Topiramate promotes neurological recovery in a new model of traumatic brain injury in rats.

The aim of this study is to investigate the neuroprotective effects of the anticonvulsant topiramate in a new model of traumatic brain injury in rats. A new model of traumatic brain injury, based on the weight-drop technique, was developed for the purpose of this study. Seventy-five male Wistar rats weighing 320-470 g were studied. All rats were anesthetized, subsequently submitted to a round craniectomy in the left parietal region and a weight of 50 g was used for the production of a cortical contusion. In study I, 44 rats were randomized in three groups to receive either topiramate 40 mg/kg (n=13), topiramate 60 mg/kg (n=14), or water for injection (n=17) i.p. 30 min after the injury and every 12 h thereafter for 3 days. The rats were tested clinically 24 h, 72 h, 10 days and 20 days after the injury. On day 21 the animals were sacrificed and the brains were removed and prepared for histopathological analysis. In study II, 19 rats were randomized to receive either topiramate 60 mg/kg (n=10) or water for injection (n=9) i.p. 30 min after the injury and every 12 h (four doses in total). 48 h after the injury the animals were sacrificed and the brains were rapidly removed and analyzed for water content with the dry-wet weight technique. The animals that received topiramate performed significantly better in neurological tests compared to the animals that received vehicle ten (P<0.05) and 20 (P<0.001) days after the injury. There was no difference between the high and the low dose of the drug. Topiramate had no effect on the anatomic volume of the lesion. The animals that received topiramate had a tendency to present with less cerebral edema formation, but the difference was not statistically significant (P>0.05). These findings suggest that topiramate promotes neurological recovery in rats after traumatic brain injury without affecting the final size of the traumatic lesion and that it might play a role in the reduction of post-traumatic cerebral edema.

Efficacy of teicoplanin, administered in two different regimens, in the treatment of experimental endocarditis due to Enterococcus faecalis.

Using a rabbit model of endocarditis, we studied the efficacy of teicoplanin against a strain of Enterococcus faecalis resistant to ampicillin. Rabbits were randomly assigned to receive no antibiotics, teicoplanin 12 or 18 mg/kg of body weight every 12h, for 9 days. The effect of treatment on bacterial counts of vegetations and survival of the animals was evaluated at the end of treatment and 10 days thereafter. The two treatment regimens of teicoplanin produced peak serum levels 18.51+/-1.84 and 34.66+/-4.19 microg/ml, and trough levels above 10 x MIC of teicoplanin for the infecting organism. Both regimens resulted in significant bacterial reduction in the vegetations as compared to the control group (p<0.001). The drug prevented relapse of the infection 10 days after discontinuation of treatment. By increasing the teicoplanin dosage no additional therapeutic benefit was observed in terms of bacterial killing, sterilization of the vegetations, and survival of the animals, although the higher doses gave numerically superior results. These findings may have meaning for the optimum use of teicoplanin in the treatment of enterococcal endocarditis.

The effects of enalapril on p53 expression in left ventricular cardiomyocytes after aortic stenosis.

ACE-inhibitors prevent the development of left ventricular hypertrophy (LVH). The tumor suppressor gene p53 up-regulates the cellular renin-angiotensin system, resulting in ANG II synthesis, which activates p53 creating a positive feedback loop. One hundred and fourteen rabbits were separated into groups A (control), B (sham-operated), C and D. In groups C and D, an aortic stenosis was performed, and in group D the animals were treated with enalapril. For p53 determination, LV specimens were examined by Western blot analysis and an immunohistochemical study was performed, except for samples from group D. In conclusion, LVH was significantly induced at 7 and 28 days after aortic stenosis with no difference between the two periods, while enalapril prevented hypertrophy in these two groups. p53 was transcriptionally activated and immunoreactively present after acute pressure overload as well as in the sham-operated group. Enalapril decreased the p53 expression at 180 min, 7 and 28 days following aortic stenosis.

Expression of PDGF-A, TGFb and VCAM-1 during the developmental stages of experimental atherosclerosis.

