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I Donta

Publications and source records attributed to I Donta.

15 recordsLinked to original sources
PubMed2006

Diabetes may increase risk for oral cancer through the insulin receptor substrate-1 and focal adhesion kinase pathway.

In light of recent epidemiological studies that associate diabetes mellitus with increased risk for oral cancer, we investigated in diabetic (type I) and normal rats with induced oral squamous cell carcinoma whether the molecular basis for that putative association involves insulin receptor substrate-1 (IRS-1) and focal adhesion kinase (FAK). Fourteen diabetic and 12 normal rats developed cancer after 4-nitroquinoline-N-oxide treatment, while six diabetic and six normal animals were used as controls. Oral sections were studied using monoclonal antibodies against IRS-1 and FAK proteins. Expression of IRS-1 was significantly higher in diabetic than normal rats, but it decreased in diabetic animals with tumor, especially in more advanced stages. FAK expression was significantly higher in rats with cancer in comparison to the ones without it, regardless the diabetes status. These data suggest that the IRS-1/FAK pathway is altered by diabetes resulting in reduced cell adhesion and possibly increasing risk for oral cancer.

Animals↗
PubMed2006

Cell proliferation and apoptosis culminate in early stages of oral oncogenesis.

Markers of cell proliferation (Ki-67 antigen) and apoptosis (Bax, Bcl-2) were studied in an experimental system of induced oral carcinogenesis in Syrian golden hamsters. Thirty-seven animals were divided into one control group and three experimental groups, which were treated with a carcinogen and sacrificed at 10, 14 and 19 weeks after treatment. The histological status of the lesions in the three experimental groups corresponded well with tumour advancement (from oral mucosal dysplasia to moderately differentiated squamous cell carcinoma). Tumour sections were studied using monoclonal antibodies against Bax, Bcl-2 and Ki-67 proteins. Pro-apoptotic Bax expression maintained high levels during all stages of oral carcinogenesis. Anti-apoptotic Bcl-2 expression decreased significantly in dysplastic and early invasion lesions and consequently increased almost to normal tissue level in consequent stages. Finally, Ki-67 expression increased sharply in initial stages of oral carcinogenesis, but significantly decreased in later stages.

Animals↗
PubMed2002

Rapid alterations of serum oxidant and antioxidant status with the intravenous administration of n-6 polyunsaturated fatty acids.

In an attempt to achieve the safe intravenous administration of two n-6 polyunsaturated fatty acids (PUFAs), gamma-linolenic acid (GLA) and arachidonic acid (AA), and to study the subsequent changes on the total oxidant and antioxidant status, various steadily increasing doses of each acid were injected intravenously at different infusion times in 28 male rabbits. Blood samples were collected at 15-min time intervals by the hepatic veins and from the carotid artery; oxidant status was determined by the thiobarbiturate assay and total antioxidant status (TAS) was assessed by a colorimetric assay. Both n-6 PUFAs were administered with safety at a dose of 25 mg/kg within 10 min accompanied by an increase of malonodialdehyde concentrations in the hepatic veins and in the carotid artery 30-45 min, respectively, after the end of the infusion of GLA and/or AA. Similar changes did not occur in red cell membranes after the infusion of AA. TAS presented reciprocal changes to malonodialdehyde production; the main consumption of TAS was observed in all samples 30-60 min after the end of the infusion of n-6 PUFAs. The above-mentioned rapid alterations occurring in both serum oxidant and antioxidant status after GLA might have a future clinical therapeutic significance in conditions like cancer and disseminated infectious diseases.

Animals↗
PubMed2001

Evidence of less severe aortic valve destruction after treatment of experimental staphylococcal endocarditis with vancomycin and dexamethasone.

