The role of the histones H3K9ac, H3K9me3, HP1γ, and H3K36me3 in oral squamous cell carcinoma loco-regional metastasis and relapse.

Molecular markers with unequivocal significance in predicting cervical lymph node metastasis of oral squamous cell carcinoma (OSCC) has not yet been identified. Histones are DNA-binding proteins that can regulate gene expression, and some studies have shown that such proteins are implicated with tumor development and progression. This study aimed to investigate the expression of some histone modifications in OSCC and their roles in cervical lymph node metastasis. To address this goal, H3K9ac, H3K9me3, HP1γ, and H3K36me3 expression levels were investigated immunohistochemically in a retrospective metastatic and non-metastatic OSCC samples. We analyzed the association between these markers with clinical-pathological data and survival rates. Hyperacetylation of H3K9ac was associated with cervical lymph node metastasis and local relapse. High expression levels of H3K9m3 were related to age and symptomatology. Furthermore, it was also found a statistically significant association between high HP1γ-expressing tumors and tumor size. However, no markers were associated with reduced overall survival rate. Our results suggest that covalent histone modifications contribute to OSCC behavior, and H3K9ac may play a critical role in OSCC-derived cervical lymph node metastasis.

Polyploidy Analysis and Attenuation of Oxidative Stress in Hepatic Tissue of STZ-Induced Diabetic Rats Treated with an Aqueous Extract of Vochysia rufa.

Diabetes mellitus (DM) is characterized by hyperglycemia and alterations in the metabolism of lipids, carbohydrates, and proteins. Due to its hypoglycemic effect Vochysia rufa is frequently used in Uberlandia, Brazil, to treat DM. Despite its popularity, there is little information about its effect on hepatic tissue. Therefore, we evaluated the histoarchitecture, oxidative stress parameters, and polyploidy of liver tissue from streptozotocin- (STZ-) induced diabetic rats treated with aqueous extract of Vochysia rufa (AEV). Histology was determined by fixing the livers, processing, and staining with HE. Oxidative stress was determined by evaluating CAT, GPx, and SOD activity in liver homogenates and hepatic mitochondria fraction and by measuring GST, GSH levels and lipid peroxidation (MDA). Polyploidy was determined by subjecting isolated hepatocyte nuclei to flow cytometry. In the diabetic group, GST activity and GSH rates decreased whereas liver homogenate analysis showed that GPx, SOD activity and MDA increased. AEV treatment restored all parameters to normal levels. The oxidative stress analysis of hepatic mitochondria fraction showed similar results. Lower polyploid cell populations were found in the diabetic rat livers, even after glibenclamide treatment. Thus, AEV treatment efficiently reduced hepatic oxidative stress caused by STZ-induced diabetes and produced no morphological changes in the histological analysis.

Alterations of antioxidant biomarkers and type I collagen deposition in the parotid gland of streptozotocin-induced diabetic rats.

BACKGROUND AND OBJECTIVE: Acarbose is a competitive inhibitor of intestinal alpha-glycosidases that slows the breakdown of sucrose and starch, thereby reducing glucose and fructose absorption. The aim of this study was to evaluate the effect of acarbose treatment on antioxidant parameters and deposition of type I collagen in the parotid glands of diabetic rats. METHODS: Diabetes mellitus was induced by intravenous injection of streptozotocin, and rats were divided into four groups: non-diabetic (NDM), diabetic (DM), diabetic treated with 25mg/kg acarbose (DMA) and non-diabetic treated with acarbose (NDMA). Changes in enzymatic antioxidant systems, such as the activity of SOD and GPx enzymes, were evaluated, and the specific staining pattern of the type I collagen fibres was investigated in the rat parotid glands. RESULTS: The DM group presented high levels of SOD and GPx enzymes, which were reduced by acarbose treatment. Tissue damage, which was indicated by an increased MDA concentration in the parotid glands of rats in the DM group, was also reversed in the DMA group. Moreover, type I collagen fibres from DM rats were more intensely stained than those of NDM rats. Acarbose treatment was effective in decreasing collagen deposition, which was shown by a decrease in staining intensity of approximately 25%. CONCLUSIONS: These results suggest that the diabetic state influences the type I collagen concentration in the parotid glands of rats. In addition, acarbose treatment was helpful in preventing the deposition of such fibres, as well the increase in oxidative stress induced by hyperglycemia.

Extendend chromatin fibers in spermatozoa of apis mellifera (HYMENOPTERA, APOIDEA)

The flow of chromatin from the nuclei of mouse liver cells and spermatozoa after treatment with concentratedsaline and detergent solutions under the simultaneous action of gravity results in the formation of extendedchromatin fibers (ECF). In mouse somatic nuclei, the increase in chromatin condensation is accompaniedby a decrease in the frequency of ECF formation. Since tightly packed chromatin with a very lysine-richhistone variant that resembles somatic H1 histones occurs in honey bee spermatozoa, we examined theformation of ECF in sperm cells of Apis mellifera, and compared the findings with data for mouse cells.Freshly prepared smears of fixed and unfixed semen from A. mellifera were lysed under the action of gravity,stained with toluidine blue at pH 4.0, and examined with polarized and unpolarized light. A protocol usingunfixed preparations and a short lysis period that resulted in abundant ECF production in mouse hepatocytes(which contain loosely-packed chromatin) and sperm cells produced ECF in only a few spermatozoa of A.mellifera. In contrast, a protocol using fixed preparations and a long lysis period produced fewer ECFs inthe former two cell types and no ECF formation in honey bee spermatozoa. The limited chromatin fluidityin A. mellifera spermatozoa may reflect their special DNA-protein composition and organization in the cellnuclei, the participation of nuclear matrix elements, a less effective disruption of the nuclear envelope andplasmalemmal components during lysis, and/or cytoplasmic spatial constraints resulting from particularitiesin the acrosomal complex.

Extended chromatin fibers in mouse testicular spermatozoa

Since in mouse spermatozoa the somatic histones are replaced by other basic proteins and there are changes in the chromatin supraorganization, different patterns of extended chromatin fiber (ECF) formation would be expected compared with those formed by somatic cells that were previously studied. In this study, we investigated the formation of ECF in mouse testicular spermatozoa after lysis with 2 M NaCl plus 1 por cento Triton X-100, and under the action of gravity. ECFs were observed under polarized light in fixed and unfixed spermatozoa subjected to lysis in a vertical position and stained with toluidine blue at pH 4.0. In unfixed preparations, all of the sperm nuclei showed ECFs, whereas in fixed preparations 60 por cento of the cells had ECF. The latter frequency was much higher than that previously reported for mouse hepatocytes. Even in cells that did not produce ECFs in vertically and horizontally lysed preparations, an ordered reorganization of the chromatin was observed after lysis. The faint positive response to acid fast green at the nuclear periphery in spermatozoa that did not develop ECF after lysis was assumed to represent residual protamine and nuclear matrix proteins. The high frequency of mouse sperm cell nuclei with ECF probably reflected the extraction of protamines from the DNA-protein complexes of sperm cell nuclei facilitated by the specific lysis protocol.