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At least 253 records · Page 14Linked to original sources
PubMed2005

Ischemia and reperfusion in skin flaps: effects of mannitol and vitamin C in reducing necrosis area in a rat experimental model.

PURPOSE: The aim of the present study was to develop an experimental model of ischemia-reperfusion injury in rat skin flap and to verify the effect of mannitol and vitamin C on reducing necrosis area. METHODS: A 6- x 3-cm groin skin flap was raised and submitted to 8 hours of ischemia by clamping the vascular pedicle and to 7 days of reperfusion. The animals were divided in four groups: S1 and S2 (10 animals each) and C and T (14 animals each). In groups S1 and S2 skin flaps were not submitted to ischemia and animals received lactated Ringer's solution (S1) and antioxidant solution (S2). In groups C and T, flaps were subjected to 8 hours of warm ischemia and animals received Lactated Ringer's solution (Group C) and antioxidant solution immediately before reperfusion, (Group T). Flap survival was evaluated on the seventh day using a paper template technique and computer-assistant imaging analysis of necrotic and normal areas. RESULTS: Statistical analysis showed no area differences between groups C and T. CONCLUSION: The experimental model provided consistent necrotic area in control groups and drugs used were not effective in improving skin flap survival.

Animals↗
PubMed2005

A new experimental model of glaucoma in rats through intracameral injections of hyaluronic acid.

An experimental model of pressure-induced optic nerve damage would greatly facilitate the understanding of the cellular events leading to ganglion cell death, and how they are influenced by intraocular pressure and other risk factors associated to glaucoma. The aim of the present report was to study the effect of a long-term increase of intraocular pressure in rats induced by intracameral injections of hyaluronic acid with respect to electroretinographic activity and retinal and optic nerve histology. For this purpose, hyaluronic acid was injected weekly in the rat anterior chamber of one eye, whereas the contralateral eye was injected with saline solution. The results showed a significant decrease of oscillatory potentials and a- and b-wave amplitude of the scotopic electroretinogram after 3 or 6 weeks of hyaluronic acid administration, respectively. These parameters were further reduced after 10 weeks of treatment with hyaluronic acid. No significant changes in anterior chamber angle structures from hyaluronic acid- and vehicle-injected eyes were observed, whereas a significant loss of ganglion cell layer cells and of optic nerve axons were detected in animals that received hyaluronic acid for 10 weeks, as compared to eyes injected with saline solution. In summary, present results indicate that the chronic administration of hyaluronic acid induced a significant decrease in the electroretinographic activity and histological changes in the retina and optic nerve that seem consistent with some features of chronic open-angle glaucoma. Therefore, this could be an experimental model to study the cellular mechanisms by which elevated intraocular pressure damages the optic nerve and the retina.

Animals↗
PubMed1990

The opioid system in neurologic and psychiatric disorders and in their experimental models.

Evidence from experimental and clinical studies suggests the involvement of the endogenous opioid system in several neurologic and psychiatric disorders (Alzheimer's, Huntington's and Parkinson's diseases, drug-induced movement disorders, Gilles de la Tourette syndrome, stroke, ischemia, brain and spinal cord injury, epilepsy, schizophrenia and affective disorders). However, its involvement is rather a secondary one, perhaps being a severe consequence of a primary, nonopioid disturbance. Thus, treatment of an opioidergic manifestation of a disorder of nonopioidergic origin is necessarily symptomatic and targets only the restoration of the opioid system; such treatment may be beneficial in ameliorating the clinical symptoms of the disorder.

Animals↗
PubMed1976

Maternal hyperphenylalaninemia: an experimental model in rats.

Experimental maternal hyperphenylalaninemia produced in pregnant F344 rats by the combined use of p-Chloro-DL-phenylalanine and L-phenylalanine reduced fetal birth weight in comparison to saline-injected controls. Offspring who experiences hyperphenylalaninemia in utero died within 5 days after birth. Fetal plasma phenylalanine levels were several times higher than maternal plasma phenylalanine levels, indicating that the placenta actively concentrates maternal phenylalanine. Fetal brain phenylalanine levels rose in direct proportion to elevations in fetal plasma phenylanaline, whereas maternal brain phenylalanine levels remained low during maternal plasma phenylalanine elevation; the contrast suggests that the maternal brain is better able than the fetal brain to screen itself against high circulating plasma phenylalanine levels.

Animals↗
PubMed1980

Assessment of cerebral damage during open-heart surgery. A new experimental model.

