Home About us Contact
|
Home About us Contact | ||
|
|
||
Additional Rats (additional + rat)
Selected AbstractsComparison of hprt and lacI mutant frequency with DNA adduct formation in N -hydroxy-2-acetylaminofluorene,treated Big Blue® rats,ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 3 2001Tao Chen Abstract N -Hydroxy-2-acetylaminofluorene (N -OH-AAF) is the proximate carcinogenic metabolite of the powerful rat liver carcinogen 2-acetylaminofluorene. In this study, transgenic Big Blue® rats were used to examine the relationship between in vivo mutagenicity and DNA adduct formation by N -OH-AAF in the target liver compared with that in nontarget tissues. Male rats were given one, two, or four doses of 25 mg N -OH-AAF/kg body weight by i.p. injection at 4-day intervals, and groups of treated and control rats were euthanized up to 10 weeks after beginning the dosing. Mutant frequencies were measured in the spleen lymphocyte hprt gene, and lacI mutant frequencies were determined in the liver and spleen lymphocytes. At 6 weeks after beginning the dosing, the hprt mutant frequency in spleen lymphocytes from the four-dose group was 16.5 × 10,6 compared with 3.2 × 10,6 in control animals. Also at 6 weeks, rats given one, two, or four doses of N- OH-AAF had lacI mutant frequencies in the liver of 97.6, 155.6, and 406.8 × 10,6, respectively, compared with a control frequency of 25.7 × 10,6; rats given four doses had lacI mutant frequencies in spleen lymphocytes of 55.8 × 10,6 compared with a control frequency of 20.4 × 10,6. Additional rats were evaluated for DNA adduct formation in the liver, spleen lymphocytes, and bone marrow by 32P-postlabeling. Adduct analysis was conducted 1 day after one, two, and four treatments with N -OH-AAF, 5 days after one treatment, and 9 days after two treatments. N- (Deoxyguanosin-8-yl)-2-aminofluorene was the major DNA adduct identified in all the tissues examined. Adduct concentrations increased with total dose to maximum values in samples taken 1 day after two doses, and remained essentially the same after four doses. In samples taken after four doses, adduct levels were 103, 28, and 7 fmol/,g of DNA in liver, spleen lymphocytes, and bone marrow, respectively. The results indicate that the extent of both DNA adduct formation and mutant induction correlates with the organ specificity for N- OH-AAF carcinogenesis in the rat. Environ. Mol. Mutagen. 37:195,202, 2001. Published 2001 Wiley-Liss, Inc. [source] Localized transmeningeal muscimol prevents neocortical seizures in rats and nonhuman primates: Therapeutic implicationsEPILEPSIA, Issue 4 2009Nandor Ludvig Summary Purpose:, To determine whether muscimol delivered epidurally or into the subarachnoid space can prevent and/or terminate acetylcholine (Ach),induced focal neocortical seizures at concentrations not affecting behavior and background electroencephalography (EEG) activity. Methods:, Rats (n = 12) and squirrel monkeys (n = 3) were chronically implanted with an epidural or subarachnoid drug delivery device, respectively, over the right frontal/parietal cortex, with adjacent EEG electrodes. Recordings were performed in behaving rats and chaired monkeys. Via the implants, either a control solution (artificial cerebrospinal fluid, ACSF) or muscimol (0.25,12.5 mm) was delivered locally as a "pretreatment," followed by the similar delivery of a seizure-inducing concentration of Ach. In five additional rats, the quantities of food-pellets consumed during epidural ACSF and muscimol (2.5 mm) exposures were measured. In a last group of four rats, muscimol (0.8,2.5 mm) was delivered epidurally during the ongoing, Ach-induced EEG seizure. Results:, In contrast to ACSF pretreatments, epidural muscimol pretreatment in rats completely prevented the seizures at and above 2.5 mm. In the monkeys, subarachnoid muscimol pretreatments at 2.5 mm completely prevented the focal-seizure,inducing effect of Ach, whereas similar deliveries of ACSF did not affect the seizures. Furthermore, 2.5 mm epidural muscimol left the eating behavior of rats intact and caused only slight changes in the EEG power spectra. Finally, muscimol delivery during Ach-induced EEG seizures terminated the seizure activity within 1,3 min. Conclusions:, The results of this study suggest that muscimol is a viable candidate for the transmeningeal pharmacotherapy of intractable focal epilepsy. [source] Upregulation of intracellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 after unilateral nerve injury in the peripheral taste systemJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2007Melissa Ann Cavallin Abstract In the peripheral taste system, activated macrophages are recruited to both sides of the tongue after unilateral sectioning of the chorda tympani nerve (CT). Neural degeneration elicits macrophage entry in other systems by upregulating vascular adhesion molecules. We hypothesized that CT sectioning leads to a bilateral increase in intracellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 expression on lingual vessels. To test this hypothesis, rats were euthanized at time points from 6 hr to 7 days post-sectioning. Frozen