PURPOSE: A considerable number of growth factors, cytokines, and adhesion molecules are implicated in the development of atherosclerotic lesions. These molecules interact in a complex network influencing the evolution of several processes, such as lipid metabolism, cellular proliferation and tissue repair. The aim of this study was to evaluate the expression of the growth factors PDGF-A, and TGFb, and the adhesion molecule VCAM-1 in the sequential steps of experimental atherogenesis. METHODS: Forty-two New Zealand white male rabbits were divided into 4 groups. The group A rabbits (n = 8) received normal diet and served as control animals. The remaining groups were fed with a diet enriched with 1% cholesterol and 6% corn oil. The rabbits of group B (n = 9) were sacrificed 1 month after the beginning of the study, of group C (n = 15) after 2 months and of group D (n = 10) after 3 months. In tissue sections of the aortic arch the antibodies of the prementioned factors were detected immunohistochemically. RESULTS: In group A only TGFb and PDGF-A were detectable. In lesions of the first month PDGF-A expression was high but declined towards the third month. VCAM-1 expression was getting more intense up to the second month and subsided thereafter. TGFb expression intensified towards the third month. Changes in the expression of these factors were statistically significant. CONCLUSION: PDGF-A, responsible for the uncontrollable growth of smooth muscle cells, and VCAM-1, regulating monocyte recruitment in the intima, acts mainly during the early stages of atherogenesis. TGFb, one of the main factors controlling the formation of connective tissue matrix, has a gradually increasing expression towards the third month contributing probably to the fibrous plaque formation.

Intramuscular administration of estrogen may promote angiogenesis and perfusion in a rabbit model of chronic limb ischemia.

OBJECTIVE: Promoting angiogenesis may be an effective treatment for patients with diffuse peripheral vascular disease. This study investigated whether estrogen can promote angiogenesis and perfusion in a rabbit model of chronic limb ischemia. METHODS AND RESULTS: Ischemia was induced in one hindlimb of 24 oophorectomized New Zealand White rabbits. Ten days later (day 0), they were randomized into 4 groups for intramuscular treatment in the ischemic limb: controls receiving saline at day 0; Estrogen-1 group receiving estradiol valerate, modified release (EVMR), 1 mg/kg at day 0; Estrogen-2 group receiving EVMR 1 mg/kg at days 0 and 15; and Estrogen-3 group receiving EVMR 2 mg/kg at day 0. Revascularization was evaluated by clinical indexes, such as ischemic/normal limb systolic blood pressure (BPR), and capillary density/muscle fiber in the abductor muscle of the ischemic limb at the time of death (day 30). At day 30 the BPR was increased in all groups (0.39+/-0.08 in the controls, 0.52+/-0.11 in the Estrogen-1 group, 0.65+/-0.13 in the Estrogen-2 group and 0.61+/-0.16 in the Estrogen-3 group, F=2.39, P=0.04). The capillary/muscle fiber at day 30 was 0.87+/-0.09, 1.08+/-0.15, 1.01+/-0.14 and 1.10+/-0.9 (F=5.01, P=0.01), respectively, in the 4 groups. The capillary/muscle fiber was related to BPR (r=0.48, P<0.02) and to 17-beta estradiol plasma levels of day 15 (r=0.58, P=0.003) and of day 30 (r=0.46, P<0.02). CONCLUSION: Administration of estrogen promotes angiogenesis and perfusion in ischemic rabbit hindlimbs. Thus, estrogen may represent a new therapeutic modality in the management of arterial insufficiency.

Stents wrapped in autologous vein: an experimental study.

OBJECTIVES: A new type of coated stent, consisting of a conventional stent covered by an autologous vein graft, was developed at our institution. BACKGROUND: Coated stents are under investigation to address stenting limitations. However, experimental implantation of coated stents covered by autologous tissue has not been reported. METHODS: An autologous vein graft was removed and carefully prepared. Subsequently, a Palmaz stent was covered by the vein graft both internally and externally. Twenty-seven stents were implanted in the normal iliac arteries of 27 pigs weighing 18 to 33 kg. In 15 of the pigs, 15 noncoated Palmaz stents were implanted in the contralateral artery; these animals served as the control group. The animals were followed up angiographically for a period ranging from 7 days to 6 months. At the time of death, the stented segments were removed, and histomorphometric analysis was performed. RESULTS: Autologous vein graft-coated stent preparation and implantation was feasible and uncomplicated. In both stents, angiographic follow-up revealed the absence of thrombosis, except for two cases of subacute thrombosis in the control group. The thickness of the intimal layer was greater in the coated stents and seems to be due to the existence of the internal vein layer ([mean +/- SD] 0.57 +/- 0.12 vs. 0.27 +/- 0.13 mm, p = 0.001). The arterial media of the coated stent segments was thinner than that in the control group (0.14 +/- 0.03 vs. 0.18 +/- 0.01 mm, p = 0.02). CONCLUSIONS: The autologous vein graft-coated stent seems to be nonthrombogenic, and only minimal hyperplasia was observed in the pigs. Further studies are needed to explore the efficacy of this technique in humans.

