species, morphological variability was observed for the spherical olfactory glomeruli, and an extensive analysis of the olfactory pathway of P. hawaiensis showed high variability in the morphology and the number of cells and glomeruli of the olfactory pathway, indicating a so-called distributed olfactory coding. It can be hypothesised that a more distributed olfactory coding was found in the common pancrustacean ancestors and insect species like Drosophila melanogaster developed a highly derived stereotyped one-to-one olfactory coding.