In vitro effect of calcium dobesilate on oxidative/inflammatory stress in human varicose veins

AIM

To determine whether calcium dobesilate can act in chronic venous insufficiency by similar antioxidant, anti-inflammatory mechanisms as in diabetic retinopathy.

METHODS

Calcium dobesilate was tested in vitro for its protective action against oxidative/inflammatory stress in human varicose veins. Varicose greater saphenous veins were obtained from 14 patients (11 men, 3 women) aged 53-65 years. Oxidative stress was induced exogenously in the vein segments, with the phenazine methosulphate (PMS)/NADH couple. Total antioxidant status (TAS) and malondialdehyde (MDA) contents were used as markers of oxidative stress.

RESULTS

Calcium dobesilate significantly prevented oxidative disturbances in the micromolar range. PMS/NADH-dependent TAS decrease was fully prevented with IC(50) = 11.4 ± 2.3 µmol/L (n = 6 veins), whereas MDA increase was fully prevented with IC(50) = (102 ± -3) µmol/L (n = 6 veins). Calcium dobesilate acted quali- and quantitatively like rutin, the reference compound. Comparison with pharmacokinetic data suggests that calcium dobesilate can act at therapeutic concentrations.

CONCLUSION

Calcium dobesilate protected human varicose veins against oxidative stress in vitro at levels that correspond to therapeutic concentrations. Further studies are required to investigate whether a similar action is found in varicose veins from patients orally treated with calcium dobesilate.

Eimeria tenella: hsp70 expression during sporogony

There is an increasing interest in identifying the parasite components involved in the maturation, development, and infectivity of intracellular protozoan parasites. In the present study, a heat shock protein (hsp) of the family of 70 kDa hsp (hsp70), which play important roles in the stage conversion and virulence of these parasites, was examined. Whereas hsp70 expression has been examined in Eimeria tenella within host tissues, in the present study, oocysts of E. tenella were used to investigate the expression of hsp70 during sporulation without interference from the host; hsp70 expression during excystation was induced by incubating sporulated oocysts under various experimental conditions to produce the stimuli necessary for sporozoites to become active and to excyst in vitro. Hsp70 was detected by immunohistochemical techniques; quantitative flow cytometric analysis was also been carried out using specific monoclonal antibodies against hsp70. Hsp70 was expressed during sporulation but was not found in sporulated oocysts after the completion of sporulation. Oocysts re-expressed hsp70 when excystation was induced. The presence of hsp70 prior to infection may preadapt the parasite for additional stress in the host and may be involved in the formation of sporozoites.

Superoxide anions produced by inflammatory cells play an important part in the pathogenesis of acid and pepsin induced oesophagitis in rabbits

BACKGROUND

Reactive oxygen metabolites have been associated with gastrointestinal injury.

OBJECTIVE

To investigate whether mucosal reactive oxygen metabolites are involved in acid and pepsin induced oesophagitis, and if so, which specific metabolites.

METHODS

The effects of free radical scavengers and the anti-inflammatory drug ketotifen on rabbit oesophagitis induced by acidified pepsin were studied. Isolated oesophageal cells were obtained before and after oesophageal injury and the generation of superoxide anion and hydrogen peroxide was analysed by flow cytometry. The presence of inflammatory cells was determined by indirect immunofluorescence with a mouse antirabbit CD11b antibody.

RESULTS

Of the free radical scavengers tested, superoxide dismutase, which reacts with the superoxide anion, significantly reduced oesophagitis, whereas catalase, which reacts with hydrogen peroxide, had only a mild effect and dimethylsulphoxide had no effect. Ketotifen significantly reduced the inflammation and also prevented the induction of oesophagitis. Isolated cells obtained from the oesophageal mucosa after acidified pepsin exposure generated increased amounts of superoxide anions, which were mainly produced by CD11b positive cells.

CONCLUSIONS

Reactive oxygen metabolites, especially superoxide anion, produced by inflammatory cells play a significant part in the genesis of oesophagitis induced by acid and pepsin in rabbits and might be a target for future medical therapy.

Flow cytometry study of the role of superoxide anion and hydrogen peroxide in cellular photodestruction with 5-aminolevulinic acid-induced protoporphyrin IX

Flow cytometry was used to investigate the participation of reactive oxygen species, other than singlet oxygen, in the cytotoxic effect of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) in vitro in A-431 squamous cell carcinoma (SCC) cells and human skin fibroblasts (HSF). We used propidium iodide to determine cellular cytotoxicity, hydroethidine to measure intracellular superoxide anion (O2-) and dihydrorhodamine 123 to assess intracellular hydrogen peroxide (H2O2) content. Our data support the importance of the incubation time with ALA in the selectivity of PDT with ALA against SCC cells, inducing minimum damage on normal HSF. Photoradiation mortality curves of the response of these cell lines to ALA-induced PpIX photosensitization correlated with the extent of photosensitizer accumulation. Intracellular O2- production correlated with cell death, increasing both in a light dose-dependent fashion in ALA treated cells. This correlation was not observed with H2O2-intracellular production. These results suggest the effectiveness of PDT with ALA in vitro in SCC, the significant participation of O2- in its phototoxic mechanism, and the usefulness of flow cytometry in the study of the cytotoxic effect of ALA-induced PpIX PDT.