Oral carcinogenesis is not achieved in different carcinogen-treated PAI-1 transgenic and wild-type mouse models.

AIM: In an effort to assess the role of plasminogen activator inhibitor-1 (PAI-1) in oral squamous cancer development and progression, two different carcinogen treatment protocols were conducted. MATERIALS AND METHODS: Protocol I included mice from a PAI-1 transgenic (Tg) breed (n=56) and their wild-type (WT) counterparts (n=56), divided into one control group and two main experimental groups, treated with 7,12-dimethylbenz[a]anthracene (DMBA) for 8 and 16 weeks, respectively. Protocol II included the same number and types of animals and groups, which were similarly treated with 4-Nitroquinoline 1-oxide (4-NQO) in drinking water. Two drugs that affect plasma PAI-1 levels, enalapril and pravastatin, were administered to certain subgroups of animals in both protocols. RESULTS: None of the animals developed macroscopically-visible oral cancer lesions. Eleven animals under Protocol I and 52 animals under Protocol II died. Skin lesions were noted only in DMBA-treated animals (n=9). Almost all animals administered with 4-NQO developed alopecia and lost weight, while two of them developed stomach tumours, and one female mouse developed a large ovarian cyst. CONCLUSION: Transgenic mice may respond differently when used in well-established carcinogen models and oral carcinogenesis is hard to achieve in these rodents.

A diet rich in monounsaturated fatty acids improves the lipid profile of mice previously on a diet rich in saturated fatty acids.

This study investigated whether switching from a diet rich in saturated fatty acids (SAFAs) to a diet rich in monounsaturated fatty acids (MUFAs) or to one with equal amounts of MUFAs-SAFAs favorably affects the lipid profile of hypercholesterolemic mice. C57BL/6 mice (n = 82) were allocated into 4 groups. The first group (control, n = 10) was fed standard chow. The 3 remaining groups (n = 24 mice/group) were fed a SAFA-rich diet for 8 weeks and were then allocated for 16 weeks to either a MUFA-rich diet, an equal in MUFAs-SAFAs-rich diet, or continued the previous SAFA-rich diet. After 8 weeks, mice consuming SAFA-rich diet had increased weight, total cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C) levels (P < .05 vs baseline). At week 24, MUFA-rich and MUFA-SAFA rich diets decreased TC and low-density lipoprotein cholesterol (LDL-C) levels (P < .05) compared with week 8. In conclusion, switching to MUFA-rich diets or substituting half of the SAFAs with MUFAs can reverse diet-induced-hypercholesterolemia.

Impact of graded hypothermia on coagulation and fibrinolysis.

BACKGROUND: Hypothermia has a detrimental effect on hemostatic mechanism. The purpose of this experimental study was to investigate the effect of graded hypothermia on markers of the anticoagulant system (antithrombin III and protein C) and fibrinolytic system (plasminogen, α(2)-antiplasmin), and on vascular wall and other tissue specimens. MATERIALS AND METHODS: Ten New Zealand rabbits were subjected to mild and then moderate core hypothermia of 32 °C for 60 min. Blood samples were obtained at normothermic (T(1)), mild (T(2)), and moderate (T(3)) hypothermic conditions. Chromogenic assay methods were used to determine quantitatively (%) the activity of antithrombin III, protein C, plasminogen, and α(2)-antiplasmin. Hypothermic values were compared with the normothermic values. Tissue and vessel wall specimens were examined under light microscope. RESULTS: Reduction of activity (%) from normothermia (T(1)) to mild (T(2)) and moderate (T(3)) hypothermia was found for antithrombin III (103.40 ± 12.54, 87.40 ± 13.50, and 82.70 ± 20.78, respectively, with statistically significant difference between T(1)-T(3): P = 0.03), for protein C (70.1 ± 7.51, 56.30 ± 8.34, and 53.1 ± 7.34, with statistically significant difference between T(1)-T(2) and T(1)-T(3): P = 0.015 for both comparisons) and α(2)-antiplasmin (97 ± 9.63, 80.60 ± 11.73, and 83.70 ± 13.94, with statistically significant difference between T(1)-T(2): P = 0.006). Plasminogen activity was increased (14.50 ± 0.52, 16.30 ± 1.63, and 17.30 ± 2.45, with statistically significant difference between T(1)-T(2) and T(1)-T(3): P = 0.033 for both comparisons). Histologic examination revealed no significant lesions on tissue and vessel wall specimens. CONCLUSIONS: The results of our study suggest that even though the hypothermia period was relatively short, the processes of coagulation and fibrinolysis were altered with simultaneous changes.

