Scientific publications of the Saarland University
Not a member yet
14321 research outputs found
Sort by
Getting to the root of SSH compromises: A multi-dimensional characterization of the SSH threat landscape
No full textThe Internet has become a critical infrastructure, attracting a vast amount of activity, including malicious threats. The Secure Shell Protocol (SSH), the successor of Telnet - designed for secure machine-to-machine communication - is one of the most widely used protocols on the Internet. Due to its ubiquity, SSH has become a prime target for attackers. Over the years, SSH attacks have evolved, and their frequency has only increased. In this thesis, we investigate the nature of these attacks, including their origins, methods, and targets. We conduct a retrospective study and a longitudinal analysis using a large honeyfarm, as well as an active analysis to identify compromised SSH servers. Through a global network of honeypots, we analyze approximately 750 million SSH sessions over a three-year period. The dataset, collected from 221 honeypots across 55 countries, reveals stark variations in activity - some honeypots observe millions of connections, while others record only a few thousand. We also analyze attacker behavior, uncovering a shift toward more exploratory attacks and increased reconnaissance efforts. Additionally, attackers increasingly leverage recently registered Autonomous Systems (ASes) to store and distribute malicious files. Our findings suggest that attackers are becoming more aware of honeypot presence, with some actively seeking to evade detection. To extend our analysis, we propose a method to identify compromised SSH servers at scale. We exploit SSH's authentication behavior, where a challenge is only issued if a public key is installed. This approach neither grants access to compromised systems (unlike testing known attacker passwords), nor requires privileged access for auditing. Applying this methodology to a comprehensive Internet scan, we identify over 21,700 compromised systems across 1,649 ASes in 144 countries. These include critical infrastructure where attackers have installed at least one of 52 verified malicious SSH keys provided by a threat intelligence company. Our investigation also uncovers insights into malicious campaigns such as the "fritzfrog" IoT botnet and threat actors like "teamtnt". Moreover, we collaborate with a national CSIRT and the Shadowserver Foundation to notify affected entities and facilitate remediation efforts. We run our measurements continuously and automatically share notifications.Das Internet hat sich zu einer kritischen Infrastruktur entwickelt und zieht eine Vielzahl von Aktivitäten an–darunter auch bösartige Bedrohungen. Das Secure Shell-Protokoll (SSH), der Nachfolger von Telnet, wurde für sichere Maschine-zu-Maschine-Kommunikation entwickelt und ist eines der am weitesten verbreiteten Protokolle im Internet. Aufgrund seiner Allgegenwärtigkeit ist SSH zu einem bevorzugten Ziel für Angreifer geworden. Im Laufe der Jahre haben sich SSH-Angriffe weiterentwickelt, und ihre Häufigkeit hat stetig zugenommen. In dieser Arbeit untersuchen wir die Eigenschaften dieser Angriffe, einschließlich ihrer Ursprünge, Methoden und Zielsysteme. Wir führen sowohl eine retrospektive Untersuchung als auch eine longitudinale Analyse unter Verwendung einer umfangreichen Honeyfarm durch, ergänzt durch eine aktive Analyse zur Identifikation kompromittierter SSH-Server. Über ein globales Netzwerk von Honeypots analysieren wir etwa 750 Millionen SSH-Sitzungen über einen Zeitraum von drei Jahren. Der Datensatz, gesammelt von 221 Honeypots in 55 Ländern, zeigt deutliche Unterschiede in Aktivitäten–einige Honeypots registrieren Millionen von Verbindungen, während andere nur wenige Tausend beobachten. Wir analysieren auch das Verhalten der Angreifer und stellen dabei eine Verschiebung hin zu explorativeren Angriffen sowie zunehmende Aufklärungsaktivitäten fest. Zudem nutzen Angreifer vermehrt kürzlich registrierte Autonome Systeme (ASes), um bösartige Dateien zu speichern und zu verbreiten. Unsere Ergebnisse deuten darauf hin, dass Angreifer sich zunehmend der Präsenz von Honeypots bewusst sind–einige versuchen sogar aktiv, einer Erkennung zu entgehen. Zur Erweiterung unserer Analyse schlagen wir eine Methode zur Identifikation kompromittierter SSH-Server im großen Maßstab vor. Dabei machen wir uns das Authentifizierungsverhalten von SSH zunutze: Eine Herausforderung für den Schlüsselaustausch wird nur dann aufgegeben, wenn ein öffentlicher Schlüssel installiert ist. Dieser Ansatz gewährt weder Zugang zu kompromittierten Systemen (anders als das Testen bekannter