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.     

Diphenylmethane diisocyanate (MDI)-induced asthma: evaluation of the immunologic responses and application of an animal model of isocyanate sensitivity

A worker developed two episodes of severe asthma 90 min after cut ting a polyurethane plate made of diphenylmethane diisocyanate (MDI) using a rapidly turning carbide blade. Intradermal skin testing with MDI-human serum albumin (MDI-HSA) and p-tolyl isocyanate-HSA (p-TMI-HSA) were positive at 0.002 mg/ml. Control subjects showed no reaction at 2 mg/ml. Bronchial provocations of the worker with MDI-HSA and p-TMI-HSA, made 1 year after the occupational asthmatic episode, were negative at 10 mg/ml. Bronchial reactivity to methacholine decreased toward normal during a 2-year follow-up. RAST using MDI-HSA or p-TM I-HSA were strongly positive when compared with binding by sera from atopic controls which contained the same amount of total IgE. RAST titres decreased during a 1-year follow-up. In the MDI-HSA RAST, inhibition studies indicated specificity of antibodies for MDI-HSA. In the p-TMI-HSA RAST. p-TMI-HSA was a very effective inhibitor whereas MDI-HSA was not. These results indicated the formation of at least two distinct groups of IgE antibodies: those reactive with MDI. and those reactive with p J-TMI determinants. Guinea pigs immunized with MDI formed antibodies with specificities similar to those of the patient. We conclude that the worker had occupational asthma accompanied by the formation of specific IgE antibodies of the specificities. The causal relationship of the antibodies to the occupational asthma remains uncertain.     

Relationship between virulence and resistance to antibiotics in pneumococci. Contribution of experimental data obtained in an animal model]

Epidemiologic data show that the organ affinity of Streptococcus pneumoniae varies across serotypes. As a result of this heterogeneous distribution, exposure to antimicrobials is greater for serotypes 6, 14, 19 and 23. Most strains with resistance to antimicrobials are found among these four serotypes. Virulence of the various serotypes of pneumococci varies with adhesion, enzyme secretion, and resistance to phagocytosis. In a mouse model of experimental septicemia, neither the origin of strains nor the acquisition of a resistant phenotype modified virulence, which appeared as an intrinsic feature specific to each phenotype. Strains belonging to serotypes 6, 14, 19 and 23 with or without resistance to antimicrobials were only very rarely virulent in the experimental model used. As an indirect result, resistance to antimicrobials and virulence were inversely related among the strains of S. pneumoniae tested.     

Pathophysiology of unilateral pulmonary aspergillosis in an experimental rat model.

Because little is known about the pathophysiology of invasive pulmonary aspergillosis (IPA), we examined changes in pulmonary and general physiology during this disease in an animal model. In a model of fatal left-sided IPA, 19 persistently neutropenic rats were monitored for clinical signs including body temperature, body weight and respiratory distress. A separate group of nine rats with IPA was used for measurements of arterial blood pressure, arterial O2 and CO2 pressure, lung compliance and surfactant function. Body temperature and body weight decreased, whereas respiratory distress increased during progression of the disease. Compared to uninfected controls, in rats with IPA arterial blood pressure and lung compliance were significantly lower, and left lung minimal surface tension was significantly higher. Right lung surfactant function was not affected. Arterial O2 and CO2 pressures were not different between rats with IPA and uninfected controls. Infection with Aspergillus fumigatus in neutropenic rats resulted in hypothermia, body weight loss and respiratory distress. Loss of left lung function was probably compensated by the uninfected right lung, even in a late stage of the disease. Circulatory failure was a major feature in the terminal phase of the infection.     