Early intestinal morphological changes following benzalkonium chloride treatment in a rat model of short bowel syndrome.

BACKGROUND: The aim of this study was to assess early morphological changes of the residual small intestine 30 days after application of Benzalkonium Chloride (BAC) in a rat model of short bowel syndrome (SBS). MATERIALS AND METHODS: Twenty nine Wistar rats (260 +/- 20 g) underwent 80% midsmall bowel resection with end to end anastomosis. In group 1 (n=14) BAC solution 0.1% was applied to a 2 cm segment of jejunum, and in group 2 (n=15) normal saline was applied in a similar manner and the rats were sacrificed 30 days after operation. Specimens for histological examination were obtained initially and at sacrifice. RESULTS: In the BAC treated jejunal segment (group 1), a statistically significant increase (p< 0.05) was noted in villous height by 33.2%, in crypt depth by 26.4%, in muscle thickness by 26%, 109.6% in intestinal diameter, and 20% in total intestinal length, compared to group 2. CONCLUSIONS: BAC application to the serosal surface of rat's jejunum in SBS is a simple method that within only 4 weeks can topically augment the natural adaptation process noticed following intestinal resection. Further research with a tapering technique performed in sequence is suggested, to prevent possible problems associated with pseudoobstruction in the long term.

Successful treatment with moxifloxacin of experimental aortic valve endocarditis due to methicillin-resistant Staphylococcus aureus (MRSA).

Moxifloxacin (MXF) is an 8-methoxyquinolone with high activity against Gram-positive bacteria. In an experimental model of aortic valve endocarditis (EAVE), the efficacy of MXF was evaluated against a strain of methicillin-resistant Staphylococcus aureus (MRSA). Rabbits with catheter-induced aortic valve vegetations were randomly assigned to a control group or to groups receiving MXF 20 mg/kg intravenous (i.v.) twice a day (bid) or vancomycin (VAN) 30 mg/kg i.v. bid for a total of eight doses (4 days). Rabbits were sacrificed 15 h after the last dose of antibiotics. In another group, treatment with MXF was extended to 5 days and rabbits were sacrificed 5 days after the last dose (10th dose) of MXF in order to detect possible relapses of endocarditis after the end of treatment (test-of-cure (TOC) study). Both MXF and VAN significantly reduced the bacterial load in vegetations (P < 0.001 vs. controls). All animals in the MXF-TOC group had sterile vegetations. MXF given at a dose of 20 mg/kg i.v. bid for 4 days was equally effective as VAN in the treatment of EAVE due to MRSA. When treatment with MXF was extended to 5 days, the cure rate reached 100% and no relapses of endocarditis were observed.

H-ras and c-fos exhibit similar expression patterns during most stages of oral oncogenesis.

BACKGROUND: H-ras and c-fos oncogenes interact in signalling pathways but their level and time course of expression during oral cancer development are unclear. The present study used an animal model for the simultaneous investigation of H-Ras and c-Fos expression in sequential stages of oral oncogenesis. MATERIALS AND METHODS: Three experimental groups of Syrian golden hamsters (A, B and C; 10 animals each) and one control group (7 animals) were used. The buccal pouches of hamsters in groups A, B and C were treated with 0.5% of the carcinogen 9,10-dimethyl-1,2-benzanthracene and were excised at 10, 14 and 19 weeks, respectively. The biopsies, which included tissue stages ranging from normal oral mucosa to moderately differentiated carcinoma, were studied immunohistochemically. RESULTS: A reduction in both H-Ras and c-Fos expression was observed from group A to B and from hyperplasias to early tumour stages, while a simultaneous increase was noted from group B to C and from well-differentiated to moderately-differentiated carcinomas. The H-ras/c-fos expression ratio had a value of approximately (1.09 +/- 0.21) in five out of seven studied tissue stages. CONCLUSION: H-Ras and c-Fos exhibit a similar expression pattern throughout most stages of oral carcinogenesis, an observation supported by the known molecular pathway connecting H-ras signalling with subsequent c-fos gene transcription.