Angreifer-Passwörter), noch erfordert er privilegierten Zugriff zur Überprüfung. Durch Anwendung dieser Methode auf einen umfangreichen Internetscan identifizieren wir über 21.700 kompromittierte Systeme in 1.649 ASes in 144 Ländern. Darunter befinden sich auch kritische Infrastrukturen, auf denen Angreifer mindestens einen von 52 verifizierten, von einem Threat-Intelligence-Unternehmen bereitgestellten, bösartigen SSH-Schlüsseln installiert haben. Unsere Untersuchung liefert darüber hinaus Einblicke in bösartige Kampagnen wie das IoT-Botnetz fritzfrog und Akteure wie teamtnt. Zudem arbeiten wir mit einem nationalen CSIRT und der Shadowserver Foundation zusammen, um betroffene Einrichtungen zu benachrichtigen und Maßnahmen zur Schadensbegrenzung zu ermöglichen. Unsere Messungen laufen kontinuierlich, und Benachrichtigungen werden automatisch geteilt
Synthese amphiphiler Blockcopolymere als Template für die Herstellung mesoporöser funktionaler Materialien
No full textDie Nanotechnologie bietet Möglichkeiten, unseren technologisierten Lebensstandard trotz des hohen Energie- und Ressourcenanspruchs mit dem Schutz unserer Umwelt zu vereinen. Die intrinsische Eigenschaft der Selbstanordnung von Blockcopolymeren durch Mikrophasenseparation kann genutzt werden, um hochgeordnete und nanoskalige Strukturen herzustellen. Die Verwendung solcher weicher Template ermöglicht auch das Einbringen spezifischer Funktionen sowie die gezielte chemische Umwandlung einzelner Bausteine. Nano- und mesoporöse Substanzen weisen eine große innere Oberfläche auf und können aus weichen Templaten durch den selektiven chemischen Abbau eines Segmentes hergestellt werden. Die Herausforderung besteht darin, die gewünschten Eigenschaften auf die molekulare Ebene zu übertragen, ein geeignetes Blockcopolymer zu designen und kontrolliert zu synthetisieren. In dieser Arbeit werden zunächst amphiphile, funktionale Blockcopolymere mittels kontrollierter Polymerisationsmethoden hergestellt und hinsichtlich ihrer molekularen Eigenschaften sowie ihrer Strukturbildung charakterisiert. Über drei spezifische Methoden werden diese zu mesoporösen (hierarchischen) Strukturen umgewandelt, welche ebenfalls hinsichtlich ihrer Struktur und Eigenschaften charakterisiert werden. Somit werden in dieser Arbeit neue Methoden zur Herstellung nanoskaliger, funktionaler Materialien etabliert, welche sensorische oder katalytische Eigenschaften zeigen, oder zur Filtration verwendet werden können.Nanotechnology offers opportunities to unite our technologized standard of living and the protection of the environment despite the high requirements in energy and resources involved. The intrinsic capability of self-assembly of block copolymers due to microphase separation can be used to produce highly ordered nanoscale structures. Using such soft templates enables the incorporation of specific functional sites as well as the targeted chemical conversion of individual building blocks. Nano- and mesoporous substances exhibit high inner surface area and can be fabricated from soft templates via selective degradation of one building block. Herein, our challenge is to transfer the targeted properties to the molecular level, to design the respective block copolymer and to synthesize it in a controlled manner. In the scope of this work, functional amphiphilic block copolymers are synthesized via controlled polymerization methods, the polymers are analyzed regarding their molecular properties as well as their structure formation capabilities. Using three specific methods, the amphiphilic block copolymers are converted to (hierarchical) mesoporous structures, which are also characterized regarding their structure and properties. Thus, in this work new methods are established for the fabrication of nanoscale, functional materials, which can exhibit sensory or catalytic properties, or can be used for filtration applications
An empirical ranking of the importance of the sources of self-efficacy for physical activity
No full textBackground: While considerable research has centered on the concept of self-efficacy
and its impact on behavior, relatively few studies have delved into the sources of self efficacy beliefs. Bandura posited that the genesis of self-efficacy beliefs is based on the
following four aspects: personal experience, vicarious experience, verbal persuasion, and
emotional state. The objective of this research paper is to ascertain the relative impor tance of each source concerning self-efficacy for physical activity to determine whether
some sources should be accorded with greater emphasis than others in future studies
aiming to foster self-efficacy beliefs for physical activity.
