All-fiber tunable devices based on high-index photonic crystal fibers filled with liquid crystals

In this paper we present all-in fiber tunable devices based on specially designed and optimized high-index photonic crystal fibers filled with nematic liquid crystals. A special host microstructured optical fibers have been designed and manufactured to ensure low-loss index guiding and mode field diameter matching to SMF-28 fiber, ensuring low losses on interconnections with leading in-out FC/PC connectorized pigtails. We present four types of tunable all-fiber devices: tunable retarders with tuning range as high as 20 λ, tunable polarizers with variable axis of polarization and continuously tunable polarization dependent losses, tunable and fully controllable polarization controller and finally indeterministic depolarizer in which depolarization is caused by random thermodynamic process. We also present a cost-effective method to achieve change in the direction of the steering electric field, which was controlled by custom-made programable controllers. Finally, we present a method for effective packaging for the proposed devices.

Molecular features as promising biomarkers in ovarian cancer

Ovarian cancer (OC) is a global challenge for modern medicine, ranking 7th for incidence and the 8th most common cause of mortality from cancers in women. Ovarian cancer has a poor prognosis, characterized by high morbidity and mortality, with detection occurring more frequently in advanced stages. Further issues lie within the heterogeneous nature of this pathology, as well as in its ability to develop multidrug resistance. Therefore, there is a burgeoning need to introduce effective screening for the general population, especially in high-risk groups such as individuals with a family history of cancer. Achieving this would be greatly assisted by identifying new biomarkers in order to, in turn, develop targeted therapies for patients. Advances in molecular biology techniques that enable cancer genetic characterization offer hope for personalized medicine. This article reviews the current findings on the biology of OC at the molecular level. Such knowledge may prove to be crucial and constitute a starting point for the development of new options for the early detection, prevention and treatment of OC.

Periodic liquid crystalline waveguiding microstructures

Different methods allowing for creating optical waveguides with liquid-crystal (LC) cores, in which molecules form periodic patterns with precisely controlled periods, are reported. The first one is based on reversible photoalignment with high-resolution selective illumination and allows to control the period of LC molecules inside silica microcapillaries. The second method employs microstructures formed in PDMS, allowing to obtain both: LC-core waveguides and a set of specially designed periodic microelectrodes used for the periodic reorientation of molecules. Using both methods, we successfully controlled the period of the patterned alignment in the range from about 500 µm and scaled it down to as small as 20 µm. We performed experimental studies on waveguiding phenomenon in such structures, in view to obtain transmission spectra typical to optical fiber gratings. Since the results achieved in experimental conditions differed from those expected, the additional numerical simulations were performed to explain the observed effects. Finally, we obtained the waveguiding in a blue phase LC, characterized by naturally created three-dimensional periodicity with periods smaller than one micrometer. In such a structure, we were able to observe first-order bandgap, and moreover, we were able to tune it thermally in nearly the whole visible spectral range.

Metabolomic profiling in children with inflammatory bowel disease

Ulcerative colitis (UC) and Crohn's disease (CD) represent inflammatory bowel diseases (IBD) with multifactorial pathogenesis, involving genetic, environmental and microbial factors. Interactions between gut microbiota and immune system result in changes in metabolic pathways. Metabolomics is a comprehensive and quantitative (or semi-quantitative) analysis of metabolites synthetized in human's biological system. It has been shown that metabolic profiling might be used to identify disease biomarkers. Recent findings confirmed alterations in the number of metabolites in patients with IBD. However, most of the studies included adult individuals with ongoing treatment which might have affected the metabolite profiling. Therefore, the aim of our study was to collect the knowledge about metabolomics in paediatric patients with CD or UC based on the currently published literature.

Cardiovascular Risk in Children with Nonalcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is the main cause of chronic liver disease in children. With the global obesity epidemic, the prevalence of NAFLD is increasing both in industrialized and developing countries. NAFLD is a multisystem disorder and a hepatic manifestation of the metabolic syndrome. Growing scientific evidence suggests that NAFLD is an independent risk factor for cardiovascular disease. This paper briefly describes the current knowledge concerning the association between NAFLD and cardiac dysfunction in children.

Can hepatokines be regarded as novel non-invasive serum biomarkers of intrahepatic lipid content in obese children?

PURPOSE

Hepatokines are proteins produced by the liver and involved in regulating glucose and lipid metabolism. However, their role as the biomarkers of intrahepatic lipid content is not clear. The aim of the study was to evaluate the serum concentration of selected hepatokines: fibroblast growth factor-21 (FGF-21), selenoprotein P (SELENOP) and sex hormone-binding globulin (SHBG) in obese children.

