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At least 145 records · Page 8Linked to original sources

PubMedDate not supplied

Features of seizures and behavioral changes induced by intrahippocampal injection of zinc sulfate in the rabbit: a new experimental model of epilepsy.

Seizure produced by intrahippocampal injection of zinc sulfate in rabbits is a new chronic model of experimental epilepsy. In this model, the clinical manifestations are easily observed and are expressed not only as partial clonic seizures, but also by secondary generalized seizures. The electrohippocampalogram (EHG) and electrocorticogram (ECoG) discharges change correspondingly during both types of seizures, and last for weeks. The mechanism for induced seizures may be partly related to the inhibitory effect of zinc sulfate injections on the acetylcholinesterase (AchE) activity in the hippocampus. The commonly used antiepileptic drugs, such as phenobarbital and phenytoin, afforded protection against the zinc-induced secondary generalized clonic seizures and alleviated the partial clonic seizures but had no influence on the EHG- and ECoG-monitored periodic bursts of spike discharges. Nitrazepam was found to antagonize both types of seizures and also transiently restored the EHG and ECoG to normal. D-penicillamine, a metal chelator, may be the most effective agent for the treatment of zinc-induced seizures; the agent, in addition to affording protection against both types of seizures, also caused the periodic burst spike discharges in EHG and ECoG to disappear.

Animals↗

PubMed1989

[A study of daunomycin rats--is it possible to use daunomycin rats as an experimental model of chronic renal failure?].

Daunomycin rats are frequently used as an experimental model of nephrotic syndrome. We accidentally left daunomycin rats for a long time, and after death, these rats showed extensive scarring of the kidney. Since then, we have been studying whether daunomycin rats can be used as an experimental model of chronic renal failure. Female Wistar rats were injected i.v. with a single dose of daunomycin 12 mg/kg or 6 mg/kg body wt. We then observed the rats for six months. The rats in the 12 mg/kg injection group died within three to six months. All rats died from chronic renal failure. The BUN and creatinine levels significantly increased from seven weeks after daunomycin 12 mg/kg injection. At the end stage, renal anemia and hyperphosphatemia were noticed. There was an inverse relationship between the life span of daunomycin rats and urine protein level at four weeks. Rats with a large amount of urine protein at four weeks died of uremia at an early age. We concluded that daunomycin rats can be used as an experimental model of chronic renal failure.

Animals↗

PubMed1985

[Antenatal cardiac surgery. Creation of an experimental model of pulmonary stenosis in the fetus and repair in utero].

An experimental model of pulmonary stenosis was created in ewes, fetus and repaired before birth by making use of the materno-foetal circulation. Eighteen ewes fetus underwent pulmonary artery banding at an average of 87 +/- 8 days' gestation (normal 135-145 days). All were reoperated before term at 132 +/- 6 days' gestation. They were divided into two groups : group I (7 fetus) was used to evaluate the experimental model of pulmonary stenosis by measuring right ventricular pressures (80 +/- 16 mmHg compared to 58 +/- 10 mmHg in control models), and the increase in right ventricular mass (2.8 +/- 0.5 X 10(-3) g vs 1.9 +/- 0.2 X 10(-3) g), left ventricular mass (2.2 +/- 0.3 X 10(-3) g vs 1.8 +/- 0.4 X 10(-3) g) and septal mass (1.8 +/- 0.3 X 10(-3) g vs 1.3 +/- 0.2 X 10(-3) g). In group II (11 fetus) the pulmonary stenosis was repaired by total clamping and patch repair. After repair and during the days just before birth, the ventricular masses decreased (RV = 2 +/- 0.3 X 10(-3) g; LV = 1.8 +/- 0.4 X 10(-3) g; septum = 1.8 +/- 0.3 X 10(-3) g) approaching values of normal control fetus. This experimental model shows that it is possible to correct cardiac lesions in utero by making use of the materno-fetal circulation and that antenatal repair of an arterial obstruction can rapidly reverse the reactional ventricular hypertrophy.

Animals↗

PubMed1983

Zinc-induced seizures: a new experimental model of epilepsy.

Seizures produced by intracerebral injection of zinc sulfate in rabbits are a new chronic model of experimental epilepsy. The main features of this model are: the animals are easily controlled, the electrocorticogram is conveniently recorded, the endpoints are definite, and the rate of seizure is higher than with other methods. The commonly used antiepileptic drugs, such as phenobarbital (30 mg/kg), diphenylhydantoin (30 mg/kg), nitrazepam (3 mg/kg), and sodium valproate (300 mg/kg), have therapeutic effects in treating this experimental epilepsy, when they are given intravenously. But they can not protect the rabbits from death, except phenobarbital.

Animals↗

PubMed1990

Congenital hydrocephalus: a new experimental model with histopathological study.