Methods: An online study with 335 healthy German adults (162 men, 173 women) aged
18−68 was conducted. The sources of self-efficacy were compared by employing
dominance analysis. This approach allows for the ordering of predictors according to
their contribution to the explained variance, thereby providing more substantial
insights and allowing for more concrete conclusions in comparison to the conventional
multiple regression approach.
Results: As expected, mastery experience was shown to be the most important source of
self-efficacy for physical activity, interestingly followed by verbal self-persuasion and
positive affective state. Together, the sources of self-efficacy accounted for about 60% of
the variance in self-efficacy.
Conclusions: Overall, understanding the etiology of self-efficacy is essential for devel oping effective and sustainable interventions to promote healthy behaviors. By focus ing on the specific sources of self-efficacy that are most pertinent, interventions can be
designed to be more effective
Fura-10, unlike fura-2, is suitable for long-term calcium imaging in natural killer (NK) cells without compromising cytotoxicity and can be combined with target cell death analysis
No full textThere are compelling reasons to opt for primary human natural killer (NK) cells when validating Ca2+ indicators.
1.) NK cells exhibit a high degree of vulnerability to stressors such as indicator loading or light exposure. 2.) The
lack of research on NK Ca2+ signaling underscores the necessity for developing reliable assays. 3.) The increased
utilization of NK cell therapies necessitates a more profound comprehension of Ca2+ dependent signal trans duction. Consequently, an assay was developed to monitor cytosolic Ca2+ signals in individual NK cells simul taneously with their cytotoxic function against cancer cells. We used this assay to assess the suitability of fura-2,
fura-PE3, fura-8, fura-10 or fura-red for quantifying Ca2+ signals in NK cells without compromising their cyto toxic function. In contrast to the widely used fura-2, its red-shifted derivative fura-10 did not interfere with NK
cytotoxicity over several hours. It exhibited a superior signal-to-noise ratio and good dynamic range, accom panied by minimal bleaching or leakage. Fura-8 and fura-red also preserved NK cell cytotoxicity, but had other
disadvantages compared to fura-10. We successfully used fura-10 to report Ca2+ signals in NK cells from blood
donors and patients diagnosed with lymphoma and leukemia over several hours at 37 ◦C during apoptotic or
necrotic killing of different cancer cells (K562, THP1, OCI-AML2, and TMD8). Additionally, we show that fura-10
is well suited to report Ca2+ signals in intact murine pancreatic islets, another stress-sensitive cell preparation.
Consequently, fura-10 is an optimal choice for measuring Ca²⁺ in primary human NK cells and other primary cell
preparations
Assessment of scintigraphic imaging with Terbium-161: A visual and quantitative analysis
No full textThe Auger emitter 161Tb is an increasingly discussed radionuclide for targeted radionuclide therapy. The aim of
this study was to assess the feasibility of scintigraphic imaging with 161Tb in terms of image quality and
quantitative capabilities by phantom measurements and to evaluate the suitability of this radionuclide for
clinical use. Phantom measurements were conducted using a standardized NEMA IEC body phantom filled with
activity concentrations ranging from 2.5 GBq to 100 MBq. Both visual and quantitative analyses were performed,
including assessment of the image calibration factor (CF), as well as the recovery coefficient (RC) and the
contrast-to-noise ratio (CNR) of the individual spheres. The results observed in this study demonstrate that
quantitative SPECT/CT imaging with 161Tb is feasible over a wide range of activity making this radionuclide
suitable for clinical applications. Acquiring a total of at least 5 million photopeak counts enables visual
detectability of lesions of diameter lower than 20 mm and quantitative calibration for dosimetry purposes
Biological upcycling of polystyrene into ready-to-use plastic monomers and plastics using metabolically engineered Pseudomonas putida
No full textThe persistent accumulation of plastic waste, particularly polystyrene (PS), poses significant environmental
challenges because of its extensive use and low recycling rates. Addressing these challenges necessitates inno vative and sustainable solutions. This study presents a strategy to upcycle PS waste into valuable chemical