The beneficial effects of therapy combining an antibiotic and dexamethasone have been reported in human studies on meningitis and in experimental studies on septic arthritis, nephritis, and endophthalmitis. Since most patients with staphylococcal endocarditis need a combination of medical and surgical treatment, the purpose of this study was to determine whether the addition of dexamethasone to vancomycin has any beneficial effect regarding the degree of valve tissue damage or the course of experimental aortic valve endocarditis caused by a methicillin-resistant strain of Staphylococcus aureus. Rabbits with catheter-induced aortic valve vegetations were randomly assigned to a control group and to groups receiving dexamethasone (0.5 mg/kg of body weight, intravenously [i.v.], twice a day [b.i.d]), vancomycin (30 mg/kg, i.v., b.i.d), or dexamethasone plus vancomycin, for a total of 10 doses (two doses per day for 5 days). The severity of valve tissue damage was significantly less in groups receiving vancomycin plus dexamethasone compared with that of the group receiving vancomycin alone (P < 0.001). The severity of tissue damage was inversely correlated with the mean polymorphonuclear leukocyte number in valve tissue. No statistically significant differences were observed between the vancomycin-treated group and the vancomycin-plus-dexamethasone-treated group in survival, blood culture sterilization rate, or reduction of the microbial burden (in CFU per gram) in valvular tissue. In conclusion, treatment with a combination of vancomycin and dexamethasone for 5 days reduces the severity of valve tissue damage in experimental staphylococcal aortic valve endocarditis. These findings could have significant implications in the treatment of staphylococcal endocarditis and deserve further confirmation in clinical trials.

Animals↗
PubMed2000

Single-oral-dose azithromycin prophylaxis against experimental streptococcal or staphylococcal aortic valve endocarditis.

Azithromycin and ampicillin protected 94 and 72% of animals challenged with Streptococcus oralis, respectively (P = 0.177), while azithromycin and vancomycin protected 59 and 94% of the methicillin-resistant Staphylococcus aureus (MRSA)-challenged animals, respectively (P = 0.018). Azithromycin is effective in preventing experimental streptococcal endocarditis, but against MRSA it is less effective than vancomycin.

Administration, Oral↗
PubMed1999

Antioxidant agent nimesulid and beta-blocker metoprolol do not exert protective effects against rat mitochondrial DNA alterations in adriamycin-induced cardiotoxicity.

Possible protective effects of two therapeutical agents (nimesulid and metoprolol) in adriamycin-induced cardiotoxicity were examined in rat cardiomyocytes at the mitochondrial DNA (mt DNA) level. Analysis by PCR revealed the presence of multiple deletions in a large region of the long arc of mt DNA which codes for several important genes involved in oxidative phosphorylation, in all animals under drug administration. No differences were found in the frequency of defective mt DNA between the animals that received only adriamycin (83%, 10/12), nimesulid and adriamycin (92%, 13/14), or metoprolol and adriamycin (80, 12/15) (p = 0.004).

Adrenergic beta-Antagonists↗
PubMed1997

Successful single-dose teicoplanin prophylaxis against experimental streptococcal, enterococcal, and staphylococcal aortic valve endocarditis.

Teicoplanin is a glycopeptide antibiotic that is administered both intramuscularly and intravenously. It has a prolonged half-life and a less toxic profile in comparison to those of vancomycin. The efficacy of a single dose of teicoplanin (18 mg/kg of body weight given intramuscularly) for the prevention of endocarditis due to Streptococcus oralis, Enterococcus faecium, and methicillin-resistant Staphylococcus aureus (MRSA) was evaluated after applying the rabbit model. Vancomycin at a single dose of 30 mg/kg given intravenously was used as the comparative agent for the prevention of endocarditis due to MRSA and E. faecium, while ampicillin at a single dose of 40 mg/kg given intravenously was used as the comparative agent for the prevention of endocarditis due to S. oralis. Rabbits in the teicoplanin group were infected at 1 h postdosing with approximately 10(7) CFU of each strain. Rabbits in the other groups were infected at 0.5 h postdosing with approximately 10(7) CFU of S. oralis (ampicillin group) or E. faecium and MRSA (vancomycin group). All rabbits were sacrificed 5 days later. Teicoplanin and vancomycin protected the animals challenged with E. faecium by 87.5 and 50%, respectively, and protected the animals challenged with MRSA by 100 and 92%, respectively. Teicoplanin and ampicillin protected the animals challenged with S. oralis by 100 and 77%, respectively. Prevention of endocarditis by teicoplanin was likely to be due to a prolonged inhibition of bacterial growth by the sustained supra-MICs. It is concluded that teicoplanin is very effective in preventing experimental streptococcal, enterococcal, and staphylococcal endocarditis and may be an attractive alternative antibiotic in patients allergic to beta-lactams, especially in the outpatient setting.

Animals↗
PubMed1995

Vancomycin or vancomycin plus netilmicin for methicillin- and gentamicin-resistant Staphylococcus aureus aortic valve experimental endocarditis.

