Optical Response of PDMS Surface Diffraction Gratings under Exposure to Volatile Organic Compounds.

Monitoring volatile organic compounds (VOCs) in indoor air is significantly gaining importance due to their adverse effects on human health. Among the diverse detection methods is optical sensing, which employs materials sensitive to the presence of gases in the environment. In this work, we investigate polydimethylsiloxane (PDMS), one of the materials utilized for gas sensing, in a novel transducer: a surface relief diffraction grating. Upon adsorption of the volatile analyte, the PDMS grating swells, and its refractive index changes; both effects lead to increased diffraction efficiency in the first diffraction order. Hence, the possibility of VOC detection emerges from the measurement of the optical power transmitted or diffracted by the grating. Here, we investigated responses of PDMS gratings with varying surface profile properties upon exposure to VOCs with different polarities, i.e., ethanol, n-butanol, toluene, chloroform, and m-xylene, and compared their response in the context of the Hansen theory of solubility. We also studied the response of the grating with a 530 nm deep surface profile to different concentrations of m-xylene, showing a sensitivity and limit of detection of 0.017 µW/ppm and 186 ppm, respectively. Structures in the PDMS were obtained as copies of sinusoidal surface gratings fabricated holographically in acrylamide photopolymer and revealed good sensing repeatability, reversibility, and a fast response time. The proposed sensing technique can be directly adopted as a simple method for VOC detection or can be further improved by implementing a functional coating to significantly enhance the sensitivity and selectivity of the device.

The Development of Optomechanical Sensors-Integrating Diffractive Optical Structures for Enhanced Sensitivity.

The term optomechanical sensors describes devices based on coupling the optical and mechanical sensing principles. The presence of a target analyte leads to a mechanical change, which, in turn, determines an alteration in the light propagation. Having higher sensitivity in comparison with the individual technologies upon which they are based, the optomechanical devices are used in biosensing, humidity, temperature, and gases detection. This perspective focuses on a particular class, namely on devices based on diffractive optical structures (DOS). Many configurations have been developed, including cantilever- and MEMS-type devices, fiber Bragg grating sensors, and cavity optomechanical sensing devices. These state-of-the-art sensors operate on the principle of a mechanical transducer coupled with a diffractive element resulting in a variation in the intensity or wavelength of the diffracted light in the presence of the target analyte. Therefore, as DOS can further enhance the sensitivity and selectivity, we present the individual mechanical and optical transducing methods and demonstrate how the DOS introduction can lead to an enhanced sensitivity and selectivity. Their (low-) cost manufacturing and their integration in new sensing platforms with great adaptability across many sensing areas are discussed, being foreseen that their implementation on wider application areas will further increase.

Surface Relief Modulated Grating in Azo Polymer-From the Tailoring of Diffraction Order to Reshaping of a Laser Beam.

Among light-responsive materials for photonics, azo polymers occupy an important position due to their optical response and the related concepts of consecutive applications. However, scientific insight is still needed to understand the effects of irradiation on the modification of the azo polymer structure and the effect of this modification on incoming probing light. In this work, we report on a surface relief grating with a maximum depth of a record-high value of 1.7 µm, inscribed holographically in a custom synthesized glassy azo polymer belonging to the poly(ether imide) family. We show that the specifically deformed polymer, forming an amplitude-modulated relief grating, has a unique dual effect on an incoming light beam of different diameters. When illuminated by a narrow probe beam, the structure acts as a variable-depth grating, enabling a continuous tuning of the diffraction efficiencies in the entire theoretically predicted range and, thus, generating or eliminating diffracted waves of specified order. Alternatively, when illuminated by a wide probe beam, the whole structure acts as an optical component reshaping the Gaussian light intensity profile into the profiles resembling the squares of Bessel functions of the zeroth- or higher orders. Moreover, a physical justification of the effects observed is provided.

The hepcidin concentration decreases in hypothyroid patients with Hashimoto's thyroiditis following restoration of euthyroidism.

The purpose of the study was to measure the hepcidin concentration and evaluate Fe homeostasis indices in a prospective study on patients with newly diagnosed hypothyroidism in the course of Hashimoto's thyroiditis (HT) and following successful therapy. The prospective observational study consisted of 34 patients. The clinical evaluation and laboratory tests were performed at diagnosis (T0) and after restoration of euthyreosis 12 weeks later (T1). The median level of hepcidin was significantly lower (p = 0.002) after recovery (7.7 [6.2-13.0] ng/mL) than that before treatment (17.4 [7.6-20.4] ng/mL), while creatinine (p = 0.011) and GFR (p < 0.001) significantly improved after euthyroidism was achieved. A positive correlation was observed between hepcidin and fT3 (p = 0.033, r = 0.465) at T0. In the females, the level of hepcidin positively correlated with ferritin concentration before (p < 0.001, r = 0.928) and after treatment (p < 0.001, r = 0.835). A statistically significant difference was observed in RDW-CV (red blood cell distribution width - coefficient of variation) between the hypothyroid and euthyroid states. In conclusion, a decrease in hepcidin concentration during the transition from the hypothyroid state to euthyroidism in patients with HT is associated with the observed dynamics in iron homeostasis, mainly reflected by improvement in RDW-CV and significant correlations between ferritin and hepcidin as well as between hepcidin and fT3.

