Mid-Infrared Photothermal Spectroscopy for the Detection of Caffeine in Beverages.

Caffeine is the most widely consumed stimulant and is the subject of significant ongoing research and discussions due to its impact on human health. The industry's need to comply with country-specific food and beverage regulations underscores the importance of monitoring caffeine levels in commercial products. In this study, we propose an alternative technique for caffeine analysis that relies on mid-infrared laser-based photothermal spectroscopy (PTS). PTS exploits the high-power output of the quantum cascade laser (QCL) sources to enhance the sensitivity of the mid-IR measurement. The laser-induced thermal gradient in the sample scales with the analytes' absorption coefficient and concentration, thus allowing for both qualitative and quantitative assessment. We evaluated the performance of our experimental PTS spectrometer, incorporating a tunable QCL and a Mach-Zehnder interferometer, for detecting caffeine in coffee, black tea, and an energy drink. We calibrated the setup with caffeine standards (0.1-2.5 mg mL-1) and we benchmarked the setup's capabilities against gas chromatography (GC) and Fourier-transform infrared (FTIR) spectroscopy. Quantitative results aligned with GC analysis, and limits of detection matched the research-grade FTIR spectrometer, indicating an excellent performance of our custom-made instrument. This method offers an alternative to established techniques, providing a platform for fast, sensitive, and non-destructive analysis without consumables as well as with high potential for miniaturization.

The Impact of Liver Failure on the Immune System.

Liver failure profoundly affects the immune system, leading to dysregulation of innate and adaptive immune response. This review explores the intricate relationship between liver function and immune homeostasis. The role of the liver as a central hub in immune response initiation is elucidated, emphasizing its involvement in hepatic inflammation induction and subsequent systemic inflammation. Cytokines, chemokines, growth factors, and lipid mediators orchestrate these immune processes, serving as both prognostic biomarkers and potential therapeutic targets in liver failure-associated immune dysregulation, which might result from acute-on-chronic liver failure (ACLF) and cirrhosis. Furthermore, the review delves into the mechanisms underlying immunosuppression in liver failure, encompassing alterations in innate immune cell functions such as neutrophils, macrophages, and natural killer cells (NK cells), as well as perturbations in adaptive immune responses mediated by B and T cells. Conclusion: Understanding the immunological consequences of liver failure is crucial for developing targeted therapeutic interventions and improving patient outcomes in liver disease management.

Alexithymia in adolescents in Poland: an important issue in the holistic approach to patients' care.

Introduction: Alexithymia is defined as a disturbed ability to identify and verbally express emotions with a limited imaginative capacity as well as externally oriented thinking. The literature on alexithymia is limited and scarce research concentrated on alexithymia in different gender groups. Aim: As alexithymia may influence the therapeutic outcome, the objective of the study was to assess the prevalence of alexithymia in adolescents in Poland, paying special attention to gender differences. Material and methods: This cross-sectional study was run on a group of 730 high school students in Poland. The mean age of this group was 17.05 ±1.18 years (age range: 15-19 years). Alexithymia was assessed with Toronto Alexithymia Scale (TAS-20). Results: Alexithymia was found in 31.0% of adolescents. 56.0% of subjects presented with signs of at least intermediate (borderline) alexithymia. Significantly more females than males suffered from alexithymia (37.0% and 20.8%, respectively; p < 0.001). TAS-20 scores were also significantly higher in females than males (55.59 ±12.32 points and 49.40 ±12.00, respectively; p < 0.001). The same phenomenon was observed for the following domains of alexithymia: difficulty in identifying feelings (DIF) and difficulty in describing feelings (DDF). However, there was no difference in gender distribution in the externally oriented thinking (EOT) domain. Conclusions: Alexithymia was shown to be common among adolescents in our country. More females than males suffer from this condition. This seems to be of importance in the holistic approach to patients' care.

Dual-Beam Photothermal Spectroscopy Employing a Mach-Zehnder Interferometer and an External Cavity Quantum Cascade Laser for Detection of Water Traces in Organic Solvents.