Development of an improved animal model of experimental autoimmune myositis

Multiple animal models of experimental autoimmune myositis (EAM) have been developed. However, these models vary greatly in the severity of disease and reproducibility. The goal of this study was to test whether vaccination twice with increased dose of rat myosin and pertussis toxin (PT) could induce EAM with severer disease in mice. BALB/c mice were injected with 1 mg rat myosin in 50% complete Freund’s adjuvant (CFA) weekly for four times and one time of PT (EAM) or twice with 1.5 mg myosin in CFA and PT (M-EAM). In comparison with that in the CFA and PT injected controls, vaccination with rat myosin and injection PT significantly reduced the muscle strength and EMG duration, elevated serum creatine kinase levels, promoted inflammatory infiltration in the muscle tissues, leading to pathological changes in the muscle tissues, demonstrating to induce EAM. Interestingly, we found that vaccination twice with the high dose of myosin and PT prevented EAM-related gain in body weights and caused significantly less muscle strength in mice. More importantly, all of the mice receiving high dose of myosin and PT survived while 3 out of 16 mice with four times of low dose of myosin died. Finally, vaccination with high dose of myosin promoted CD4⁺ and CD8⁺ T cell infiltration in the muscle tissues and up-regulated MHC-I expression in the muscle tissues of mice. Hence, the new model of EAM is a time-saving, efficient and easily replicable tool for studying autoimmune myositis.     

实验性牙周炎大鼠模型的建立

背景：建立实验性牙周炎大鼠模型是研究牙周病的基本方法之一,目前常用的建模方法存在许多弊端,需要进一步改进。 目的：建立一种近似于人类临床的牙周炎动物模型方法。 方法：将20只8周龄的Wistar大鼠随机分为实验组和对照组,锐分离实验组大鼠双侧下颌第一磨牙颊侧牙龈,局部黏结慢性牙周炎患者的牙石于牙颈部,滴入慢性牙周病炎患者的唾液10 μL/次,2次/d;对照组大鼠牙齿不做处理。两组大鼠均喂以高糖黏性食物。 结果与结论：造模14 d后实验组动物一般生物学特征和牙周组织病理、X射线变化均符合典型牙周炎表现。局部黏结牙石加混合细菌感染的方法建立的大鼠牙周炎模型可以模拟人类牙周炎的组织变化,是一种接近于人类临床的简单、实惠、有效的建模方法。     

Complement-dependent acute immunologic lung injury in an experimental model resembling Goodpasture's syndrome

Rabbit antiserum to rat lung injected into normal rats elicits acute pulmonary lesions characterized by alveolar and perivascular hemorrhage and edema resembling the acute lung injury in patients with Goodpasture's Syndrome. Within 1 hr after injection of anti-lung antibodies, rat serum complement activity decreases significantly. Fluorescent anti-rabbit IgG and fluorescent anti-rat C3 stain alveolar septa and glomeruli in a linear membrane-like pattern suggesting localization of IgG on either basement membranes or endothelial cells of alveolar capillaries and on basement membranes of glomerular capillaries. Anti-lung antibodies are not pathogenic when given to rats decomplemented with a purified cobra venom factor. This finding supports the hypothesis that immunologic lung injury requires localization of anti-lung antibodies followed by activation and fixation of complement at the site of impending injury.The acute lung lesions elicited by sublethal doses of anti-lung serum are transient, disappearing within 24 hr. Four days after injection, lung-localizing heterologous IgG, but not host C3, is demonstrable immunohistochemically in target organs. This is an experimental counterpart of some of the reported immunohistochemical studies of lung tissue specimens from patients with Goodpasture's Syndrome, wherein the tissue localization of C3 was not observed, suggesting that C3 may be involved only at certain stages of the disease.     

Multiple myeloma and related disorders. Lessons from an animal model

This short review of our own work presents two aspects of the studies on multiple myeloma (MM) in an animal model--the aging C57BL/KaLwRij mouse: 1. the immunological/biological aspect of the development of monoclonal B-cell proliferative disorders, the so-called monoclonal gammopathies (MG), and 2. the use of the mouse myeloma of the 5TMM lines for studies on the etiology/pathogenesis of MM and for developing new ways of treatment of this disease. Our research revealed that there are at least four major mechanisms in the development of MG. Many of the results were confirmed in clinical studies and lead to a new classification of MG according to their biology and possible pathogenesis. Most of MG can be classified into one of the following categories: 1. B-cell malignancies, 2. B-cell benign neoplasia, 3. MG due to an immunodeficiency with T/B cell imbalance, and 4. Antigen driven MG.     

