Relationship between microbiologic and histologic features in bacterial pneumonia.

To investigate the relationship between the lung damage resulting from pneumonia and the local bacterial burden, we conducted a study comparing histologic and bacteriologic findings in pigs infected with bacterial pneumonia while free of antibiotic therapy and previous or concomitant lung disease. Seventy-eight lung specimens were obtained from 17 animals. The main findings are the following: (1) histologic lesions of pneumonia as well as parenchymal bacterial burden were unevenly distributed within the lungs and even within the lung segments; (2) specimens showing histologic evidence of pneumonia had significantly higher bacterial counts than specimens with bronchial infection and specimens with neither bronchial nor lung infection; (3) there was no significant difference in bacterial counts between lesions defined as pneumonia, confluent pneumonia and abscessed pneumonia; (4) we could not define a clearcut threshold for quantitative cultures to discriminate the presence or absence of pneumonia. This study providing experimental insights into the relationship between microbiologic and histologic features in bacterial pneumonia confirms previous findings in humans. Although, for investigational purpose, lung cultures can be helpful in determining the bacterial etiology of pneumonia, these data do not support the use of quantitative cultures for establishing a definite diagnosis of pneumonia.

Coxsackievirus B3-induced chronic myocarditis in mouse: use of whole blood culture to study the activation of TNF alpha-producing cells.

The pathogenesis of CVB3-induced chronic myocarditis remains unknown. Activated monocytes and macrophages may maintain ongoing inflammation during a persistent CVB3 infection and possibly represent the major mechanism leading to chronic myocarditis. We decided to study the activation status of cells by studying TNF alpha secretion in vitro using whole blood culture in CVB3-induced murine chronic myocarditis. Seven DBA/2 +/+ mice and 18 NMRI nu/nu mice were inoculated intraperitoneally with 5x10(5) pfu of CVB3, and mice were mock-infected. Thirty-one days post-infection, all mice were sacrificed, blood samples were obtained from the heart, and the heart was removed. Enteroviral genomic detection by RT-PCR, virus isolation and histological analysis of heart samples were performed. Heparinized whole blood (25 microliters) was cultured for 4 hr and 24 hr in sterile 96 well-plate containing 225 microliters RPMI in the presence or the absence of activators (LPS + PHA). The TNF alpha levels in the whole blood from mock-infected DBA/2 (n = 4) and NMRI nu/nu mice (n = 5) were not different. A moderate increase of TNF alpha was observed in three out of five DBA/2 mice with negative CVB3 that had no histological abnormalities in myocardium. An increased level of TNF alpha was found in the sole DBA/2 mouse with positive CVB3 detection and chronic myocarditis. An increased level of TNF alpha was found in one out of nine NMRI nu/nu mice with positive CVB3 detection and chronic myocarditis and in one out of seven mice with positive CVB3 detection exempt of lesions in myocardium. In other infected mice, the level of TNF alpha was normal. Enteroviral genome was not detected in the blood from infected mice at 31 days post-infection. The increased TNF alpha level in some mice may be designed for a beneficial inflammatory and immune response, however, an exaggerated release may be associated with an adverse effect. The normal TNF alpha level in whole blood cultures from mice with chronic myocarditis does not exclude enhanced cytokine production at infected loci such as myocardial tissue. This is the first report to use whole blood cultures to study the production of cytokines in virus-induced disease in a small animal model.

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.

[Evaluation of spatial discrimination performances of newborn infants with the visual pursuit of structured stimuli]. / Evaluation des capacités de discrimination spatiale des enfants nouveau-nés par la poursuite visuelle de stimulus structurés.

Pursuit eye movements have been recorded with the photo-oculographic technique from newborn infants during the presentation of stimulations specific for spatial discrimination functions. 72.5 per cent of 51 subjects whose eye movements have been recorded have successfully followed stimuli of spatial frequency up to 0.4 cycles per degree. Estimations of grating visual acuity are similar to those provided by the preferential looking technique.