Skin emitted volatiles analysis for noninvasive diagnosis: the current advances in sample preparation techniques for biomedical application.

Human skin emits a series of volatile compounds from the skin due to various metabolic processes, microbial activity, and several external factors. Changes in the concentration of skin volatile metabolites indicate many diseases, including diabetes, cancer, and infectious diseases. Researchers focused on skin-emitted compounds to gain insight into the pathophysiology of various diseases. In the case of skin volatolomics research, it is noteworthy that sample preparation, sampling protocol, analytical techniques, and comprehensive validation are important for the successful integration of skin metabolic profiles into regular clinical settings. Solid-phase microextraction techniques and polymer-based active sorbent traps were developed to capture the skin-emitted volatile compounds. The primary advantage of these sample preparation techniques is the ability to efficiently and targetedly capture skin metabolites, thus improving the detection of the biomarkers associated with various diseases. In further research, polydimethyl-based patches were utilized for skin research due to their biocompatibility and thermal stability properties. The microextraction sampling tools coupled with high sensitive Gas Chromatography-Mass Spectrometer provided a potential platform for skin volatolomes, thus emerging as a state-of-the-art analytical technique. Later, technological advancements, including the design of wearable sensors, have enriched skin-based research as it can integrate the information from skin-emitted volatile profiles into a portable platform. However, individual-specific hydration, temperature, and skin conditions can influence variations in skin volatile concentration. Considering the subject-specific skin depth, sampling time standardization, and suitable techniques may improve the skin sampling techniques for the potential discovery of various skin-based marker compounds associated with diseases. Here, we have summarised the current research progress, limitations, and technological advances in skin-based sample preparation techniques for disease diagnosis, monitoring, and personalized healthcare applications.

Regioselective Dichotomy in Ru(II)-Catalyzed C-H Annulation of Aryl Pyrazolidinones with 1,3-Diynes.

Herein, we present a substrate-controlled regiodivergent strategy for the selective synthesis of C3 or C2-alkynylated indoles via ruthenium-catalyzed [3 + 2]-annulation of readily available pyrazolidinones and 1,3-diynes. Remarkably, C3-alkynylated indoles were obtained in good yields when 1,4-diarylbuta-1,3-diynes were employed as the coupling partners. On the other hand, dialkyl-1,3-diynes led to the selective formation of C2-alkynylated indoles. The key features of the strategy are the operationally simple conditions and external-oxidant-free, broad-scope, and substrate-switchable indole synthesis. Scale-up reactions and further transformations expanded the synthetic utility of the protocol.

Simultaneous determination of exhaled breath vapor and exhaled breath aerosol using filter-incorporated needle-trap devices: A comparison of gas-phase and droplet-bound components.

Breath-composition analysis is a well-established, non-invasive method for early disease diagnosis and investigating exposure history. However, this analytical approach is hampered by the aerosol nature of breath samples and/or low concentrations of volatile organic compounds. Conventionally, two separate methods have been applied to study gas phase and breath droplets, although these approaches are expensive and time-consuming. To address this issue, for the first time a needle-trap device packed with Carboxen, which served as a sorbent for the extraction of volatile analytes from the gas-phase, and electrospun polyacrylonitrile filter, which used to capture breath aerosol was applied to breath characterization. The performance of the developed device was subsequently compared to that of Carboxen-loaded thin-film microextraction, which was employed for the first time to extract free gas-phase components. Both methods were optimized, validated, and applied for the screening of breath samples obtained from volunteers. Obtained figures of merits are as follows: limits of detection (0.01-0.2 ng mL-1), recovery (81-108%) and repeatability (<13%). To investigate the effect of droplets, breath samples acquired with and without a face mask were compared. While both methods yielded similar results for the breath samples obtained with the mask, the needle-trap device was able to provide higher concentrations of volatile organic compounds for the samples acquired without a mask due to its enhanced ability to trap droplets. Additionally, tests were also conducted to investigate breath composition after accidental exposure to chemicals. The results of these tests revealed that polar compounds tended to partition to breath droplets and were eliminated from the body more quickly, while non-polar compounds tended to remain in the gas phase and were eliminated at a slower rate.

