Morphological Changes in the Midgut of Aedes aegypti L. (Diptera: Culicidae) Larvae Following Exposure to an Annona coriacea (Magnoliales: Annonaceae) Extract

Bioinsecticides are important in the control of disease vectors, but data regarding their physiological effects on target insects are incomplete. This study describes morphological changes that occur in the midgut of third instar Aedes aegypti L. (Diptera: Culicidae) following treatment with a methanolic extract of Annona coriacea (Magnoliales: Annonaceae). Dissected midguts were subdivided into anterior and posterior regions and analyzed by light and scanning electron microscopy. Insects exposed to the extract displayed intense, destructive cytoplasmic vacuolization in columnar and regenerative midgut cells. The apical surfaces of columnar cells exhibited cytoplasmic protrusions oriented toward the lumen, suggesting that these cells could be involved in apocrine secretory processes and/or apoptosis. We report that A. coriacea extracts induced morphological alterations in the midgut of A. aegypti midgut larvae, supporting the use of plant extracts for control of the dengue vector.     

Multiple histone modifications in euchromatin promote heterochromatin formation by redundant mechanisms in Saccharomyces cerevisiae

Background  

Methylation of lysine 79 on histone H3 by Dot1 is required for maintenance of heterochromatin structure in yeast and humans. However, this histone modification occurs predominantly in euchromatin. Thus, Dot1 affects silencing by indirect mechanisms and does not act by the recruitment model commonly proposed for histone modifications. To better understand the role of H3K79 methylation gene silencing, we investigated the silencing function of Dot1 by genetic suppressor and enhancer analysis and examined the relationship between Dot1 and other global euchromatic histone modifiers.     

Differential effects of cholera toxin and pertussis toxin on the c-fos and c-jun mRNA expression in rat C6 glioma cells

Cholera toxin (CTX) increased c-fos mRNA level whereas it down-regulated the c-jun mRNA level in rat C6 glioma cells. In contrast to the action of CTX, pertussis toxin (PTX) did not affect either c-fos or c-jun mRNA level. The elevated c-fos mRNA level induced by CTX was significantly inhibited by the co-treatment with dexamethasone (DEX). However, DEX did not affect CTX-induced down-regulation of c-jun mRNA level. Cycloheximide (CHX) increased c-fos and c-jun mRNA levels. CHX caused a super-induction of CTX-induced c-fos mRNA level. Our results suggest that CTX-, but not PTX-, sensitive G-proteins may play an important role for c-fos mRNA up-regulation and c-jun mRNA down-regulation. In addition, DEX appears to have a selective inhibitory action against c-fos mRNA expression regulated by CTX. Ongoing protein synthesis inhibition is required for the superinduction of c-fos, but not c-jun, mRNA induced by CTX.     

Prevalence of Toxocara canis, Toxascaris leonina and Dirofilaria immitis in dogs in Chuncheon, Korea (2004)

The intestines and hearts of dogs were examined for Toxocara canis, Toxascaris leonina, and Dirofilaria immitis, after necropsy between June 26 and September 29, 2004 in Chuncheon, Korea. Of the 662 dogs examined, 6 were infected with T. canis (0.9%), 86 with T. leonina (13.0%). Fifty dogs were infected with D. immitis among 500 dogs examined (10.0%). Five were co-infected with T. canis and T. leonina, and three were co-infected with T. leonina and D. immitis. The cumulative positive infection rate for three species was 134/662 (20.2%). Considering previously reported seropositive rates of T. canis excretory-secretory antigen, i.e., 5% in the adult population in Korea, the possibility of toxocariasis caused by T. leonina should be reevaluated.     

Benzothiadiazole enhances the elicitation of rosmarinic acid production in a suspension culture of Agastache rugosa O. Kuntze

Callus and suspension cultures were established from the leaves of Agastache rugosa. The suspension cell growth was maximum at 15 days after inoculation. The cellular content of rosmarinic acid increased slowly and reached maximum (0.42 mg g^–1 dry wt) during the stationary phase of culture, after 18 days of inoculation. The addition of yeast extract preparation (MW <10000) at 50 g ml^–1 elevated the rosmarinic acid content up to 5.7-fold of that found in non-elicited suspension cells. The elicitation of yeast extract preparation was further 2-fold enhanced by the presence of benzothiadiazole, a synthetic activator of plant systemic acquired resistance, as compared to yeast extract alone. These results showed that benzothiadiazole can be used as a tool for enhancing secondary metabolite accumulation in cell cultures.     