Cell senescence and a mechanism of clonal evolution leading to continuous cell proliferation, loss of heterozygosity, and tumor heterogeneity: studies on two immortal colon cancer cell lines.

Extensive karyotypic analysis was performed on early and late passages of two continuous human cell lines, SW480 and SW620, that were derived from the same colon cancer patient. We cultivated these two cell lines in vitro for a period of 24 months and periodically examined their chromosome constitution. SW480 cells, from passage 138, were injected subcutaneously into 20 nude mice. The tumors that grew in nude mice were then cultivated in vitro for several passages to compare histopathologic findings and tumor growth patterns with clonal chromosomal profiles. Despite some karyotypic diversity, the two cell lines exhibited common marker chromosomes and followed similar patterns of evolution. During subsequent passages, acquisition of new chromosomal abnormalities gave rise to sidelines with a near-diploid genome that frequently underwent endoreduplication. Genomic instability seemed to play an important role in the emergence, growth, and subsequent elimination of the heterogenous sidelines by selection, clonal expansion, and cell death by senescence. Despite continuous growth, both the cell lines occasionally showed telomeric associations and random dicentric and multicentric formations. These lesions were considered evidence of cell senescence and were related to the disappearance of particular sidelines through evolution. Successful evolutionary steps were characterized by elimination of pre-existing marker chromosomes that were subsequently replaced in the karyotype by their cytologically intact homologous chromosomes possibly after selective endoreduplication. Frequent loss of heterozygosity for the chromosomes taking part in this process is postulated. We suggest that one of the mechanisms by which cancer cells bypass senescence may be related to their potential for continuous clonal diversification.

Chromosomal markers associated with metastasis in two colon cancer cell lines established from the same patient.

The purpose of this study was to identify specific chromosomal abnormalities that might be involved in colon cancer metastasis. For this reason, we performed extensive karyotypic analysis on two colon cancer cell lines (SW480 and SW620) established from two surgical biopsies taken at different intervals and representing different stages of the disease from the same patient. Despite the karyotypic heterogeneity, several marker chromosomes were shared between the two cell lines, indicating their common origin. We hypothesized that these shared chromosomal aberrations might be critical for the continuous growth of the tumor cells and, therefore, were retained through progression of the disease. Duplication of 16q and new or additional structural chromosomal abnormalities involving breakpoints 3p21, 8p11, 10q25, 13q14, 14q11 and 15q15 were observed as the characteristic anomalies only in the SW620 cell line. As SW620 was established from the abdominal metastatic lesion of the patient, we postulated that the acquisition of these new markers in the progression steps of the primary tumor might represent "hot-spots" that possibly contain genes crucial for metastatic potential in colon cancer.

Pharmacokinetics of arteether in dog.

A pharmacokinetic study has been conducted in six beagle dogs after i.m. administration of 25 mg/kg of arteether, a qinghaosu (artemisinin) derivative of high anti-malarial activity. Arteether plasma concentrations were measured during a 24 h period using HPLC with an electrochemical detector in the reductive mode. The pharmacokinetic parameters were established using an open two-compartment model. Results showed a relatively rapid absorption phase: T1/2ka was 0.300 +/- 0.096 h and a mean elimination half-life of 27.95 +/- 11.93 h. Cmax was 110 +/- 16 ng/ml, Cltot/F was 1.69 +/- 0.34 ml/min and AUC was 2797 +/- 476 ng/ml/h.

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.

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.