Improving the privacy of optical steganography with temporal phase masks

Temporal phase modulation of spread stealth signals is proposed and demonstrated to improve optical steganography transmission privacy. After phase modulation, the temporally spread stealth signal has a more complex spectral-phase-temporal relationship, such that the original temporal profile cannot be restored when only dispersion compensation is applied to the temporally spread stealth signals. Therefore, it increases the difficulty for the eavesdropper to detect and intercept the stealth channel that is hidden under a public transmission, even with a correct dispersion compensation device. The experimental results demonstrate the feasibility of this approach and display insignificant degradation in transmission performance, compared to the conventional stealth transmission without temporal phase modulation. The proposed system can also work without a clock transmission for signal synchronization. Our analysis and simulation results show that it is difficult for the adversary to detect the existence of the stealth transmission, or find the correct phase mask to recover the stealth signals.

Adenovirus-mediated leptin expression normalises hypertension associated with diet-induced obesity

In our previous study, moderate increases in plasma leptin levels achieved via administration of recombinant adenovirus containing the rat leptin cDNA were shown to correct the abnormal metabolic profile in rats with diet-induced obesity, suggesting that these animals had developed resistance to the metabolic effects of leptin, which could be reversed by leptin gene over-expression. However, the effect of this therapeutic strategy on blood pressure was not investigated. The present study aimed to determine whether a moderate increase of endogenous plasma leptin levels affected arterial blood pressure in rats with diet-induced obesity and hypertension. The major finding from the present study was that the natural rise in plasma leptin with weight-gain is insufficient to counterbalance high blood pressure associated with obesity, additional increases of circulating leptin levels with adenoviral leptin gene therapy led to normalisation of blood pressure in high-fat diet-induced obese and hypertensive rats. Mechanistically, the reduction of blood pressure by leptin in obese rats was likely independent of alpha-adrenergic and acetylcholinergic receptor mediation. This is the first study to demonstrate that further increases in circulating leptin levels by leptin gene transfer during obesity could reduce blood pressure.

Palmitic acid and docosahexaenoic acid opposingly regulate the expression of insulin-degrading enzyme in neurons

Previous results show that treatment with saturated fatty acids, such as palmitic acid (PA), induces the pathology of Alzheimer's disease (AD), while treatment with polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), protects against AD pathology. However, the pharmacological mechanism underlying these opposite effects of fatty acids on AD is not well understood. Here, we show that PA treatment significantly reduced the expression of insulin-degrading enzyme (IDE), an important protease responsible for the degradation of amyloid-beta (A beta) in neural cells, while incubation with DHA up-regulated IDE levels in primary hippocampal neurons. Moreover, pre-incubation with PA attenuated the DHA-induced IDE expression. Taken together, these results suggest the opposite effects of saturated fatty acids and polyunsaturated fatty acids on the expression of IDE, indicating a novel mechanism underlying the pharmacological function of fatty acids in AD intervention.

Transitory blocking of pulmonary artery and veins as a novel strategy in pulmonary surgery: an experimental study in a rabbit model

BACKGROUNDS

Transitory blocking of the pulmonary artery and veins is now being applied in the treatment of local advanced non-small cell lung cancer in our department. We performed this study to establish a pulmonary vessel blocking model in rabbits and investigate the features of lung ischemia-reperfusion injury.

METHODS

126 New Zealand rabbits were randomized into 3 groups: group I, sham group; group II, left pulmonary artery blocking, and group III, left pulmonary artery and veins blocking. The physiological data as well as the blood and tissue samples were harvested at the time of thoracotomy, at 1 h after ischemia and 1, 2, 4, 6 and 24 h after reperfusion, respectively. Lung injury was assessed histologically by determining the levels of malondialdehyde, superoxide dismutase, myeloperoxidase and water content.

RESULTS

The hemodynamics were stable in all three groups. The levels of malondialdehyde, myeloperoxidase, and water content of lung tissue were all significantly increased in groups II and III when compared with group I at 1, 2, 4 and 6 h after reperfusion. They almost all returned to baseline at 24 h after reperfusion. However, there was no significant difference observed between groups II and III at either time point. A similar change in the process of lung ischemia-reperfusion injury was observed under light and electron microscopes in group II and in group III.