We describe a new experimental model of fetal hydrocephalus in the lamb. 14 sheep were operated on at 100-120 days gestation for the insertion of a catheter into the fetal aqueduct of Sylvius to block cerebrospinal fluid (CSF) flow. After the operation the intracranial pressure (ICP) was measured daily from the distal end of the catheter. The progress of ventricular dilatation was recorded by ultrasound. At ICP 100 mm/H2O the animals were killed for postmortem examination of the fetuses. Neuropathological examination showed massive dilatation of the ventricles. The ependymal cells appeared to be flat and the cellular lining disrupted. Growth of pseudocysts, cellular stratification and proliferation of the paraventricular germinal cells were observed also. With our new experimental model we were able to control the rise in ICP and correlate the evolution of the anatomical damage with the duration of high ICP and with the gestational age at which it began. Our model can also be used at early stages of gestation for reversing the development of hydrocephalus. It might therefore provide information on the suitability of fetal hydrocephalus surgery.

Animals↗

PubMed1990

Chronic achilles paratenonitis with tendinosis: an experimental model in the rabbit.

An experimental model for inducing chronic Achilles paratenonitis with tendinosis in the rabbit is presented. Thirteen rabbits were exercised in a kicking machine producing passive flexions and extensions of the ankle joint. Active contractions of the triceps surae muscles were induced by electric stimulation via surface electrodes. The animals were exercised for 5 to 6 weeks, with a rate of 150 flexions and extensions per minute for 2 h, three times a week. Light microscopic examination showed degenerative changes of the tendon, and increased number of capillaries, infiltrates of inflammatory cells, edema, and fibrosis in the paratenon. We conclude that chronic Achilles paratenonitis with tendinosis can be experimentally induced in a standardized manner in rabbits.

Achilles Tendon↗

PubMed2004

[Lung transplantation in rats: a viable experimental model].

OBJECTIVES: To incorporate a new fast, safe, and reversible anesthetic procedure into the experimental model of lung transplantation (LT) using a cuff technique originally described by Mizuta. MATERIAL AND METHOD: Eighty-eight Sprague-Dawley rats were used in the experimental model. Thirty left LTs were performed, using 60 rats. The donor heart-lung block was excised by median sternotomy with dissection of the left lung and cuffs (intravenous catheters cut into 3-mm sections) were put in place. The left lung was implanted in the recipient by lateral thoracotomy using the cuffs for anastomoses. The duration of surgery and postoperative complications were recorded. Also noted were signs of ischemia-reperfusion injury, and acute rejection of the transplanted lung. RESULTS: We discarded lungs excised from 8 animals when developing the experimental model. Transplants could not be completed in 10 rats due to technical problems, despite satisfactory excision. Of the rats who received a transplant, 4 died in the first 24 hours and 26 survived to 48 hours. They were then killed and examined. The state of the anastomoses was good and signs of ischemia-reperfusion injury, as well as acute rejection were observed in the parenchyma of the transplanted lung. CONCLUSIONS: LT with cuffs in rats is a valid, reliable, reproducible, and cheap model for studying ischemia-reperfusion injury and rejection in LT. The surgical technique is complex, requiring experienced surgeons and a long learning process. Modification of the technique to more closely resemble the surgical procedure in humans is possible, thus facilitating interpretation and allowing more reliable extrapolation to humans.

Animal Experimentation↗

PubMed1998

Inflammation measurement and immunocharacterization of cell proliferation in an experimental model of proliferative vitreoretinopathy.

An experimental model of proliferative vitreoretinopathy was developed in the rabbit eye by injecting a solution of human platelet-rich plasma. In this model we evaluated the progression with time of intraocular inflammation and the rate and origin of cell proliferation. A sterile solution adjusted to 107 platelets was injected into the right eye of a total of 46 pigmented and 14 albino rabbits. Animals were sequentially sacrificed at days 7, 14, 21 and 1 month after injection. Clinical evaluation of vitreoretinal proliferation, using a classification in six grades, and of anterior segment inflammation assessed by a Laser Flare Meter, were done for 1 month after injection, before histopathological analysis. Eighty percent of eyes developed tractional retinal detachment in 1 month. Histopathology showed intense cell migration and proliferation in the area of the ciliary body, as early as the seventh day, then further increasing rapidly. Infiltrates were composed of cytokeratin- and vimentin-expressing cells. Abnormal expression of vimentin was also found in ciliary and retinal epithelia and in M¿ller cells. Inflammation measured by the Laser Flare Meter was maximal at day 11 and then reached a plateau at significantly higher levels than controls. Albino rabbits showed significantly lower grades of proliferation, as compared to pigmented rabbits. This study thus clarified some characteristics of experimental vitreoretinal proliferations that that proved similar to those in human diseases, such as the involvement of ciliary body and retinal pigment epithelium, the existence of inflammatory reactions preceding cell proliferation and strong changes in intermediate filaments. This may provide a simple and valuable model for antiproliferative assays and shed some light on the pathogenesis of intraocular proliferative disorders.