A new experimental technique for the assessment of cerebral cellular damage during extracorporeal circulation is described. It is based upon the direct measurement of the enzyme creatine phosphokinase (CPK) and the brain-specific isoenzyme CPK-B in cerebrospinal fluid of dogs submitted to conventional techniques of cardiopulmonary bypass (CPB). Highly significant elevations occur during a 60 min period of CPB in CSF levels of total CPK and CPK-B isoenzyme. These elevated levels persist at 24 hours postoperation, despite full clinical recovery in the dogs. In a comparative study of the effects of introducing a 40 micrometer arterial line screen filter during the period of CPB, there was a highly significant reduction in total CPK and CPK-B levels in the filtered group (p < 0.005).

Animals↗
PubMedDate not supplied

Effects of non-susceptible hosts on the infection with Trypanosoma cruzi of the vector Triatoma infestans: an experimental model.

We tested experimentally the effects of the presence of non-susceptible hosts on the infection with Trypanosoma cruzi of the vector Triatoma infestans. The experiment consisted in two treatments: with chickens, including two chickens (non-susceptible hosts) and two infected guinea pigs (susceptible hosts), and without chickens, including only two infected guinea pigs. The hosts were held unrestrained in individual metal cages inside a closed tulle chamber. A total of 200 uninfected T. infestans third instar nymphs were liberated in each replica, collected on day 14, and examined for infection and blood meal sources on day 32-36. The additional presence of chickens relative to infected guinea pigs: (a) significantly modified the spatial distribution of bugs; (b) increased significantly the likelihoods of having a detectable blood meal on any host and molting to the next instar; (c) did not affect the bugs' probability of death by predation; and (d) decreased significantly the overall percentage of T. infestans infected with T. cruzi. The bugs collected from inside or close to the guinea pigs' cages showed a higher infection rate (71-88%) than those collected from the chickens' cages (22-32%). Mixed blood meals on chickens and guinea pigs were detected in 12-21% of bugs. Although the presence of chickens would decrease the overall percentage of infected bugs in short term experiments, the high rate of host change of T. infestans would make this difference fade out if longer exposure times had been provided.

Animals↗
PubMedDate not supplied

[Usefulness of Doppler echocardiography in the analysis of left ventricular isometric relaxation time in an experimental model of myocardial reperfusion].

UNLABELLED: Modifications of left ventricular isometric relaxation time (LVIRT) were analyzed in an experimental model of myocardial reperfusion (MR). In a prospective study, 19 mongrel dogs were studied with open chest, mechanical ventilation and hemodynamic monitoring. A catheter was inserted in the middle third of the anterior descending artery (ADA) for registry of its pressure. The ADA was ligated distal to the first diagonal branch for 15 min and subsequently untied. Epicardial Echo/Doppler registries were obtained in basal conditions, at 5 and 15 min of ischemia and at 5, 15, 30 and 60 min after MR. Mobility and changes in thickness of the interventricular septum (IVS) were analyzed, and LVIRT was measured in all of the periods mentioned. There were no significant changes in the thickness of IVS. LVIRT increased in comparison to the basal registry at 5 and 15 min of ischemia (p < 0.0001) and returned to basal values with MR (p < 0.05). CONCLUSIONS: Acute myocardial ischemia prolongs LVIRT, in this model, during MRLVIRT returned to normal. In the experimental model, measurement of LVIRT may be used as criterion for reperfusion.

Animals↗
PubMed1993

[Experimental models of nasal hypersensitive reaction].

An experimental animal models of nasal hypersensitive reaction had been developed in twelve guinea pigs by intranasal applications of 2.4-toluene diisocynate (TDI). Symptoms, morphological appearance of the nasal mucosal scrapings and tissue pathology were studied, and the histamine content in the turbinates evaluated. The results showed a typical picture of nasal hypersensitive reaction. A plenty of eosinophils and mast cells was found on the surface of the nasal mucosa. A marked infiltration of the eosinophils was seen not only in the subepithalial connective tissue but also in the epithelial layer and in the enlarged venous vessels. Significantly higher levels of histamine were detected in the mucosa from TDI treated animals than in control animals (P < 0.01). We consider the experimental models to be ideal.

Animals↗
PubMed2005

A new experimental model to study preneoplastic lesions in achalasia of the esophagus.

PURPOSE: Develop an experimental model to study esophageal preneoplastic lesions induced by diethylnitrosamine in rats with achalasia. METHODS: Male Wistar rats were divided into four groups: control--C (n=8); rats with megaesophagus--B (n=8); rats treated with DEN--D (n=15) and rats with megaesophagus plus DEN--BD (n=15). Megaesophagus can be experimentally obtained in rats by topical application of benzalkonium chloride. The morphology and PCNA labeling index of the epithelium were evaluated. RESULTS: The morphometric analysis showed an increase in epithelial thickness in the animals of group BD (2166+/-1012 mm2) when compared to the other groups (C = 878+/-278 mm2; B = 1746+/-144 mm2 and D = 1691+/-697 mm2), mainly due to basal layer hyperplasia, besides an increase in the keratin of the superficial layer. The PCNA labeling index in the basal layer was significantly higher in the group BD (0.695+/-0.111) when compared to the other groups (C = 0.490+/-0.132; B = 0.512+/-0.215 and D = 0.477+/-0.198). CONCLUSIONS: Our data confirm in an experimental model the previous observation in humans of increased epithelial cell proliferation during the esophageal carcinogenic process in achalasia and may be useful to further studies on the mechanisms of the esophageal carcinogenesis and the the design of follow-up endoscopic studies for patients with achalasia.