CONCLUSIONS

The features of lung ischemia-reperfusion injury were similar when blocking the pulmonary artery and veins compared with blocking the pulmonary artery alone. Moreover, it might be safe to block the pulmonary vessels within 1 h during pulmonary surgery.

Age-related accumulation of 3-nitrotyrosine and nitro-A2E in human Bruch's membrane

Age-related macular degeneration (AMD) is a disease leading to severe visual loss and legal blindness in the elderly population. The pathophysiology of AMD is complex and may include genetic predispositions, accumulation of lipofuscin and drusen, local inflammation and neovascularization. Recently four independent research groups have identified a commonly inherited variant (Y402H) of the complement factor H gene in the genome from different groups of AMD patients. The Y402H variant of CFH significantly increases the risk of AMD and links the genetics of the disease with inflammation. During inflammation there is activation of inducible nitric oxide synthase and release of nitric oxide, which in principal could lead to non-enzymatic nitration within extracellular deposits and/or intrinsic extracellular matrix protein components of human Bruch's membrane. We have identified two biomarkers for non-enzymatic nitration in aged human Bruch's membrane, indicative of inflammation, that include 3-nitrotyrosine identified in Bruch's membrane preparations and nitrated A2E from the lipid soluble extract of the Bruch's membrane preparation. Approximately 30-40 times more A2E is observed in samples of the organic soluble extract of lipofuscin compared to the extract of Bruch's membrane. It is of interest to note that although A2E is a major constituent of RPE lipofuscin, nitrated A2E could not be detected in RPE extracts. We show here that nitro-A2E is a specific biomarker of nitrosative stress in Bruch's membrane and its concentration correlates directly with tissue age.

Radiation dose to the lens using different temporal bone CT scanning protocols

BACKGROUND AND PURPOSE

Temporal bone CT is performed frequently in clinical practice. At the same time, the eye lens are exposed to ionizing radiation without any useful diagnostic information delivered. Our aim was to investigate the radiation dose to the lens of the eye by using temporal bone CT scanning with different protocols.

MATERIALS AND METHODS

Direct axial and coronal CT by using a conventional sequential scanning mode (140 kV, 220 mAs/section, 1.25-mm thickness, 1.25-mm increment, 16 x 0.625 mm collimation, the glabellomeatal line as a scanning baseline), a routine helical scanning mode (140 kV, 220 mAs/section, 0.315 pitch, 0.67-mm thickness, 0.33-mm increment, 16 x 0.625 collimation, the orbitomeatal line as a scanning baseline), and a modified helical scanning mode (acanthiomeatal line as a scanning baseline; other parameters, same as above) was performed on an exsomatized cadaveric head. CTDI(vol) and DLP were recorded for each scanning mode, and effective doses were calculated. Organ doses for the lens were measured with TLDs.

RESULTS

When the sequential scanning mode was used, the gross effective dose was 1.21 mSv and the organ dose to the lens was 50.96 and 1.73 mGy, respectively, for direct axial and coronal imaging. The effective dose was 0.803 mSv in routine helical scanning, while the lens dose was 40.17 mGy. With the modified helical scanning mode, the effective dose was as same as that for the routine helical scanning, but the lens dose was reduced significantly to 10.33 mGy.

CONCLUSIONS

The effective doses resulting from sequential axial and coronal scanning were 1.51 times higher than the dose from helical scanning, and the lens dose was 1.31 times higher. With the modified helical scanning mode, thinner section images could be used to reformat axial, coronal, and sagittal images with a further 74.3% reduction in lens dose beyond that achieved with the conventional helical protocol.

