The effects of different doses of melatonin on lipid peroxidation in diet-induced hypercholesterolemic rats.

This study aims to see in an animal experiment how differently the low and high doses of melatonin affect the antioxidant status and peroxidation of lipids. Forty-two male Wistar-Albino rats weighing about 200 gr (180-220) aged 6-7 months were used. Of these rats, 12 were fed with normal rat chow for 12 weeks. The latter ones were divided into two groups, each containing 6 rats. Group 1 (control group) received daily intraperitoneal injections of NaCl (0.9%; w/v). Group 2 was injected ethanol daily (4%; v/v; i.p.) to see the effects of ethanol in which we dissolved melatonin. Thirty rats were fed with a diet enriched with cholesterol (2%; w/w), cholic acid (0.5%; w/w) and propilthyouracil (0.5%; w/w) for 12 weeks. These rats were divided into three groups each containing 10 rats. The low-dose group received melatonin 1 mg/kg/d; i.p. (group 3), the high-dose group received melatonin in a dose of 10 mg/kg/d; i.p. (group 4), and only the cholesterol group did not get any vehicle (group 5). Total cholesterol (TC), LDL cholesterol (LDL-C), total antioxidant capacity (TAC), oxidized LDL (oLDL) and TBARS lelvels were measured in all groups. The produced high-cholesterol diet increased LDL cholesterol. Melatonin decreased the extent of this plasma lipoprotein increase and also prevented the oxidation of it. This effect was clearer when the dose was higher. Antioxidant status seems to be also dose-dependent (Tab. 2, Ref. 33).

Effects of estrogens on oxidative protein damage in plasma and tissues in ovariectomised rats.

PURPOSE: To assess estrogen-related changes in the redox status of the brain and liver proteins as well as the systemic oxidative stress in ovarectomised (OVX) rats METHODS: Twelve-week-old, sexually mature female Sprague-Dawley rats (200-250g) were randomly divided into four groups: The following treatment combinations were administrated daily to all in 0.05 ml 96% ethanol solution by gastric gavage. (1) Sham operation (2) OVX rats (3) OVX rats [0.02 mg/kg/day of 17beta-estradiol (E2) and 0.01 mg/kg/day of norethisterone acetate] (4) OVX rats [E2 (0.01 mg/kg/day) and drospirenon (0.02 mg/kg/day)]. Estrogen levels were determined using routine clinical-chemistry methods. We also measured protein oxidation parameters such as protein carbonyl (PCO), total thiol (T-SH) and the other oxidative stress markers malondialdehyde (MDA) and glutathione (GSH). RESULTS: Ovariectomy resulted in abnormal elevation of plasma and tissue oxidative stress markers and changes in redox status of the proteins in tissue dependent manner. Supplementation of various estrogens combinations partially alleviated these abnormalities and restored redox homeostasis of proteins after the ovariectomy. Among the studied protein oxidation parameters, plasma and tissue PCO levels of the OVX rats were higher than those of the control groups (P < 0.01). Hormone replacement therapies (HRT) caused a decrease in PCO and MDA in both plasma and tissue of the OVX rats (P < 0.01). HRT in OVX rats decreased plasma MDA and increased liver and brain GSH (P < 0.01). Liver MDA levels of the Drospirenon-treated rats were lower than in the norethisterone acetate group (P < 0.01). On the other hand, Drospirenon increases brain GSH s more effectively than norethisterone acetate (P < 0.01). After bilateral oopherectomy, plasma and tissue T-SH levels decreased in the OVX group compared with control (P < 0.01). Norethisterone acetate increased plasma T-SH more effectively than Drospirenon (P < 0.05) CONCLUSIONS: The study showed the extent of oxidative protein damage (OPD) in this model of estrogen deficiency. The protective effect of estrogens against tissue specific OPD suggests that estrogens play an important role within the antioxidant defense systems in plasma, liver and brain. The exact molecular mechanisms leading to these findings are not yet completely known. Meanwhile, hormone replacement therapy for the prevention of OPD in a tissue specific manner may be required.

