Symmetry preserving nonlinear observer for attitude estimation with magnetometer only.

This paper addresses designing a nonlinear symmetry observer for nano-satellite attitude determination with only Three-Axis Magnetometer (TAM). Hence, two nested filters are delineated to compensate for the lack of data and to solve the observability problem. In the first filter, the magnetic field derivative is estimated by the extended Kalman filter. Subsequently, the magnetic field and its derivative are applied in the second filter. The proposed methodology relies on invariant observers under the action of a Lie group to estimate the attitude and angular velocity simultaneously. Later, the invariant error dynamic equations are utilized in designing the observer. Consequently, the desired performance of this proposed observer tuned by periodic Riccati differential equation is validated through both simulation and exponential stability proof.

Oct4 transcription factor in conjunction with valproic acid accelerates myelin repair in demyelinated optic chiasm in mice.

Multiple sclerosis is a demyelinating disease with severe neurological symptoms due to blockage of signal conduction in affected axons. Spontaneous remyelination via endogenous progenitors is limited and eventually fails. Recent reports showed that forced expression of some transcription factors within the brain converted somatic cells to neural progenitors and neuroblasts. Here, we report the effect of valproic acid (VPA) along with forced expression of Oct4 transcription factor on lysolecithin (LPC)-induced experimental demyelination. Mice were gavaged with VPA for one week, and then inducible Oct4 expressing lentiviral particles were injected into the lateral ventricle. After one-week induction of Oct4, LPC was injected into the optic chiasm. Functional remyelination was assessed by visual-evoked potential (VEP) recording. Myelination level was studied using FluoroMyelin staining and immunohistofluorescent (IHF) against proteolipid protein (PLP). IHF was also performed to detect Oct4 and SSEA1 as pluripotency markers and Olig2, Sox10, CNPase and PDGFRα as oligodendrocyte lineage markers. One week after injection of Oct4 expressing vector, pluripotency markers SSEA1 and Oct4 were detected in the rims of the 3rd ventricle. LPC injection caused extensive demyelination and significantly delayed the latency of VEP wave. Animals pre-treated with VPA+Oct4 expressing vector, showed faster recovery in the VEP latency and enhanced myelination. Immunostaining against oligodendrocyte lineage markers showed an increased number of Sox10+ and myelinating cells. Moreover, transdifferentiation of some Oct4-transfected cells (GFP+ cells) to Olig2+ and CNPase+ cells was confirmed by immunostaining. One-week administration of VPA followed by one-week forced expression of Oct4 enhanced myelination by converting transduced cells to myelinating oligodendrocytes. This finding seems promising for enhancing myelin repair within the adult brains.

Evaluation of Serum and Urinary Neopterin Levels as a Biomarker for Occupational Exposure to Crystalline Silica.

BACKGROUND: Crystalline silica is a commonly used mineral in various industries and construction activities, and it is so important introducing potential biomarkers to identify early indicators of biological effects in its high-risk occupational exposures. AIM: The present study was aimed to assess the blood and urinary neopterin as an early biomarker of exposure in the workers of an insulator manufacturing plant who are exposed to crystalline silica. SUBJECTS AND METHODS: This analytical descriptive study was done among two groups of exposed workers (n = 55) and unexposed office workers (n = 38) of an insulator manufacturing plant. Statistical software R was used to determine sample size and select the participants by random sampling among nonsmoker workers. Sampling of airborne silica in breathing zone of participants was done based on the National Institute for Occupational Safety and Health method 7601. The urinary and blood samples were collected and prepared for analysis by high-performance liquid chromatography to determine the level of urinary and serum neopterin. All of the statistical analyses were carried out using SPSS 22. RESULTS: The airborne silica concentration was significantly different between two exposed and unexposed groups (P < 0.001, 0.27 [0.11] vs. 0.0028 [0.0006] mg/m3, respectively). The urinary neopterin in exposed group is significantly higher than the unexposed one (P < 0.001, 97.67 [30.24] vs. 55.52 [2.18] µmol/mol creatinine, respectively). Neopterin level of serum in exposed group is higher than the unexposed group, and there is a significant difference between them (P < 0.001, 6.90 [2.70] vs. 2.20 [1.20] nmol/l, respectively). The positive significant correlations were found between silica exposure concentration with urinary and serum neopterin (P < 0.001, r = 0.36 and 0.59, respectively). CONCLUSIONS: Considering the sensitively and easily measurement of neopterin in biological fluid and also the statistically significant positive relationships which were found between the airborne silica concentration and neopterin levels in the present study, the serum and urinary neopterin levels can be considered the potential biomarkers of silica exposure for doing further comprehensive studies in this area.

Dry-powder form of chitosan nanospheres containing influenza virus and adjuvants for nasal immunization.

The objective of this study was to develop and statistically optimize chitosan nanospheres. For this purpose chitosan powder was turned into nanospheres using tripolyphosphate as a crosslinker and through ionic gelation. D-optimal response surface design was applied to optimize the nanospheres. Their size and polydispersity index (PDI) were measured as the dependant variables. Then the inactivated influenza virus and/or CpG ODN or Quillaja saponin (QS) were incorporated into the chitosan nanospheres. The release profiles of the antigen and both adjuvants were obtained. The toxicity of the formulations was tested by XTT using Calu 6 cell lines. The size distribution and PDI of plain chitosan nanospheres was 581.1 ± 32.6 and 0.478 ± 0.04. After 4 h the release of antigen, QS and CpG from the chitosan matrix were 33, 36 and 62%, respectively. The inactivated virus remained intact during preparation, as revealed by the SDS-PAGE method. Differential scanning calorimetry and Fourier Transform Infrared Spectroscopy indicated no serious structural changes in the chitosan carrier in the presence of either the antigen or the immunoadjuvants. Although the antigen loaded into chitosan nanospheres showed slight cytotoxicity on lung-cancer cells, co-encapsulation of the adjuvant (especially CpG) lowered this effect. The results demonstrated that chitosan as a carrier and immunostimulator, along with CpG or QS adjuvants, creates a potential influenza vaccine delivery system which can be administered nasally.