Chloroform,carbon tetrachloride and glutathione depletion induce secondary genotoxicity in liver cells via oxidative stress

Chemical carcinogens are generally classified as genotoxic or non-genotoxic. However, weak genotoxicity at high concentrations is sometimes observed and interpretation is often problematic. In addition, certain rodent carcinogens exert their effects at doses associated with cytotoxicity and compensatory hyperplasia may be a contributing factor to tumourogenesis. We hypothesise that certain substances, at high concentrations, can induce an oxidative stress via the depletion of glutathione (GSH) and other antioxidant defences and that this may lead to indirect genotoxicity, that could contribute to carcinogenicity. In support of this, human HepG2 cells treated with buthionine sulphoximine (BSO) to deplete GSH, exhibited DNA strand breaks alongside elevated 8-oxodeoxyguanosine (8-oxodG) and malondialdehyde deoxyguanosine (M(1)dG) adducts under conditions associated with lipid peroxidation. Chloroform and carbon tetrachloride are rodent carcinogens with characteristics as described above. In female rat hepatocytes, chloroform treatment resulted in a small dose-dependent increase in M(1)dG adducts (4 mM and above), DNA strand breakage (8 mM and above) and lipid peroxidation, in the absence of any associated increase in DNA oxidation. GSH depletion only occurred in association with cytotoxicity (20 mM; lactate dehydrogenase release). Alongside lipid peroxidation, carbon tetrachloride (1 and 4 mM) produced a small elevation in M(1)dG adducts and DNA strand breaks and increases in 8-oxodG were observed at the threshold of, and concomitant with, cytotoxicity (4 mM). These effects may contribute to high dose genotoxicity and carcinogenicity. Non-linearity in the dose response is expected on the basis of depletion of antioxidants, and therefore, a pragmatic threshold for biologically relevant responses should exist.     

Ranibizumab: A Review of its Use in Myopic Choroidal Neovascularization

Ranibizumab (Lucentis^®) is the first inhibitor of vascular endothelial growth factor (VEGF)-A licensed for the treatment of visual impairment due to choroidal neovascularization (CNV) secondary to pathologic myopia (i.e. myopic CNV). The drug inhibits biologically active isoforms of VEGF-A and is administered via intravitreal injection, with the number of treatments required depending on disease activity. The clinical benefit of such a ranibizumab regimen in adults with myopic CNV was demonstrated in a randomized, double-masked, active comparator-controlled, phase III trial known as RADIANCE. In this trial, intravitreal ranibizumab was superior to the standard licensed therapy available to these patients thus far, namely intravenous verteporfin plus photodynamic therapy (verteporfin PDT), in improving visual acuity from month 1 through month 3 of treatment, with improvements in some aspects of vision-related function also evident with ranibizumab versus verteporfin PDT at 3 months. Improvements in vision were sustained for up to 12 months in ranibizumab recipients and were mirrored by improvements in anatomic outcomes. Few ranibizumab injections were required over the trial, with more than 60 % of patients not needing to receive the drug from month 6 to 11. Ranibizumab was generally well tolerated in RADIANCE, with few patients experiencing serious ocular or non-ocular adverse events.     

The host defense peptide LL‐37 is detected in human parotid and submandibular/sublingual saliva and expressed in glandular neutrophils

The human host defense peptide, LL‐37, is an important player in the first line of defense against invading microorganisms. LL‐37 and its precursor, hCAP18, have been detected in unstimulated whole saliva but no reports showing hCAP18/LL‐37 in isolated, parotid, and/or submandibular/sublingual saliva have been presented. Here, we measured the levels of hCAP18/LL‐37 in human parotid and submandibular/sublingual saliva and investigated the expression of hCAP18/LL‐37 in parotid and submandibular gland tissue. Parotid and submandibular/sublingual saliva was collected from healthy volunteers, and the levels of hCAP18/LL‐37 in saliva were analyzed by dot blot, ELISA, and western blotting. Cellular expression of hCAP18/LL‐37 in human parotid and submandibular glands was investigated by immunohistochemistry. Immunoreactivity for hCAP18/LL‐37 was detected in both parotid and submandibular/sublingual saliva of all individuals. The concentration of hCAP18/LL‐37 was similar in parotid and submandibular/sublingual saliva, and was determined by densitometric scanning of each dot and normalization to the total protein concentration of each sample, and by ELISA. Double immunohistochemistry revealed that intravascular neutrophils of both parotid and submandibular glands express hCAP18/LL‐37. For the first time, we demonstrate hCAP18/LL‐37 in isolated human parotid and submandibular/sublingual saliva and expression of hCAP18/LL‐37 in glandular intravascular neutrophils, indicating that neutrophils of the major salivary glands contribute to the LL‐37 content of whole saliva.