We report on a mid-infrared (mid-IR) photothermal spectrometer for liquid-phase samples for the detection of water in organic solvents, such as ethanol or chloroform, and in complex mixtures, such as jet fuel. The spectrometer is based on a Mach-Zehnder interferometer (MZI) employing a He-Ne laser, a mini-flow cell with two embedded channels placed in the interferometer's arms, and a tunable external cavity quantum cascade laser (EC-QCL) for selective analyte excitation in a collinear arrangement. In this study, the bending vibration of water in the spectral range 1565-1725 cm-1 is targeted. The interferometer is locked to its quadrature point (QP) for most stable and automated operation. It provides a linear response with respect to the water content in the studied solvents and photothermal analyte spectra, which are in good agreement with FTIR absorbance spectra. The method is calibrated and validated against coulometric Karl Fischer (KF) titration, showing comparable performance and sensitivity. Limits of detection (LODs) for water detection in the single-digit ppm range were obtained for chloroform and jet fuel due to their low background absorption, whereas lower sensitivity has been observed for water detection in ethanol due to pronounced background absorption from the solvent. In contrast to KF titration, which requires toxic reagents and produces waste, the developed method works reagent-free. It can be applied in an online format in the chemical industry as well as for fuel quality control, being industrial applications where traces of water need to be accurately determined, preferably in real-time. It thus holds great promise as a green alternative to the offline KF titration method, which is the current standard method for this application.

Prevalence and quality of life of facial acne: a cross-sectional study in high school students in Poland.

Introduction: Acne is a frequent chronic inflammatory disease, which affects most commonly adolescents. It might have a negative effect on patients' well-being. Aim: To appraise the prevalence of facial acne among adolescents and to assess how acne of different clinical severity influences quality of life in this age group. Material and method: This cross-sectional study was conducted on a representative sample of individuals aged 15-19 years in high schools in Poland. A total of 730 students were included in the final analysis. Standardized photographs according to the Investigator's Global Assessment (IGA) were used for self-assessment of both the presence and severity of facial acne. The Dermatology Life Quality Index (DLQI) was employed to evaluate subjects' quality of life (QoL) impairment. Results: Facial acne was found in 547 (74.9%) respondents with no significant difference in acne prevalence among females (75.1%) and males (74.6%). The vast majority of acne individuals (90.9%) suffered from minimal and mild acne, moderate acne was reported by 7.3% and severe one by 1.8% of acne students. Acne had a small effect on QoL (DLQI mean score of 2.8 ±3.6 points); females had significantly more decreased QoL than males (3.17 ±3.74 and 1.76 ±2.69 points, respectively). QoL impairment positively correlated with the clinical severity of facial acne. Conclusions: Facial acne is a common health problem in adolescents. Although it is not very severe in the majority of subjects it significantly decreases their QoL. Therefore, acne should be treated as a serious skin condition requiring a holistic approach to the patients.

Mid-IR refractive index sensor for detecting proteins employing an external cavity quantum cascade laser-based Mach-Zehnder interferometer.

Novel laser light sources in the mid-infrared region enable new spectroscopy schemes beyond classical absorption spectroscopy. Herein, we introduce a refractive index sensor based on a Mach-Zehnder interferometer and an external-cavity quantum cascade laser that allows rapid acquisition of high-resolution spectra of liquid-phase samples, sensitive to relative refractive index changes down to 10-7. Dispersion spectra of three model proteins in deuterated solution were recorded at concentrations as low as 0.25 mg mL-1. Comparison with Kramers-Kronig-transformed Fourier transform infrared absorbance spectra revealed high conformance, and obtained figures of merit compare well with conventional high-end FTIR spectroscopy. Finally, we performed partial least squares-based multivariate analysis of a complex ternary protein mixture to showcase the potential of dispersion spectroscopy utilizing the developed sensor to tackle complex analytical problems. The results indicate that laser-based dispersion sensing can be successfully used for qualitative and quantitative analysis of proteins.

Beyond Beer's Law: Why the Index of Refraction Depends (Almost) Linearly on Concentration.