Does nesfatin-1 influence the hypothalamic-pituitary-gonadal axis in adult males with obstructive sleep apnoea?

There is growing evidence that obstructive sleep apnoea (OSA) influences the hypothalamic-pituitary-gonadal axis (HPG axis) in men. The aim of the study was to assess the association of nesfatin-1 with HPG axis disturbances in OSA. This is a prospective study with consecutive enrolment. It comprises 72 newly diagnosed OSA patients ((AHI: apnoea-hypopnea index) 18 subjects: 5 ≤ AHI < 15; 24: 15 ≤ AHI < 30; 30: AHI ≥ 30) and a control group composed of 19 patients (AHI < 5). All patients underwent polysomnography and fasting blood collection for nesfatin-1, testosterone, luteinising hormone (LH), high-sensitivity C-reactive protein (hsCRP), aspartate transaminase (AST), alanine aminotransferase (ALT), creatinine and glucose. Groups had similar levels of LH, nesfatin-1 and testosterone (p = 0.87; p = 0.24; p = 0.08). Nesfatin-1 was not correlated to LH (p = 0.71), testosterone (p = 0.38), AHI (p = 0.34) or the oxygen desaturation index (ODI) (p = 0.69) either in the whole group, or in sub-groups. The study did not reveal any association between the HPG axis and nesfatin-1 in OSA adult males. It is possible that nesfatin-1 is not a mediator of HPG axis disturbances in adult patients with OSA.

Hepcidin and Iron Homeostasis in Patients with Subacute Thyroiditis and Healthy Subjects.

PURPOSE: Hepcidin is an acute-phase protein involved also in regulation of iron homeostasis. The aim of the study was to prospectively assess for the first time the hepcidinEL concentration in patients with subacute thyroiditis (SAT), to identify biochemical determinants of hepcidinEL concentration and evaluate the potential role of hepcidin in SAT diagnosis and monitoring. METHODS: Out of 40 patients with SAT initially recruited, restrictive inclusion criteria fulfilled 21 subjects aged 45 ± 10 years and 21 healthy control subjects (CS). HepcidinEL concentration, thyroid status, and iron homeostasis were evaluated at SAT diagnosis and following therapy and compared with CS. RESULTS: The median hepcidinEL concentration at SAT diagnosis is higher than that in CS (48.8 (15.9-74.5) ng/mL vs. 18.2 (10.2-23.3) ng/mL, p = 0.009) and is significantly lower after treatment (4.0 (1.2-10.0) ng/mL, p = 0.007) compared with CS. The ROC analysis for hepcidinEL at SAT diagnosis revealed that area under the curve (AUC) is 0.735 (p = 0.009), and the cut-off for hepcidinEL concentration is 48.8 ng/mL (sensitivity 0.52 and specificity 0.95). HepcidinEL in SAT patients correlated with CRP (r = 0.614, p = 0.003), ferritin (r = 0.815, p < 0.001), and aTPO (r = -0.491, p = 0.024). On multiple regression, the correlation between hepcidinEL and ferritin was confirmed (p < 0.001). CONCLUSIONS: SAT is accompanied by a significant increase in hepcidin, which reflects an acute-phase inflammatory process. Parameters of iron homeostasis improved significantly while inflammatory indices got lower following recovery. The potential role of hepcidin as a predictive factor of the risk of SAT relapse needs to be assessed in studies on larger groups of SAT patients.

Ghrelin as a potential molecular marker of adrenal carcinogenesis: In vivo and in vitro evidence.