A family of amphiphilic dioxidovanadium(V) hydrazone complexes as potent carbonic anhydrase inhibitors along with anti-diabetic and cytotoxic activities.

A family of dioxidovanadium(V) complexes (1-4) of the type [Na(H2O)x]+[VVO2(HL1-4)]- (x = 4, 4.5 and 7) where HL2- represents the dianionic form of 2-hydroxybenzoylhydrazone of 2-hydroxyacetophenone (H2L1, complex 1), 2-hydroxy-5-methylacetophenone (H2L2, complex 2), 2-hydroxy-5-methoxyacetophenone (H2L3, complex 3) and 2-hydroxy-5-chloroacetophenone (H2L4, complex 4), have been synthesized and characterized by analytical and spectral methods. These complexes exhibited the potential abilities to suppress the erythrocytes carbonic anhydrase enzymatic activity in type 1 and type 2 diabetic patients (in vitro), promising antidiabetic activity against T2 diabetic mice (in vivo). They also exhibited significant cytotoxic activity against cervical cancer (SiHa) cells (in vitro) as the IC50 value of complexes 1, 2 and 4 is substantially lower than the value found for cisplatin while that of 3 is comparable and follow the order: 4 < 1 < 2 < 3 and can kill the cells by apoptosis via the generation of reactive oxygen species (ROS). The complexes are soluble both in water and octanol media and also non-toxic at working concentrations. The antidiabetic activity of these four complexes follows the order: 4 > 2 > 1 > 3 while both the carbonic anhydrase and cytotoxic activity follow the order: 4 > 1 > 2 > 3 suggesting that complex 4, containing electron withdrawing Cl atom is the most reactive while 3 with electron donating OCH3 group is the least reactive species. The molecular docking study on hCA-I and hCA-II demonstrates that complexes interact via hydrogen bonding as well as different types of π-stacking.

Breath-Based Diagnosis of Infectious Diseases: A Review of the Current Landscape.

Various analytical methods can be applied to concentrate, separate, and examine trace volatile organic metabolites in the breath, with the potential for noninvasive, rapid, real-time identification of various disease processes, including an array of microbial infections. Although biomarker discovery and validation in microbial infections can be technically challenging, it is an approach that has shown great promise, especially for infections that are particularly difficult to identify with standard culture and molecular amplification-based approaches. This article discusses the current state of breath analysis for the diagnosis of infectious diseases.

Recent advances in breath analysis to track human health by new enrichment technologies.

Detection of biomarkers in exhaled breath has been gaining increasing attention as a tool for diagnosis of specific diseases. However, rapid and accurate quantification of biomarkers associated with specific diseases requires the use of analytical methods capable of fast sampling and preconcentration from breath matrix. In this regard, solid phase microextraction and needle trap technology are becoming increasingly popular in the field of breath analysis due to the unique benefits imparted by such methods, such as the integration of sampling, extraction, and preconcentration in a single step. This review discusses recent advances in breath analysis using these sample preparation techniques, providing a summary of recent developments of analytical methods based on breath volatile organic compounds analysis, including the successful identification of various biomarkers related to human diseases.

Augmentation of sensitivity of FBG strain sensor for biomedical operation: publisher's note.

This publisher's note reports a correction to Appl. Opt.57, 6906 (2018)APOPAI0003-693510.1364/AO.57.006906.

Rhodium(III)-Catalyzed Directed C-H Dienylation of Anilides with Allenes Leads to Highly Conjugated Systems.

Allenes are unique coupling partners in transition-metal-catalyzed C-H functionalization leading to a variety of products via alkenylation, allenylation, allylation, and annulation reactions. The outcome is governed by both the reactivity of the allene and the formation and stability of the organometallic intermediate. An efficient Rh(III)-catalyzed, weakly coordinating group-directed dienylation of electronically unbiased allenes is developed using an N-acyl amino acid as a ligand. Further elaboration of the dienylated products to construct polycyclic compounds is also described.