Albinism↗

PubMed1978

[Experimental models: nutrition and intestinal cancers].

Experimental models of colonic carcinoma chemically induced in rats explored the effects of several factors involved in colon carcinogenesis: high fat level of the diet, quality and quantity of fat, fecal excretion of neutral and acid steroids, intestinal microflora and fiber content of the diet. They suggested an association linking colon cancer to dietary fat and fecal acids and neutral sterols.

Animals↗

PubMed1978

Staphylococcal keratitis. Experimental model in guinea pigs.

An experimental model of staphylococcal keratitis in guinea pigs was devised that is suitable for quantitative evaluation of therapy. The growth curve in the cornea of a virulent strain of Staphylococcus aureus was determined. The organism multiplied rapidly, reached a peak in about 12 hours, and began to decline in numbers after three days. Infections were relatively resistant to therapy begun 24 hours after infection was established. Treatment started earlier when fewer bacteria were present was more effective than treatment begun later. Treatment begun at the time of infection, which might be considered prophylaxis, was highly effective. When treatment was begun eight hours after infection, tobramycin sulfate and gentamicin sulfate solutions administered topically in doses of 20 mg/ml were more effective than topical bacitracin, erythromycin, clindamycin phosphate, or a solution containing polymyxin B sulfate, neomycin sulfate, and gramicidin. Bacitracin and erythromycin ointments were ineffective.

Administration, Topical↗

PubMed1975

Concentration of antibiotics in renal interstitial fluid: an experimental model.

In a new canine experimental model the time concentration relationship of cephalothin in serum, urine, soft tissue interstitial fluid (STIF) and renal interstitial fluid (RIF) were compared simultaneously. Antibiotic concentration in RIF was less than urinary levels but exceeded the serum concentration. Urinary antibiotic concentration does not necessarily reflect concentration in the renal interstitium. This model helps to understand the basic pharmacokinetics of antibiotics in the renal interstitium where pyelonephritis occurs.

Animals↗

PubMed1989

Taenia crassiceps: experimental model of intraocular cysticercosis.

An experimental model of Taenia crassiceps intraocular cysticercosis was developed in rabbits. The objectives of this study were to analyze the pathophysiology of this parasitic infection and to evaluate the humoral immune response. Cysticerci, inoculated in the anterior chamber of the eye, were able to grow; no inflammatory changes in the eye or anticysticercus antibodies in serum or in aqueous humor were detected during the 12-day period. In contrast, rabbits that had previously been either infected intraperitoneally with living T. crassiceps cysts or immunized intramuscularly with T. crassiceps antigenic extract developed an intense inflammatory reaction in the eye and high levels of antibodies were detected in serum and aqueous humor even before the intraocular inoculation of parasites. Furthermore, intraocular cysticerci showed minimal growth and some were eliminated. These findings support the concept that the eye is an immunologically privileged site in the nonimmunized host and the importance of the immune response in the elimination of this parasitic infection.

Animals↗

PubMedDate not supplied

In vivo thrombolysis. An experimental model in rhesus monkeys.

An experimental model of diffuse thromboembolism in the intrarenal circulation of the rhesus monkey was produced by intra-arterial injection of homogenised, homologous [125-I]fibrin. A sequential study of thromolysis was carried out using the conventional method of determining the thromboembolic index in the arteries of both kidneys together with radioautography and counting of radioactivity in the renal homogenate. Quantitative estimation of radioactivity in the renal homogenate, as well as radioautography of kidney sections provided more accurate and sensititve indices of the thrombolytic process than the conventional thrombembolic index. Studies on blood coagulation and fibrinolysis revealed only mild changes corresponding to the dynamics of thrombolysis in vivo. It was further noted that the thrombolytic mechanism in rhesus monkeys is very active and can clear thromboemboli from the intrarenal arteries within 8 days of their induction

Animals↗

PubMed1995

Transposition of the antropylorus for anal incontinence--an experimental model in the pig.

An experimental model in the pig rendered incontinent of feces was developed to assess the sphincteric activity of the transposed antropylorus. In the control group, normal defecation was studied clinically, radiologically, and manometrically. Nineteen 7- to 10-week-old pigs were rendered incontinent by resection of 20 cm of colon and rectum to below the dentate line. The antropylorus was prepared on its own blood supply and transposed to the anus, initially with a colostomy, which was closed 15 to 21 days later. Clinically these pigs passed semisolid stool in a piecemeal fashion. Contrast defecography showed hold-up at the pylorus, reflux of contrast into the colon, with pyloric contraction independent of antral stimulation. Manometry showed pyloric contraction with rise in antral pressure and independence. The authors conclude that transposition of an antropyloric segment to the anus provides a sphincter-like mechanism and could have application in fecal incontinence.

