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Copyright of Klimik Journal / Klimik Dergisi is the property of DOC Design & Informatics Co. Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ion channels activated around the subthreshold membrane potential determine the likelihood of neuronal firing in response to synaptic inputs, a process described as intrinsic neuronal excitability. Long-term plasticity of chemical synaptic transmission is traditionally considered the main cellular mechanism of information storage in the brain; however, voltage- and calcium-activated channels modulating the inputs or outputs of neurons are also subjects of plastic changes and play a major role in learning and memory formation. Gamma oscillations are associated with numerous higher cognitive functions such as learning and memory, but our knowledge of their dependence on intrinsic plasticity is by far limited. Here we investigated the roles of potassium and calcium channels activated at near subthreshold membrane potentials in cholinergically induced persistent gamma oscillations measured in the CA3 area of rat hippocampal slices. Among potassium channels, which are responsible for the afterhyperpolarization in CA3 pyramidal cells, we found that blockers of SK (K Ca 2) and K V 7.2/7.3 (KCNQ2/3), but not the BK (K Ca 1.1) and IK (K Ca 3.1) channels, increased the power of gamma oscillations. On the contrary, activators of these channels had an attenuating effect without affecting the frequency. Pharmacological blockade of the low voltage-activated T-type calcium channels (Ca V 3.1-3.3) reduced gamma power and increased the oscillation peak frequency. Enhancement of these channels also inhibited the peak power without altering the frequency of the oscillations. The presented data suggest that voltage- and calcium-activated ion channels involved in intrinsic excitability strongly regulate the power of hippocampal gamma oscillations. Targeting these channels could represent a valuable pharmacological strategy against cognitive impairment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Klemz, Wildner, Tütüncü and Gerevich.)

In studies that target specific functions or organs, the response is often overlaid by indirect effects of the intervention on global metabolism. The metabolic side of these interactions can be assessed based on total energy expenditure (TEE) and the contributions of the principal energy sources, carbohydrates, proteins and fat to whole body CO 2 production. These parameters can be identified from indirect calorimetry using respiratory oxygen intake and CO 2 dioxide production data that are combined with the response of the 13 CO 2 release in the expired air and the glucose tracer enrichment in plasma following a 13 C glucose stable isotope infusion. This concept is applied to a mouse protocol involving anesthesia, mechanical respiration, a disease model, like hemorrhage and therapeutic intervention. It faces challenges caused by a small sample size for both breath and plasma as well as changes in metabolic parameters caused by disease and intervention. Key parameters are derived from multiple measurements, all afflicted with errors that may accumulate leading to unrealistic values. To cope with these challenges, a sensitive on-line breath analysis system based on substrate-integrated hollow waveguide infrared spectroscopy and luminescence (iHWG-IR-LS) was used to monitor gas exchange values. A Bayesian statistical model is developed that uses established equations for indirect calorimetry to predict values for respiratory gas exchange and tracer data that are consistent with the corresponding measurements and also provides statistical error bands for these parameters. With this new methodology, it was possible to estimate important metabolic parameters (respiratory quotient (RQ), relative contribution of carbohydrate, protein and fat oxidation f carb , f fat and f prot , total energy expenditure TEE) in a resolution never available before for a minimal invasive protocol of mice under anesthesia.

Metal oxide (MOX) sensors are increasingly gaining attention in analytical applications. Their fundamental operation principle is based on conversion reactions of selected molecular species at their semiconducting surface. However, the exact turnover of analyte gas in relation to the concentration has not been investigated in detail to date. In the present study, two optical sensing techniques-luminescence quenching for molecular oxygen and infrared spectroscopy for carbon dioxide and methane-have been coupled for characterizing the behavior of an example semiconducting MOX methane gas sensor integrated into a recently developed low-volume gas cell. Thereby, oxygen consumption during MOX operation as well as the generation of carbon dioxide from the methane conversion reaction could be quantitatively monitored. The latter was analyzed via a direct mid-infrared gas sensor system based on substrate-integrated hollow waveguide (iHWG) technology combined with a portable Fourier transform infrared spectrometer, which has been able to not only detect the amount of generated carbon dioxide but also the consumption of methane during MOX operation. Hence, a method based entirely on direct optical detection schemes was developed for characterizing the actual signal generating processes-here for the detection of methane-via MOX sensing devices via near real-time online analysis. Graphical Abstract.

According to their materials and operating parameters, metal oxide (MOX) sensors respond to target gases only by a change in sensor resistance with a lack in selectivity. By the use of infrared spectroscopy, highly discriminatory information from samples at a molecular level can be obtained and the selectivity can be enhanced. A low-volume gas cell was developed for a commercially available semiconducting MOX methane gas sensor and coupled directly to a mid-infrared gas sensor based on substrate-integrated hollow waveguide (iHWG) technology combined with a Fourier transform infrared spectrometer. This study demonstrates a sensing process with combined orthogonal sensors for fast, time-resolved, and synergic detection of methane and carbon dioxide in gas samples.