Catalpol attenuates MPTP induced neuronal degeneration of nigral-striatal dopaminergic pathway in mice through elevating glial cell derived neurotrophic factor in striatum

The protective effect of an iridoid catalpol extracted and purified from the traditional Chinese medicinal herb Rehmannia glutinosa on the neuronal degeneration of nigral-striatal dopaminergic pathway was studied in a chronic 1-methyl-4-phenyl-1,2,3,4-tetrahydropyridine (MPTP)/probenecid C57BL/6 mouse model and in 1-methyl-4-phenylpyridimium (MPP(+)) intoxicated cultured mesencephalic neurons. Rotarod performance revealed that the locomotor ability of mice was significantly impaired after completion of model production and maintained thereafter for at least 4 weeks. Catalpol orally administered for 8 weeks (starting from the second week of model production) dose dependently improved the locomotor ability. HPLC revealed that catalpol significantly elevated striatal dopamine levels without changing the metabolite/dopamine ratios. Nor did it bind to dopamine receptors. Therefore it is unlikely that catalpol resembles any of the known compounds for treating Parkinsonism. Instead, catalpol dose dependently raised the tyrosine hydroxylase (TH) neuron number in substantia nigra pars compacta (SNpc), the striatal dopamine transporter (DAT) density and the striatal glial cell derived neurotrophic factor (GDNF) protein level. Linear regression revealed that both the TH neuron number and DAT density were positively correlated to the GDNF level. In the cultured mesencephalic neurons, MPP(+) decreased the dopaminergic neuron number and shortened the neurite length, whereas catalpol showed protective effect dose dependently. Furthermore, the expression of GDNF mRNA was up-regulated by catalpol to a peak nearly double of normal control in neurons intoxicated with MPP(+) for 24 h but not in normal neurons. The GDNF receptor tyrosine kinase RET inhibitor 4-amino-5-(4-methyphenyl)-7-(t-butyl)-pyrazolo-[3,4-d]pyrimidine (PP1) abolished the protective effect of catalpol either partially (TH positive neuron number) or completely (neurite length). Taken together, catalpol improves locomotor ability by attenuating the neuronal degeneration of nigral-striatal dopaminergic pathway, and this attenuation is at least partially through elevating the striatal GDNF expression.

The Presence of Hepatitis B Surface Antigen in the Ova of Pregnant Women and Its Relationship with Intra-Uterine Infection by Hepatitis B Virus

Vertical transmission of hepatitis B virus (HBV) has been proposed to play an important role in mother-to-child transmission, although the extent to which vertical transmission via oocytes contributes to neonatal HBV infection remains unknown. Ovarian biopsies were collected during caesarean sections in 68 clinically asymptomatic pregnant women who were carriers of HBV. The presence of hepatitis B surface antigen (HBsAg) in the ova of pregnant women was determined by immunohistochemistry. Serum markers of HBV infection in pregnant women and their neonates were analysed. It was found that, of 68 women, the ova were positive for HBsAg in only one woman and her neonate was negative for any serum HBV markers 3 days after birth. Of 68 neonates, one was positive for serum HBV markers 3 days after birth and his mother's ova were negative for HBsAg. These findings indicate that vertical transmission via oocytes may not be the major route of HBV intra-uterine infection.

The glycoprotein Ibalpha-von Willebrand factor interaction induces platelet apoptosis

BACKGROUND

The interaction of glycoprotein (GP) Ibalpha with von Willebrand factor (VWF) initiates platelet adhesion, and simultaneously triggers intracellular signaling cascades leading to platelet aggregation and thrombus formation. Some of the signaling events are similar to those occurring during apoptosis, however, it is still unclear whether platelet apoptosis is induced by the GPIbalpha-VWF interaction.

OBJECTIVES

To investigate whether the GPIbalpha-VWF interaction induces platelet apoptosis and the role of 14-3-3zeta in apoptotic signaling.

METHODS

Apoptotic events were assessed in platelets or Chinese hamster ovary (CHO) cells expressing wild-type (1b9) or mutant GPIb-IX interacting with VWF by flow cytometry or western blotting.