Ultrahigh-resolution interrogation of a fiber Bragg grating sensor based on higher order four-wave mixing.

The performance of a highly sensitive strain sensor based on nonlinear four-wave mixing (FWM) using a fiber Bragg grating (FBG) is investigated. The power change due to the wavelength shift induced by very small strain over the FBG is significantly magnified by a higher order FWM process. Strain sensitivity of 5.547 dBm/µÏµ is achieved and minimum wavelength shift of 2.18×10-6 nm (which corresponds to a strain of 1.80×10-3 µÏµ) is detected with uniform FBG, whereas in case of chirped FBG (CFBG) strain sensitivity of 0.3 dBm/µÏµ with minimum detectable wavelength shift of 4×10-5 nm (which corresponds to a strain of 0.033 µÏµ) is obtained.

Total Synthesis of the Proposed Structure of Mycobactin J.

The total synthesis of the proposed structure of mycobactin J (MJ), a metabolite of Mycobacterium tuberculosis, is presented. The highlights of the synthesis include a careful control of the Z-stereochemistry of the unsaturated long chain fatty acid, a biomimetic construction of the oxazoline building block and the carriage of an unprotected phenol throughout the synthesis.

Augmentation of sensitivity of FBG strain sensor for biomedical operation.

The performance of a highly sensitive strain sensor based on nonlinear four wave mixing (FWM) using two uniform fiber Bragg gratings (FBGs) is investigated. Strain is measured by the proposed setup with high resolution and precision. It is observed that the wavelength shift induced by very small strain over the FBG is significantly magnified by the higher-order FWM process. The sensitivity is enhanced by a factor of nine based on a wavelength shift of the eighth-order FWM product. Strain sensitivity of 11.23 pm/µÏµ is achieved against initial strain sensitivity of 1.23 pm/µÏµ. The proposed scheme can provide a strain measurement range of about 3500 µÏµ. Application of the proposed setup in the cardiac and respiratory systems is also studied, and the results are found to be reliable and accurate, even if the applied strain on the FBG is of the order of 0.1 µÏµ.

Non-invasive diagnosis of type 2 diabetes in Helicobacter pylori infected patients using isotope-specific infrared absorption measurements.

Helicobacter pylori causes several gastrointestinal diseases and may also contribute to the development of type 2 diabetes (T2D). Several studies suggest that there might be a potential link between H. pylori infection and T2D, but it still remains the subject of debate. Here, we first report the cumulative effect of H. pylori infection and T2D by exploiting the excretion kinetics of 13C/12C and 18O/16O isotope ratios of exhaled breath CO2 in response to an oral dose of 13C-enriched glucose in individuals with T2D and non-diabetic controls (NDC) harbouring the H. pylori infection. Using a high-resolution integrated cavity output spectroscopy (ICOS) technique in the infrared region, we observed that the isotopic fractionations of 13C and 18O in breath CO2 are distinctly altered in H. pylori infected T2D patients as well as in H. pylori infected NDC. Several optimal diagnostic cut-off points of 13C and 18O isotopes of breath CO2 were also determined which exhibited the diagnostic sensitivity and specificity of ∼97 % and thus suggesting that breath 13C and 18O isotopes might be considered as potential biomarkers for the non-invasive assessment of the gastric pathogen prior to the onset of T2D. This may open a new diagnostic strategy for treating these common diseases in an alternative way.

Isotope-specific breath analysis to track the end-stage renal disease during hemodialysis.

