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At least 271 records · Page 15Linked to original sources
PubMed2005

Renal vascular responses in an experimental model of preeclampsia.

In pregnancy there is an attenuated response to vasoconstrictors and pressor agents, including Angiotensin II (Ang II). This effect is reverted in preeclampsia. We evaluated the renal pressor response induced by Ang II in an experimental model of preeclampsia based on the development of feto-placental ischemia produced by a subrenal aortic coarctation (SRAC). Dose-response curves for Ang II were obtained in an isolated perfused kidney preparation comparing groups of SRAC pregnant and non-pregnant rats in the presence and absence of losartan (AT1 antagonist) or PD123319 (AT2 antagonist). Kidneys from the experimental model of pre-eclampsia showed an enhanced response to AngII. In addition, losartan (10 nM) inhibited the vasopressor effect to Ang II in this model but not in the control group. PD 123319 (1 nM), increased the response in both groups, but the effect was more evident in the pre-eclamptic group. This suggests modifications in the relative participation of renal vascular receptors AT1/AT2 induced by an experimental model of pre-eclampsia, with an increased participation of AT1 and a decreased participation of AT2.

Angiotensin II↗
PubMed1995

Experimental models of tracheobronchial stenoses: a useful tool for evaluating airway stents.

BACKGROUND: Stent implantation is a conservative alternative to open operation for treating benign tracheobronchial strictures. Most of the presently available stents were primarily designed for endovascular use. Their respiratory use entails a risk of iatrogenic complications. From a scientific and from an ethical point of view these risks justify preclinical evaluation of new respiratory stents in experimental models of central airway stenoses. Therefore, an attempt was made to develop such models in piglets and adult minipigs. METHODS: Tracheal stenoses were obtained by creating first a segmental tracheomalacia through extramucosal resection of cartilaginous arches. The fibrous component of the stenoses was then obtained through bronchoscopic application of a caustic agent causing progressive deep mucosal and submucosal injury. Stenoses of the main bronchi were created by topical application of the caustic agent only. RESULTS: These models demonstrated the typical features of benign fibromalacic tracheobronchial stenoses with constant recurrence after mechanical dilation. Preliminary experiments showed that short-term problems of tolerance of stent prototypes are easily demonstrable in these models. CONCLUSIONS: These experimental models, which simulate quite realistically human diseases, offer the opportunity to perfect new tracheobronchial stents specifically designed for respiratory use and to evaluate their long-term tolerance before their use in humans.

Animals↗
PubMedDate not supplied

[An experimental model of enteric klebsiellosis].

Acute enteric infection was reproduced in rabbits, used as an experimental model, receiving Aspergillus flavus metabolites with food for 15 days and inoculated rectally with enterotoxigenic strain Klebsiella pneumoniae K24 6723. Pathomorphological study revealed the penetration of Klebsiella into microplicate cells of the intestinal epithelium, the proliferation of bacteria in the lamina propria and in the cupolas of Peyer's patches, as well as in phagolysosomes of leukocytes and macrophages. The lesion of the mucous membrane in both large and small intestine, accompanied by the hyperplasia of lymphoid follicles, was noted. As a rule, surface epithelium was dystrophically changed and peeled off into the lumen of the intestine. The specificity of such lesion was confirmed by the detection of Klebsiella in Coons' direct immunofluorescence test. The experimental model confirmed the role of a decrease in immunological protective reactions of the body, caused the action of A.flavus metabolites, in the development of the infectious process, initiated by opportunistic enterobacteria.

Animals↗
PubMed1994

Experimental model of graft vs. host disease in non-immunosuppressed F1 (CBA/J x C57BL/6) mice.