Calcification of implanted vascular tissues associated with elastin in an experimental animal model.

We have previously studied the process of calcification in bioprosthetic porcine heart valves crosslinked with glutaraldehyde. Observations using light microscopy had indicated that calcification of elastic fibers occurs in implanted heart valves, in addition to calcification associated with collagen fibers. To determine the contribution of elastin to the process of calcification, small pieces of rabbit aorta were cross-linked with 0.2% glutaraldehyde, rinsed in buffer, and implanted subcutaneously in young adult male rats. Cross-linked jugular vein implants were included as controls. After an implantation period of 1 month or longer, we observed many areas of calcification in the aortic media associated with elastin and fewer such areas associated with collagen. The elastin-rich aortic tissues accumulated more calcium than venous tissues. Calcium deposits appeared similar in both allogenic and xenogeneic implants. Calcified areas viewed under the electron microscope included intercellular nonfibrous material. Calcified areas involved predominantly the outer layers of elastic fibers. Calcific deposits included needle-like crystals of hydroxyapatite but often consisted of an amorphous flocculant material surrounded by crystals. The close spatial relationship of hydroxyapatite crystals and elastic membranes seen in this study may be relevant to the initiation of dystrophic calcification in glutaraldehyde cross-linked aortic grafts.     

Development of an experimental animal model for reactive arthritis induced by Yersinia enterocolitica infection.

We attempted to induce experimental arthritis in rats by systematically testing the effect of Yersinia infections in five strains of rats, using the intragastric, intraperitoneal, and intravenous routes of inoculation. We observed that Lewis rats which were given 10(4) to 10(5) Yersinia enterocolitica WA organisms via the intravenous route consistently developed arthritis. The arthritis was most severe at 3 weeks and subsided at 6 weeks. No arthritis was observed when this bacterial strain was administered to Buffalo, Fisher, DA, and LDA rats. No replicable bacteria were detected in the joints. This aseptic characteristic parallels that seen in the human condition and establishes this as an animal model of Yersinia-induced arthritis. The probable reason for arthritis development in only the Lewis rats became apparent when we analyzed the numbers of live bacteria in the spleens and livers of these infected animals. The arthritis-susceptible Lewis rats harbored 10-fold more bacteria than the arthritis-resistant rat strains, and this systemic infection also persisted for a significantly longer period. Speculations as to why human subjects who develop Yersinia-induced arthritis are genetically predisposed have been centered principally around the role of the HLA-B27 histocompatibility antigens. The present study reveals a heretofore unrecognized critical factor: the susceptibility of the hosts to the virulence of the infectious organisms. In addition, the present animal model will provide the necessary tool for the investigation of this and other important host and bacterial factors.     

Intestinal lesions associated with disseminated candidiasis in an experimental animal model

In human patients, disseminated candidiasis, a life-threatening disease for immunocompromised patients, is often associated with intestinal lesions. In this study, we demonstrate that immunosuppressed gnotobiotic (IGB) piglets orally inoculated with wild-type Candida albicans developed extensive intestinal lesions and disseminated infection. Severe ulceration of the ileal mucosa was observed overlying regions of colonization and necrosis of the gut-associated lymphoid tissue. Despite the high susceptibility of IGB piglets to many microbial pathogens, an avirulent mutant strain of C. albicans failed to produce intestinal lesions and exhibited poor dissemination, demonstrating that these effects required virulent organisms. It is likely that in IGB piglets, as in human patients, intestinal lesions provide the mechanism for escape of C. albicans from the gastrointestinal tract. Multinucleated giant cells containing fungal organisms were observed within lymph nodes and lymphatic vessels, and as with other pathogens, such cells could provide a mechanism for dissemination of C. albicans.     

Sympathectomy alleviates mechanical allodynia in an experimental animal model for neuropathy in the rat.