Metastases following biopsy of oral carcinoma in hamsters and the role of local prebiopsy bleomycin.

BACKGROUND: This animal study researches the effect of biopsy on metastasis of oral carcinoma. MATERIALS AND METHODS: Sixty hamsters developed oral tumors after treatment with 9,10-dimethyl-1,2-benzanthracene and were then divided into six groups. Animals of groups 1 and 2 did not receive any treatment, while groups 3-6 were biopsied at the end of the 14th week and groups 5 and 6 also received a prebiopsy intratumoral injection of bleomycin. Animals of groups 1, 3, 5 and 2, 4, 6 were sacrificed at the 17th and 19th week respectively. Specimens of tumors, ipsilateral cervical lymph nodes, lungs and livers were obtained from all animals and histologically examined. RESULTS: All animals developed oral squamous cell carcinomas. In group 4, four out of ten animals showed metastases to the cervical lymph nodes, and one out of four showed a distant metastasis to the lung. CONCLUSION: Delay of treatment following biopsy can increase the risk of cervical lymph node metastases which can be reduced by an intratumoral administration of bleomycin.

Diabetes and oral oncogenesis.

Oral squamous cell carcinoma (OSCC) is the sixth most common malignancy in humans including type I diabetic and normal rats. Tobacco and alcohol, as well as dysregulation of oncogenes and tumor suppressor genes, epigenetic changes and mitochondrial mutations have been implicated in OSCC development. Recent epidemiological studies have incriminated diabetes mellitus as a risk factor for the development of OSCC, as well as oral premalignant lesions. Recently, an animal model was employed to study the influence of diabetes on signal transduction pathways in every stage of oral cancer development, from normal mucosa to hyperplasia, dysplasia, early invasion, well differentiated OSCC and moderately differentiated OSCC. Diabetes was induced by streptozotocin and chemical carcinogenesis was induced by the carcinogen 4-nitroquinoline N-oxide. The expression of EGFR, erbB2, erbB3, FGFR-2, FGFR-3, c-myc, N-ras, ets-1, H-ras, c-fos and c-jun, the tumor suppressor genes p53 and p16, apoptosis markers Bax and Bcl-2, and the cell proliferation marker Ki-67 in the sequential stages of rat oral oncogenesis was investigated. Diabetes seems to promote the activation of the Ras/Raf/MAPK signal transduction pathway mainly by induction of erbB2 and erbB3 receptors, leading to increased cell proliferation, while there was no difference in apoptosis levels during oncogenesis.

The co-expression of c-myc and p53 increases and reaches a plateau early in oral oncogenesis.

BACKGROUND: The balance between cell proliferation and apoptosis plays a significant role in cancer development. The expressions of the p53 and c-myc genes, both strongly related to cell proliferation and apoptosis, were studied in sequential histological grades of oral carcinogenesis in an animal model. MATERIALS AND METHODS: Thirty-seven hamsters were divided into three groups (A,B,C), which were treated with 9,10-dimethyl-1,2-benzanthracene and sacrificed at 10,14 or 19 weeks, respectively, after treatment. The histological status of the oral lesions in the experimental groups corresponded well with tumour advancement (from dysplasia to moderately-differentiated carcinoma). Tumour sections were studied immunohistochemically. RESULTS: The expressions of both p53 and c-myc increased significantly in precancer stages and then reached a plateau. The same pattern was observed in the animal groups with the culmination of expression of both genes in group A. CONCLUSION: The coexpression of p53 and c-myc proteins in the earlier stages of oral oncogenesis may be used for the early detection of premalignant lesions.

Successful moxifloxacin prophylaxis against experimental streptococcal aortic valve endocarditis.