Beer's empiric law states that absorbance is linearly proportional to the concentration. Based on electromagnetic theory, an approximately linear dependence can only be confirmed for comparably weak oscillators. For stronger oscillators the proportionality constant, the molar attenuation coefficient, is modulated by the inverse index of refraction, which is itself a function of concentration. For comparably weak oscillators, the index of refraction function depends, like absorbance, linearly on concentration. For stronger oscillators, this linearity is lost, except at wavenumbers considerably lower than the oscillator position. In these transparency regions, linearity between the change of the index of refraction and concentration is preserved to a high degree. This can be shown with help of the Kramers-Kronig relations which connect the integrated absorbance to the index of refraction change at lower wavenumbers than the corresponding band. This finding builds the foundation not only for refractive index sensing, but also for new interferometric approaches in IR spectroscopy, which allow measuring the complex index of refraction function.

Mid-Infrared Dispersion Spectroscopy as a Tool for Monitoring Time-Resolved Chemical Reactions on the Examples of Enzyme Kinetics and Mutarotation of Sugars.

Ongoing technological advancements in the field of mid-infrared (MIR) spectroscopy continuously yield novel sensing modalities, offering capabilities beyond traditional techniques like Fourier transform infrared spectroscopy (FT-IR). One such advancement is MIR dispersion spectroscopy, utilizing a tunable quantum cascade laser and Mach-Zehnder interferometer for liquid-phase analysis. Our study assesses the performance of a custom MIR dispersion spectrometer at its current development stage, benchmarks its performance against FT-IR, and validates its potential for time-resolved chemical reaction monitoring. Unlike conventional methods of IR spectroscopy measuring molecular absorptions using intensity attenuation, our method detects refractive index changes (phase shifts) down to a level of 6.1 × 10-7 refractive index units (RIU). This results in 1.5 times better sensitivity with a sevenfold increase in analytical path length, yielding heightened robustness for the analysis of liquids compared to FT-IR. As a case study, we monitor the catalytic activity of invertase with sucrose, observing the formation of resultant monosaccharides and their progression toward thermodynamic equilibrium. Anomalous refractive index spectra of reaction mixtures, with substrate concentrations ranging from 2.5 to 25 g/L, are recorded, and analyzed at various temperatures, yielding Michaelis-Menten kinetics findings comparable to the literature. Additionally, the first-time application of two-dimensional correlation spectroscopy on the recorded dynamic dispersion spectra correctly identifies the mutarotation of reaction products (glucose and fructose). The results demonstrate high precision and sensitivity in investigating complex time-dependent chemical reactions via broadband refractive index changes.

Mid-IR dispersion spectroscopy - A new avenue for liquid phase analysis.

Mid-IR dispersion spectroscopy is an attractive, novel approach to liquid phase analysis that extends the possibilities of traditional methods based on the detection of absorption via intensity attenuation. This technique detects inherent refractive index changes (phase shifts) induced by IR light interaction with absorbing matter. In contrast to classic absorption spectroscopy, it provides extended dynamic range, baseline-free detection, constant sensitivity, and inherent immunity to power fluctuation. In this paper, we provide a detailed experimental and theoretical characterization and verification of this method with special focus on broadband liquid sample analysis. For this purpose, we develop a compact benchtop dispersion spectroscopy setup based on an EC-QCL coupled to a Mach-Zehnder interferometer. Phase-locked interferometric detection enables to fully harness the advantages of the technique. By instrument operation in the quadrature point combined with balanced detection, the full immunity towards laser power fluctuations and the environmental noise can be achieved. On the example of ethanol (0.5-50% v/v) dissolved in water, it is experimentally demonstrated that changes of the refractive index function are linearly related to concentration also for strongly absorbing, highly concentrated samples beyond the validity of the Beer-Lambert law. Characterization of the sensitivity and noise behavior indicates that the optimum applicable pathlength for liquid analysis can be extended beyond the ones for absorption spectroscopy. Experimental demonstration of the advantages over classical absorption spectroscopy illuminates the potential of dispersion spectroscopy as upcoming robust and sensitive way of recording IR spectra of liquid samples.

Applications of Silk Fibroin in Human and Veterinary Medicine.