CONTEXT: Adrenal tumours belong to one of the most prevalent neoplasms. It is a heterogeneous group with different aetiology, clinical manifestation and prognosis. Its histopathologic diagnosis is difficult and identification of differentiation markers for tumorigenesis is extremely valuable for diagnosis. DESIGN: To assess ghrelin expression and the relationship among ghrelin, IGF2 and the clinicopathological characteristics of adrenal tumours. To investigate the influence of ghrelin on ACC cell line proliferation. MATERIALS AND METHODS: Expression of ghrelin and IGF2 in a total of 84 adrenal tissue samples (30 adenoma, 12 hyperplasia, 8 myelolipoma, 20 pheochromocytoma, 7 carcinoma and 7 unchanged adrenal glands) were estimated. Every operated patient from whom samples were obtained underwent clinicopathological analysis. All the parameters were compared among the groups examined and correlations between these were estimated. H295R cell line was incubated with ghrelin to assess its effect on proliferation and migration rate. RESULTS: The highest ghrelin expression was observed in carcinoma samples and the lowest in the control group. Ghrelin expression was 21 times higher in carcinoma (P = .017) and 2.4 times higher in adenoma (P = .029) compared with controls. There were no statistically significant differences between myelolipoma (P = .093) and pheochromocytoma (P = .204) relative to the control. Ghrelin level was significantly higher in carcinoma compared to adenoma (P = .049) samples. A positive correlation between ghrelin and IGF2 expression was observed only in myelolipoma (P = .001). Ghrelin at concentrations of 1 × 10-6  mol/L and 1 × 10-8  mol/L significantly stimulated proliferation and migration rate in the H295R cell line. CONCLUSION: Ghrelin appears to be an essential factor in driving adrenal tumours development.

Red cell distribution width - a new marker for exacerbation of heart failure in patients with hypothyroidism following radioiodine therapy.

INTRODUCTION: Cardiovascular diseases constitute a major cause of health problems and death in developed countries across the world. The increased value of the index of distribution of red blood cells volume (RDW) may be a prognostic marker in patients diagnosed with chronic heart failure (CHF). Hypothyroid patients present higher RDW values if compared to healthy controls. Taking into consideration that RDW might be both affected by thyroid status and CHF, we decided to determine the effect of concomitant hypothyroidism following radioiodine therapy (RIT) and CHF on hematological parameters. MATERIALS AND METHODS: Patients with toxic nodular goiter and heart failure with concomitant anemia were included. Patients underwent treatment with radioiodine before the planned heart transplant or pacemaker implantation (combined ICD/CRT-D). After RIT patients were divided into the three subgroups: with overt hypothyroidism (TSH ≥ 10µIU/mL, Group I), subclinically hypothyroid patients (TSH 4.3-9.0 µIU/mL, Group II) and with high-normal level of TSH (2.6-4.2 µIU/mL, Group III). RESULTS: Significant correlation between TSH and RDW was observed (r=0.46; P < 0.0001) after RIT, whereas no correlation between serum TSH levels and TIBC and Fe was observed. In Group I significant correlation between TSH and RDW (r= 0.48; P = 0.002) after RIT was observed, whereas in two other subgroups there were no significant correlation. CONCLUSIONS: Subclinical hypothyroidism or high-normal levels of TSH did not affect RDW in a significant manner in the studied population. Our results demonstrates that overt hypothyroidism may contribute to deterioration of CHF reflected in changes of RDW value. < p > < /p >.

Association between bone remodeling and inflammatory markers in obstructive sleep apnea in relation to disease severity.

INTRODUCTION    There is growing evidence that obstructive sleep apnea (OSA) influences both bone metabolism and structure. Chitinase­3­like protein 1 (YKL­40) is a novel inflammatory and remodeling marker, the levels of which were shown to increase in OSA. YKL­40 can probably alter the bone turnover. OBJECTIVES    The aim of the study was to assess a possible interplay between YKL­40 and bone turnover markers in patients with different stages of OSA, and to evaluate the relation between bone mass, severity of OSA, and YKL­40 levels. PATIENTS AND METHODS    The study involved 72 male patients with OSA. They were divided into 3 groups according to disease severity, using the apnea-hypopnea index (AHI): group 1 (n = 18; 5≤ AHI <15), group 2 (n = 25; 15≤ AHI <30), and group 3 (n = 29; AHI ≥30). All patients underwent polysomnography and densitometry. Fasting blood samples were collected for YKL­40, C­terminal telopeptide of typeI collagen (CTX), procollagen type 1 N­terminal propeptide (P1NP), and other markers. RESULTS    P1NP differed between groups 1 and 2, as well as groups 1 and 3 (P = 0.02). Group 2 had higher CTX levels than group 1 (borderline significance, P = 0.05). A simple linear regression analysis showed that serum YKL­40 levels were associated with the levels of CTX (P <0.0001, ß = 0.9871) and P1NP (P <0.0001, ß = 0.9780). CONCLUSIONS    Our study might suggest that YKL­40 is associated with bone turnover in OSA. We may assume that this marker influences both bone formation and destruction; thus, OSA could be characterized by preserved bone mineral density.

Thyroid ectopy - diagnostic and therapeutic challenges before and in the era of TSH neonatal screening.