products, including adipic acid, hexanediol, hexamethylenediamine, and nylon-6,6, using metabolically engi neered Pseudomonas putida KT2440. This process involves the photolytic degradation of PS into benzoic acid,
followed by microbial conversion into cis,cis-muconate (MA) and chemical synthesis of the final products. The
engineered strains withstood 30 mM concentrations of PS-derived aromatics and converted them stoichiomet rically into MA in the presence of glucose as a growth substrate. 13C metabolic flux analysis revealed energy and
redox limitations in the presence of 25 mM benzoate and 300 mM MA. The cells responded to stress by enhancing
the flux for periplasmic glucose oxidation and fluxes through the NADPH-forming dehydrogenases; this process
caused more than 40 % glucose‑carbon loss into byproducts. Fine-tuned dynamic glucose and benzoate feeding
enabled high-level MA production. Energy-optimized genome-reduced strains were used to increase carbon ef ficiency. A final MA titer of over 65 g L− 1 was achieved in fed-batch fermentation. This process was demonstrated
using the glucose derived from a viscose textile waste blend as the growth substrate and resulted in fully waste based products. The resulting adipic acid and hexamethylenediamine were polymerized into nylon-6,6 with
properties comparable to those of petrochemical-derived polymers, revealing a sustainable pathway for PS
upcycling. This research provides a proof-of-concept for bacterial upgrading of PS-derived substrates and a viable
method for managing plastic waste and producing valuable chemical products
Die Neutrophilen-Lymphozyten-Ratio als prädiktiver Wert für epileptische Frühanfälle nach ischämischem Schlaganfall: Eine Fall-Kontroll-Studie
No full textEpileptische Frühanfälle nach einem Schlaganfall sind mit erhöhter Mortalität und
dem Risiko für die spätere Entwicklung einer Epilepsie verbunden. Ziel dieser Studie ist
es, potenzielle Risikofaktoren für diese epileptischen Anfälle zu ermitteln, wobei der
Schwerpunkt auf Blutparametern wie der Neutrophilen-Lymphozyten-Ratio liegt, welche
ein Biomarker für Entzündungen ist.
Es wurden zwischen 2017 und 2019 wegen eines ischämischen Schlaganfalls in der
neurologischen Abteilung des Universitätsklinikums des Saarlandes behandelte Patien-
ten1 retrospektiv identifiziert. 44 von ihnen erlitten einen erstmaligen epileptischen Anfall
innerhalb von 7 Tagen nach dem Schlaganfall. Sie wurden im Verhältnis 1:2 in Alter und
Geschlecht mit Kontrollpersonen gematcht, die einen ischämischen Schlaganfall, jedoch
keine epileptischen Frühanfälle erlitten hatten. Bei Aufnahme wurden demografische Da-
ten, die Merkmale des Schlaganfalls sowie Blutparameter erhoben. Mit Hilfe logistischer
Regression wurden die mit epileptischen Frühanfällen assoziierten Variablen identifiziert
und die Fläche unter der Receiver Operating Characteristic Curve (AUROC) zur Ab-
schätzung ihrer Vorhersagegenauigkeit verwendet.
In der univariablen logistischen Regression waren die Neutrophilen-Lymphozyten-
Ratio (p = 0,035), National Institutes of Health Stroke Scale (NIHSS, p = 0,016) und eine
kortikale Lokalisation des Schlaganfalls (p = 0,03) signifikant mit dem Auftreten von epi-
leptischen Frühanfällen nach ischämischem Schlaganfall assoziiert. Es zeigte sich eine
signifikante positive Beziehung zwischen Neutrophilen-Lymphozyten-Ratio und NIHSS,
rS(87) = 0,383, p < 0,001. In der multivariablen logistischen Regression waren die Neutro-
philen-Lymphozyten-Ratio-Werte (adjustierte Odds Ratio = 1,097, 95% Konfidenzinter-
vall [1,005, 1,197]; p = 0,038) nach Adjustierung für Alter, Geschlecht, NIHSS und
Schlaganfalllokalisation unabhängig mit dem Auftreten von epileptischen Frühanfällen
assoziiert. Der AUROC-Wert für die Neutrophilen-Lymphozyten-Ratio betrug 0,639 (95%
Konfidenzintervall [0,517, 0,761]), wobei 2,98 der beste prädiktive Cut-off-Wert war. Höhere Neutrophilen-Lymphozyten-Ratio-Werte sind demnach signifikant mit einem
erhöhten Risiko für epileptische Frühanfälle verbunden. Dieser Biomarker ist vielverspre-
chend, um das Risiko einer Entstehung solcher Frühanfälle einzuschätzen.Early post-stroke seizures (EPSS) are associated with an increased risk of mortality
and post-stroke epilepsy. This study aims to identify potential risk factors for EPSS, fo-
cusing on blood parameters, such as the neutrophil-to-lymphocyte ratio (NLR), which is
a biomarker for inflammation.