Animals↗

PubMed1991

Postmortem absorption of drugs and ethanol from aspirated vomitus--an experimental model.

Using human cadavers an experimental model was developed to simulate the agonal aspiration of drug- and alcohol-laden vomitus. By needle puncture, an acidified (N/20 HCl) 60-ml slurry of drugs (paracetamol 3.25 g, dextropropoxyphene 325 mg) and ethanol 3% w/v was introduced into the trachea. After 48 h undisturbed at room temperature, blood samples were obtained from ten sites. Ethanol and drug concentrations were highest in the pulmonary vessels in all five cases studied. Pulmonary vein mean ethanol was 58 mg% (range 13-130), paracetamol 969 mg/l (range 284-1934), propoxyphene 70 mg/l (range 11-168). Pulmonary artery mean ethanol was 53 mg% (range 10-98), paracetamol 476 mg/l (range 141-882), propoxyphene 29 mg/l (range 7.6-80). Ethanol and drug concentrations in aortic blood were higher than in the left heart and concentrations in the superior vena cava were higher than in the right heart, suggesting direct diffusion into these vessels rather than diffusion via the pulmonary and cardiac blood. Potential interpretive problems arising from this phenomenon can be avoided by using femoral vein blood for quantitative toxicological analysis.

Absorption↗

PubMed1981

Snuff-induced lesions of the oral mucosa - an experimental model in the rat.

An experimental model in the white rat has been developed in order to study the influence of snuff on oral mucosa. A test canal in the lower lip, with one orifice buccally to the incisors and one on the lip side, was created by surgical means. The connection between the canal and the oral cavity was made to ensure the presence of saliva in the canal so that physiological conditions resembling those of the oral cavity were obtained. The canal was filled with snuff morning and night 5 days a week. The mean value for the maximal retention time of the snuff was 6 h. The animals tolerated the dose and time of exposure without signs of severe toxic symptoms. Histological examination of the canals after 9 months of exposure to snuff showed a mildly to moderately hyperplastic epithelium with hyperorthokeratosis. Locally deep proliferations of epithelium with acanthotic rete pegs could be seen. In the stratum basale hyperplasia with disturbed polarity and hyperchromatic nuclei and single mitosis were noted.

Animals↗

PubMed1993

Respiratory distress syndrome in copper deficiency: an experimental model developed in rats.

An experimental model has been developed to investigate the effect of copper deficiency on lung maturity in the newborn rat. Three groups of female Sprague-Dawley rats were used: the copper-deficient group was fed with a copper-free diet; the control group received a copper-adequate diet, and the pair-fed group was fed with a limited copper diet. After gestation and delivery, 35% of the newborn copper-deficient group showed respiratory distress syndrome (RDS). The neonatal lungs were isolated and processed for ultrastructural and biochemical study: A greater thickness of the air-blood barrier was observed in the lungs of the copper-deficient group, however, no other differences were observed in the rest of the pulmonary structures. Quantitative differences in pulmonary surfactant were not found in the three groups. The thickness of the air-blood barrier might explain the RDS observed in the copper-deficient newborns.

Animals↗

PubMed2002

Muscle damage and autoantibody fixation in an experimental model of autoimmune myopathy.

An experimental model of autoimmune myopathy was designed using parental antigens (muscle mitochondrial fraction) in F1 hybrid rats (male Wistar x female Sprague-Dawley). The immune response was modulated by spleen fragment transplant from either Wistar (W) or F1. Antibody fixation and inflammatory reaction were studied in Extensor digitorum longus and soleus muscles. Immunization without spleen transplant resulted in antibody fixation mainly in capillaries and incompletely around muscle fibers; whorled fibers were found in 1/3 of F1 rats immunized with antigen from W rats. Spleen transplants from Sprague Dawley (SD) rats were usually accepted by F1; in some animals, antibodies surrounded completely muscle fibers and the percentage of animals showing soleus muscle lesions was increased. Spleen transplants from non immunized F1 were usually rejected by immunized F1; antibody reaction was found inside fibers of most of the rats, muscle damage was present in 40% of the animals immunized with W, but absent in those immunized with SD antigen. In conclusion, this model can be used to study immunological responses to alloantigens (parental to F1). Spleen fragment transplant modulates the immune response. There was discrepancy between antibody fixation and muscle damage. The immunological response was different according to muscle fiber type composition and/or microcirculatory characteristics.

Animals↗