With more than a thousand constituents at trace level concentrations, exhaled breath analysis (EBA) allows for non-invasive point-of-care (POC) disease diagnostics and metabolic status monitoring in or close to real-time. A number of biomarkers in breath may be used to not only identify diseases and disease progression but also to monitor therapeutic interventions. Although the relationship of selected breath components/biomarkers with certain disease pathologies is well established, diagnosing the exhaled breath composition remains an analytical and practical challenge due to the concentration levels of molecules of interest, i.e., low parts-per-billion (ppb) regime and below. Besides the analytical assessment of breath components via conventional methods such as gas chromatography coupled to mass spectrometry and related techniques, the application of cascade laser spectroscopy (CLS) is relatively new and exhibits several advantages when aiming for compact and user-friendly trace gas sensors with high molecular selectivity, the required sensitivity, and potentially reasonable instrumental costs. This trend article highlights the current status and potential of CLS in breath diagnostics with a focus on recent advancements in instrumentation and application along with future prospects and challenges. Graphical abstract Cascade laser technology in the mid-infrared spectral range enables sensitive and molecularly selective exhaled breath analysis with near real-time response, label-free detection, and point-of-care feasibility.

Nitrogen-based fertilizers have been used in modern agricultural activities resulting in a relevant emission source of nitrogen gases into the atmosphere, mainly nitric oxide (NO), nitrogen dioxide (NO 2 ), and nitrous oxide (N 2 O). Furthermore, the burning of fossil fuels is the most significant emission source of NO x (i.e., NO + NO 2 ), being the controlling of vehicle exhaust system an essential task. Those compounds can be related to air pollution effects either directly, by emitting a powerful greenhouse gas (i.e., N 2 O), or indirectly, by formation of nitric acid (HNO 3 ) or ammonium nitrate (NH 4 NO 3 ) from NO or NO 2 , responsible for the increase of acid rain and particulate material into the atmosphere. This context requires appropriate sensor technology facilitating in situ and simultaneous monitoring of nitrogen emitted gases, with easiness of operation and compact dimensions. In this communication, we describe an innovative mid-infrared chemical sensor platform for the in situ, real-time, and simultaneous quantification of gaseous NO, NO 2 , and N 2 O by combining a compact Fourier transform infrared (FT-IR) spectrometer with the so-called substrate-integrated hollow waveguide (iHWG) as a miniaturized gas cell. The optical platform enabled limits of detection of 10, 1, and 0.5 ppm of NO, NO 2 , and N 2 O, respectively. The linear concentration range evaluated in this study is suitable for the application of the sensing platform in vehicle exhaust air samples. Given the high adaptability of the developed infrared sensing device toward preconcentration or ultraviolet conversion modules and also considering the potential for combining tunable interband cascade lasers (ICLs) in lieu of the FT-IR spectrometer, we anticipate the application of the sensing platform for in situ determination of nitrogen gases in a wide range of scenarios.

A multiparameter gas sensor based on distributed feedback interband cascade lasers emitting at 4.35 μm and ultrafast electro-spun luminescence oxygen sensors has been developed for the quantification and continuous monitoring of 13 CO 2 / 12 CO 2 isotopic ratio changes and oxygen in exhaled mouse breath samples. Mid-infrared absorption spectra for quantitatively monitoring the enrichment of 13 CO 2 levels were recorded in a miniaturized dual-channel substrate-integrated hollow waveguide using balanced ratiometric detection, whereas luminescence quenching was used for synchronously detecting exhaled oxygen levels. Allan variance analysis verified a CO 2 measurement precision of 1.6‰ during a 480 s integration time. Routine online monitoring of exhaled mouse breath was performed in 14 mechanically ventilated and instrumented mice and demonstrated the feasibility of online isotope-selective exhaled breath analysis within microliters of probed gas samples using the reported combined sensor platform.

Exhaled breath offers monitoring bio markers, as well as diagnosing diseases and therapeutic interventions. In addition, vital functions may be non-invasively monitored online. Animal models are frequently used in research for determining novel therapeutic approaches and/or for investigating biological pathways. The exhaled carbon dioxide concentration, exhaled and inhaled oxygen concentration, and the subsequent respiratory quotient (RQ) offer insight into metabolic activity. One may adapt breath sampling systems and equipment designed for human applications to large animal studies. However, such adaptations are usually impossible for small animals due to their minuscule breath volume. Here, we present a system for the online monitoring of exhaled breath in a 'mouse intensive care unit' (MICU) based on a modified Fourier-transform infrared spectrometer equipped with a substrate-integrated hollow waveguide gas cell, and a luminescence-based oxygen flow-through sensor integrated into the respiratory equipment of the MICU. Thereby, per-minute resolution of O 2 consumption and CO 2 production was obtained, and the 95% confidence range of the determined RQ was ±0.04 or approximately ±5% of the nominal value. Changes in the RQ value caused by intervention in either the metabolic or respiratory system may therefore reliably be detected.