Vitamin E protects against the development of radiation-induced pulmonary fibrosis in rats.

AIMS: To investigate whether the application of vitamin E with or without pentoxifylline could modify the development of radiation-induced pulmonary fibrosis. MATERIALS AND METHODS: Wistar albino rats were supplemented with either vitamin E or pentoxifylline or with both vitamin E and pentoxifylline after a single dose of 14 Gy thoracic irradiation. Supplementation was started the day after irradiation and continued until the rats were sacrificed. As a quantitative end point, the extent of fibrosis was evaluated with a scale from 0 (normal lung) to 8 (total fibrous obliteration of the field) at pathological examination of the lung tissue. RESULTS: A significant reduction in fibrosis was obtained in the group of rats supplemented with vitamin E with or without pentoxifylline, when compared with the group that had irradiation only. CONCLUSION: This experimental study showed that vitamin E supplementation immediately after irradiation protected rats against radiation-induced pulmonary fibrosis. The combination with pentoxifylline was more effective, although pentoxifylline itself had limited efficacy, which was not statistically significant.

Aromatase inhibitors decrease radiation-induced lung fibrosis: Results of an experimental study.

PURPOSE: In experimental and clinical trials, tamoxifen (TAM) has been shown to increase radiation-induced lung fibrosis (RILF). Furthermore, aromatase inhibitors (AI) have been shown to be superior to TAM in the adjuvant setting and preclinical data suggest that letrozole (LET) sensitizes breast cancer cells to ionizing radiation in other studies. In this experimental study, we evaluated whether AI have any impact on the development of RILF in rats. MATERIALS AND METHODS: 60 female wistar- albino rats were divided into 6 groups: Control (group A), RT alone (group B), RT + TAM (group C), RT + anastrozole (ANA group D), RT + LET (group E), and RT + exemestane (EXE, group F). RT consisted of 30 Gy in 10 fractions to both lungs with an anterior field at 2 cm depth. Equivalent doses for 60 kg adult dose per day of TAM, ANA, LET, and EXE were calculated according to the mean weight of rats and orally administrated with a feeding tube. Percentage of lung with fibrosis was quantified with image analysis of histological sections of the lung. The mean score values were calculated for each group. the significance of the differences among groups were calculated using one way ANOVA test and Tukey HSD post-hoc test. RESULTS: Mean values of fibrosis were 1.7, 5.9, 6.7, 2.5, 2 and 2.2 for groups A, B, C, D, E, and F, respectively (p = 0.000). TAM increased RT-induced lung fibrosis but without statistical significance. Groups treated with RT + AI showed significantly less lung fibrosis than groups treated with RT alone or RT + TAM (p = 0.000). RT + AI groups showed nearly similar RT-induced lung fibrosis than control group. CONCLUSIONS: In this study, we found that AI decreased RT-induced lung fibrosis to the control group level suggesting protective effect.

Does pentoxifylline increase radiation response of Ehrlich mammary carcinoma in mice?

PURPOSE: The presence of hypoxic cells in solid tumors is generally considered as a limiting factor for the complete control of tumors by radiation therapy. Pentoxifylline is a methylxanthine derivative that produces hemorrheologic effects which increase tissue oxygen levels. In this study we aimed to determine whether pentoxifylline would enhance the radiation response of Ehlrich mammary carcinoma in mice. MATERIALS AND METHODS: Ehrlich mammary carcinoma cells were subcutaneously transplanted into the nape of 27 male Balb/c mice. Twelve animals were injected with 50 mg/kg of pentoxifylline intraperitoneally (i.p.) and irradiated 30 min after the administration (study group). Fifteen mice were irradiated without receiving pentoxifylline (control group). All animals were exposed to a single dose of 40 Gy with Co60 gamma rays locally to the tumor site. The effect of pentoxifylline was assessed by the reduxtion rate in tumor volume (mm(3)) which was measured at least 3 times a week until mice were dead. RESULTS: The reduxtion rate of tumor volume on day 4, relative to the initial volume, was 42% in the control group and 61.6% in the study group (p=0.24). The survival of mice in the two groups was not significantly different (p=0.08). CONCLUSION: Although the reduction rate of tumor volume was higher in the study group, the difference was not statistically significant. Pentoxifylline can not be considered as a radiation enhancer in Ehrlich mammary carcinoma.