Patients treated for ischemic stroke between 2017 and 2019 in the neurology depart-
ment of Saarland University Medical Center were retrospectively identified. 44 of them
had a first epileptic seizure within 7 days after the stroke. They were matched 1:2 for age
and sex with controls who had an ischemic stroke but no EPSS. Information on de-
mographics, stroke characteristics, and blood parameters were collected on admission.
Logistic regression was used to identify variables associated with EPSS and the area
under the receiver operating characteristic curve (AUROC) to estimate their predictive
accuracy.
Neutrophil-to-lymphocyte ratio (NLR, p = 0.035), National Institutes of Health Stroke
Scale (NIHSS, p = 0.016) and cortical localization of stroke (p = 0.03) were significantly
associated with the occurrence of early post-stroke seizures in univariable logistic re-
gression. There was a significant positive relationship between neutrophil-to-lymphocyte
ratio and NIHSS, rS(87) = 0.383, p < 0.001. In multivariable logistic regression, the neu-
trophil-to-lymphocyte ratio values (adjusted odds ratio = 1.097, 95% confidence interval
(CI) [1.005, 1.197]; p = 0.038) were independently associated with the occurrence of
EPSS after adjusting for age, sex, NIHSS, and stroke localization. The AUROC for NLR
was 0.639 (95% CI [0.517, 0.761]) with 2.98 as the best predictive cut-off value.
Thus, higher neutrophil-to-lymphocyte ratio values are significantly associated with
increased risk of early post-stroke seizures. This biomarker appears promising to assess
the risk of developing such early seizures
Does the quality of pain relief after major surgery influence the risk of postoperative complications? A prospective observational study
No full textObjectives
Effective postoperative acute pain management continues to be a challenge. It
remains uncertain whether poorly controlled postoperative pain influences the risk of
postoperative complications. Therefore, we aimed to investigate whether indicators of
poor pain control increase the likelihood of cardiac, pulmonary, infectious, thrombo embolic, and surgical complications, as well as of prolonged use of analgesics.
Methods
This prospective observational study combines treatment data from the Ger man net-ra registry and claims data from the second-largest public health insurer
BARMER (Mar 1, 2021-Mar 31, 2022). A total of 539 adult inpatients who had
undergone major surgery and received planned postoperative care from acute pain
services were analyzed. Adjusted binary logistic regression models were fitted to
compare patients with inadequately (NRS>3) and adequately controlled pain, with
(NRS>6) and without pain peaks, and with slow or rapid pain recovery (median split
of the time to sustained adequate pain control NRS≤3) with regard to the risk of
postoperative complications and prolonged use of analgesics as a proxy of chronic
postoperative pain. Results
Patients with inadequately controlled pain within the first three postoperative days
had more than twice the risk of complications (adjOR 2.56; 95% CI 1.43–4.80,
p=0.002), as did patients with slow pain recovery (adjOR 2.21; 95% CI 1.35–3.64,
p=0.002). No significant effect could be observed for pain peaks (adjOR 1.27; 95%
CI 0.64 to 2.42, P=0.478). Inadequate pain control did not significantly affect pro longed use of analgesics (adjOR 1.87; 95% CI 0.98–3.72, p=0.064), nor did pain
peaks or recovery speed show any influence.