The underlying mechanisms towards the progression of end-stage renal disease (ESRD) in chronic kidney disease (CKD) are poorly understood and it still remains a major clinical stumbling block for early detection of CKD. Most patients with CKD pass through ESRD with the necessity of frequent hemodialysis (HD) treatment. At present, plasma urea and creatinine levels are examined in most CKD patients to monitor their health status after dialysis. But it is impossible to get immediate feedback on the patients' health as the conventional tests involve the collection of blood samples, laboratory processing for a prolonged period of time and, finally, analysis of those samples. However, the test results are very important in deciding the treatment plan for those ESRD patients. Here, we show that the enzymatic activity of carbonic anhydrase in erythrocytes is distinctly altered in ESRD subjects under HD. This, in turn, leads to the isotopic enrichments of oxygen-18 (18O) and carbon-13 (13C) of CO2 during respiration in HD treatment. High-resolution cavity-enhanced absorption spectroscopic measurements show that 18O and 13C-isotopic fractionations of breath CO2 are correlated with Kt/V values, suggesting a novel unifying strategy for ESRD patients that can be used as an isotope-specific methodology for non-invasive assessment of dialysis adequacy and hence 12C18O16O and 13C16O16O could be used as novel markers for tracking the physiological parameters of ESRD individuals. Our findings suggest that the monitoring of 18O and 13C isotopes of breath CO2 may facilitate the proper management of advanced CKD patients. The primary advantage of this isotopic breath test is that it may reduce the valuable time lag between the completion of dialysis and obtaining the clinical report on the status of patients' health.

New Strategy for in Vitro Determination of Carbonic Anhydrase Activity from Analysis of Oxygen-18 Isotopes of CO2.

The oxygen-18 isotopic (18O) composition in CO2 provides an important insight into the variation of rate in isotopic fractionation reaction regulated by carbonic anydrase (CA) metalloenzyme. This work aims to employ an 18O-isotope ratio-based analytical method for quantitative estimation of CA activity in erythrocytes for clinical testing purposes. Here, a new method has been developed that contains the measurements of 18O/16O isotope ratios during oxygen-18 isotopic exchange between 12C16O16O and H218O of an in vitro biochemical reaction controlled by erythrocytes CA and estimation of enzymatic activity of CA from the isotopic composition of CO2. We studied the enrichments of 18O-isotope of CO2 with increments of CA activities during isotopic fractionation reaction. To check the influence of subject-specific body temperature, pH, H218O, and cellular produced CO2 on this reaction, we performed the in vitro experiments in closed containers with variations of those parameters. Finally, we mimicked the exchange reaction at 5% [CO2], 5‰ [H218O], pH of 7.4, and temperature of 37 °C to create the physiological environment equivalent to that of the human body and monitored the exchange kinetics with variations of CA activities, and subsequently, we derived the quantitative relation between the 18O-isotope of CO2 and CA activity in erythrocytes. This assay may be applicable for rapid and simple quantification of carbonic anhydrase activity which is very important to prevent the carbonic-anhydrase-associated disorders in human.

13C isotopic abundances in natural nutrients: a newly formulated test meal for non-invasive diagnosis of type 2 diabetes.

A new method to replace commercially prepared 13C-labelled glucose with naturally available 13C-enriched substrates could result in promotion of the clinical applicability of the isotopic breath test for detection of type 2 diabetes (T2D). Variation of the carbon-13 isotope in human breath depends on the 13C enrichment in the diet taken by subjects. Here, we formulated a new test meal comprising naturally available 13C-enriched foods and subsequently administered it to non-diabetic control (NDC) subjects and those with T2D. We found that the new test meal-derived 13C enrichment of breath CO2 was significantly lower in T2D compared with NDC. Furthermore, from our observations T2D exhibited higher isotopic enrichment of oxygen-18 (18O) in breath CO2 compared with NDC following ingestion of the new meal. We determined the optimal diagnostic cut-off values of 13C (i.e. δ 13C‰ = 7.5‰) and 18O (i.e. Î´ 18O‰ = 3.5‰) isotopes in breath CO2 for precise classification of T2D and NDC. Our new method involving the administration of naturally 13C-abundant nutrients showed a typical diagnostic sensitivity and specificity of about 95%, suggesting a valid and potentially robust global method devoid of any synthetically manufactured commercial 13C-enriched glucose which thus may serve as an alternative diagnostic tool for routine clinical applications.

Targeting erythrocyte carbonic anhydrase and 18O-isotope of breath CO2 for sorting out type 1 and type 2 diabetes.