Using a rabbit model of aortic valve endocarditis, we studied the efficacy of vancomycin alone or in combination with netilmicin and/or rifampin against a methicillin- and gentamicin-resistant strain of Staphylococcus aureus (MGRSA). Antibiotics were given for 6 to 12 days, as follows: vancomycin (15 mg/kg of body weight every 12 h [BID] intravenously), vancomycin plus netilmicin (2.5 mg/kg BID intramuscularly), vancomycin plus rifampin (10 mg/kg BID intramuscularly), and vancomycin plus netilmicin plus rifampin at the same routes, dosages, and schedules mentioned above. Netilmicin was given to two additional groups at a higher dosage (6 mg/kg every 24 h intramuscularly) alone or in combination with vancomycin (15 mg/kg BID intravenously) for 12 days. All regimens resulted in undetectable bacterial counts in a significant proportion of vegetations (except netilmicin alone) or reduced the bacterial counts in the vegetations compared with the counts in the untreated controls (P<0.01 to P<0.001). No resistance to rifampin or netilmicin developed during therapy. It is concluded that in the treatment of experimental aortic valve endocarditis caused by MGRSA (i) vancomycin as monotherapy is as efficacious as the triple combination, (ii) the addition of netilmicin (once daily or BID) to vancomycin does not improve the efficacy of the latter antibiotic, even in the presence of rifampin, and (iii) a 12-day course in more effective than a 6-day one, but not at a statistically significant level.

Animals↗
PubMed1993

Efficacy of ceftazidime and aztreonam alone or in combination with amikacin in experimental left-sided Pseudomonas aeruginosa endocarditis.

The in vivo efficacies of ceftazidime, aztreonam, and the combinations of ceftazidime with amikacin and aztreonam with amikacin were studied in the rabbit left-sided endocarditis model by using two strains of Pseudomonas aeruginosa, one multisusceptible and one multiresistant, in a total of 156 animals. Antibiotics were given intramuscularly for 10 days, as follows: amikacin, 7 mg/kg of body weight every 8 h, and ceftazidime and aztreonam, 50 mg/kg every 8 h. All regimens except amikacin alone significantly reduced the number of CFU per gram of vegetation (P < or = 0.008), but only for the multisusceptible strain for which sterile vegetations were obtained in 20, 25, 21, 75, and 53% of the groups treated with amikacin, ceftazidime, aztreonam, and the combination groups ceftazidime-amikacin and aztreonam-amikacin, respectively (ceftazidime plus amikacin versus controls, P = 0.001). Regarding the decrease in the numbers of colonies in vegetations, (i) all regimens significantly reduced the number of CFU per gram of vegetation (P < 0.001), (ii) results with ceftazidime-amikacin compared with those with monotherapy were significantly different (P < or = 0.007), and (iii) results with aztreonam-amikacin, although better than those with monotherapy, were marginally not statistically significant. At 1 h postdose, mean amikacin, aztreonam, and ceftazidime levels in serum were 35 +/- 19.4, 89.6 +/- 8.16, and 92.61 +/- 11.52 micrograms/ml, respectively. It was concluded that the combination of ceftazidime, and possibly aztreonam, with amikacin given at high doses and short intervals could have a place in the therapy of patients with left-sided endocarditis caused by P. aeruginosa.

Amikacin↗
PubMed1982

Effect of beta-adrenergic blockade on physiologic growth in the Wistar rat.

The effect of propranolol (Pr) on body weight was studied in 144 Wistar rats of both sexes from weaning to 17 weeks of age. Pr was administered to 77 of these rats (chosen at random), in a dose of 100 mg/kg body weight daily. Body weights were monitored every third day throughout the study. During their 17th week of age, all the rats were weighed for the last time and then sacrificed. The following organs were carefully dissected and weighed: brain, thymus, lungs, heart, liver, kidneys, adrenals, testes and ovaries. Gain in body weight was significantly reduced in the propranolol treated animals compared to control in both sexes. Organ weights were also less in propranolol-treated rats except for the kidneys of both sexes and the heart and testes of the males. However, the ratio of most organ weights per body weight was greater, indicating that the inhibition of weight gain was less severe in those organs compared to that of total body weight.

Adrenergic beta-Antagonists↗
PubMed1982

[Changes in tissue enzymes during "in situ" renal ischemia with or without protection of the kidneys].