Gas analysis via mid-infrared (MIR) spectroscopic techniques has gained significance due to its inherent molecular selectivity and sensitivity probing pronounced vibrational, rotational, and roto-vibrational modes. In addition, MIR gas sensors are suitable for real-time monitoring in a wide variety of sensing scenarios. Our research team has recently introduced so-called substrate-integrated hollow waveguides (iHWGs) fabricated by precision milling, which have been demonstrated to be useful in online process monitoring, environmental sensing, and exhaled breath analysis especially if low sample volumes (i.e., few hundreds of microliters) are probed with rapid signal transients. A logical next step is to establish ultralightweight, potentially disposable, and low-cost substrate-integrated hollow waveguides, which may be readily customized and tailored to specific applications using 3D printing techniques. 3D printing provides access to an unprecedented variety of thermoplastic materials including biocompatible polylactides, readily etchable styrene copolymers, and magnetic or conductive materials. Thus, the properties of the waveguide may be adapted to suit its designated application, e.g., drone-mounted ultralightweight waveguides for environmental monitoring or biocompatible disposable sensor interfaces in medical/clinical applications.

In this study, an innovative approach based on fiberoptically coupled substrate-integrated hollow waveguide (iHWG) gas cells for the analysis of low sample volumes suitable for remote broad- and narrow-band mid-infrared (MIR; 2.5-20 μm) sensing applications is reported. The feasibility of remotely addressing iHWG gas cells, configured in a double-pass geometry via a reflector, by direct coupling to a 7-around-1 mid-infrared fiber bundle is demonstrated, facilitating low-level hydrocarbon gas analysis. For comparison studies, two iHWGs with substrate dimensions of 50 × 50 × 12 mm (L × W × H) and geometric channel lengths of 138 and 58.5 mm, serving as miniature light-guiding gas cells, were fiber-coupled to a Fourier transform infrared spectrometer enabling broadband MIR sensing. In addition to the fundamental feasibility of this concept, the achievable sensitivity toward several gaseous hydrocarbons and the reproducibility of assembling the fiber-iHWG interface were investigated.

This study shows the first combination of a ring-shaped vertically emitting quantum cascade laser (riQCL) providing two distinct emission wavelengths combined with a substrate-integrated hollow waveguide (iHWG). This ultra-compact riQCL-iHWG gas sensing device enables the simultaneous detection of two vapor phase species - here, furan and 2-methoxyethanol - providing distinctive absorption features at the emission wavelengths of the riQCL (i.e., 1144 and 1170 cm -1 ). Hence, multianalyte gas sensing via a unique mid-infrared (MIR) sensor concept is demonstrated.

Tunable diode laser absorption spectroscopy (TDLAS) is an excellent analytical technique for gas sensing applications. In situ sensing of relevant hydrocarbon gases is of substantial interest for a variety of in-field scenarios including environmental monitoring and process analysis, ideally providing accurate, molecule specific, and rapid information with minimal sampling requirements. Substrate-integrated hollow waveguides (iHWGs) have demonstrated superior properties for gas sensing applications owing to minimal sample volumes required while simultaneously serving as efficient photon conduits. Interband cascade lasers (ICLs) are recently emerging as mid-infrared light sources operating at room temperature, with low power consumption, and providing excellent potential for integration. Thereby, portable and handheld mid-infrared sensing devices are facilitated. Methane (CH4) is among the most frequently occurring, and thus, highly relevant hydrocarbons requiring in situ emission monitoring by taking advantage of its distinct molecular absorption around 3 μm. Here, an efficient combination of iHWGs with ICLs is presented providing a methane sensor calibrated in the range of 100 to 2000 ppmv with a limit of detection at 38 ppmv at the current stage of development. Furthermore, a measurement precision of 0.62 ppbv during only 1 s of averaging time has been demonstrated, thereby rendering this sensor concept useful for in-line and on-site emission monitoring and process control applications.

