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Results for “Models, Experimental”

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At least 55 records · Page 3Linked to original sources

PubMed1985

Phagocytic function in the isolated perfused rat liver. An experimental model.

An experimental model for measuring the phagocytic function of the isolated perfused rat liver is described. A progressive rise in phagocytosis was observed with increasing liver blood flow. This is due to an increase in total particle uptake by the liver with no alteration in the rate constant for phagocytosis except at the highest flow rate. Phagocytosis is substantially greater in the livers of 100-day-old rats than in 21-day-old rats, but the number of particles ingested per unit weight by the older rats is significantly less. Liver phagocytosis is shown to be both temperature- and oxygen-dependent, but independent of nutritional status and animal gender. This model may be useful for assessing the effects of drugs and toxins on hepatic phagocytosis.

Age Factors↗

PubMed1994

Changes in the temporomandibular joint caused by the vertical facial pattern. Study on an experimental model.

An experimental model reproducing open bite or verticalized facial pattern was used to study its effect on the temporomandibular joints. 140 Wistar rats were used, divided into 3 groups: bilateral resection of the masseteric muscle, simulated muscular resection and control group. A series of radiological, morphological and histological tests were analyzed. The posterior rotation of the jaw caused by muscular resection although not producing a degenerative effect, did produce specific articular changes in the temporomandibular joint components.

Animals↗

PubMed1998

Endogenous endophthalmitis by Fusarium solani: an animal experimental model.

An experimental model of endophthalmitis by Fusarium solani in immunocompetent mice that could be useful for evaluating the efficacy of different treatments and the pathogenicity of the fungus in ocular structures was established. Five clinical isolates of F. solani were injected into the lateral tail vein of groups of 20 mice, in order to produce systemic infection with ocular infection. Inocula of 5 x 10(6) conidia per mouse were used. The eyes of the animals that died were enucleated for histopathological study to determine the degree of ocular infection. We found fungal infections in 34% of the mice studied. Panophthalmitis was detected in 16 animals, four with bilateral infections. Fungal endophthalmitis can become a severe complication of systemic mycoses by F. solani.

Animals↗

PubMedDate not supplied

Meningeal carcinomatosis: development of an experimental model.

An experimental model of meningeal carcinomatosis has been produced by intracisternal inoculation of Walker 256 carcinoma cell suspension into Wistar rats. The tumor grows rapidly and is fatal in about 15 days if 10(6) cells are injected. The histopathological pattern observed is similar to that seen in diffuse leptomeningeal involvement of systemic cancer in human beings. The model will be useful for investigating the pathophysiology of the neurological disability produced by meningeal carcinomatosis and the efficacy of chemotherapeutic agents.

Animals↗

PubMed1986

Pathophysiology of equine postoperative ileus: effect of adrenergic blockade, parasympathetic stimulation and metoclopramide in an experimental model.

An experimental model of postoperative ileus was developed in ponies using trauma to, and exposure of, a length of small intestine which gave rise to a reproducible and reversible set of changes in gut activity. This was assessed by recordings of electrical and mechanical activity and by propulsion of spheres from stomach to anus. Activity was depressed, especially in the stomach and colon, and transit was slowed. All drugs given increased electromechanical activity but propranolol was the least effective and did not alter the delayed transit of spheres. Yohimbine was more effective and the addition of bethanechol produced a little extra propulsive action. Metoclopramide had the best effect, virtually returning transit to normal and was the only drug fully restoring coordination of gastric and small intestinal activity which was disrupted by the ileus procedure. Loss of gastroduodenal coordination is probably the central lesion in equine ileus and may be mediated by dopamine.

Animals↗

PubMed1975

The lymphoid bone marrow. An experimental model.

An experimental model is proposed whereby rat bone marrow is converted to a lymphoid-like tissue. A single i.p. injection of hydroxyurea (250 mg/kg body weight) destroys replicating marrow cells in DNA synthesis. Bone marrow erythroblasts constitute the vast majority of cells in cycle under the steady-state of hematopoiesis. Six hours following a single injection of hydroxyurea, selective damage of erythroblasts is noted. The depleted erythroid compartment appears to be replenished by cells of a lymphoid configuration. At 24 hr after injection the erythroid compartment is restored to normal activity. It is suggested that 6 hr after administration of hydroxyurea, lymphoid cells of rat bone marrow may be a source of stem cells for the depleted erythroid compartment.

Animals↗

PubMed1990

1990 Volvo Award in clinical sciences. The consistency and accuracy of roentgenograms for measuring sagittal translation in the lumbar vertebral motion segment. An experimental model.