Protective covering of surgical wounds with honey impedes tumor implantation.

HYPOTHESIS: Tumor implantation (TI) development at the surgical wound following cancer surgery is still an unresolved concern. Trocar site recurrence, which is likely a form of TI, has become one of the most controversial topics and, with the widespread acceptance of laparoscopic surgery, has caused renewed interest in questions about TI. Honey has positive effects on wound healing. Physiological and chemical properties of honey might prevent TI when applied locally. DESIGN, INTERVENTIONS, AND MAIN OUTCOME MEASURES: Sixty BALB/c strain mice, divided into 2 groups, were wounded in the posterior neck area. Group 1 mice formed the control group, and group 2 mice had wounds coated with honey before and after tumor inoculation. All wounds were inoculated with transplantable Ehrlich ascites tumor. The presence of TI was confirmed in the wounded area by histopathological examination on the 10th day. RESULTS: Tumor implantation was achieved in all group 1 animals and verified by palpable mass and histopathological examination. In group 2 mice, although TI could not be detected macroscopically, it was revealed by pathological examination in 8 cases. Tumor implantation was less likely in group 2 mice (8 of 30 vs 30 of 30; P<.001). CONCLUSIONS: Tumor implantation was markedly decreased by the application of honey pre- and postoperatively. It is possible that the physiological and chemical properties of honey protected wounds against TI. Honey could be used as a wound barrier against TI during pneumoperitoneum in laparoscopic oncological surgery and in other fields of oncological surgery.

The effects of calcium channel blockers, verapamil, nifedipine and diltiazem, on metabolic control in diabetic rats.

The effects of calcium channel blockers (CCB)-verapamil, nifedipine, diltiazem on metabolic control in streptozotocin-induced long-term diabetes in rats were investigated. Diabetes mellitus was induced by single intravenous injection of streptozotocin (65 mg/kg body wt.). The animals were divided into five groups: a healthy control group, a diabetic group and three diabetic groups treated with one of the calcium channel blockers (verapamil, 25 mg/kg/day, nifedipine, 20 mg/kg/day, and diltiazem, 30 mg/kg/day, respectively). Body weight, glycemia, glycated hemoglobin and total serum protein levels of these animals were measured at the beginning and at the end (after 13 weeks) of the experiment. It was observed that diabetic animals who were not treated with CCB had lost weight at the end of the experiment (P < 0.01). The blood glucose and glycated hemoglobin levels were increased in the diabetic group in comparison to the healthy control group (P < 0.001). However, the calcium channel blockers seem to have beneficial effects on body weight, glycated hemoglobin and blood glucose levels.

Vascularization pattern of C6 glioma is modified with medroxyprogesterone acetate and ibuprofen in Wistar rat brain.

Beneficial effects of medroxyprogesterone acetate (MPA) in cancer therapy is partly mediated via its antiangiogenic activity. The same is true for the antitumoral action of non-steroidal antiinflammatory drugs. We have studied two liposoluble drugs, MPA and the analgesic ibuprofen, on glioma vascularization in vivo. In this study we have shown that, until the sacrifice at 27. day after tumor inoculation in the right hemisphere, MPA had a slight though insignificant activity to reduce the fatality of C6 glioma, growing in right cerebral hemisphere of male Wistar rats. But ibuprofen both alone or with MPA had no effect on survival with gavage application of a 30 mg/kg/day dosing regime. On histological analysis, intra- and peritumoral vessels were counted. Progesterone seemed to lower intratumoral, but to increase peritumoral vessels, especially glomeruloids, around the tumor mass. Coadministration of ibuprofen acted to suppress the peritumoral vessel increase, and to enhance lymphomonocytic infiltration around tumor vessels.

