Telomerase increasing compound protects hippocampal neurons from amyloid beta toxicity by enhancing the expression of neurotrophins and plasticity related genes.

The telomerase reverse transcriptase protein, TERT, is expressed in the adult brain and its exogenic expression protects neurons from oxidative stress and from the cytotoxicity of amyloid beta (Aß). We previously showed that telomerase increasing compounds (AGS) protected neurons from oxidative stress. Therefore, we suggest that increasing TERT by AGS may protect neurons from the Aß-induced neurotoxicity by influencing genes and factors that participate in neuronal survival and plasticity. Here we used a primary hippocampal cell culture exposed to aggregated Aß and hippocampi from adult mice. AGS treatment transiently increased TERT gene expression in hippocampal primary cell cultures in the presence or absence of Aß and protected neurons from Aß induced neuronal degradation. An increase in the expression of Growth associated protein 43 (GAP43), and Feminizing locus on X-3 genes (NeuN), in the presence or absence of Aß, and Synaptophysin (SYP) in the presence of Aß was observed. GAP43, NeuN, SYP, Neurotrophic factors (NGF, BDNF), beta-catenin and cyclin-D1 expression were increased in the hippocampus of AGS treated mice. This data suggests that increasing TERT by pharmaceutical compounds partially exerts its neuroprotective effect by enhancing the expression of neurotrophic factors and neuronal plasticity genes in a mechanism that involved Wnt/beta-catenin pathway.

Dynamic nuclear polarization magnetic resonance imaging and the oxygen-sensitive paramagnetic agent OX63 provide a noninvasive quantitative evaluation of kidney hypoxia in diabetic mice.

Renal hypoxia may play an important role in the progression of diabetic nephropathy. However, tools that noninvasively and quantitatively measure oxygen tension in the kidney are lacking. Here, we evaluated the feasibility of a noninvasive and quantitative imaging technique using dynamic nuclear polarization magnetic resonance imaging (DNP-MRI) in combination with the oxygen-sensitive paramagnetic agent OX63 for measuring oxygen tension in the kidney. Our results demonstrate that the DNP-MRI technique can yield quantitative maps of oxygen tension in the mouse renal cortex. Using this procedure, we also showed that oxygen tension was less elevated in the renal cortex of both streptozotocin-induced type 1 diabetic mice and db/db mice, a model of type 2 diabetes, than in the renal cortex of age-matched control mice of each respective model. Oxygen tension in streptozotocin-exposed mice was significantly improved by insulin treatment. Thus, the noninvasive and quantitative DNP-MRI technique appears to be useful for studying the pathophysiological role of hypoxia.

Disposition of tris(4-chlorophenyl)methanol and tris(4-chlorophenyl)methane in male and female Harlan Sprague Dawley rats and B6C3F1/N mice following oral and intravenous administration.

Tris(4-chlorophenyl)methane (TCPME) and tris(4-chlorophenyl)methanol (TCPMOH) have been detected in various biota and human tissues. The current studies were undertaken to investigate the disposition and metabolism of TCPME and TCPMOH in rats and mice. [14C]TCPME was well absorbed (≥66%) in male rats and mice following a single oral administration of 1, 10, or 100 mg/kg. The excretion of [14C]TCPME-derived radioactivity in urine (≤2.5%) and feces (≤18%) was low. The administered dose was retained in tissues (≥ 64%) with adipose containing the highest concentrations. The metabolism of TCPME was minimal. The disposition and metabolism of [14C]TCPME in females was similar to males. The time to reach maximum concentration was ≤7 h, the plasma elimination half-life was ≥31 h, and the bioavailability was ≥82% following a 10 mg/kg oral dose of [14C]TCPME in male rats and mice. The disposition of [14C]TCPMOH was similar to that of [14C]TCPME. Following an intravenous administration of [14C]TCPME or [14C]TCPMOH in male rats and mice, the pattern of disposition was similar to that of oral administration. In conclusion, both TCPME and TCPMOH are readily absorbed and highly bioavailable following a single oral administration pointing to importance of assessing the toxicity of these chemicals.

Topical Delivery of Senicapoc Nanoliposomal Formulation for Ocular Surface Treatments.

Topical ophthalmologic treatments have been facing great challenges with main limitations of low drug bioavailability, due to highly integrative defense mechanisms of the eye. This study rationally devised strategies to increase drug bioavailability by increasing ocular surface residence time of drug-loaded nanoliposomes dispersed within thermo-sensitive hydrogels (Pluronic F-127). Alternatively, we utilized sub-conjunctival injections as a depot technique to localize nanoliposomes. Senicapoc was encapsulated and sustainably released from free nanoliposomes and hydrogels formulations in vitro. Residence time increased up to 12-fold (60 min) with 24% hydrogel formulations, as compared to 5 min for free liposomes, which was observed in the eyes of Sprague-Dawley rats using fluorescence measurements. Pharmacokinetic results obtained from flushed tears, also showed that the hydrogels had greater drug retention capabilities to that of topical viscous solutions for up to 60 min. Senicapoc also remained quantifiable within sub-conjunctival tissues for up to 24 h post-injection.

Senicapoc: Repurposing a Drug to Target Microglia KCa3.1 in Stroke.