The inability to envisage the acute onset and progression of type 1 diabetes (T1D) has been a major clinical stumbling block and an important area of biomedical research over the last few decades. Therefore there is a pressing need to develop a new and an effective strategy for early detection of T1D and to precisely distinguish T1D from type 2 diabetes (T2D). Here we describe the precise role of the enzymatic activity of carbonic anhydrase (CA) in erythrocytes in the pathogenesis of T1D and T2D. We show that CA activities are markedly altered during metabolism of T1D and T2D and this facilitates to the oxygen-18 (18O) isotopic fractionations of breath CO2. In our observations, T1D exhibited considerable depletions of 18O-isotopes of CO2, whereas T2D manifested isotopic enrichments of 18O in breath CO2, thus unveiling a missing link of breath18O-isotopic fractionations in T1D and T2D. Our findings suggest that the alterations in erythrocytes CA activities may be the initial step of altered metabolism of T1D and T2D, and breath 18O-isotope regulated by the CA activity is a potential diagnostic biomarker that can selectively and precisely distinguish T1D from T2D and thus may open a potential unifying strategy for treating these diseases.

Salivary IgA versus HIV and Dental Caries.

INTRODUCTION: The inter-relationship of Human Immunodeficiency Virus (HIV) infection and dental caries as well as Salivary Immunoglobulin-A (S-IgA) level appear to remain under explored while a manual and electronic search of the literature was made. Hence, the present study was undertaken to assess the relationship of S-IgA and dental caries status in HIV positive children. AIM: The aim of this study was to find out the relationship of S-IgA antibody with dental caries by measuring the concentration of IgA in saliva of HIV positive and negative children and determine the dental caries status in HIV positive and HIV negative children, which may help in treatment planning and prevention of the same. MATERIALS AND METHODS: A total of 28 HIV positive children aged between 6-14 years and 28 age matched HIV negative children were included in this study and both samples were randomly selected from the same Non-Governmental Organization (NGO). The HIV status of both these samples was confirmed from their medical records provided by the NGO. Only 2cc of unstimulated saliva was collected from both groups in special tubes coded numerically using the method described by Collins and Dawes and the samples were analyzed to measure the concentration of IgA using commercially available ELISA kit (DRG Diagnostics, Germany). Examination of dental caries was carried out according to WHO criteria (1997) using a flat mouth mirror and CPI probe. RESULTS: In HIV +ve group mean S-IgA level was calculated as 81.61 ± 6.20 µg/ml, mean DMFT was 3.86 ± 3.37, mean deft was 4.75 ± 2.86. In HIV -ve group mean S-IgA level was calculated as 145.57 ± 17.83µg/ml, mean DMFT was 2.54 ± 0.69, mean deft was 2.43 ± 2.01. Strong-ve correlation between S-IgA and DMFT (r = -0.781, t = 6.38, p < 0.001) and negative but Not Significant (N.S.) correlation (r = -0.19, t = 0.99, p > 0.05) between S-IgA and deft was found in HIV +ve group. Strong -ve correlation between S-IgA and DMFT (r = -0.655, t = 4.42, p < 0.001), S-IgA and deft (r = -0.942, t =14.32, p=<0.001) was found in HIV-ve group. CONCLUSION: This study suggests that the individuals who are suffering from IgA deficiency in general, are more susceptible to dental caries than normal individuals.

A comparative evaluation of dental caries status among hearing-impaired and normal children of Malda, West Bengal, evaluated with the Caries Assessment Spectrum and Treatment.