An experimental model of the L4-L5 lumbar motion segment was developed that allowed precise manipulation of sagittal translation, rotation of L5 relative to L4, tilt of L4 on L5, and control of roentgenogram quality (image clarity) by placing a water bath between the tube and the vertebral body. A series of experiments were designed to systematically assess the consistency and accuracy of sagittal translation measurements from roentgenograms of varying quality, using different measurement protocols and various rater combinations on models with varying degrees of concomitant motions (rotations and tilts). Study 1 assessed the effects of roentgenogram quality, raters, and seven measurement methods on the consistency and accuracy of evaluating translations in the sagittal plane. Results indicated very high reliabilities across roentgenogram quality, raters, and measurement. As expected, high-quality roentgenograms were more accurately evaluated than lower-quality roentgenograms. However, closer inspection of the consequences of errors in measured translations indicated surprisingly high false-positive and false-negative rates, with significant differences observed between measurement methods. Study 2 assessed the effects of concomitant motions and measurement methods on the consistency and accuracy of evaluations. Within-rater consistency and accuracy indices were remarkably high and similar across measurement methods and degrees of concomitant motions. However, important differences in the false-positive and false-negative rates were again observed. Method 2, described by Morgan and King, demonstrated the overall best performance and the least interference due to concomitant motions. Study 3 assessed the effects of raters and measurement methods on the consistency of measuring translation in clinical roentgenograms, where concomitant motion factors may be present, but not explicitly considered. Results indicated substantially lower within- and between-rater consistency estimates relative to consistencies obtained from the model, although these magnitudes were similar to those reported by others evaluating clinical roentgenograms. The implications of lower consistency estimates relative to increased false-positive and false-negative rates must be more closely examined. These studies present evidence suggesting that high consistency and accuracy indices do not ensure acceptable false-positive and false-negative rates and, thus, provide empirical evidence supporting the view that using roentgenograms as a basis for diagnosing instability often can lead to errors in classification. This is less so when observed translations are relatively large (+/- 5+ mm) on roentgenograms that are relatively clear, with little obliquity, and when concomitant motions are minimal.(ABSTRACT TRUNCATED AT 400 WORDS)

Awards and Prizes↗

PubMed1993

Fetal tendon healing: development of an experimental model.

An experimental model was developed to study the process of fetal tendon healing. The flexor digitorum profundus tendons of the right hindlimb of 14 fetal lambs were partially lacerated at 100 days' gestation (term 145 days) and then studied macroscopically and histologically at several postinjury intervals (2, 4, 7, 14, 28, 42, and 56 days); two lambs were studied at each interval. A similar procedure was done in 14 adult sheep, who served as a control group. The fetal lambs showed no subcutaneous scarring, the digital sheath and tendon healed 2 weeks after injury, and a smooth, gliding surface was reconstituted. Collagen fibers were randomly arranged at 1 week but became organized along the tendon axis by 2 weeks. No adhesions, ruptures, or triggering was noted in the healing fetal tendons. Normal morphology was restored by 6 weeks. In the adult, dense subcutaneous scarring was noted, the digital sheath healed by 4 weeks and the tendon gap by 6 weeks, but a smooth gliding surface was not restored. Collagen fibers were randomly arranged at 2 weeks and became organized along the tendon axis by 4 weeks after injury. There were no dense adhesions or ruptures, but 25 percent of the tendons showed triggering.

Animals↗

PubMed1995

[Development and progression of pyogenic spondylitis in a canine experimental model].

An experimental model was prepared to investigate the process of inflammation in pyogenic spondylitis. Forty-seven mongrel dogs were used, involving 24 mature and 23 immature dogs. Under intravenous pentobarbital anaesthesia, the lumbar vertebral bodies were approached posterolaterally and inoculated using a small piece of gauze soaked in a staphylococcus aureus suspension. Roentgenographic and histological examinations were regularly performed for 24 weeks after the inoculation. Histologically, acute inflammation started within 1 or 2 weeks, and subsided by 5 or 6 weeks in both the mature and immature dogs. In 55% of the dogs, the inflammation was confined within the vertebral body, in 10% it invaded into the intervertebral disc, and in 35% inflammation invaded into the anterior longitudinal ligament. In the immature dogs, thickening of the trabeculae and the anterior cortex was observed around the inflammatory focus more often than in the mature dogs. The epiphyseal line acted as a barrier against invasion by the inflammation in the immature dogs. However, direct invasion of the inflammatory process into the disc could have occurred through the vascular buds which were the terminal branches of the metaphyseal artery close to the disc in both the mature and immature dogs. In contrast to the results reported by Ohno who inoculated the lumbar discs of mongrel dogs with staphylococcus aureus, in the present study, the disc space remained intact and was replaced by fibrous tissue. Consequently, it was concluded that pyogenic spondylitis should be defined as a different clinical entity from discitis.

Animals↗

PubMed1985

Pulmonary trapping of platelets and fibrin after musculoskeletal trauma: an experimental model.