Stroke is the leading cause of serious long-term disability and the fifth leading cause of death in the United States. Treatment options for stroke are few in number and limited in efficacy. Neuroinflammation mediated by microglia and infiltrating peripheral immune cells is a major component of stroke pathophysiology. Interfering with the inflammation cascade after stroke holds the promise to modulate stroke outcome. The calcium activated potassium channel KCa3.1 is expressed selectively in the injured CNS by microglia. KCa3.1 function has been implicated in pro-inflammatory activation of microglia and there is recent literature suggesting that this channel is important in the pathophysiology of ischemia/reperfusion (stroke) related brain injury. Here we describe the potential of repurposing Senicapoc, a KCa3.1 inhibitor, to intervene in the inflammation cascade that follows ischemia/reperfusion.

Improvements in haemolysis and indicators of erythrocyte survival do not correlate with acute vaso-occlusive crises in patients with sickle cell disease: a phase III randomized, placebo-controlled, double-blind study of the Gardos channel blocker senicapoc (ICA-17043).

Red blood cell (RBC) hydration is regulated in part by the Ca(2+) -activated K(+) efflux (Gardos) channel. Senicapoc selectively blocks potassium efflux through the Gardos channel, reducing RBC dehydration and haemolysis, and increasing haemoglobin levels in sickle cell disease (SCD). This randomized, placebo-controlled trial was designed to determine the safety and clinical efficacy of senicapoc in SCD patients. One hundred and forty-five patients were randomized to receive senicapoc and 144 patients to receive placebo for 52 weeks. Consistent with a previous study, patients in the senicapoc group had significantly increased haematocrit, haemoglobin, and decreased numbers of both dense erythrocytes and reticulocytes when compared to the placebo group. The unblinded Data Monitoring Committee terminated this study early due to a lack of efficacy when it determined that, despite improvements in anaemia and haemolysis, no significant improvement in the rate of sickle cell painful crises was observed in patients treated with senicapoc compared to those on placebo (0·38 vs. 0·31, respectively). Comparisons of the times to first, second and third crises between the senicapoc and placebo groups were not statistically significant. Nausea and urinary tract infections occurred more frequently in the senicapoc group than placebo. Serious adverse events were similar in the two groups.

Prevention of mitochondrial oxidative damage using targeted antioxidants.

Mitochondrial-targeted antioxidants that selectively block mitochondrial oxidative damage and prevent some types of cell death have been developed. These antioxidants are ubiquinone and tocopherol derivatives and are targeted to mitochondria by covalent attachment to a lipophilic triphenylphosphonium cation. Because of the large mitochondrial membrane potential, these cations accumulated within mitochondria inside cells, where the antioxidant moiety prevents lipid peroxidation and protects mitochondria from oxidative damage. The mitochondrially localized ubiquinone also protected mammalian cells from hydrogen peroxide-induced apoptosis while an untargeted ubiquinone analogue was ineffective against apoptosis. When fed to mice these compounds accumulated within the brain, heart, and liver; therefore, using these mitochondrial-targeted antioxidants may help investigations of the role of mitochondrial oxidative damage in animal models of aging.

Effects of tris(4-chlorophenyl)methanol on the rat following short-term oral exposure.

The systemic toxicity of tris(4-chlorophenyl)methanol (TCPM) was studied in male and female rats following 4 weeks dietary exposure dosed at 1, 10 and 100 ppm. An increased spleen to body weight ratio was observed in males at 10 and 100 ppm and in females at 100 ppm. An increased liver to body weight ratio was detected in both sexes at 100 ppm. Dose-related increases in hepatic Phase-I (AH, APDM, EROD and PROD) and Phase-II (UDPGT, GST) enzyme activities were observed generally at 10 and 100 ppm, with the elevation in PROD activity being the most marked. Increased urinary ascorbic acid was detected in both males and females after 1 week of treatment at 100 ppm and after 4 weeks of treatment at 10 and 100 ppm. At 10 and 100 ppm, elevated % lymphocytes were found in males, and higher white blood cell and lymphocyte counts were observed in females. In the liver, mild to moderate cytoplasmic changes consistent with proliferation of smooth endoplasmic reticulum were present in rats of both sexes at 10 and 100 ppm, and increased number of hepatocytes undergoing apoptosis were observed in male rats at 100 ppm. Mild splenic changes consisting of sinus hyperplasia in males and females at 100 ppm and mantle zone atrophy in males at 100 ppm were also observed. It was concluded that TCPM at a dietary concentration of 10 ppm (equivalent to 1.2 mg/kg/day) produced systemic changes in rats that included various hepatic effects, increased splenic weight, and modulations in white blood cells and lymphocyte counts.

Metabolism of triphenylmethane colours II. Absorption, excretion and distribution of Benzyl Violet 4B (FD and C Violet No. 1) in rats.

Absorption, excretion and distribution of Benzyl Violet 4B were investigated in rats, deterimining the colour by the 2-wavelength technique. This colour was hardly absorbed when given orally; only 0.89% of the dose was recovered from the bile after 24 h. On the other hand, it was rapidly excreted through the bile when given intravenously; the cumulative recovery of biliary excretion amounted to 88.4% at 4 h and 95.9% at 24 h. The levels of the colour distributed in the liver, kidney abdominal muscle and blood serum were in the range of 1--3 microgram/g of tissue in rats fed a diet containing 5% Benzyl Violet 4B for 8 weeks, whereas they were slightly lower in rats fed the diet for 18 weeks. When rats were given the colour intravenously, there was no sex-related difference in the distribution of the colour in either Wistar or Sprague--Dawley rats, but the disappearance of the colour from the brain, liver, abdominal muscle, abdominal skin and ear of Sprague--Dawley rats was slower than from those of Wistar rats.