Discussion
We observed a clear link between postoperative quality of pain control and complica tions, along with a trend towards prolonged use of analgesics. Therefore, postoper ative acute pain should be regularly assessed and minimized until resolved. Further
research into patient- and procedure-specific factors is essential to reduce adverse
pain-related outcomes
Development and Verification of a Physiologically Based Pharmacokinetic Model of Furmonertinib and Its Main Metabolite for Drug–Drug Interaction Predictions
No full textFurmonertinib demonstrated potent efficacy as a newly developed tyrosine kinase inhibitor for the treatment of patients with
epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer. In vitro research showed that fur monertinib is metabolized to its active metabolite AST5902 via the cytochrome P450 (CYP) enzyme CYP3A4. Furmonertinib
is a strong CYP3A4 inducer, while the metabolite is a weaker CYP3A4 inducer. In clinical studies, nonlinear pharmacoki netics were observed during chronic dosing. The apparent clearance showed time- and dose-dependent increases. In this
evaluation, a combination of in vitro data using radiolabeled compounds, clinical pharmacokinetic data, and drug–drug
interaction (DDI) data of furmonertinib in oncology patients and/or in healthy subjects was used to develop a physiologically
based pharmacokinetic (PBPK) model. The model was built in PK-Sim Version 11 using a total of 44 concentration-time
profiles of furmonertinib and its metabolite AST5902. Suitability of the predictive model performance was demonstrated
by both goodness-of-fit plots and statistical evaluation. The model predicted the observed monotherapy concentration pro files of furmonertinib well, with 32/32 predicted AUClast (area under the curve until the last concentration measurement)
values and 32/32 maximum plasma concentration (Cmax) ratios being within twofold of the respective observed values. In
addition, 8/8 predicted DDI AUClast and Cmax ratios with furmonertinib as a victim of CYP3A4 inhibition or induction were
within twofold of their respective observed values. Potential applications of the final model include the prediction of DDIs
for chronic administration of CYP3A4 perpetrators along with furmonertinib, considering auto-induction of furmonertinib
and its metabolite AST5902
Effects of noise traumata of different strengths on hearing functions of C57BL/6N mice
Full text linkNoise-induced hearing loss is a common pathology in humans. Mice serve as model organism for unraveling the underlying mechanisms. Moderate noise (100 dB SPL, 2 h, 8 -16 kHz) can irreversibly damage the cochlea by destroying part of the presynapses and/or postsynapses of the inner hair cells in the high frequency region without permanently increasing hearing thresholds. This phenomenon termed hidden hearing loss was first demonstrated by Kujawa and Liberman (2009) in CBA/CaJ mice. The C57BL/6N mouse line has been widely used for genetic manipulation, e.g. for generating knock-out and knock-in mice, which can help to gain mechanistic insights into noise-induced hearing loss. The aim of this thesis was to explore hearing function after application of two different noise traumata - 106 and 112 dB SPL - in C57BL/6N mice.
Hearing function was assessed two days before, directly after trauma and up to four weeks after trauma by auditory brainstem response (ABR) audiometry with click and pure tone stimulation. A previously applied noise trauma of 100 dB SPL (2 h, 8-16 kHz octave band, (Nasri, 2023)) caused a permanent threshold shift at 45 kHz in C57BL/6N mice. The more intense traumata applied in this study (106 and 112 dB SPL) caused a larger damage. Both the amount of temporary (TTS) as well as permanent threshold shifts (PTS) and the range of affected frequencies scaled with trauma strength. In the case of TTS, recovery was almost complete on day 14. Four weeks after the 106 dB SPL trauma, the amplitude growth functions of ABR waves I were reduced for the frequencies of 11, 16, and 22 kHz, which indicates loss of functional synaptic connections between inner hair cells and spiral ganglion neurons. In a fellow dissertation, Philipp Schätzle showed trauma-induced loss of ~50 % of synaptic ribbons in inner hair cells in the mid-basal region (Blum et al., 2024), which was largely responsi-ble for the reduction of the amplitude of ABR wave I by 72 % at 22 kHz four weeks after the 106 dB SPL trauma.
Similarly, growth functions of ABR wave I amplitudes evoked by click stimulation were reduced four weeks after both the 106 and the 112 dB SPL trauma. Mean amplitudes of click-ABR 40 dB over threshold were reduced for the waves I to V four weeks after the 106 dB SPL trauma and for waves I, III, IV, and V four weeks after the 112 dB SPL trauma. By contrast, peak latencies of waves I to V at 40 dB over threshold were not altered by either trauma suggesting that latencies of click responses relative to threshold are not a sensitive measure for loss of functional connections between inner hair cells and spiral ganglion neurons.
Although both the 106 and the 112 dB SPL trauma did not cause cellular outer hair cell loss (Blum et al., 2024) a functional impairment of outer hair cells is likely, which will lead to increased hearing thresholds independent of the loss of threshold-determining auditory nerve Ia fibers. Future studies on hidden and overt hearing loss in genetic mouse models therefore should not only analyze ABR properties and the fate of pre- and postsynapses but also include measurements of the distortion product otoacoustic emissions as an indicator of outer hair cell function