A new experimental model is described in which pulmonary changes identical with the adult respiratory distress syndrome (ARDS) can be induced by reproducible musculoskeletal trauma in anesthetized pigs. The pigs were studied in maintained anesthesia for 3 days after the trauma under standardized conditions. The intrapulmonary aggregation of platelets and fibrin was monitored by external detection of radioactivity arising from pretrauma intravenous injection of 51Cr-labeled platelets and 125I-labeled fibrinogen. Pulmonary trapping of platelets and fibrin was significantly greater in the traumatized pigs than in nontraumatized but otherwise identically handled controls. Radiologic and morphologic changes corresponding to ARDS developed in the traumatized animals, but not in the controls. The experimental model offers new possibilities for study of factors influencing the occurrence and development of ARDS. After further experimental evaluation, the procedure for registering pulmonary microembolism by external detection may be useful in the clinical management of ARDS.

Animals↗

PubMedDate not supplied

The role of phospholipase A2 in the pathogenesis of respiratory damage in hemorrhagic necrotizing pancreatitis--assessment of a new experimental model.

The new experimental model has been set as a standard with the purpose to explore and analyze the role of phospholipase A2 in predicting the severity of acute pancreatitis with specific interest for the onset of hemorrhagic necrotizing pancreatitis and pleuropulmonary complications. The experiments were performed on dogs (n = 25), and acute pancreatitis was induced with the injection of 10% sodium-taurocholate into pancreatic duct. Four experimental groups of animals were formed, so that 2 groups had lymph held by draining the thoracic duct. In the other two groups, the lymph had been put into system circulation, so that the nylon bag was set around the pancreas in order to prevent pancreatic juice to be spilt into abdominal cavity. The analyses of the levels of amylase, lipase, pancreatic amylase and phospholipase A2 in of serum, lymph and exudate were performed. The positive correlation was found between increased concentration of phospholipase A2 in serum and reduction of partial pressure of oxygen and pH of blood and the degree of severity of respiratory failure. The speed and intensity of development of the acute hemorrhagic necrotizing pancreatitis, as well as the severity of pulmonary complications might be estimated upon the of increase of the levels of phospholipase A2 in serum and lymph. This experimental model enables the studying of pathogenesis of acute pancreatitis and systemic complications.

Amylases↗

PubMed1980

Immunologically induced tubulo-interstitial nephritis: experimental models in rats.

Experimental models of immunologically induced tubulo-interstitial nephritis (TIN) in rats are described. Antitubular basement membrane (anti-TBM) nephritis was demonstrated to be a TIN resulting from an antigen antibody reaction. Renal transplant rejection and the local graft-vs-host (GVH) reaction were cell-mediated immune reactions in which the antigen was possibly shared by kidney structures. A cellular immune reaction to locally applied antigens was shown to be the basis for another experimental model of TIN, possibly originating from activated mediator systems.

Animals↗

PubMed1985

The sonographic evaluation of hydronephrosis with progressive ureteric obstruction. An experimental model.

An experimental animal model was set up to examine the interrelationship between urine flow and progressive ureteric stenosis in producing sonographically detectable hydronephrosis. In four rabbits with mild ureteric stenosis or no stenosis the renal pelvis showed little distension even with rapid diuresis. Progressively tighter ureteric stenoses resulted in progressive renal pelvic distension accentuated by diuresis. The implication is that the normal, unobstructed ureter in the rabbit is able to remove urine from the kidney as fast as it may be produced, even during conditions of maximal diuresis. Therefore, in the absence of any other factor that may contribute to overdistension of the upper urinary tract, a state of diuresis will not simulate hydronephrosis.

Animals↗

PubMed2000

The ischemic heart--experimental models.

Results obtained by experimental studies of the ischemic heart have been of tremendous importance for the understanding of physiology, biochemistry and lately also the molecular genetics of the heart. Experimental models in use for the study of the ischemic heart involve studies on the integrated organism, experiments with isolated hearts or multicellular preparation, and also studies of cells isolated from the heart. Regional ischemia in the anaesthetized animal has been a standard model. Knowledge about infarct size limitation as well as heart function in acute and chronic ischemia has been obtained based on experiments in a wide variety of species. The isolated perfused heart has been subjected to extensive use. As a result, the understanding of intracellular processes is constantly developing. Cell models and transgenic-mice models represent promising additions. Each model and each species has certain advantages and disadvantages. Variability in susceptibility towards ischemia and reperfusion is also present. The consequences of ischemia can be described as contractile dysfunction and stunning, arrhythmia and infarction each representing different endpoints of injury. The experimental model is also heavily dependent on the endpoint that is chosen for the study. Results obtained in one experimental model can, therefore, not be generalized into universal conclusions about the ischemic heart. With respect to the human and the disease caused by myocardial ischemia, fragments of knowledge put together from different types of experimental models create the background for successful design of potential treatment.

