Chronic-alcohol exposure alters IGF1 signaling in H9c2 cells via changes in PKC delta.

Previously, we have demonstrated that chronic-alcohol exposure alters insulin-like growth factor 1 (IGF1) signaling in adult rat heart cells. This report examines the effects of alcohol in vitro on the expression of protein kinase C (PKC) alpha, delta, and epsilon using the embryonic heart cell line, H9c2, and how this may be linked to changes in IGF1 signal transduction. Western blot analyses of H9c2 protein preparations demonstrate that there are significant increases in the total protein levels of PKC delta and epsilon after 4 days exposure to alcohol, and similar increases were found after 2 and 6 days exposure. In addition, there was a significant increase in PKC delta and epsilon in the membranal fractions and a decrease in the cytosolic fractions. No change was found in the expression or activity levels for PKC alpha. Chronic-alcohol exposure (100 mM, 4 days) increased the basal tyrosine kinase activity of the IGF1 receptor (IGF1R), and altered its rate of activation. Chronic-alcohol exposure also reduced the rate of Erk1/Erk2 activation by IGF1. Chronic alcohol blocked the proliferative effects of IGF1 on cell growth and reduced cell viability both in the presence and absence of IGF1, and this alcohol-induced reduction in cell viability was blocked using siRNA to inhibit PKC delta. In addition, a reduction in the amount of myosin light chain 2 was found in the alcohol-exposed cells. In conclusion, chronic alcohol alters PKC delta and epsilon expression and activity, and suppresses the IGF1 signaling pathway in embryonic heart cell culture. Blockage of PKC delta expression using siRNA inhibits the suppressive effects of alcohol on cell viability.     

Effects of sub-toxic concentrations of camphorquinone on cell lipid metabolism

The biological effects of camphorquinone (CQ), an initiator for light-polymerized resins, have been reported to relate to its ability to generate free radicals and cause radical-induced membrane damage via lipid peroxidation. However, the effects of CQ on lipids other than peroxidation may result in unfavorable tissue responses especially at concentrations that are not overtly toxic to cells. The purpose of the current study was to examine the effects of CQ on cell lipid metabolism at subtoxic concentrations, with or without visible light irradiation. HCP and THP-1 cells were exposed to CQ with or without light irradiation under clinically relevant conditions and lipid metabolism was analyzed using 14C-labeling and thin-layer chromatography. We found that CQ increased synthesis of neutral lipids, such as triglycerides, from 7 to nearly 15% of the total and diglycerides from 2% to about 3% of the total in HCP cells, while synthesis of phospholipids, such as sphingomyelin, was decreased by 1-1.5%. In THP-1 cells cholesterol synthesis increased more than 2-fold and cholesterol ester synthesis increased more than 5-fold. Light-activated CQ did not differ significantly in terms of its bioactivity compared to no-light conditions. We conclude that CQ significantly altered the metabolism of several important structural lipids in two cell types at sub-toxic concentrations that are clinically relevant. These changes in lipid metabolism may in turn affect membrane integrity and permeability and possibly lead to significant changes in cell responses.     

RKIP regulates CCL5 expression to inhibit breast cancer invasion and metastasis by controlling macrophage infiltration

Accumulating evidence suggests that presence of macrophages in the tumor microenvironment add to the invasive and tumor-promoting hallmarks of cancer cells by secreting angiogenic and growth factors. RKIP is a known metastasis suppressor and interferes with several steps of metastasis. However, the mechanistic underpinnings of its function as a broad metastasis suppressor remain poorly understood. Here, we establish a novel pathway for RKIP regulation of metastasis inhibition through the negative regulation of RANTES/CCL5 thereby limiting tumor macrophage infiltration and inhibition of angiogenesis. Using a combination of loss- and gain-of-function approaches, we show that RKIP hinders breast cancer cell invasion by inhibiting expression of the CC chemokine CCL5 in vitro. We also show that the expression levels of RKIP and CCL5 are inversely correlated among clinical human breast cancer samples. Using a mouse allograft breast cancer transplantation model, we highlight that ectopic expression of RKIP significantly decreases tumor vasculature, macrophage infiltration and lung metastases. Mechanistically, we demonstrate that the inhibition of the CCL5 expression is the cause of the observed effects resulting from RKIP expression. Taken together, our results underscore the significance of RKIP as important negative regulator of tumor microenvironment.     