An N-terminal 78 amino acid truncation of REIC/Dkk-3 effectively induces apoptosis

Overexpression of REIC/Dkk-3 (a tumor suppressor gene) induces cancer cell apoptosis through endoplasmic reticulum (ER) stress. Therefore, the identification of the portion of REIC/Dkk-3 that causes ER stress may be essential for the development of cancer treatment based on REIC/Dkk-3. Here, we made several truncated forms of REIC/Dkk-3 and investigated their therapeutic potentials against prostate cancer. Among three truncated forms, a variant comprising the N-terminal 78 amino acid region of REIC/Dkk-3 (^1-78REIC/Dkk-3) most strongly induced ER stress and apoptosis in human prostate cancer cells (PC3). For in vivo gene expression, we coupled a biodegradable polymer with naked DNA, which attained robust trans-gene expression in PC3-derived subcutaneous tumor. In therapeutic experiments, we demonstrated that multiple direct injections of polymer-conjugated ^1-78REIC/Dkk-3 plasmid provoke ER stress and significantly reduced the subcutaneous tumor volume compared with the control group. We suggest this non-viral strategy may be an effective alternative to viral gene therapy.     

Inhibitory effects of gallic acid and quercetin on UDP-glucose dehydrogenase activity

We have examined polyphenols as potential inhibitors of UDP-glucose dehydrogenase (UGDH) activity. Gallic acid and quercetin decreased specific activities of UGDH and inhibited the proliferation of MCF-7 human breast cancer cells. Western blot analysis showed that gallic acid and quercetin did not affect UGDH protein expression, suggesting that UGDH activity is inhibited by polyphenols at the post-translational level. Kinetics studies using human UGDH revealed that gallic acid was a non-competitive inhibitor with respect to UDP-glucose and NAD⁺. In contrast, quercetin showed a competitive inhibition and a mixed-type inhibition with respect to UDP-glucose and NAD⁺, respectively. These results indicate that gallic acid and quercetin are effective inhibitors of UGDH that exert strong antiproliferative activity in breast cancer cells.     

Simulation of human atherosclerotic femoral plaque tissue: the influence of plaque material model on numerical results

Background

Due to the limited number of experimental studies that mechanically characterise human atherosclerotic plaque tissue from the femoral arteries, a recent trend has emerged in current literature whereby one set of material data based on aortic plaque tissue is employed to numerically represent diseased femoral artery tissue. This study aims to generate novel vessel-appropriate material models for femoral plaque tissue and assess the influence of using material models based on experimental data generated from aortic plaque testing to represent diseased femoral arterial tissue.

Methods

Novel material models based on experimental data generated from testing of atherosclerotic femoral artery tissue are developed and a computational analysis of the revascularisation of a quarter model idealised diseased femoral artery from a 90% diameter stenosis to a 10% diameter stenosis is performed using these novel material models. The simulation is also performed using material models based on experimental data obtained from aortic plaque testing in order to examine the effect of employing vessel appropriate material models versus those currently employed in literature to represent femoral plaque tissue.

Results

Simulations that employ material models based on atherosclerotic aortic tissue exhibit much higher maximum principal stresses within the plaque than simulations that employ material models based on atherosclerotic femoral tissue. Specifically, employing a material model based on calcified aortic tissue, instead of one based on heavily calcified femoral tissue, to represent diseased femoral arterial vessels results in a 487 fold increase in maximum principal stress within the plaque at a depth of 0.8 mm from the lumen.

Conclusions

Large differences are induced on numerical results as a consequence of employing material models based on aortic plaque, in place of material models based on femoral plaque, to represent a diseased femoral vessel. Due to these large discrepancies, future studies should seek to employ vessel-appropriate material models to simulate the response of diseased femoral tissue in order to obtain the most accurate numerical results.