PATIENTS AND METHODS

The cross-sectional study included 86 obese children with suspected liver disease. Nonalcoholic fatty liver disease (NAFLD) was diagnosed in children with liver steatosis in ultrasound with elevated alanine aminotransferase (ALT) serum activity and excluded other liver diseases. The total intrahepatic lipid content (TILC) was assessed by magnetic resonance proton spectroscopy (¹H-MRS).

RESULTS

The concentration of FGF-21 and SELENOP was significantly higher and SHBG significantly lower in children with NAFLD compared to controls. Only FGF-21 level was significantly higher in NAFLD children than in obese patients without NAFLD. The significant positive correlation of FGF-21 with ALT, gamma glutamyltransferase (GGT), triglycerides, homeostatic model assessment-insulin resistance (HOMA-IR), the degree of liver steatosis in ultrasound and TILC in ¹H-MRS were found. The ability of serum FGF-21 to diagnose severe liver steatosis was significant.

CONCLUSIONS

FGF-21 can be considered as a suitable biomarker in predicting TILC and fatty liver in obese children.

Increased serum concentration of ceramides in obese children with nonalcoholic fatty liver disease

Background

Hepatic lipid accumulation is closely related to the development of insulin resistance, which is regarded as one of the most significant risk factors of nonalcoholic fatty liver disease (NAFLD). Although the exact molecular pathway leading to impaired insulin signaling has not been definitively established, ceramides are suspected mediators of lipid induced hepatic insulin resistance. Therefore, the aim of the study was to evaluate the serum ceramides concentration in obese children with NAFLD.

Methods

The prospective study included 80 obese children (aged 7–17 years, median 12 years) admitted to our Department to diagnose initially suspected liver disease. Patients with viral hepatitis (HCV, HBV, CMV), autoimmune (AIH), toxic and metabolic (Wilson’s disease, alfa-1–antitrypsin deficiency) liver diseases and celiac disease were excluded. NAFLD was diagnosed based on pediatric diagnostic criteria in obese children with liver steatosis in ultrasound (US) as well as elevated alanine transaminase (ALT) serum activity after exclusion of other major liver diseases listed before. Ultrasonography was used as a screening method and for qualitative assessment of the steatosis degree (graded according to Saverymuttu scale). Advanced steatosis was defined as a score > 1. The total intrahepatic lipid content (TILC) was assessed by magnetic resonance proton spectroscopy (¹HMRS) which is the most accurate technique for assessment of ectopic fat accumulation. Fasting serum concentration of ceramides was measured in 62 children.

Results

NAFLD was diagnosed in 31 children. Significant, positive correlation was found between total serum concentration of ceramides and insulin (r = 0.3, p = 0.02) and HOMA-IR (r = 0.28, p = 0.03). Total ceramide concentration as well as specific fatty acid-ceramides (FA-ceramides) concentrations, namely: myristic, palmitic, palmitoleic, stearic, oleic, behenic and lignoceric were significantly higher (p = 0.004, p = 0.003, p = 0.007, p < 0.001, p = 0.035, p = 0.008, p = 0.003, p = 0.006, respectively) in children with NAFLD compared to controls (n = 14). Moreover, children with NAFLD had significantly higher activity of ALT (p < 0.001) and GGT (p < 0.001), HOMA-IR (p = 0.04), BMI (p = 0.046), waist circumference (p = 0.01) steatosis grade in ultrasound (p < 0.001) and TILC in ¹HMRS (p < 0.001) compared to children without NAFLD. We did not find significant differences in total and FA-ceramide species concentrations between children with mild (grade 1) and advanced liver steatosis in ultrasonography (grade 2–3).

Conclusion

Elevated ceramide concentrations in obese patients together with their significant correlation with insulin resistance parameters suggest their association with molecular pathways involved in insulin signaling impairment known to be strongly linked to pathogenesis of non-alcoholic fatty liver disease.

Hematological parameters in adolescents with hyperuricemia

OBJECTIVE

To examine the association between hematological indices and serum uric acid in adolescents with hyperuricemia.

METHODS

10-year retrospective cohort study of 607 patients with hyperuricemia registered with the Pediatric Nephrology Department.

RESULTS

There was a statistically significant positive correlation between serum uric acid levels and BMI Z-scores (r=0.406, P<0.001), white and red blood cell counts, hemoglobin and hematocrit. Higher levels of hemoglobin, hematocrit and red blood cells were found in adolescents with metabolic syndrome than in groups without this condition.

CONCLUSION

Hematological parameters could be important biological markers of cardiometabolic risk in adolescents with hyperuricemia.