The experimental model of graft vs. host disease (GvHD) has a potential use in the evaluation of different manipulation procedures of the immune system applicable to development of vaccines. In the present study an experimental model of GvHD in F1 (CBA/J x C57BL/6) mice by means of the parenteral inoculation of spleen lymphoid cells from parental male CBA/J to 10-day-old animals (experimental group) was developed. Animals inoculated with Medium 199 (n = 42) (Medium 199 group), or with splenic lymphoid cells either from the hybrids (n = 16) (F1 group), or from mice of the inbred strain Balb/c (n = 10) (Balb/c group) were used as controls. In all groups body and spleen weights, relative spleen index (RSI), and spleen index (SI) were determined. Additionally, histopathologic and morphometric studies were done in the spleens of the animals studied. Significant increases in body and spleen weights, RSI, and lymphocytic perimeter and area were associated with distinctive splenic GvHD lesions found in the experimental group. The experimental SI value was higher than twice the SI value of any of the control groups. We conclude that ours is a useful model of GvHD with many potential applications in the field of vaccine production.

Animals↗
PubMed2004

Neurocutaneous island flap:: an experimental model using the rabbit ear.

The rabbit ear has often been used as an experimental model; however, a neurocutaneous flap has never been described before. The authors examined the reliability of a skin cartilage flap with a pedicle composed only of a sensory nerve with its vascular network in a rabbit model: A 2 x 2-cm cutaneous cartilage flap was harvested on the dorsal side of the ear bilaterally. Vessels were tied and cut on the 4 sides of the flap, including the central auricular artery and vein. The nerve was cut at the distal side of the flap and was "skeletonized" to the extent of 1 cm on the proximal side, meticulously preserving its vascular network. Subsequently, the flap was elevated with the cartilage as a composite flap and was sutured back to its natural site. The authors elevated 28 skin cartilage flaps on the dorsal side of both the ears of 14 New Zealand White rabbits, centered on the central neurovascular axis. All 28 flaps survived. In the control group of 7 rabbits, the artery, vein, and nerve (pedicle) were severed, and the skin cartilage island was sutured back as a composite graft. None of these 14 grafts survived. In 4 additional rabbits, the authors performed a histologic examination 1 day, 3 days, 7 days, and 3 weeks postoperatively of the neurovascular axis after the same skin cartilage flap was harvested. They compared these results with the histologic examination of the nerve of the contralateral nonoperated ear, and noted a marked dilatation and multiplication of blood vessels in the operated ear beginning on day 1 postoperatively. The presence of this neurocutaneous vascularization should be considered when other kinds of flaps (venous flaps or others) are used as experimental models using the rabbit ear.

Animals↗
PubMed1975

Bacterial renal infection in rats produced by direct injection of bacteria into renal tissue--an experimental model.

A new method for producing an experimental model of renal infection in rats is described. It is based on a direct injection of a concentrated E. coli suspension either into both kidneys or only one of them. The method is simple and takes little time; the mortality of experimental animals is low. A focal acute purulent renal inflammation is elicited which tends to propagate towards the papilla. A significant renal infection persists at least over six weeks. The renal infection model is suitable for testing the antibacterial activities of drugs, as documented by the results of a therapeutical experiment with gentamicin and other agents.

Animals↗
PubMed1990

The evolution of a clinically relevant experimental model for the realistic evaluation of long-length (80-cm) arterial prostheses.

A new carotid-femoral experimental model has been developed which has significant clinical relevance to human limb salvage bypass grafting in the areas of graft length, hemodynamics and tissue environment. More significantly, the graft healing pattern observed with this model is similar to what is seen in humans. Therefore, this experimental model provides a challenging and critical site for dynamic healing studies and comparisons of different types of vascular prostheses.

Animals↗
PubMed1990

Experimental models of temporal lobe epilepsy: new insights from the study of kindling and synaptic reorganization.

Temporal lobe epilepsy is a common localization-related epileptic syndrome characterized by complex partial seizures, ictal and interictal epileptic discharges arising from limbic structures of the temporal lobe, and association with hippocampal sclerosis. Temporal lobe epilepsy may follow perinatal injury and febrile convulsions, may be progressive, and frequently becomes refractory to standard antiepileptic therapy. The neurobiology that underlies these features of temporal lobe epilepsy is not known. Recent studies in experimental models have provided new insights that may help clarify the relationship of seizures, hippocampal sclerosis, and temporal lobe epilepsy. Observations from the study of the hippocampus with kainic acid-induced lesions, the kindling model, and other experimental models of epilepsy have demonstrated that seizures induce structural and electrophysiologic alterations in hippocampal pathways that may lead to increased excitability and could play a role in the development and progression of temporal lobe epilepsy. These alterations include mossy fiber synaptic reorganization, induction of NMDA-mediated synaptic transmission, and progressive hippocampal neuronal loss induced by brief kindled seizures. Some of the structural alterations induced by kindling have also been observed in the human epileptic temporal lobe, raising the possibility that mechanisms operative in kindling may play a role in the pathogenesis of hippocampal sclerosis and in the syndrome of human temporal lobe epilepsy.