The demographical, clinical, and therapeutical features of patients with brucellar spondylodiscitis (BS) were evaluated in this study. Of the 96 patients with brucellosis, 20 (20.8%) were diagnosed with spondylodiscitis. Patients who had BS were more likely to be older (p = 0.001), have higher erythrocyte sedimentation rates (p = 0.01), and more likely to be anemic (p = 0.017). Lumbar segment (18/20) was frequently involved region. BS was complicated with paravertebral or epidural abscess in seven, radiculitis in six, and psoas abscess in five of cases. Antibiotic regimens including two or three antibiotics with combination of doxycycline, rifampin, and streptomycin were used. In this series, the mean duration of antimicrobial therapy was 18 weeks (range 12-56 weeks). Attention is drawn to this disease given the need for prolonged duration of treatment especially in complicated cases in order to avoid possible sequelae.

Mouse sepsis models are used to gain insight into the complex processes involved with patients suffering from glucose metabolism disorders. Measuring the expiratory release of (13)CO(2) after administering stable labeled (13)C(6)-glucose enables assessment of the in vivo integrity and functionality of key metabolic processes. In the present study, we demonstrate that Fourier transform infrared spectroscopy operating in the mid-infrared spectral regime (2-20 μm) combined with hollow waveguide gas sensing modules simultaneously serving as a miniaturized gas cell and as a waveguide are capable of quantitatively monitoring (13)CO(2) enrichment levels in low volume mouse breath samples.

Aim: To determine the distribution of viral genotypes for primary or acquired lamivudine resistance., Methods: A total of 283 patients with chronic hepatitis B virus (HBV) infection (245 patients with chronic hepatitis B and 38 inactive hepatitis B surface antigen carriers) were included in the study. The HBV genotype was determined by using quantitative real-time polymerase chain reaction and sequence analysis, and tyrosine-methionine-aspartate-aspartate (YMDD) motif mutations were determined using the reverse transcriptase hybridization method., Results: Lamivudine resistance was determined in a total of 25 (10.7%) chronic hepatitis B patients. Eight subjects (4%) had primary resistance to lamivudine, and 17 (53.1%) had secondary resistance to lamivudine. Genotype D, which was isolated from 267 of the patients with chronic HBV infection, was the dominant genotype in Turkey., Conclusion: Identification of YMDD motif mutations should have a positive impact on the selection of proper antiviral medication for patients, even for those who are nucleoside naïve.

Sinonasal mucormycosis is a rare, life-threatening and insidious fungal infection. Uncontrolled diabetes mellitus and immunsupression are the most important risk factors. The infection is clinically characterized by black necrotic tissues and crusting in the nasal cavity. In acute fulminant rhinosinusitis and particularly in infections caused by mucor species, black scar tissues seen on the nasal mucosa are pathognomonic. High level of suspicion in the risk group the diagnosis is confirmed by histopathological examination. The rhinoorbital form is even rarer and the findings may range from orbital pain to ophtalmoplegia and blindness. In this report we present a 72-year-old female patient with uncontrolled type 2 diabetes mellitus who was admited with the complaints of exophtalmos in the left eye, diplopia and headache. In the physical examination there was purulent discharge in the middle meatus and left orbital abscess was detected on computed tomography. We performed an emergency endoscopic sinus surgery. While we did not observe any necrotic tissues, granulation tissues were detected and pus was drained from the orbital cavity. The result of the histopathological examination was reported as invasive mucormycosis. We presented this case to emphasize the importance of early diagnosis and treatment of rhinoorbital mucormycosis.

The prevalence of Parkinson's disease (PD) in sub-Saharan Africa is still a matter of debate. The few studies that have been conducted have shown prevalences lower than those in the western world. Whether this represents a genuine finding is unclear to date. In northern Tanzania, we have conducted a hospital-based evaluation and a community-based door-to-door study to assess the prevalence of Parkinsonism, including that of PD. Over a period of 8 months, all patients admitted to a mid-size rural hospital were screened for PD. In parallel, 1,569 people aged >or=50 years were recruited from the communities and assessed for PD with standard questions. Sampling was performed according to the method of "multistage cluster sampling." The questions had previously been tested in a pilot study prior to the survey. People who screened positive were examined by a specialist neurologist. In the hospital, eight of 740 people with neurological diagnoses had Parkinsonism, of whom three patients had a diagnosis of PD. In the community-based study, 18 people answered positively to least one of the 12 screening questions. However, the diagnosis of PD could not be confirmed by further examination in any of them. The prevalence of PD in northern Tanzania was found to be very low. This result would need confirmation in studies with larger populations, ideally of different African ethnicities.

Crimean-Congo hemorrhagic fever (CCHF) is an acute, tick-borne viral disease, with the potential for human to human transmission. Infection often has severe hemorrhagic manifestations and considerable mortality. Healthcare workers (HCWs) caring for patients with CCHF constitute a major risk group for infection. Although nosocomial transmission from patients to HCWs accounts for a significant proportion of CCHF cases and outbreaks worldwide, transmission of CCHF from patient to patient has not previously been reported. A case of nosocomial transmission of CCHF from patient to patient at a hospital is described.