CONTEXT: Dental caries is one of the major modern-day diseases of dental hard tissue. It may affect both normal and hearing-impaired children. AIMS: This study is aimed to evaluate and compare the prevalence of dental caries in hearing-impaired and normal children of Malda, West Bengal, utilizing the Caries Assessment Spectrum and Treatment (CAST). SETTINGS AND DESIGN: In a cross-sectional, case-control study of dental caries status of 6-12-year-old children was assessed. SUBJECTS AND METHODS: Statistically significant difference was found in studied (hearing-impaired) and control group (normal children). In the present study, caries affected hearing-impaired children found to be about 30.51% compared to 15.81% in normal children, and the result was statistically significant. Regarding individual caries assessment criteria, nearly all subgroups reflect statistically significant difference except sealed tooth structure group, internal caries-related discoloration in dentin, and distinct cavitation into dentine group, and the result is significant at P < 0.05. STATISTICAL ANALYSIS USED: Statistical analysis was carried out utilizing Z-test. RESULTS: Statistically significant difference was found in studied (hearing-impaired) and control group (normal children). In the present study, caries effected hearing-impaired children found about 30.51% instead of 15.81% in normal children, and the result was statistically significant (P < 0.05). Regarding individual caries assessment criteria, nearly all subgroups reflect statistically significant difference except sealed tooth structure group, internal caries-related discoloration in dentin, and distinct cavitation into dentine group. CONCLUSIONS: Dental health of hearing-impaired children was found unsatisfactory than normal children when studied in relation to dental caries status evaluated with CAST.

Insulin sensitivity index (ISI0, 120) potentially linked to carbon isotopes of breath CO2 for pre-diabetes and type 2 diabetes.

New strategies for an accurate and early detection of insulin resistance are important to delay or prevent the acute onset of type 2 diabetes (T2D). Currently, insulin sensitivity index (ISI0,120) is considered to be a viable invasive method of whole-body insulin resistance for use in clinical settings in comparison with other invasive sensitivity indexes like homeostasis model assessment (HOMA), and quantitative insulin sensitivity check index (QUICKI). To investigate how these sensitivity indexes link the (13)C/(12)C-carbon isotopes of exhaled breath CO2 to pre-diabetes (PD) and type 2 diabetes in response to glucose ingestion, we studied excretion dynamics of (13)C/(12)C-isotopic fractionations of breath CO2. Here, we show that (13)C/(12)C-isotope ratios of breath CO2 were well correlated with blood glucose, insulin, glycosylated-hemoglobin as well as with HOMA-IR and 1/QUICKI. Conversely, the strongest correlation was observed between 1/ISI0,120 and breath CO2 isotopes. Consequently, we determined several optimal diagnostic cut-off points of 1/ISI0,120 and (13)CO2/(12)CO2-isotope ratios to distinctively track the evolution of PD prior to the onset of T2D. Our findings suggest that isotopic breath CO2 is a novel method for accurate estimation of ISI0,120 and thus may open new perspectives into the isotope-specific non-invasive evaluation of insulin resistance for large-scale real-time diabetes screening purposes.

Mechanisms linking metabolism of Helicobacter pylori to (18)O and (13)C-isotopes of human breath CO2.

The gastric pathogen Helicobacter pylori utilize glucose during metabolism, but the underlying mechanisms linking to oxygen-18 ((18)O) and carbon-13 ((13)C)-isotopic fractionations of breath CO2 during glucose metabolism are poorly understood. Using the excretion dynamics of (18)O/(16)O and (13)C/(12)C-isotope ratios of breath CO2, we found that individuals with Helicobacter pylori infections exhibited significantly higher isotopic enrichments of (18)O in breath CO2 during the 2h-glucose metabolism regardless of the isotopic nature of the substrate, while no significant enrichments of (18)O in breath CO2 were manifested in individuals without the infections. In contrast, the (13)C-isotopic enrichments of breath CO2 were significantly higher in individuals with Helicobacter pylori compared to individuals without infections in response to (13)C-enriched glucose uptake, whereas a distinguishable change of breath (13)C/(12)C-isotope ratios was also evident when Helicobacter pylori utilize natural glucose. Moreover, monitoring the (18)O and (13)C-isotopic exchange in breath CO2 successfully diagnosed the eradications of Helicobacter pylori infections following a standard therapy. Our findings suggest that breath (12)C(18)O(16)O and (13)C(16)O(16)O can be used as potential molecular biomarkers to distinctively track the pathogenesis of Helicobacter pylori and also for eradication purposes and thus may open new perspectives into the pathogen's physiology along with isotope-specific non-invasive diagnosis of the infection.