Animals↗
PubMed2002

Suppression of atrial fibrillation by multisite and septal pacing in a novel experimental model.

OBJECTIVES: To evaluate the preventive efficacy of multisite and septal atrial pacing in an experimental model. METHODS: Sterile right atrial pericarditis was induced in 12 foxhounds to provide an anatomical substrate for atrial fibrillation (AF). As a trigger mechanism, atrial extrasystoles were simulated by constant asynchronous pacing at a cycle length of 1000 ms from randomly selected right or left atrial electrodes, using a biatrial epicardial multielectrode with 128 bipoles. Additionally, a transvenous pacing lead was screwed into the interatrial septum. Four electrodes located in the high and low right (HRA/LRA) and left atrium (HLA/LLA) were selected for preventive multisite stimulation. Constant pacing at a cycle length 30 ms below sinus rate was applied from the following site(s): HRA, septal, HRA+LRA, HRA+LLA, HRA+LRA+LLA and HRA+LRA+HLA+LLA (order randomized). Number and duration of AF episodes were studied during 10 min intervals, separated by 5 min pauses, respectively. To validate the model, the protocol was repeated 10 min after i.v. bolus administration of D,L-sotalol (1 mg/kg body weight). RESULTS: The number of AF episodes decreased with increasing number of pacing sites, reaching statistical significance compared to HRA stimulation for quadruple-site and single-site septal pacing only (P<0.05). Single-site septal was as efficient as quadruple-site pacing in suppressing AF. The duration of AF episodes was not significantly affected by the pacing configuration. D,L-sotalol almost completely suppressed AF irrespective of the pacing configuration used. CONCLUSIONS: In this novel experimental model, quadruple-site and septal pacing effectively suppress paroxysmal AF.

Adrenergic beta-Antagonists↗
PubMed1978

Comparison of antibiotic assays using different experimental models and their possible clinical significance.

Different experimental models were applied to study the pharmacokinetics of antibiotics in "interstitial fluid" ("i.f.") in rabbits. Two types of tissue cages were used and the results from these experiments were compared with those obtained analysing the antibiotic concentration in the mucous membrane of the oral bucca and maxillary sinus in rabbits. A similar determination was done in the mucous membrane of sinus in man. The concentration of antibiotics in the "i.f." from steel-net chambers in rabbits closely follows that of the mucous membranes of the maxillary sinus in man and the oral bucca in rabbits. Experimental bacterial infections of the tissue cages resulted in decreased amounts of biologically active antibiotics in the "i.f." for some antibiotics compared to that of the uninfected cages. An increase of the concentration of antibiotics in the infected cages was noted simultaneously with a decrease in the number of viable bacteria during the healing process. The clinical significance of the models will be discussed.

Animals↗
PubMed2005

An experimental model of an electrical injury to the peripheral nerve.