Animals↗
PubMed1993

Ocular melanoma: an experimental model in New Zealand white rabbits.

An experimental model is suggested for reproducing ocular melanoma in New Zealand white rabbits using B16 melanoma cells and protocols differing with respect to either tumour origin (subcutaneous fragments of melanoma B16 or B16-F10 tumour cell cultures) or implant site (the anterior chamber or subchoroidal). In 20 animals, 20 mg of methylprednisolone acetate was injected subconjunctivally as a local immunosuppressant. The only protocol resulting in tumour was inoculation of 4 x 10(6) B16-F10 melanocytes into the anterior chamber of the eye. Trans-scleral injections of cell suspensions produced tumour growth in 43% (13/30) of animals so treated. Thirteen animals developed non-neoplastic pigmented lesions formed of numerous melanophages. Another 19 animals showed non-pigmented lesions caused by reaction to the surgical procedures. Subconjunctivally injected methylprednisolone acetate did not increase the incidence of tumour growth.

Animals↗
PubMed1981

An experimental model to study bile and exocrine pancreatic secretion from mice.

An in vivo experimental model to obtain exocrine pancreatic secretion and bile from mice has been developed. It consists of a microsurgical procedure in anesthetized mice. The bile-pancreatic common duct and the duodenum were individualized, isolated, and cannulated using a stereoscopic microscope to obtain pure pancreatic juice, pure bile, bile-pancreatic juice, and duodenal contents. Intravenous injection of secretin as a pancreatic secretion stimulant was used with this experimental model. Fluid color an enzymatic activity were used as indicators of the fluid purity. In order to evaluate the overall procedure, mortality under surgery and volumes of samples obtained (expressed as microliters/30 minutes) before and after administration of secretin was measured. Results from a total of 524 mice of the BALB/c and DBA/2J-cri inbred strains were evaluated.

Animals↗
PubMed1995

Experimental model for local administration of nerve growth factor in microsurgical nerve reconnections.

An experimental model for local administration of neuronotrophic substances at the site of peripheral nerve lesion is presented. The model consists of a subcutaneously located silicone reservoir and a connecting tube with its distal end fixed in the proximity of the severed and repaired nerve. The results of the preliminary tests of the model are presented. Sixty Sprague-Dawley rats were divided into two groups: control (saline-treated) (n = 30) and NGF-treated (n = 30). After axotomy of the sciatic nerve, an epineurial repair is performed. NGF or saline is injected daily into the subcutaneous reservoir during the first 3 weeks after axotomy and a single dose in the fourth week. The regenerated nerve observed in the NGF-treated group after four weeks of treatment presents a greater percentage of myelinated axons, thicker myeline sheaths, and more mature endoneurial layers. This experimental model provides a reliable and quantitative way to deliver neuronotrophic substances in site and at different administration rates.

Animals↗
PubMed2006

Experimental models for the evaluation of treatment of allergic rhinitis.

OBJECTIVE: To review the experimental models used for the clinical evaluation of treatments for allergic rhinitis. DATA SOURCES: Peer-reviewed clinical studies and review articles were selected from the PubMed database using the following relevant keywords: allergic rhinitis in combination with efficacy, wheal and flare, nasal challenge, park, cat room, or exposure unit. Regulatory guidance documents on allergic rhinitis were also included. STUDY SELECTION: The authors' knowledge of the field was used to limit references with emphasis on recent randomized and controlled studies. References of historical significance were also included. RESULTS: Traditional outpatient studies are universally accepted in the evaluation of treatment for allergic rhinitis. Experimental models provide ancillary information on efficacy at different stages of treatment development. Skin histamine and allergen challenge, as well as direct nasal challenge with histamine and allergen, are often used as early steps in assessing drug efficacy. Exposure units, park settings, and cat rooms better approximate real life by drawing on the natural mode of allergen exposure and delivering the sensitizing allergen to allergic individuals in the ambient air. Park studies make use of allergens in the outdoors, whereas cat rooms and exposure units present the sensitizing allergens indoors, with the latter providing consistent predetermined allergen levels. Exposure unit and park studies are acknowledged for the determination of onset of action and are also suited to the measurement of duration of effect and other measures of efficacy. Onset and duration of effect are 2 important pharmacodynamic properties of antihistamines and nasal corticosteroids as determined by the Allergic Rhinitis and Its Impact on Asthma and the European Academy of Allergology and Clinical Immunology workshop group. CONCLUSIONS: All challenge models serve as important instruments in the evaluation of antiallergic medications and provide additional information to complement traditional studies.