sections of tongue were processed for immunohistochemical staining for ICAM-1 and VCAM-1. Tongue homogenates from additional rats were analyzed with ELISA. ICAM-1 expression increases first on the denervated side of the tongue at 24 hr post-section and then on the uninjured side at 48 hr post-section. ICAM-1 remains elevated through Day 7 post-sectioning on both sides of the tongue. Dietary sodium restriction, which prevents the macrophage response to nerve sectioning, had no effect on ICAM-1 levels. VCAM-1+ vessels are increased on the denervated side of the tongue at 24,48 hr post-section in control-fed rats. However, dietary sodium restriction prevents the increase. These results indicate that vascular adhesion molecules are differentially regulated by CT sectioning. We suggest that macrophage entry, migration, and modulation of taste function are downstream of dynamic expression of adhesion molecules. © 2006 Wiley-Liss, Inc. [source] Effects of Ciprofloxacin-Dexamethasone on Myringotomy Wound Healing,THE LARYNGOSCOPE, Issue 3 2007Patricia A. Hebda PhD Abstract Objective: To evaluate the effects of the ciprofloxacin-dexamethasone (CDX) combination ototopical treatment after myringotomy on tympanic membrane (TM) healing in ears with eustachian tube obstruction (ETO) and unobstructed ears. Study Design: Prospective, randomized, masked, controlled. Methods: ETO was created in the left ear of 30 rats to induce a model of otitis media with effusion (OME). After 3 weeks, bilateral myringotomy was performed (day 0). Animals were randomized into three groups to receive no treatment or bilateral once daily ototopical treatment with balanced salt solution (BSS, vehicle) or CDX for 13 days. Bilateral otomicroscopy was performed on days 7, 14, and 28. On day 14, five randomly selected animals per group were humanely euthanized and the TM harvested for histology. Three additional rats provided normal negative control ears for histologic comparisons. Results: On day 14, TM perforation healing rates were 100% in all ears of untreated and BSS-treated animals, 89% (8/9) in CDX-treated obstructed ears, and 30% (3/10) in CDX-treated unobstructed ears (P < .05 vs. BSS). On day 28, 100% (5/5) of the CDX-treated unobstructed ears and 80% (4/5) of the CDX-treated obstructed ears were healed. Histology showed initial TM thickening postmyringotomy in all ears but no significant qualitative differences between groups on day 28. Conclusion: Myringotomy healing was transiently modulated by treatment with CDX but proceeded normally after CDX discontinuation. This early modulation might enhance middle ear drainage and middle ear concentrations of CDX when tympanostomy tube surgery is performed in patients with active OME and ETO, thus potentially reducing otorrhea and preventing or treating infection. It would not be expected to increase the risk of premature tube extrusion or adversely affect normal healing of the TM after usual spontaneous extrusion. [source] Rebound phenomenon in tissue plasminogen activator activity of parietal peritoneum after anastomosing colon in rats with bacterial peritonitisBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 7 2000M. M. P. J. Reijnen Background This study aimed to measure the fibrinolytic response, which plays a role in adhesion and abscess formation, of the parietal peritoneum to surgery in the presence and absence of bacterial peritonitis. Methods In 48 male Wistar rats bacterial peritonitis was induced using caecal ligation and puncture (CLP). Some 24 h after CLP (day 0), 12 rats were killed and biopsies were taken from the parietal peritoneum. The remaining 36 rats were reoperated whereby the ligated caecum was resected followed by resection of a 1-cm segment of the descending colon and end-to-end anastomosis. Thirty additional rats underwent resection of a 1-cm segment and anastomosis of the descending colon without any previous procedure. One-third of the rats were killed on days 1, 3 and 7 after anastomosing the colon, and biopsies were taken from the parietal peritoneum. From ten untreated rats, biopsies were taken for measurement of baseline levels. All biopsies were homogenized and tissue plasminogen activator (tPA) activity was measured using an enzyme-linked immunosorbent assay. Results Some 24 h after inducing peritonitis (day 0), tPA activity was significantly (P < 0·0001) decreased compared with baseline levels. One day after anastomosis in rats with peritonitis, tPA activity was in the same range as baseline values, while tPA activity was significantly increased on days 3 and 7 after anastomosis, in comparison to baseline levels (P = 0·0002). There was no significant difference in tPA activity compared with baseline levels 1, 3 and 7 days after anastomosing colon in normal rats. Conclusion In rats with bacterial peritonitis, tPA activity in the parietal peritoneum was depressed after 24 h; 24,48 h after inducing peritonitis, tPA activity increased, reaching supranormal levels at days 3,7. Surgery alone does not influence tPA activity of the parietal peritoneum. © 2000 British Journal of Surgery Society Ltd [source] | |||||||||||||