OBJECTIVE: Injury to the peripheral nerves is a common complication found in patients suffering from electrical burns. At present, there are many kinds of experimental models for electrical injury, but no report describes an animal-based experimental model for a relatively simple electrical injury to the peripheral nerves. We have designed and constructed a specific device to generate increasingly severe electrical shocks of a known voltage for the experiment. This device can simulate injuries of different degrees (minor, medium and severe) caused by shock to the right sciatic nerve of rats. METHOD: Thirty Sprague-Dawley rats were randomly divided into Group I (3600 V, n=10), Group II (1000 V, n=10) and Group III (500 V, n=10). The voltage required for the electrical shock was generated by the above-mentioned device and was adjusted to deliver 3600, 1000 and 500 V, respectively. The specific voltage, as mentioned above, was delivered three times to the right sciatic nerve of the rats. The shock duration was set to last for 10 ms. The time interval between the shocks was 3 min. Three rats were randomly selected from each group to observe changes in the morphology, electric physiology of the nerve and their histology the first, second and fourth week after injury. RESULTS: All rats survived the injuries. Leg function was partially impaired and swellings occurred on the injured extremity. However, by the second week after the injury the rats had recovered. Digit ulcers were observed by the fourth week after injury in Groups I and II. Neural electric physiology showed that the recovery rate of the neural conduction velocity (RNCV) disappeared in part or in whole immediately after the injury in experimental rats. RNCV recovered up to 65% in Group III and to 7% in Group II by the fourth week after injury, however, RNCV did not recover in Group I at all. Histology showed that blood vessel embolism occurred within the injured nerve. A large number of nerve fibres experienced Waller degeneration while the myelin sheath was vacuolated. The neural plate disintegrated largely by the first week after injury and the myelin sheath disintegrated into a loose structure by the second week after injury in Group I. Group II displayed a similar situation as Group I, wherein some nerve fibres experienced Waller degeneration and disintegration. Regenerative myelin appeared in some rats at about the fourth week after injury. The following changes were seen in Group III: The degree of neural injuries was different. The point of entry of the electric currents showed obvious Waller degeneration and disintegration of the myelin sheath, while some nerves showed a regenerated myelin sheath by the second week after injury. The morphology (such as quantity and diameter) of the injured myelin was basically normal by the fourth week after injury. CONCLUSION: This device can produce controlled injuries to the sciatic nerve giving different degrees of severity (minor, medium and severe), by means of varying the electrical shock voltage and shock duration on the rats. It is a useful model for experimental studies of injuries to peripheral nerves.

Animals↗
PubMed1994

A new experimental model: for further investigation of the secondary changes following spinal cord injury.

To investigate the pathophysiology of spinal trauma, several experimental models have been used. In this study, the authors present a new experimental model for further investigation of secondary damage following spinal injury. Nd:YAG laser irradiation was applied to the spinal cord of guinea pigs to produce an injury. A 30 Watt (20 Joule) laser produced paraparesis. The injury was evaluated with evoked potentials, lipid peroxidation values, and histopathological examination.

Animals↗
PubMed2006

[Post infectious irritable bowel syndrome experimental model].

Irritable bowel syndrome may be consisted of several subsets of functional disorders including a subset of post inflammatory and post infectious disorders. Animal models revealed prolonged hyper-kinesis of the intestinal muscle and visceral hyperalgesia in adult mice previously received phychological stress or bowel irritation in neonatal period. Murine infectious experiment reproduced adult post infectious functional disorders. Involvement of acute phase Th2 cytokine production and prolonged TGFbeta1 production contribute to intestinal hyper-kinesis in post nematode infectious rat model. Pathogenesis of irritable bowel syndrome may be further subdivided by the results of experimental models, and a novel therapeutic approach is expected from such experimental models.

Animals↗
PubMed1997

An experimental model for infiltration of malignant lymphoma to the eye and brain.

Currently there is no adequate experimental model available whereby the lethal infiltration of malignant lymphoma to the eye and CNS can be studied. Variant S49 mouse lymphoma cells that exhibit cell-cell adhesion properties (named Rev-2-T-6) were inoculated intraperitoneally into Balb/C mice at the ages of 6-60 days postnatal. Mice inoculated between days 6-11 postnatal developed signs of eye and CNS involvement with an apparent peak (58% of mice) at day 7. None of the mice inoculated beyond day 11 exhibited such signs. Histological analysis of these sites revealed tumorous infiltrates into a variety of structures in the orbit, intraocular tissues, along the optic nerve and in the brain. Additional analysis of the histopathological data, based on the structures demonstrating the highest frequency of lymphoma infiltration, suggests preferred routes of lymphoma entry to the brain and eye. Thus, entry to the brain can occur mainly through the choroid plexus and cranial nerves or cranial nerve ganglia. Entry to the eye may occur from the brain (along the optic nerve), and through hematogenous infiltration of orbital structures. No data were found that would support retrograde infiltration of the lymphoma from the eye to the brain. These findings present an experimental model for addressing the molecular mechanisms that govern homing of malignant lymphoma to the eye and brain, as well as the development of experimental therapeutic modalities for malignant lymphoma in these organs.