We attempted to determine the effects of surgical sympathectomy on an animal model for neuropathic pain. The L5 and L6 spinal nerves on one side were tightly ligated in anesthetized rats. Mechanical sensitivity of the affected hind paw was significantly elevated from the first day after the surgery as evidenced by the increased occurrence of foot withdrawal to innocuous mechanical stimulation applied with von Frey filaments to the hind paw. The increased mechanical sensitivity continued for three weeks, at which time surgical sympathectomy was performed by removing the L2-L6 sympathetic chain. The sympathectomy produced an immediate and almost complete reversal of the increased mechanical sensitivity, whereas sham sympathectomy had no effect. The data suggest that sympathectomy alleviates mechanical allodynia in this experimental animal model.     

Induction of muscle weakness by local inflammation: an experimental animal model

Objective and design:  The objective of this study was to characterize the response of skeletal muscle to a localized inflammation induced by the inflammatory agent casein. Methods:  An inflammatory agent, casein, was injected into the right hindlimb and saline was injected into the left hindlimb of normal adult mice, once daily for six consecutive days. Inflammatory response was monitored by immunohistochemical labeling of leukocytes. Muscle protein levels were determined by electrophoresis and muscle function was determined by isometric force measurements. Results:  Local inflammation was induced by casein in association with the accumulation of extensive neutrophils and macrophages in the solues muscle. This local inflammation resulted in a shift in myosin heavy chain (MHC) isoform expression and a significant reduction in total MHC concentration in the soleus. Maximal twitch and tetanic forces were significantly reduced in the inflamed soleus. Contractile function in soleus was fully restored after two weeks of recovery, along with the restoration of protein concentration and the disappearance of inflammatory cells. Conclusion:  This study establishes a unique and robust model in which mechanisms of local inflammation induced muscle protein degradation, reduction of contractile force, and subsequent recovery from this condition can be further studied. Received 22 February 2008; returned for revision 17 April 2008; received from final revision 2 July 2008; accepted by M. Parnham 7 July 2008     

Comparison of clinical and postmortem diagnosis of pulmonary embolism.

The incidence of pulmonary embolism and the number of clinically missed diagnoses of it in necropsies carried out between 1960 and 1984 at this department were investigated. Pulmonary embolism primarily affects elderly people with serious underlying disease; in this study it was found more often in women. The incidence of pulmonary embolism (9% of all necropsies) was unchanged during the period studied. In contrast, pulmonary embolism as the "sole" cause of death increased (p less than 0.0005). Although most pulmonary emboli were the immediate cause of death, the clinical diagnosis was often missed (in 84% of all cases). Furthermore, such clinically missed diagnoses increased over the years (p less than 0.005), especially in patients with heart disease and cancer. Without necropsy there will be considerable underdiagnosis of pulmonary embolism, therefore providing a misleading figure in the death statistics for this often fatal disease.     

Increased sensitivity to lead -- animal model: feline porphyria.

Individuals with the genetically inherited condition of latent porphyria have been previously hypothesized (1) as being a potential high risk group to elevated lead exposure. More specifically, persons with either clinical symptoms of porphyria or the latent form who also are exposed to excessive lead may have their clinical symptoms exacerbated or possibly induced prematurely, respectively. This paper presents evidence that an animal model (i.e., domestic cats with congenital porphyria) may facilitate the testing of the previous hypothesis.     