Three methods of preservation of the in situ temporarily ischaemic kidney were compared in dogs. The study was carried out in 24 dogs, divided in 4 groups. Each group included 4 dogs in which the ischaemic time was 60 minutes, and 3 dogs in which the ischaemic time was 90 minutes. The experimental animals of the first group served as controls (warm ischaemia); in the second group renal hypothermia was accomplished by an arterial infusion of Collins' solution at 4 degrees C; in the third group preservation of the kidney was attempted only by an arterial infusion of inosine (90-120 mg/kg); finally in the fourth group, the infusion of Collins' solution was combined with infusion of inosine (800-1 000 mg/l Collins' solution). The assessment of the damage of the ischaemic kidney was made by histo-enzymological analysis of renal tissue specimens received from each animal just before initiation of the ischaemia and on the 21st post-operative days. The enzymes examined in this analysis were: Alkaline Phosphatase, ATP-ase, Glutamate Dehydrogenase, Glucose-6-phosphatase, Hydroxybutyrate Dehydrogenase and gamma-GT. These studies have shown that the ischaemic kidney is best preserved by the arterial infusion of Collins' solution with simultaneous infusion of inosine.

Adenosine Triphosphatases↗
PubMedDate not supplied

Pharmacokinetics of calcium dobesilate in beagle dogs after a single administration.

A pharmacokinetic study was carried out in beagle dogs after a single intravenous infusion of 100 mg/kg of calcium dobesilate, a dose claimed to produce a cardiac lymphagogue effect. This effect on cardiac lymphatics is known to contribute to the reduction of myocardial infarct size after coronary artery occlusion. At the end of the intravenous infusion, which lasted about 30 minutes, the plasma level was 263 +/- 68 micrograms/ml, falling to 56 +/- 23 micrograms/ml by the third hour. This high plasma level of calcium dobesilate between the end of the infusion and the 3rd hour might explain the pharmacological effect of the drug on the cardiac lymphatic system.

Animals↗
PubMedDate not supplied

Pharmacokinetics of calcium dobesilate in beagle dogs after repeated administration.

Many pharmacological findings suggest that repeated intravenous administration of calcium dobesilate improves myocardial lymphatic drainage, accelerates removal of degradation products and other toxic substances by increasing the number of functioning lymphatics and thus limits infarct size after experimental coronary artery occlusion. The aim of the present study was to investigate the relationship between the blood levels of calcium dobesilate and the pharmacological effect described above using the same dosage schedule. During the first six hours after intravenous administrations, at one hour interval, of three doses each of 100 mg/kg of calcium dobesilate, the average plasma level ranged from 414 micrograms/ml to 95 micrograms/ml with a plateau between the second and fourth hour. During this period, which is the most crucial for the ischemic myocardium, the effect of calcium dobesilate attained its optimum as evidenced by a statistically significant increase in the number of lymphatics visualized by lymphangiography and the reduction of infarct size measured by planimetry, by weight or by tomography. The plasma levels before the 18th hour were still higher than 10 micrograms/ml but no measurable calcium dobesilate was detected in the plasma at the 20th hour which indicates total elimination of the drug from the blood and thus precluding any risk of accumulation. The present results confirm that the doses of calcium dobesilate used in the pharmacological studies correspond to an adequate blood level.

Animals↗
PubMedDate not supplied

The influence of hemodilution on left ventricular function.

In nine anesthetized mongrel dogs anemia was produced by exchanging blood with plasma substitute thus reducing hemoglobin gradually in three steps. Aortic, atrial and ventricular blood pressures, cardiac output, electrocardiogram, phonocardiogram and the first derivative of the left ventricular pressure were continuously monitored. Blood samples were taken to determine hemoglobin, blood gases and whole blood viscosity. Progressive hemodilution resulted in a significant increase in cardiac output and left ventricular stroke work, while total peripheral resistance, oxygen content and whole blood viscosity decreased significantly. There were no significant changes in cardiac pressures, myocardial contractility, diastolic pressure time index and blood gases. The oxygen supply/demand ratio had gradually declined, while electrocardiogram showed no significant changes. These results suggest that moderate isovolemic hemodilution in animals with normal coronary vessels does not impair left ventricular function as this was manifested by the unchanged hemodynamic and electrocardiographic findings.

Animals↗