Fundamental limits on persistent activity in networks of noisy neurons

Neural noise limits the fidelity of representations in the brain. This limitation has been extensively analyzed for sensory coding. However, in short-term memory and integrator networks, where noise accumulates and can play an even more prominent role, much less is known about how neural noise interacts with neural and network parameters to determine the accuracy of the computation. Here we analytically derive how the stored memory in continuous attractor networks of probabilistically spiking neurons will degrade over time through diffusion. By combining statistical and dynamical approaches, we establish a fundamental limit on the network’s ability to maintain a persistent state: The noise-induced drift of the memory state over time within the network is strictly lower-bounded by the accuracy of estimation of the network’s instantaneous memory state by an ideal external observer. This result takes the form of an information-diffusion inequality. We derive some unexpected consequences: Despite the persistence time of short-term memory networks, it does not pay to accumulate spikes for longer than the cellular time-constant to read out their contents. For certain neural transfer functions, the conditions for optimal sensory coding coincide with those for optimal storage, implying that short-term memory may be co-localized with sensory representation.     

Comparison of Tc-99m MAA Planar Versus SPECT/CT Imaging for Lung Shunt Fraction Evaluation Prior to Y-90 Radioembolization: Are We Overestimating Lung Shunt Fraction?

CardioVascular and Interventional Radiology - To compare lung shunt fraction (LSF) prior to Y-90 radioembolization calculated using planar imaging versus SPECT/CT in patients with hepatocellular...     

A Major Pitfall to Avoid: Retroclival Hematoma due to Odontoid Fracture

Background

Retroclival hematoma (RCH) is a rare occurrence. The hemorrhage is usually small and hidden and can be easily missed on CT scan. Here, we report the association of a RCH with an odontoid fracture.

Methods

Case report and review of the literature.

Results

We describe a case of a 75-year-old man with a history of squamous cell carcinoma of the tongue base, treated with chemo-radiation. He was on warfarin for atrial fibrillation. He presented to the hospital 6 weeks after falling from standing height, with headache, neck pain, and stiffness. Clinical examination did not show any focal neurologic deficits. INR measured 4 days before admission was 6.0, but therapeutic at 2.4 on the day of admission. CT scan of the head showed a RCH. CT angiogram of the neck unexpectedly showed a type II odontoid fracture with instability of the upper cervical spine and extension of the hematoma to the upper cervical spine. Anticoagulation was reversed with factor IX complex (Bebulin). He underwent C1–C2 fusion without any complications. The immediate post-operative period was unremarkable. Unfortunately, he succumbed to airway obstruction due to mucus plugging 14 days into hospitalization.

Conclusions

In the appropriate clinical setting, when a RCH is found, further imaging should be considered to rule out fracture of the cervical spine. Odontoid fractures can lead to compression of the spinal cord or lower medulla. To prevent neurologic injury and subsequent complications, prompt recognition of type II odontoid fracture should lead to immediate spine stabilization.     

Design,synthesis, and biological evaluation of 1‐ethyl‐3‐(thiazol‐2‐yl)urea derivatives as Escherichia coli DNA gyrase inhibitors

Discovery of novel DNA gyrase B inhibitors remains an attractive field in the search for new antibacterial drugs to overcome the known bacterial resistance mechanisms. In the present study, we designed and synthesized novel ethylurea derivatives of 4,5,6,7‐tetrahydrobenzo[1,2‐d]thiazole‐2,6‐diamine, 2‐(2‐aminothiazol‐4‐yl)acetic acid, and benzo[1,2‐d]thiazole‐2,6‐diamine and evaluated their Escherichia coli DNA gyrase inhibition. The most potent DNA gyrase inhibitors in the prepared library of compounds were benzo[1,2‐d]thiazoles 32–34 , 36 , and 37 with IC₅₀ values in the low micromolar range. The most promising inhibitors identified were evaluated against selected Gram‐positive and Gram‐negative bacterial strains. Compound 33 showed a MIC of 50 μM against an E. coli efflux pump‐defective strain, which suggests that efflux decreases the on‐target concentrations of these compounds.     

The impact of head and neck radiation on airway management: a retrospective data review

Canadian Journal of Anesthesia/Journal canadien d'anesthésie -