Vigabatrin has an anxiolytic effect in the elevated plus-maze test of anxiety.

tau-Vinyl GABA (vigabatrin, GVG) is a novel antiepileptic drug that irreversibly inhibits GABA transaminase and elevates GABA levels in all parts of the brain. In the present study, we investigated the anxiolytic and behavioral effects of GVG in the elevated plus-maze and the hole board compared to diazepam. Doses of 500 and 1,000 mg/kg GVG were injected IP to different groups of male Wistar rats and animals were tested either 4 or 24 h after injection. Animals administered diazepam (1.5 mg/kg, IP) and saline (1 ml) were tested 20 min after injection. GVG and diazepam were found to decrease significantly the number of squares visited and rearing; both had a suppressant effect on locomotor activity. Neither drug had an effect on exploration (head dipping). GVG at a dose of 1,000 mg/kg was shown to have a similar anxiolytic activity either after 4 or 24 h as diazepam, while GVG at 500 mg/kg did not show any significant anxiolytic effect.

Oxidative protein damage parameters in plasma in chronic experimental diabetes in rats.

An increase in oxidative stress may contribute to the development of oxidative protein damage (OPD) in the streptozotocin-diabetic rat. To show the effect of hyperglycemia in promoting OPD, we determined protein carbonyl (PCO), nitrotyrosine (NT), total thiol (T-SH) and advanced oxidation protein product (AOPP) levels as markers of OPD, and lipid hydroperoxide (LHP) levels as a marker of lipid peroxidation in plasma of acute and chronic diabetic male Sprague-Dawley rats and their controls. The levels of the studied markers, except NT, were determined by colorimetric methods. NT levels were measured by ELISA. Plasma PCO and AOPP levels of chronic diabetic rats were increased significantly compared with those of both acute diabetic rats and the controls. Plasma NT levels of the three groups were not different. Plasma T-SH levels of acute diabetics were increased significantly compared with those of the controls while T-SH increase in the chronic diabetics was not significant. Plasma LHP levels were increased significantly in the chronic diabetic rats compared with those of the controls. The increase in plasma PCO, AOPP, LHP levels in chronic but not in acute diabetic rats may be indicating that persistence of hyperglycemia is involved in the evolution of OPD while plasma NT levels do not seem to reflect OPD in diabetes.

Selenium-induced activation of brain Na(+)-K(+)-ATPase in rats.

The influence of selenium supplementation on the activity of Na(+)-K(+)-ATPase and on the degree of free radical generation was studied in brain tissue of rats. Selenium was administered for 5 months in drinking water, and was measured in plasma by the fluorometric method at the end of the experimental period. Animals were sacrificed and brain tissue homogenates were used for enzyme assay and for assessment of lipid peroxide formation. Brain tissue from rats who received selenium showed significantly increased Na(+)-K(+)- ATPase activity but also significantly decreased lipid peroxide farmation. Since this enzyme is known to be inhibited by oxygen free radicals, selenium supplementation appears to exert a beneficial effect on the Na(+)-K(+)-ATPase activity by preventing free radical-induced damage.

Suppression of atherogenesis by n-3 fatty acids in the cholesterol-fed rabbit.

The effects of n-3 fatty-acid supplementation on serum lipids, platelet aggregation, and the development of atherosclerotic lesions were studied in the cholesterol-fed rabbit. Serum total cholesterol and LDL cholesterol values were significantly reduced in comparison with those of the nonsupplemented cholesterol-fed group (p less than 0.005, p less than 0.0025, respectively), though still higher than those of the control group (p less than 0.0025, p less than 0.0125 respectively). Platelet aggregation was reduced below that of the cholesterol-fed and the control levels (p less than 0.0005, p less than 0.0025, respectively). The endothelial injury encountered in cholesterol-fed rabbits was inhibited in the supplemented group. It is concluded that n-3 fatty acids suppress atherogenesis in this animal model by interfering with platelet aggregation and lipid metabolism.