RESULTS

Ristocetin-induced GPIbalpha-VWF interaction elicited apoptotic events in platelets, including phosphatidylserine exposure, elevations of Bax and Bak, gelsolin cleavage, and depolarization of mitochondrial inner transmembrane potential. Apoptotic events were also elicited in platelets exposed to pathologic shear stresses in the presence of VWF; however, the shear-induced apoptosis was eliminated by the anti-GPIbalpha antibody AK2. Furthermore, apoptotic events occurred in 1b9 cells stimulated with VWF and ristocetin, but were significantly diminished in two CHO cell lines expressing mutant GPIb-IX with GPIbalpha truncated at residue 551 or a serine-to-alanine mutation at the 14-3-3zeta-binding site in GPIbalpha.

CONCLUSIONS

This study demonstrates that the GPIbalpha-VWF interaction induces apoptotic events in platelets, and that the association of 14-3-3zeta with the cytoplasmic domain of GPIbalpha is essential for apoptotic signaling. This finding may suggest a novel mechanism for platelet clearance or some thrombocytopenic diseases.

Aflatoxin-albumin adducts and correlation with decreased serum levels of vitamins A and E in an adult Ghanaian population

A study of aflatoxin (AF) exposure and the levels of vitamins A and E was carried out with a group of 507 Ghanaian participants. AFB(1)-albumin adducts (AFB-AA) were measured by radioimmunoassay and vitamins A and E were measured by high-performance liquid chromatography (HPLC). The average level of serum AFB-AA was 0.94 +/- 0.64 (range = 0.1-4.44) pmol mg(-1) albumin. Mean levels of vitamins A and E were 1.32 +/- 0.48 (range = 0.41-4.85) micromol l(-1) and 15.68 +/- 4.12 (range = 6.35-30.40) micromol l(-1), respectively. A significantly negative correlation was found between serum AFB-AA and vitamin A levels (r = -0.110, p = 0.013). An even stronger, significant negative, correlation was found between serum AFB-AA and vitamin E levels (r = -0.149, p < 0.001). Serum AFB-AA levels were statistically higher (median = 0.985 pmol mg(-1) albumin) in subjects who had low levels of both vitamins A and E as compared with the levels (median = 0.741 pmol mg(-1) albumin) subjects who had high vitamins A and E levels (p(trend) = 0.001). To verify these findings, blood samples were again collected from 165 of the 507 people 3 months after the initial collection. Significantly negative correlations were confirmed between levels of serum AFB-AA and both vitamins A (r = -0.232, p = 0.003) and E (r = -0.178, p = 0.023). Again, high serum AFB-AA concentrations (median = 1.578 pmol mg(-1) albumin) were found in subjects with low levels of vitamins A and E compared with the concentrations (median = 1.381 pmol mg(-1) albumin) in subjects with high levels of vitamins A and E (p(trend) = 0.002). These data show that AF exposure was associated with decreased levels of serum vitamins A and E in high-risk human populations, which may significantly influence the incidence of AF-related adverse health effects.

Effects of bone morphogenetic protein-2 on proliferation and angiogenesis in oral squamous cell carcinoma

Experimental data and limited patient experience suggest that rhBMP-2 can be used to regenerate bone in acquired segmental defects of the mandible. Most of these defects are caused by resection of oral squamous cell carcinoma (OSCC) and the biologic effects of rhBMP-2 on these carcinoma cells are unknown. The objective of this study was to determine whether rhBMP-2 produces adverse effects on proliferation and angiogenesis in OSCC, two biologic processes critical to tumor formation. In vitro studies included treating OSCC cells with rhBMP-2 or an adenoviral vector containing the cDNA for BMP-2. In vivo studies involved co-transplantation of OSCC cells with bone marrow stromal cells genetically modified to over express BMP-2, to mimic a clinically relevant scenario for regenerating bone using cell-based therapy in a wound containing microscopic residual disease. Proliferation, as measured by a MTT assay in vitro and tumor growth in vivo was not affected by treatment with BMP-2. Angiogenesis, measured by secretion of the proangiogenic molecules VEGF and IL-8 in vitro and microvessel density in vivo, was not affected. Exposure of OSCC cells to BMP-2 does not stimulate proliferation or angiogenesis. Further studies are needed before using rhBMP-2 for bone tissue engineering in oral cancer-related defects.