Animals↗
PubMed1990

Experimental model of acute appendicitis in the rabbit with determination of leucine amino peptidase (LAP) and acid phosphatase (acid-P) activities in portal blood samples.

The activities of leucine amino peptidase (LAP) and acid phosphatase (Acid-P), conceivable markers of acute appendicitis, were determined in the portal blood of rabbits with acute appendicitis. An experimental model of acute appendicitis was established using No.-O silk ties to block the base of the appendix. The clinical and histopathological picture of acute appendicitis was seen after 12 hr in all the rabbits in the model group (9/9) and in none of the control group. Catheterization of the superior mesenteric vein was performed in rabbits with acute appendicitis, and portal blood samples were taken at 0, 6, and 12 hr for assay of LAP and Acid-P activities. No statistically significant difference between the experimental group and the control group, in the activities of LAP and Acid-P, was found at any time interval. The experimental model of acute appendicitis in the rabbit which is described here is simple and carries a high rate of success. This is probably the first report of using continuous catheterization and repeated sampling of portal blood, for the measurement of enzyme activities, in an experimental model of acute appendicitis. It was concluded that serum LAP and Acid-P activities cannot be used as markers for acute appendicitis.

Acid Phosphatase↗
PubMedDate not supplied

Hemorrhoids: an experimental model in monkeys.

PURPOSE: Hemorrhoids are a matter of concern due to a painful outcome. We describe a simple, easy and reliable experimental model to produce hemorrhoids in monkeys. METHODS: 14 monkeys (Cebus apella) were used. After general anesthesia, hemorrhoids were induced by ligation of the inferior hemorrhoidal vein, which is very alike to humans. The vein was located through a perianal incision, dissected and ligated with a 3-0 vicryl. The skin was sutured with a 4-0 catgut thread. Animals were kept in appropriate cages and evaluated daily. RESULTS: Nine days later there were hemorrhoidal piles in the anus in fifty percent (50%) of the animals. Outcome was unremarkable. There was no bleeding and all animals showed no signs of pain or suffering. CONCLUSION: This is an affordable and reliable experimental model to induce hemorrhoids for experimental studies.

Animals↗
PubMed1993

Choledocho-ureteral anastomosis in the rat. A new experimental model of long-term, total, internal bile diversion.

Choledocho-ureteral anastomosis is a new experimental model of total bile diversion in the rat. The anastomosis is carried out using a polyethylene tutor drain and requires neither an external drain nor restraint of the animal. After 14 days of diversion, bile flow fell by 53% and there were no biological signs of cholestasis. The rats survived for up to 2 months. Choledocho-ureteral anastomosis is a reliable and simple experimental model which can be used to study the effects of prolonged interruption of enterohepatic bile-acid circulation.

Anastomosis, Surgical↗
PubMed1989

Regeneration of skeletal muscle fibers from autologous satellite cells multiplied in vitro. An experimental model for testing cultured cell myogenicity.

An experimental model used to test in vivo myogenicity of autologous satellite cells multiplied in vitro is described. Free muscle autotransplantation served as the basis and was combined with x-irradiation. Administration of 1500, 2500, and 3500 rad doses 24 hours before or after ischemia showed that inhibition of spontaneous regeneration is dose dependent and more efficient when irradiation was applied before injury. A single dose of 2500 rad before injury resulted in the formation of a cystic structure ideal for cell implantation. FITC-latex beads and/or carbocyanine dyes were internalized by mononucleated satellite cells in vitro. Labeling did not affect survival or development of these cells. No sign of marker release or spreading from labeled to unlabeled cells was detectable unless by the fusion process. These labels were retained for several weeks. Grafting of labeled dense cellular suspensions into x-irradiated ischemic muscles indicated that satellite cells retain their myogenic characteristic and are able to reform fully differentiated muscle fibers.

Animals↗