Despite TSH screening in newborns is currently conducted in most developed countries, patients with thyroid ectopy born before the procedure was introduced or those in whom the screening failed to establish diagnosis, might still appear. In the paper we revise the current state of knowledge regarding the clinical presentation, diagnosis and treatment of patients with thyroid ectopy. As an example, we report diagnostic and therapeutic difficulties in our three patients with thyroid ectopy remaining undiagnosed and untreated during early childhood. Introduction of neonatal screening for congenital hypothyroidism does not guarantee that all patients with thyroid ectopy will be correctly diagnosed and properly treated due to the possibility of falsely negative result of TSH screening or lack of compliance from parents. Visualization of an ectopic thyroid on ultrasound examination may be challenging for unexperienced sonographists; muscles in the thyroid bed may be misdiagnosed as heterogeneous and hypoechogenic thyroid gland with features suggesting autoimmune thyroid disease. Thyroid scintiscan is crucial for confirmation of the diagnosis of thyroid ectopy. In conclusion, hypothyroidism due to thyroid developmental anomaly should be taken into consideration in case of hypothyroidism and normal thyroid autoantibodies in a patient at any age.

Anemia in thyroid diseases.

Anemia is a frequent, although often underestimated, clinical condition accompanying thyroid diseases. Despite the fact that anemia and thyroid dysfunction often occur simultaneously, the causative relationship between the disorders remains ambiguous. Thyroid hormones stimulate the proliferation of erythrocyte precursors both directly and via erythropoietin production enhancement, while iron-deficient anemia negatively influences thyroid hormone status. Thus, different forms of anemia might develop in the course of thyroid dysfunction. Normocytic anemia is the most common, while macrocytic or microcytic anemia occurs less frequently. Anemia in hypothyroidism might result from bone marrow depression, decreased erythropoietin production, comorbid diseases, or concomitant iron, vitamin B12, or folate deficiency. Altered iron metabolism and oxidative stress may contribute to anemia in hyperthyroidism. The risk of anemia in autoimmune thyroid disease (AITD) may be related to pernicious anemia and atrophic gastritis, celiac disease, autoimmune hemolytic syndrome, or rheumatic disorders. The coexistence of anemia and thyroid disease constitutes an important clinical problem. Thus, the aim of this review was to provide a comprehensive summary of data on the prevalence, potential mechanisms, and therapy of anemia in the course of thyroid diseases from the clinical and pathogenetic perspectives. Thyroid dysfunction and AITD should be considered in a differential diagnosis of treatment-resistant or refractory anemia, as well as in the case of increased red blood cell distribution width. Of note, the presence of AITD itself, independently from thyroid hormone status, might affect the hemoglobin level.

Orbital radiotherapy in the management of Graves' orbitopathy--current state of knowledge.

The treatment of Graves' orbitopathy (GO) remains a diagnostic and therapeutic challenge for clinicians worldwide. The elimination of risk factors, such as encouraging smoking cessation and achieving euthyroidism, are the most important and usually sufficient treatment methods in most mild cases. A course of selenium may also be beneficial. High-dose systemic corticosteroid therapy remains the first-line therapy in moderate-to-severe orbitopathy; however in some patients such treatment may be insufficient. Radiotherapy for GO has been used for decades and is considered to be effective in active GO, although less than systemic corticosteroids. Unfortunately, there are only eight randomised studies that may be analysed to assess its true effectiveness and applicability. It has been indicated that radiotherapy affects mainly eye motility and soft tissue changes, with almost no influence on exophthalmos. The combination of these two therapies has proven to be even more effective than either treatment alone, especially in subjects with resistant or recurrent GO. Orbital radiotherapy seems to be a safe procedure with few adverse effects observed long after the therapy. It should be avoided in patients with retinopathy, due to diabetes mellitus and hypertension, and in young subjects (< 35 years old). Orbital radiotherapy, as a safe and generally effective second-line therapy, is used in some countries as a supporting method during the second course of systemic corticosteroid therapy, if the response to the first course is unsatisfactory. Further randomised, double-blind studies are needed to confirm fully its clinical usefulness.

Unexpected conversion from hypothyroidism to an euthyroid state due to Graves' disease in a patient with an ectopic thyroid.

A 15-year-old woman was diagnosed with hypothyroidism and unilateral ectopic thyroid. Levothyroxine treatment was introduced; however, the patient was non-compliant and took the medication irregularly. When she presented to an endocrinologist at the age of 30, she had not been using levothyroxine for at least 6 months. Surprisingly, she was clinically and biochemically euthyroid. Due to decreased echogenicity on ultrasound examination, enhanced vascularization on Color Doppler examination and increased concentration of anti-TSH receptor autoantibodies, she was diagnosed with Graves' disease. Eventually, she underwent total thyroidectomy due to diagnosis of follicular neoplasm in fine-needle aspiration biopsy of the focal lesion found in the thyroid gland. To our knowledge, our patient is the first described with ectopic thyroid, presenting a nodular variant of Graves' disease and no signs of orbitopathy, who was initially hypothyroid and became euthyroid in the course of autoimmune thyroid disease.