Biocompatibility and immunology in the encapsulation of islets of Langerhans (bioartificial pancreas).

Successful transplantation of encapsulated islets (bioartificial pancreas) would circumvent problems of islet availability and rejection in the treatment of insulin-dependent diabetes with biological organ replacement. Alginates are widely used as a hydrogel matrix or membrane for immunoprotected transplantation. A major problem in the use of diffusion-based devices is the biocompatibility of the material used. The foreign body reaction after implantation of empty microcapsules into different compartments in rats, dogs and pigs is evaluated in this article. However, biocompatibility of the bioartificial pancreas has three different aspects: reaction of the entrapped islet to the encapsulation technique and material; reaction of the recipient against the incorporated device ( = foreign body reaction); and finally the reaction of the recipient against the encapsulated islet ( = immunology of bioartificial pancreas). It is obvious from different experiments that even if foreign body reactions (reactions against material) are almost abolished the recipient may react against material released from the encapsulated islet. In conclusion, transplantation of encapsulated islets induces various morphological reactions (i.e. inflammation and fibrosis) as a result of a variety of donor and recipient related factors. Therefore, the use of an adequate animal model that reflects the human situation is essential for progress in the development of a bioartificial pancreas.

Influence of eicosapentaenoic acid and vitamin E on hepatic hydroxyproline content in rabbits fed cholesterol-rich diet.

The effect of eicosapentaenoic acid (EPA) and vitamin E on hepatic hydroxyproline content, as an index of collagen was examined in rabbits receiving cholesterol rich diets for a period of 45 days. Rabbits were divided as control (A) and cholesterol fed groups (B, C, D). Group C received 80 mg. of EPA and group D received 100 IU of vitamin E daily in addition to the cholesterol rich diet (2% w/w) which was solely given to group B. The maintenance of rabbits on high cholesterol diets resulted in significantly increased liver cholesterol concentrations. This effect was most pronounced in rabbits receiving cholesterol alone. Hepatic triglyceride levels remained unchanged in all cholesterol-fed rabbits, but total phospholipid levels in liver significantly decreased in EPA and vitamin E supplemented rabbits. An interesting finding was the increase in hepatic hydroxyproline content in rabbits following the administration of EPA and vitamin E to cholesterol rich diet.

Influence of eicosapentaenoic acid and vitamin E on brain cortex Ca2+ ATPase activity in cholesterol-fed rabbits.

The influence of eicosapentaenoic acid (EPA) and vitamin E on brain cortex Ca2+ ATPase activity was examined in rabbits receiving cholesterol-rich diets for a period of 45 days. Rabbits were divided as control (A) and cholesterol-fed groups (B, C, and D). Group C received 80 mg of EPA and group D received 100 IU of vitamin E every day in addition to the cholesterol-rich (2%, w/w) diet which was solely given to Group B. Rabbits receiving cholesterol alone had a significant reduction in brain microsomal phospholipid level. Microsomal free cholesterol and polyunsaturated fatty acids (PUFA) were significantly increased in all experimental groups. Cortex microsomal Ca2+ ATPase activity was found to be inhibited in all cholesterol-fed rabbits as compared to controls, but the highest inhibition was seen in rabbits fed cholesterol alone. Additions of EPA or Vitamin E to the cholesterol-rich diets resulted in a recovery of the enzymatic activity. It is concluded that cholesterol feeding without any addition of PUFA or antioxidant agent might cause an inhibition of brain Ca2+ ATPase activity in rabbits, thereby leading to the dysfunction in ion transport and neurotransmitter release.

Intra-articular injection of tenoxicam in rats: assessment of the local effects on the articular cartilage and synovium.