OBJECTIVES: Studies related to the prophylactic efficacy of fluoroquinolones against infective endocarditis are scarce. The aim of this study was to evaluate the efficacy of moxifloxacin, a quinolone active in vitro against Gram-positive cocci, in preventing streptococcal aortic valve endocarditis. METHODS: Non-bacterial thrombotic endocarditis of the aortic valve was induced by the insertion of a polyethylene catheter. Twenty-four hours later, rabbits were randomly assigned to a control group, and groups receiving either two doses of ampicillin (40 mg/kg, intravenously), 2 h apart, or a single dose of moxifloxacin (15 mg/kg, intravenously). Ampicillin and moxifloxacin were administered 0.5 and 1 h, respectively, prior to the intravenous inoculation of 10(7) cfu of Streptococcus oralis. RESULTS: Eighty-nine percent of the control animals developed infected vegetations. In rabbits challenged with this very high inoculum, moxifloxacin and ampicillin prevented endocarditis in 80% (P < 0.001 versus controls) and in 50% (P = 0.022 versus controls) of animals, respectively. The difference between ampicillin and moxifloxacin was not statistically significant (P = 0.128). CONCLUSIONS: Moxifloxacin was at least as effective as ampicillin in preventing streptococcal endocarditis.

Management of carbon tetrachloride-induced acute liver injury in rats by syngeneic hepatocyte transplantation in spleen and peritoneal cavity.

AIM: Acute hepatitis may seldom have a fulminant course. In the treatment of this medical emergency, potential liver support measure must provide immediate and sufficient assistance to the hepatic function. The goal of our study was to study the adequacy of hepatocyte transplantation (HCTx) in two different anatomical sites, splenic parenchyma and peritoneal cavity, in a rat model of reversible acute hepatitis induced by carbon tetrachloride (CCl(4)). METHODS: After CCl(4) intoxication, 84 male Wistar rats used as recipients were divided in to four experimental groups accordingly to their treatment: Group A (n=24): intrasplenic transplantation of 10x10(6) isolated hepatocytes, Group B (n=24): intraperitoneal transplantation of 20x10(6) isolated hepatocytes attached on plastic microcarriers, Group C (n=18): intrasplenic injection of 1 mL normal saline (sham-operated controls), Group D (n=18): intraperitoneal injection of 2.5 mL normal saline (sham-operated controls). Survival, liver function tests (LFT) and histology were studied in all four groups, on d 2,5 and 10 post-HCTx. RESULTS: The ten-day survival (and mean survival) in the 4 groups was 72.2% (8.1+/-3.1), 33.3% (5.4+/-3.4), 0% (3.1+/-1.3) and 33.3% (5.4+/-3.6) in groups A, B, C, D, respectively (P(AB)<0.05, P(AC)<0.05, PBD=NS). In the final survivors, LFT (except alkaline phosphatase) and hepatic histology returned to normal, independently of their previous therapy. Viable hepatocytes were identified within splenic parenchyma (in group A on d 2) and both in the native liver and the fatty tissue of abdominal wall (in group B on d 5). CONCLUSION: A significantly better survival of the intrasplenically transplanted animals has been demonstrated. Intraperitoneal hepatocytes failed to promptly engraft. A different timing between liver injury and intraperitoneal HCTx may give better results and merits further investigation.

Rapid alterations of serum fatty acids with the intravenous administration of an arachidonate solution.

Polyunsaturated fatty acids (PUFAs) have been shown to possess a considerable anti-tumor and anti-bacterial effect in vitro. In an attempt to achieve serum concentrations of these acids similar to those applied in vitro, a solution of ethyl ester of arachidonic acid (AA) was administered intravenously at 25 mg/kg within 10 min in six male rabbits. Blood samples were collected before and 60 min after infusion from catheters inserted in the hepatic veins and in the carotid artery. Analysis of serum fatty acids was performed by gas chromatography mass spectrometry. Elevated concentrations of elongated fatty acids were detected in the hepatic veins after infusion. Mean concentrations of arachidonate in the hepatic veins and the carotid arteries after infusion of AA were 2.77 and 3.73 microM, respectively. It is concluded that the intravenous administration of a solution of AA might result in increased hepatic biosynthesis of serum saturated and unsaturated fatty acids of elongated carbon chains. The increasing interest for the application of PUFAs in therapeutics renders further study mandatory to clarify the significance of these findings.