Cataract is a key factor in the morbidity associated with diabetes. While the pathogenesis of diabetic cataract formation is poorly understood, previous research has identified aldose reductase ...(ALR2) as a key player. To elucidate a potential role for this enzyme in diabetic cataract formation, we created a series of transgenic mice designed for expression of human ALR2 (AKR1B1) in epithelial and outer cortical fiber cells of the lens. One of the founder lines, designated PAR39, developed an early onset cataract that involved formation of a plaque of cells at the anterior aspect of the lens. These cells appear to separate from the anterior epithelium and undergo a dramatic change that is reminiscent of the epithelial to mesenchymal transition (EMT). We characterized this phenotype in the PAR39 strain by examining rates of cell proliferation and by immunostaining for markers of EMT. Incorporation of the thymidine analog bromodeoxyuridine (BrdU) was used to estimate cell proliferation in two functional areas of the lens epithelium: the mitotically active germinative zone (GZ) and the less proliferative center zone (CZ). Staining cell nuclei with diamido 4′,6-diamidino-2-phenylindole (DAPI) was used to establish a total cell count in the demarcated areas. Lens epithelium in PAR39 transgenic mice demonstrated a decrease in the percentage of BrdU/DAPI staining within the GZ as compared to nontransgenic littermate controls (8.1% vs. 10.9%). A similar decrease in BrdU/DAPI was observed in the CZ (0.6% compared to 3.3%). However, cell density was greater within the GZ of PAR39 mice as compared with nontransgenic controls, while it was not significantly different in the CZ among the two groups. Furthermore, cells associated with the epithelial plaque did not stain positive for BrdU, but were strongly positive for alpha-smooth muscle actin, a classical marker for EMT. These findings suggest that ALR2 over-expression is associated with an alteration in the balance between proliferation and apoptosis of epithelial cells in the mouse lens, and that cells associated with epithelial plaques in the PAR39 lens have features in common with cells undergoing EMT.
Risk assessment studies on aquatic pollution, a threat to water quality and aquatic biota, often rely on animal capture and experimentation. However, ethical concerns surrounding animal use have ...prompted the development and use of alternative methods. This study investigates the viability of primary hepatocyte cultures from
Oreochromis niloticus
as an in vitro tool for environmental contaminant screening, focusing on cadmium as a pollutant model. Isolated hepatocytes were cultured on plates using a mixture of supplemented L15/F12 media. Freezing conditions were tested for cell stock preservation. The cultured hepatocytes were exposed to 0.5, 5, and 50 µM of cadmium to assess cell viability, reactive oxygen and nitrogen species, and antioxidant molecules. Results demonstrated a concentration and time-dependent decrease in cell viability upon cadmium exposure. Cadmium exposure also induced an imbalance in the antioxidant defense system, leading to increased reactive oxygen species levels and lipid peroxidation. These findings validate the cadmium toxicity to primary hepatocytes and confirm the applicability of commonly used biomarkers in animal-based ecotoxicology and risk assessment studies. The replication of these biomarkers in primary hepatocyte cultures provides an ethical alternative to reduce animal testing in ecotoxicology. Lastly, the study highlights the potential of primary hepatocyte cultures as an in vitro tool for evaluating the toxicity of environmental contaminants and supports the integration of this tool in future environmental risk assessment studies, promoting sustainable water resource management while reducing reliance on animal experimentation.
Graphical abstract
To summarize important talking points from a 2016 symposium focusing on real-world challenges to advancing precision medicine in radiation oncology, and to help radiation oncologists navigate the ...practical challenges of precision, radiation oncology.
The American Society for Radiation Oncology, American Association of Physicists in Medicine, and National Cancer Institute cosponsored a meeting on precision medicine in radiation oncology. In June 2016 numerous scientists, clinicians, and physicists convened at the National Institutes of Health to discuss challenges and future directions toward personalized radiation therapy. Various breakout sessions were held to discuss particular components and approaches to the implementation of personalized radiation oncology. This article summarizes the genomically guided radiation therapy breakout session.
A summary of existing genomic data enabling personalized radiation therapy, ongoing clinical trials, current challenges, and future directions was collected. The group attempted to provide both a current overview of data that radiation oncologists could use to personalize therapy, along with data that are anticipated in the coming years. It seems apparent from the provided review that a considerable opportunity exists to truly bring genomically guided radiation therapy into clinical reality.
Genomically guided radiation therapy is a necessity that must be embraced in the coming years. Incorporating these data into treatment recommendations will provide radiation oncologists with a substantial opportunity to improve outcomes for numerous cancer patients. More research focused on this topic is needed to bring genomic signatures into routine standard of care.