The properties of silk make it a promising material for medical applications, both in human and veterinary medicine. Its predominant amino acids, glycine and alanine, exhibit low chemical reactivity, reducing the risk of graft rejection, a notable advantage over most synthetic polymers. Hence, silk is increasingly used as a material for 3D printing in biomedicine. It can be used to build cell scaffolding with the desired cytocompatibility and biodegradability. In combination with gelatine, silk can be used in the treatment of arthritis, and as a hydrogel, to regenerate chondrocytes and mesenchymal cells. When combined with gelatine and collagen, it can also make skin grafts and regenerate the integumentary system. In the treatment of bone tissue, it can be used in combination with polylactic acid and hydroxyapatite to produce bone clips having good mechanical properties and high immunological tolerance. Furthermore, silk can provide a good microenvironment for the proliferation of bone marrow stem cells. Moreover, research is underway to produce artificial blood vessels using silk in combination with glycidyl methacrylate. Silk vascular grafts have demonstrated a high degree of patency and a satisfactory degree of endothelial cells coverage.

Adolescents' Knowledge and Attitudes Related to Hand Eczema: A Cross-Sectional Study.

Background: Hand eczema (HE) is a common inflammatory skin disease occurring in subjects of any age. Literature data on knowledge of HE in different age-groups are scarce. Purpose: To evaluate knowledge and attitudes related to HE among adolescents. Methods: A total of 258 high school students were invited to participate in this project. A specially designed questionnaire created on the base of previous studies was used to assess adolescents' knowledge of HE. HE was self-reported answering the validated single question "Have you ever had hand eczema?" Results: Data from 243 students (94.2% response rate) were obtained for final analysis. There were 117 (48.1%) females and 126 (51.9%), males with a mean age of 16.0±1.7 years. Sixty-eight students (28%) reported a personal history of HE, and 32.8% declared having knowledge of HE. More females than males (P=0.023) declared that they knew what HE was (39.3% and 26.2%, respectively). Hand cream was used on a regular basis by 49% of adolescents. Females used hand cream more frequently (P<0.001) than males. No difference in declared knowledge of HE was found between subjects with and without a personal history of hand lesions. Students declaring having adequate knowledge of HE used hand cream more commonly (P=0.045). Conclusion: Although HE is a common disease in the general population, including adolescents, less than a third of subjects were aware of this entity. Almost half were using hand cream, but interestingly, personal history of HE did not increase the regular application of hand cream.

Plasma untargeted metabolomics with proteinase K discloses phospholipid signature associated with pulmonary arterial hypertension.

Pulmonary arterial hypertension is a rare but life-threatening and clinically heterogeneous disease. The diagnostic schedule of this disorder is complex, and no specific indicator of the arterial etiology has been explored. In this study, untargeted plasma metabolomics was applied to evaluate the metabolic fingerprints of pulmonary arterial hypertension patients. Plasma samples were prepared using a new approach, which applies proteinase K during the sample preparation procedure to increase the metabolite coverage. The metabolic fingerprints were determined via LC-MS and subsequently analyzed with the use of both uni- and multivariate statistics. A total of 21 metabolites were discovered to be significantly altered in pulmonary arterial hypertensive patients. The metabolites were mainly related to the phospholipid metabolic pathways. In this study, decreases were found in the phosphatidylcholines (PCs) [PC(32:0), PC(40:7), PC(42:7)], phosphatidylethanolamine PE(18:0/18:2), lysophosphatidylethanolamines (LPEs) [LPE(22:6), LPE(18:2), LPE(18:0), LPE(20:4), LPE(20:1), LPE(20:0)], lysophosphatidylcholine LPC(20:4) and lysophosphatidylserine LPS(19:0), as well as increase of sphingomyelin SM(36:2), in the plasma samples of pulmonary arterial hypertensive patients in comparison to the control group. Besides their function as components of the biological membranes, these metabolites are also involved in the intracellular signaling pathways that are related to cell proliferation and apoptosis. The results obtained during this study confirm the potential of (untargeted) metabolomics to identify the molecular characteristics of the pathophysiology of pulmonary arterial hypertension. The clinical relevance of this study constitutes the selection of a metabolic panel that can potentially detect and properly diagnose the disease.

Absence of Staphylococcus aureus in Wild Populations of Fish Supports a Spillover Hypothesis.