Animals↗

PubMed2001

Evaluation of the safety of recombinant P-selectin glycoprotein ligand-immunoglobulin G fusion protein in experimental models of localized and systemic infection.

P-selectin is a major component in the early interaction between platelets, endothelial cells, and inflammatory cells in the initial phases of the innate immune response. The major ligand for P-selectin is P-selectin glycoprotein ligand-1 (PSGL-1) and this ligand is expressed on the surface of monocyte, lymphocyte, and neutrophil membranes. A truncated form of recombinant human P-selectin glycoprotein ligand-1 has been covalently linked to immunoglobulin G (rPSGL-Ig) and this fusion peptide functions as a competitive inhibitor of PSGL-1. As an inhibitor of neutrophil-endothelial cell adherence, rPSGL-Ig is in early clinical development for the treatment of ischemia reperfusion injury. To determine the potential for deleterious effects from inhibition in P-selectin-mediated neutrophil attachment in the presence of bacterial infection, the effects of therapeutic doses of rPSGL-Ig were tested in three standard laboratory sepsis models. The experimental models included: the murine systemic Listeria monocytogenes infection model, the Pseudomonas aeruginosa bacteremia model in neutropenic rats, and the cecal ligation and puncture (CLP)-induced peritonitis model in rats. Recombinant human PSGL-Ig had no adverse effects on mortality or immune clearance in systemic bacterial infection in any of the three infection models. The PSGL-1 inhibitor did significantly decrease local neutrophil infiltration and bacterial clearance in the peritoneum following CLP, but this did not increase the systemic levels of proinflammatory cytokines, the quantitative levels of bacteremia, or the overall mortality rate following CLP. The results indicate that rPSGL-Ig did not exacerbate infection in these experimental sepsis models.

Animals↗

PubMed2003

Gut pain and hyperalgesia induced by capsaicin: a human experimental model.

Human experimental visceral pain models using chemical stimulation are needed for the study of visceral hyperexcitability. Our aim was to stimulate the human gut with chemical activators (capsaicin, glycerol) and measure quantitatively the induced hyperexcitability to painful mechanical gut distension. Ten otherwise healthy subjects with an ileostoma participated. Increasing volumes of capsaicin 50 microg/ml (0.25, 0.5, 0.75, 1.0, 1.5, 2.0, and 3 ml), glycerol (2.5, 5, and 10 ml) or saline (2.5, 5, and 10 ml) intermingled with sham stimuli were randomly applied to the ileum via the stomal opening at three occasions separated by a week. After each application, pain intensity, qualities, and referred pain area were assessed together with the pain threshold to distension of the proximal gut. 'Boring' and 'hot' pain were evoked in all subjects by low doses (median 0.5 ml) of capsaicin. The median pain onset, peak pain, and pain duration were 55, 85, and 420 s, respectively. Referred somatic pain developed around the stomal opening with a correlation between the pain area and pain intensity. After application of capsaicin, significant hyperalgesia was found to distension of the gut (a 28% reduction pressure in pain threshold). No significant manifestations were found after application of glycerol and saline. Application of capsaicin to the human ileum induces pain and mechanical hyperalgesia. Specific activation of nociceptors in the gut mucosa provides new possibilities to study clinical relevant visceral pain mechanisms.

Adult↗

PubMed1999

Experimental models of pancreatitis.

Experimental animal models are helpful tools that have been employed to study pancreatitis for more than a century. Although not closely related to all aspects of the human disease, they have contributed greatly to our current understanding of the pathophysiology and cell biology of this disease. They have also become a standard means of testing innovative treatments against pancreatitis. This article reviews the experimental models of acute pancreatitis in common use, their severity, the criteria for the selection of an appropriate model, standards in monitoring and relevance to clinical disease. Despite their undoubted value in elucidating the mechanisms involved in the early cellular events and pathophysiology of acute pancreatitis, these models have not lent themselves to the development of effective new therapies. Models of chronic pancreatitis are also reviewed. The development of a reproducible model relevant to human chronic pancreatitis remains challenging. Experimental models of chronic pancreatitis have not yet added greatly to the understanding of the pathogenesis of this disease in man.

Animals↗

PubMed1996

Neuropathology of thiamine deficiency: an update on the comparative analysis of human disorders and experimental models.

This paper provides a re-examination of the neuroanatomical consequences of thiamine deficiency in light of more recent studies of human disorders and models of experimental thiamine deficiency. A major goal is to elucidate the relative roles of thiamine deficiency and chronic alcohol consumption in the pathogenesis of Wernicke-Korsakoff syndrome (WKS). Particular emphasis is placed on the role of thiamine deficiency in lesions to basal forebrain, raphe, locus coeruleus, white matter and cortex and their role in the cognitive and memory disturbances of human WKS and experimental models of thiamine deficiency.

Animals↗