Peptide mimetics of the RGDF sequence in which Arg-Gly has been replaced with 5-(4-amidinophenyl)pentanoyl mimetic has led to a 1000-fold increase in inhibitory potency over the natural RGDF ligand. ...The guanidine residue of the arginine may be involved in a reinforced ionic interaction with a carboxylate of the receptor which could explain the dramatic increase in potency upon replacement with benzamidine. This hypothesis is supported by the observation of low inhibitory potency of the corresponding benzylamine (18) and no activity with the corresponding imidazoline derivative (19); plus, ab initio calculations on the respective complexes suggest that the benzamidine-carboxylate is more favorable than the guanidine-carboxylate interaction. The ED50 for the inhibition of ex vivo collagen induced platelet aggregation in the dog for SC-52012 (1) was 0.32 microgram/kg/min by iv infusion with a pharmacodynamic half-life for recovery of approximately 40 min.
FALLS' GUIDELINES AND OSTEOPOROSIS ASSESSMENT Kamel, Hosam K.; Vamc, Clement J. Zablocki
Journal of the American Geriatrics Society (JAGS),
06/2002, Letnik:
50, Številka:
6
Journal Article
Intravenous therapy has been shown to be beneficial in the prevention of acute platelet-associated thrombotic events. However, orally active agents would be advantageous for chronic therapy. ...Fibrinogen receptor antagonists block the fibrinogen/platelet interaction and thus inhibit a step required for thrombus formation. To date, no orally active fibrinogen binding inhibitors have been characterized. SC-54684A, now in clinical trial, is the orally active prodrug of a potent and specific fibrinogen binding antagonist.
We measured inhibition of 125I-fibrinogen binding to activated platelets and inhibition of aggregation in platelet-rich plasma to selected agonists and showed IC50s of 1.0 x 10(-8) and 3 to 7 x 10(-8) mol/L, respectively. Specificity of the active moiety was determined by studying its effect on the binding of (1) neutrophils to interleukin (IL)-1 beta-stimulated endothelial cells, (2) endothelial cells to fibronectin, and (3) vitronectin to isolated vitronectin and fibrinogen receptors. No effect was observed on the binding neutrophils to IL-stimulated endothelial cells or endothelial cell binding to fibronectin. There was a fivefold separation between binding to isolated receptors of vitronectin and fibrinogen. Collagen-induced aggregation was inhibited by 80%, and bleeding time was increased approximately 2.5-fold when the active moiety was infused to steady state at 0.2 micrograms/kg per minute in dogs. When the ester prodrug was given orally and the active moiety was given intravenously, the oral systemic activity was approximately 20%. Pharmacokinetic analysis after intravenous infusion of the prodrug or active moiety showed that the prodrug was rapidly converted to the active moiety; the active moiety had a t1/2 of 6.5 hours. When the prodrug was administered both orally and intravenously, the systemic availability of the active moiety was 62%.
SC-54684A, an orally active antiplatelet drug now in clinical trial, is shown to be a potent, specific fibrinogen binding inhibitor that blocks platelet aggregation to a wide variety of known stimuli and has good bioavailability in animals.
The use of full agonists of the A(1)-adenosine receptor (A(1)-ADOR) as antiarrhythmic agents is limited by their actions to cause high-grade atrioventricular (AV) block, profound bradycardia, atrial ...fibrillation, and vasodilation. It may be possible to avoid these undesired actions by use of partial agonists. We determined the effects of CVT-2759, a potential partial agonist of A(1)-ADORs, on guinea pig hearts. CVT-2759 (0.1-100 microM) increased the S-H interval of the isolated heart from 45 +/- 1 to 60 +/- 3 ms (P < 0. 01) with a half-maximal effect at 3.1 microM. CVT-2759 did not cause second-degree AV block. CVT-2759 significantly attenuated the actions of the full agonists N(6)-cyclopentyladenosine and adenosine. CVT-2759 caused a moderate slowing of atrial rate by </=13% and did not shorten the durations of either the atrial or the ventricular monophasic action potential. Coronary conductance was increased by CVT-2759 only at concentrations >10 microM. In contrast, CVT-2759 was a full agonist to decrease cAMP content of rat adipocytes and Fischer rat thyroid line 5 cells. Results of radioligand binding assays indicated that CVT-2759 stabilized a high-affinity, G protein-coupled state of the A(1)-ADOR in membranes prepared from rat adipocytes but not in membranes prepared from the guinea pig brain. The results suggest that a weak A(1)-ADOR agonist, such as CVT-2759, may be useful to slow AV nodal conduction and thereby ventricular rate without causing AV block, bradycardia, atrial arrhythmias, or vasodilation.
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