Staphylococcus aureus is a human commensal and opportunistic pathogen that also infects other animals. In humans and livestock, where S. aureus is most studied, strains are specialized for different host species. Recent studies have also found S. aureus in diverse wild animals. However, it remains unclear whether these isolates are also specialized for their hosts or whether their presence is due to repeated spillovers from source populations. This study focuses on S. aureus in fish, testing the spillover hypothesis in two ways. First, we examined 12 S. aureus isolates obtained from the internal and external organs of a farmed fish. While all isolates were from clonal complex 45, genomic diversity indicates repeated acquisition. The presence of a φSa3 prophage containing human immune evasion genes suggests that the source was originally human. Second, we tested for S. aureus in wild fish that were isolated from likely sources. In particular, we sampled 123 brown trout and their environment at 16 sites in the remote Scottish Highlands with variable levels of exposure to humans, birds, and livestock. This screen found no S. aureus infection in any of the wild populations or their environment. Together, these results support that the presence of S. aureus in fish and aquaculture is due to spillover from humans rather than specialization. Given the trends of increasing fish consumption, a better understanding of the dynamics of S. aureus spillover in aquaculture will mitigate future risks to fish and human health. IMPORTANCE Staphylococcus aureus is a human and livestock commensal but also an important pathogen responsible for high human mortality rates and economic losses in farming. Recent studies show that S. aureus is common in wild animals, including fish. However, we do not know whether these animals are part of the normal host range of S. aureus or whether infection is due to repeated spillover events from true S. aureus hosts. Answering this question has implications for public health and conservation. We find support for the spillover hypothesis by combining genome sequencing of S. aureus isolates from farmed fish and screens for S. aureus in isolated wild populations. The results imply that fish are unlikely to be a source of novel emergent S. aureus strains but highlight the prominence of the spillover of antibiotic-resistant bacteria from humans and livestock. This may affect both future fish disease potential and the risk of human food poisoning.

Facial acne causes stigmatization among adolescents: A cross-sectional study.

BACKGROUND: Stigmatization is defined as a discrediting mark which sets the person from others and hindering interpersonal relationships. Literature data on stigma in acne subjects are scarce. AIMS: This study was undertaken to assess feelings of stigmatization in adolescents with facial acne. MATERIAL/METHODS: The study was performed on 730 high-school students aged 15 to 19 years with the mean age of 17.05 ± 1.18 years. Self-reported acne was found in 74.9% of subjects. The severity of acne was self-assessed with the standardized color images based on Investigators Global Assessment (IGA). Stigmatization was studied with 6-Item Stigmatization Scale (6-ISS) and Perceived Stigmatization Questionnaire (PSQ). Additionally, quality of life (QoL) was evaluated with Dermatology Life Quality Index (DLQI). RESULTS: 58% of adolescents with acne presented with feelings of stigmatization. Within the acne population, stigmatization was significantly more common in females than in males (p < 0.001). The mean level of stigmatization according to 6-ISS was significantly higher in acne sufferers than in those free from acne (1.68 ± 2.42 points and 0.55 ± 1.50 points, respectively; p < 0.001). Feelings of stigmatization were significantly more pronounced by females than males (p < 0.001). Staring at the skin and the fact that others are not attracted to person due to skin lesions were main problems raised by the study participants with acne. 6-ISS scores correlated with acne severity (r = 0.278; p < 0.001) and both 6-ISS and PSQ scores with QoL impairment (r = 0.530; p < 0.001 and r = 0.341; p < 0.001, respectively). CONCLUSIONS: Facial acne is a highly stigmatized skin disease and requires a holistic therapeutic approach.

Alexithymia in Adolescents with Acne: Association with Quality of Life Impairment and Stigmatization.

Alexithymia seems to be more common among patients with skin diseases. However, studies on acne patients are very limited. We conducted this study to evaluate alexithymia in adolescents with acne. In our cross-sectional study, 730 high school students (mean age: 17.05 ± 1.18 years) were recruited. The Toronto Alexithymia Scale (TAS-20) was used to measure alexithymia, the Dermatology Life Quality Index (DLQI) was employed to study quality of life (QoL), and the 6-item Stigmatization Scale (6ISS) was used to evaluate the level of stigmatization in acne subjects. Alexithymia was found in 31% of adolescents, with similar prevalence among those with and without acne (31.3% and 30.1%, respectively). The mean scoring on the TAS-20 in patients with acne (53.1 ± 12.8 points) was not significantly different from that of the non-acne group (53.5 ± 11.9 points). However, significant correlations between TAS-20 scores and QoL assessments (r = 0.332, p < 0.001) as well as stigmatization level (r = 0.284, p < 0.001) were found. These correlations were also significant for the domains of alexithymia described as difficulty in identifying feelings (DIF) and difficulty in describing feelings (DDF), but not for externally oriented thinking (EOT). The findings clearly showed that acne does not predispose to alexithymia; however, alexithymia in acne subjects is related to impaired QoL and stigmatization.