Large animal model of chronic pulmonary hypertension

A large animal model is needed to study artificial lung attachment in a setting simulating chronic lung disease with significant pulmonary hypertension (PH). This study sought to create a sheep model that develops significant PH within 60 days with a low rate of mortality. Sephadex beads were injected in the pulmonary circulation of sheep every other day for 60 days at doses of 0.5, 0.75, and 1 g (n = 10, 10, 7). Mean pulmonary artery pressure, pulmonary capillary wedge pressure, and cardiac output were obtained every 2 weeks. In the 0.5, 0.75, and 1-g groups, 90, 70, and 14.3% of sheep completed the study, respectively, with the remainder experiencing heart failure. By the 60th day, pulmonary vascular resistance had increased (p < 0.01) from 0.89 +/- 0.3 to 3.2 +/- 0.9 mm Hg/(L/min) and from 0.9 +/- 0.3 to 4.3 +/- 3.2 mm Hg/(L/min) in the 0.5 and 0.75-g groups, respectively. Significant right ventricular hypertrophy was observed in the 0.75-g group but not in the 0.5-g group. Data from the 1-g group were insufficient for analysis due to high mortality. Thus, the 0.5 and 0.75-g groups generate significant PH, but the 0.75-g group is a better model of chronic PH in lung disease due to the development of right ventricular hypertrophy.     

Changes in transglutaminase activity in an experimental model of pulmonary fibrosis induced by paraquat.

An experimental model of pulmonary fibrosis has been developed by dosing rats with one-fifth the LD50 dose of the herbicide paraquat on 5 consecutive days. Approximately 50% of the rats died within 4 days of the completion of dosing, showing macroscopic changes and wet weight increases in the lung consistent with severe oedema. Those animals which died between Days 4 and 10 had markedly increased levels of hydroxyproline in the lung, maximum at Day 6, and increased prolyl hydroxylase activity, maximum at Day 4. These changes, together with an increase in thymidine incorporation into DNA, and increased lung DNA content, were consistent with the development of fibrosis. Measurement of transglutaminase activity in the lung showed marked increases at Days 4 and 10 after completion of dosing. This activity paralleled closely the changes in prolyl hydroxylase activity and became increasingly associated with particulate protein present in the "nuclear pellet" fraction. The presence of zymogen plasma transglutaminase trapped in lung homogenates could not be demonstrated but the contribution by the active plasma transglutaminase (Factor XIIIa) to increases shown at Day 4 cannot be ruled out.     

L-3-n-butylphthalide promotes restoration after an experimental animal model of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating type of stroke with high morbidity and mortality, and the effective therapies for ICH remain to be explored. L-3-n-butylphthalide (NBP) is widely used in the treatment of ischemic stroke. However, few studies evaluated the therapeutic effects of NBP on ICH. Therefore, the present study aims to evaluate the effects of NBP on ICH and its potential mechanism. The rats were randomly divided into sham-operated group, saline-treated (ICH + saline) group, and NBP-treated (ICH + NBP) group. The ICH model of SD rats induced by IV collagenase was established. The modified Garcia JH score was used to detect the neurological deficit in rats. Western Blot and immunohistochemistry analysis was applied to test the levels of UBIAD1 and caspase-3 expressions in the perihematomal region. The rates of apoptotic cells were detected by TUNEL staining. The results showed that NBP up-regulated the expression of UBIAD1, reduced the apoptotic cells in the perihematomal region, and improved the neurological deficit. Taken together, our study added some new evidence to the application of NBP in ICH treatment.     

Development of an animal experimental model for a bileaflet mechanical heart valve prosthesis

The objective of this study was to develop a pre-clinical large animal model for the in vivo hemodynamic testing of prosthetic valves in the aortic position without the need for cardiopulmonary bypass. Ten male pigs were used. A composite valved conduit was constructed in the operating room by implanting a prosthetic valve between two separate pieces of vascular conduits, which bypassed the ascending aorta to the descending aorta. Prior to applying a side-biting clamp to the ascending aorta for proximal grafting to the aortic anastomosis, an aorta to femoral artery shunt was placed just proximally to this clamp. The heart rate, cardiac output, Vmax, transvalvular pressure gradient, effective orifice area and incremental dobutamine stress response were assessed. A dose-dependent increase with dobutamine was seen in terms of cardiac output, Vmax, and the peak transvalvular pressure gradient both in the native and in the prosthetic valve. However, the increment was much steeper in the prosthetic valve. No significant differences in cardiac output were noted between the native and the prosthetic valves. The described pre-clinical porcine model was found suitable for site-specific in-vivo hemodynamic assessment of aortic valvular prosthesis without cardiopulmonary bypass.