Optical nonlinearity of a dual-frequency nematic liquid crystal via temperature-mediated mapping of dielectric anisotropy.

Liquid crystals are of great interest in the field of nonlinear optics due to their efficient response to low intensity light fields. Here we present a new, to the best of our knowledge, mechanism of a nonlinear optical response which is observed for a dye-doped dual-frequency nematic liquid crystal. The local increase in temperature caused by the absorption of light beam in the liquid crystal medium leads to spatial variation and inversion of the sign of the dielectric anisotropy. When an alternating current electric field with a frequency close to the cross-over frequency is applied to the liquid crystal cell, the planar orientation sustains at the beam periphery, but elastic deformation occurs in the irradiation region. In the case of a dye dopant with negative absorption dichroism, a first-order orientational transition with large bistability region is obtained.

Association of Grip Strength, Upper Arm Circumference, and Waist Circumference with Dementia in Older Adults of the WiSE Study: A Cross-Sectional Analysis.

OBJECTIVE: We examined the associations of handgrip strength, upper arm circumference, and waist circumference with dementia among Singapore older adults. DESIGN: Cross-sectional epidemiological study. SETTING: Residential homes, day care centres, nursing homes and institutions. PARTICIPANTS: 2,565 men and women aged 60 years and above who participated in the Well-being of the Singapore Elderly (WiSE) study in 2013. MEASUREMENTS: Socio-demographic correlates, dietary habits, health behaviours, grip strength, upper arm circumference, and waist circumference were collected. Grip strength was measured using a hand dynamometer with the dominant hand. Upper arm circumference was measured using a measuring tape around the thickest part of the upper arm while waist circumference measured in centimetres was measured at the narrowest part of the body between the chest and hips for women, and measured at the level of the umbilicus for men. Dementia was diagnosed using the 10/66 dementia diagnostic criteria. RESULTS: Mean grip strength was 13.07 kg (SE=0.60) for people with dementia and 21.98 kg (SE=0.26) for people without dementia. After adjusting for all factors, grip strength remained significantly associated with dementia (p <0.0001). Upper arm circumference was associated with dementia (p <0.0001) but this association was only significant in the univariate analysis. Waist circumference was not significantly associated with dementia. CONCLUSIONS: Lower grip strength was independently associated with dementia in the older adult population in Singapore. Further research needs to be done to ascertain whether this association exists for specific types of dementia and look into the relationship of other anthropometric measurements with dementia in Singapore.

Establishment of functional acinar-like cultures from human salivary glands.

Disorders of human salivary glands resulting from therapeutic radiation treatment for head and neck cancers or from the autoimmune disease Sjögren syndrome (SS) frequently result in the reduction or complete loss of saliva secretion. Such irreversible dysfunction of the salivary glands is due to the impairment of acinar cells, the major glandular cells of protein, salt secretion, and fluid movement. Availability of primary epithelial cells from human salivary gland tissue is critical for studying the underlying mechanisms of these irreversible disorders. We applied 2 culture system techniques on human minor salivary gland epithelial cells (phmSG) and optimized the growth conditions to achieve the maintenance of phmSG in an acinar-like phenotype. These phmSG cells exhibited progenitor cell markers (keratin 5 and nanog) as well as acinar-specific markers-namely, α-amylase, cystatin C, TMEM16A, and NKCC1. Importantly, with an increase of the calcium concentration in the growth medium, these phmSG cells were further promoted to acinar-like cells in vitro, as indicated by an increase in AQP5 expression. In addition, these phmSG cells also demonstrated functional calcium mobilization, formation of epithelial monolayer with high transepithelial electrical resistance (TER), and polarized secretion of α-amylase secretion after ß-adrenergic receptor stimulation. Taken together, suitable growth conditions have been established to isolate and support culture of acinar-like cells from the human salivary gland. These primary epithelial cells can be useful for study of molecular mechanisms involved in regulating the function of acinar cells and in the loss of salivary gland function in patients.

First-order optical Freedericksz transition in a dye-doped nematic liquid crystal.

A first-order optical Freedericksz transition in a nematic liquid crystal doped by a small quantity of a dichroic dye with negative dichroism is observed. The initial homeotropic state corresponds to maximum absorption for the linearly polarized incident beam, while reorientation reduces absorption increasing the optical torque: this process produces the positive feedback leading to the observed bistable behavior.

TRPV4 mediates tumor-derived endothelial cell migration via arachidonic acid-activated actin remodeling.

Changes in intracellular calcium [Ca(2+)](i) levels control critical cytosolic and nuclear events that are involved in the initiation and progression of tumor angiogenesis in endothelial cells (ECs). Therefore, the mechanism(s) involved in agonist-induced Ca(2+)(i) signaling is a potentially important molecular target for controlling angiogenesis and tumor growth. Several studies have shown that blood vessels in tumors differ from normal vessels in their morphology, blood flow and permeability. We had previously reported a key role for arachidonic acid (AA)-mediated Ca(2+) entry in the initial stages of tumor angiogenesis in vitro. In this study we assessed the mechanism involved in AA-induced EC migration. We report that TRPV4, an AA-activated channel, is differentially expressed in EC derived from human breast carcinomas (BTEC) as compared with 'normal' EC (HMVEC). BTEC display a significant increase in TRPV4 expression, which was correlated with greater Ca(2+) entry, induced by AA or 4αPDD (a selective TRPV4 agonist) in the tumor-derived ECs. Wound-healing assays revealed a key role of TRPV4 in regulating cell migration of BTEC but not HMVEC. Knockdown of TRPV4 expression completely abolished AA-induced BTEC migration, suggesting that TRPV4 mediates the pro-angiogenic effects promoted by AA. Furthermore, pre-incubation of BTEC with AA induced actin remodeling and a subsequent increase in the surface expression of TRPV4. This was consistent with the increased plasma membrane localization of TRPV4 and higher AA-stimulated Ca(2+) entry in the migrating cells. Together, the data presented herein demonstrate that: (1) TRPV4 is differentially expressed in tumor-derived versus 'normal' EC; (2) TRPV4 has a critical role in the migration of tumor-derived but not 'normal' EC migration; and (3) AA induces actin remodeling in BTEC, resulting in a corresponding increase of TRPV4 expression in the plasma membrane. We suggest that the latter is critical for migration of EC and thus in promoting angiogenesis and tumor growth.