Miniaturized optoelectronic tweezers controlled by GaN micro-pixel light emitting diode arrays.

A novel, miniaturized optoelectronic tweezers (OET) system has been developed using a CMOS-controlled GaN micro-pixelated light emitting diode (LED) array as an integrated micro-light source. The micro-LED array offers spatio-temporal and intensity control of the emission pattern, enabling the creation of reconfigurable virtual electrodes to achieve OET. In order to analyse the mechanism responsible for particle manipulation in this OET system, the average particle velocity, electrical field and forces applied to the particles were characterized and simulated. The capability of this miniaturized OET system for manipulating and trapping multiple particles including polystyrene beads and live cells has been successfully demonstrated.

The Role of Chloride Channels in the Multidrug Resistance.

Nowadays, one of medicine's main and most challenging aims is finding effective ways to treat cancer. Unfortunately, although there are numerous anti-cancerous drugs, such as cisplatin, more and more cancerous cells create drug resistance. Thus, it is equally important to find new medicines and research the drug resistance phenomenon and possibilities to avoid this mechanism. Ion channels, including chloride channels, play an important role in the drug resistance phenomenon. Our article focuses on the chloride channels, especially the volume-regulated channels (VRAC) and CLC chloride channels family. VRAC induces multidrug resistance (MDR) by causing apoptosis connected with apoptotic volume decrease (AVD) and VRAC are responsible for the transport of anti-cancerous drugs such as cisplatin. VRACs are a group of heterogenic complexes made from leucine-rich repetition with 8A (LRRC8A) and a subunit LRRC8B-E responsible for the properties. There are probably other subunits, which can create those channels, for example, TTYH1 and TTYH2. It is also known that the ClC family is involved in creating MDR in mainly two mechanisms-by changing the cell metabolism or acidification of the cell. The most researched chloride channel from this family is the CLC-3 channel. However, other channels are playing an important role in inducing MDR as well. In this paper, we review the role of chloride channels in MDR and establish the role of the channels in the MDR phenomenon.

Tat-induced FOXO3a is a key mediator of apoptosis in HIV-1-infected human CD4+ T lymphocytes.

The high mutation rate of HIV is linked to the generation of viruses expressing proteins with altered function whose impact on disease progression is unknown. We investigated how HIV-1 viruses lacking Env, Vpr, and Nef affect CD4(+) T cell survival. We found that in the absence of these proteins, HIV-1-infected CD4(+) primary T cells progress to the G(0) phase of the cell cycle and to cell death, indicating that viruses expressing inactive forms of these proteins can contribute to the CD4(+) T cell decline as the wild-type virus, suggesting that other HIV proteins are responsible for inducing apoptosis. Apoptosis in these cells is triggered by the alteration of the Egr1-PTEN-Akt (early growth response-1/phosphate and tensin homolog deleted on chromosome 10/Akt) and p53 pathways, which converge on the FOXO3a (Forkhead box transcription factor O class 3a) transcriptional activator. The FOXO3a target genes Fas ligand and TRAIL, involved in the extrinsic apoptotic pathway, and PUMA, Noxa, and Bim, which are part of the intrinsic apoptotic pathway, were also up-regulated, indicating that HIV infection leads to apoptosis by the engagement of multiple apoptotic pathways. RNAi-mediated knockdown of Egr1 and FOXO3a resulted in reduced apoptosis in HIV-infected HeLa and CD4(+) T cells, providing further evidence for their critical role in HIV-induced apoptosis and G(0) arrest. We tested the possibility that Tat is responsible for the T cell apoptosis observed with these mutant viruses. The induction of Egr1 and FOXO3a and its target genes was observed in Jurkat cells transduced by Tat alone. Tat-dependent activation of the Egr1-PTEN-FOXO3a pathway provides a mechanism for HIV-1-associated CD4(+) T cell death.