Allergens↗
PubMed1995

A caprine experimental model for studies on inflammation.

A new experimental model for in vivo studies on local inflammation in the goat is presented. The teat and udder cisterns were separated by a surgical procedure, resulting in the teat cistern being an isolated pouch which is easily accessible through the teat canal and suitable for experimental studies. The surgery was consistently successful in closing the passage and no post-surgical complications were observed. The model was applied to a study of the inflammatory response induced by infusion of Salmonella endotoxin. A marked response was observed as measured by the accumulation of leukocytes, serum albumin and N-acetyl-beta-D-glucosaminidase (NAGase) in the test cistern. An initial increase in serum albumin, indicating an increase in the epithelial permeability, was observed from 1.5 h after endotoxin infusion. Approximately 0.5 h later, the cell count started to increase, reaching its peak level 3 h after infusion. The NAGase concentration was closely correlated with the cell count. The model provides new possibilities for in vivo studies on local inflammation and fulfils many of the requirements of an inflammatory model; for example, it allows non-traumatic repeated samplings from the same animal. The goat is a suitable experimental animal for many studies and, as each goat has two teats, intra-goat comparisons can be performed.

Acetylglucosaminidase↗
PubMed1996

Which experimental model to choose to study arterial thrombosis and evaluate potentially useful therapeutics?

The use of experimental models of arterial thrombosis both in vivo and ex vivo in animals and ex vivo in humans is an obligatory step for the understanding of mechanisms involved in thrombogenesis as well as in the evaluation of anti-thrombotic therapeutics. Arterial thrombogenesis is a complex phenomenon which involves multiple systems, mechanisms and parameters. Therefore studies of thrombogenesis from a pathological as well as a therapeutic point are necessary for understanding this problem in its entirety. For these reasons, it is necessary to use models as representative as possible of the human pathological condition. Besides these theoretical requirements, practical needs have also to be fulfilled (accessibility of the models, adaptation to the type of the technique to different animal model and/or of the size of the animal to the amount of molecule available, cost...) which necessarily lead to some compromises. In this review we have tried to underline the criteria for the choice, characteristics, advantages and disadvantages of the major models commonly accepted and used, in such a form that the reader who may not be an expert in the field would be led either to a choice of a particular model for a specific purpose or to appreciate a paper or a report based on an experimental model of arterial thrombosis. In vitro models of arterial thrombosis are so far removed from reality and due to their nature can generate so much artifacts that we have omitted their discussion from this paper.

Animals↗
PubMed2006

Contemporary experimental models of traumatic brain injury.

This review article aims to bring investigators' attention to experimental models of traumatic brain injury, widely employed in research in western countries and almost unknown in Eastern Europe. We describe the most successful animal models that cause neurotrauma by applying mechanical energy to the head, skull or dura. It attempts to provide a short compendium of the main characteristics of each of these experimental models of TBI in respect to main human neurotrauma features, histological findings and behavioral impairment in neurologic motor and cognitive function.

Animals↗
PubMed2001

Abdomen release in prone position does not improve oxygenation in an experimental model of acute lung injury.

OBJECTIVE: To analyze the effect of abdomen release in the prone position on oxygenation in an experimental model of acute lung injury. DESIGN: Experimental randomized controlled study. SETTING: Experimental laboratory of a tertiary university hospital. PARTICIPANTS: Mixed-breed adolescent pigs weighing between 25-31 kg. INTERVENTIONS: Thirty minutes after pulmonary edema was produced with oleic acid, the animals were turned prone and randomized into two groups: group I or control (n = 9), lying directly on the operating table; and group II (n = 11) with abdomen release, with positioning rolls under the upper part of the chest wall and the pelvis to allow free movement of the abdomen. MEASUREMENTS AND RESULTS: The gas exchange, respiratory mechanics, hemodynamics, intra-abdominal pressure (IAP) and the extravascular lung water (EVLW), determined by double indicator dilution method (DI), were recorded at baseline (time 0) and at 30, 60, 90, 120 and 150 min. The PaO2/FIO2 increased in both groups at 30 min after the pigs were placed in the prone position (time 60) and then decreased progressively until the end of the experimental period, with no statistical differences between the groups at any time (73.1 +/- 14.5 vs 79.5 +/- 14.9 at 150 min). Abdomen release was not associated with changes in the respiratory mechanics, EVLW or intra-abdominal pressure. CONCLUSIONS: Abdomen release in prone position does not improve oxygenation in an experimental model of acute lung injury.

Animals↗