This study investigated the possible local adverse effects of intra-articular administration of tenoxicam in the rat knee joint. A total of 50 rats were given 0.25 ml of a standard preparation of tenoxicam by injection into the right knee joint and 0.25 ml of 0.9% saline solution by injection into the left knee joint as a control. Groups of 10 rats were killed 24 h, 48 h, 7 days, 14 days and 21 days after tenoxicam administration. Two rats were sham operated; one was killed on the first day and the other on the second day after this procedure. All the joints were prepared and sectioned for histological examination. Tissue loss and oedema were observed in the specimens obtained 24 h and 48 h after treatment with tenoxicam. No pathological changes were observed in the 7-day, 14-day and 21-day specimens, or in the control joints. Caution should be exercised when using intra-articular tenoxicam for post-operative analgesia.

Maternal cocaine abuse resulting in necrotizing enterocolitis--an experimental study in a rat model.

The aim of this study was to assess the relation between the use of cocaine during pregnancy and development of necrotizing enterocolitis in a rat model. Different doses of cocaine HCl were given to pregnant Wistar Albino rats during gestation. Total number of live births, mean birth weight, mean placental weight and histopathological examination of the maternal uterus, placenta, embryonal G-I tract and liver were investigated. These results were compared with a control group and showed that the number of live births, mean birth weight and mean placental weight were lower than in non-cocaine controls. Histopathologic examinations revealed severe inflammation and vascular changes in the uterus and placenta. We also observed focal necrosis, necrobiosis, cellular debris, haemorrhage, inflammatory reactions in the G-I tract of embryos. These findings indicate that maternal cocaine abuse should probably be considered a major risk factor for development of NEC in baby rats and embryos.

[Inverted papilloma. Apropos of a multicentric case]. / Le papillome inversé. A propos d'un cas multicentrique.

Inverted papilloma is a benign, neoplastic condition of the sinusonasal cavity, independent from other polypoid lesions of the same area. Our case, presented below is, we believe, unique in that it lends credit to the possible multicentric origin of the disease; which started in the right nasal fossa, followed by the left and then the right tympanic cavities in that order.

The impact of trastuzumab on radiation-induced pulmonary fibrosis: results of an experimental study.

There are no data regarding the late toxicity of trastuzumab (T) administration with radiotherapy (RT). In this experimental study, we aimed to asses if concurrent or sequential administration of T has any impact for the development of radiation-induced pulmonary fibrosis in rats. Fifty-four female Wistar-albino rats were divided into 6 groups. First group of rats (Group 1; concurrent T) had irradiation to whole thoracic region concurrently with T. Second group (Group 2: sequential T-RT) received thoracic irradiation, 1 week after T. Third group (Group 3: sequential RT-T) had thoracic irradiation first and they had T injection 1 week after RT. Fourth group (Group 4: T only) had only T application. Fifth group (Group 5: RT) had only RT. The last group (Group 6: sham) of rats were observed without any application. A single dose of 12 Gy was given to both lungs with an anterior field at 2 cm depth. T dose which was equivalent to 6 mg/kg adult dose was calculated for each rat, and injected by the tail vein. As an end point the extent of pulmonary fibrosis for each field was graded on a scale from 0 (normal lung or minimal fibrous thickening) to 4 (total fibrous obliteration of the field) at histopathological examination. The mean value of fibrosis scores were 1.44, 1.77, 1.75 and 1.62 for Group 1, 2, 3 and 5, respectively, without any statistically significant differences among them (P>0.05). The mean value of fibrosis scores for Group 4 and 6 were 0.25 and 0.33, respectively (P>0.05). When the mean value of fibrosis scores of the groups which had RT with or without T, compared with the observation and the T only groups, the difference was significant (P<0.05) (one-way ANOVA and Tukey HSD post hoc tests) As a conclusion: addition of T to thoracic irradiation either sequentially or concomitantly did not increase radiation-induced pulmonary fibrosis in rats.