[Morphologic and biochemical kinetics of the pathogenesis of acute lung injury by endotoxin in rats]. / Cinetica morfologica e biochimica della patogenesi del danno polmonare acuto da endotossina nel ratto.

BACKGROUND AND AIM: To highlight the intervention sequence of cells and their products (RO degree and NO) involved in the pathogenesis of lung injury caused by the instillation of endotoxin in rats. EXPERIMENTAL DESIGN: An experimental comparative study in rats. MATERIALS AND METHODS: The experiments were performed using intratracheal instillation of endotoxin in rats (5 mg/kg in 0.125 ml of saline solution). Untreated rats or those instilled with saline solution alone formed the control group. All animals were sacrificed 12, 24 and 48 hours after instillation and the following studies were performed on both lungs: 1) morphological study (optical and electronic); 2) assay of lung MDA; 3) NADPH-diaphorase evaluation using a histochemical method. RESULTS: Lung damage evolves gradually over 48 hours. After the first 12 hours, neutrophil granulocytes were present in the lung capillaries together with monocytes; monocytes were also present in the interstitium. During the following hours, monocytes differentiated into macrophages and, once activated, the granulocytes passed into the interstitium. The parenchyma appears to be extensively altered. Tissular MDA gradually increases until it reaches a maximum level (p < 0.01 vs basal) at 48 hours. Positivity for NADPH-d in macrophage and/or fibroblastic cells was evident after 24 hours and increased after 48 hours. CONCLUSIONS: Acute lung injury caused by endotoxin involves both NO and RO degree. Their production is related to different cell types and follows slightly different kinetic.

Cyclosporin-A affects the organization of cytoskeleton of normal human keratinocytes in culture.

Cyclosporin-A (CsA) is a potent immunoregulatory molecule which has been widely used in many immunomediated and inflammatory skin diseases. It inhibits the proliferation of keratinocytes, but its possible effects(s) on cell differentiation are poorly known. To address this issue, we have studied the influence of CsA on the assembly of intermediate filaments by normal human keratinocytes in culture. Control keratinocytes were flat; the cells which had not reached confluence stained intensely for vimentin and weakly for cytokeratins; confluent cells stained with intermediate intensity for both types of proteins and the cells adhering on the top of others, interpreted as the best differentiated ones, stained for cytokeratins but not for vimentin. CsA (1.6 micrograms/ml for 10 days) inhibited the growth of keratinocytes, which never reached confluence; most cells appeared small and roundish, only some stained for cytokeratins and few for vimentin. By electron microscopy, a well organized meshwork of tonofibrils was recognized in many control keratinocytes, but never in CsA-treated keratinocytes. We propose that the cytoskeleton could be a target of CsA and that its alteration mediates other effects of CsA on keratinocytes, including those on cell growth.

Odontogenic jaw cysts: light and electron microscopical investigations.

Light and electron microscopy were used to analyze the epithelial lining of odontogenic cysts excised from edentulous regions of the jaws. Clinically, three cases were identified as keratocysts, and 21 cases as cysts other than keratocysts ("non-keratocysts"). The epithelium of the former was found to achieve keratinization over most of the surface and to never contain mucus secreting cells. The epithelium of the latter appeared to be in part stratified squamous, with cells loosely connected to each other, and in part stratified columnar, with superficial cells connected to each other by tight junctions and secreting mucus. The results suggest that cysts arising from edentulous regions of the jaws may be either keratocysts or cysts with heterogeneous, non-keratinizing epithelium; the content of keratocysts can be formed mainly by shedding of cornified epithelial layers, and that of non-keratocysts by mucus secretion from columnar epithelium associated to fluid filtration through non-keratinizing squamous epithelium.

Evolution of endotoxin induced acute lung injury in the rat.

To clarify the evolution of acute lung injury induced by endotoxin, the progression of lung damage in 26 rats submitted to intratracheal instillation of 5 mg/kg body weight endotoxin was examined by blood gas analysis, computerized tomography, light and electron microscopy. Hypoxaemia, hypercapnia, acidosis and inhomogeneous bilateral infiltrates developed gradually within 48 hours. Monocytes appeared within blood capillaries and the instertitium by 12 hours after treatment, then migrated into alveoli and underwent progressive differentiation into macrophages by 24 hours after treatment. Granulocytes were found within blood capillaries at an early stage, but outside capillaries only at 48 hours. Hyperplasia of type II pneumocytes and hypertrophy of interstitial fibroblasts also occurred at 48 hours. These data suggest that the pathogenesis of endotoxin induced pulmonary injury proceeds through an early phase of granulocyte migration inside capillaries and monocyte extravasation, an intermediate phase of monocyte differentiation into macrophages inside alveoli and a late phase of diffuse infiltration of alveoli by newly differentiated macrophages and late-extravasated neutrophils.

Congenital nystagmus: fine structure of human extraocular muscles.

The ultrastructure of the extraocular muscles of patients affected by congenital nystagmus is still to be defined. Specimens obtained from patients suffering from either oculomotor congenital nystagmus or nystagmus associated with strabismus were studied and compared with specimens obtained from patients enucleated for various pathologies but not affected by any oculomotor system disorder. The scleral myotendinous junction and the muscle body (venter) were examined. In both these areas, damaged muscle fibers were found. 'Mitochondrial cores' and concentric myofibrils characterized the extraocular muscles of the patients with oculomotor congenital nystagmus. In the extraocular muscles of the patients affected by nystagmus associated with strabismus we also found mitochondria with concentric cristae surrounding a highly electron-dense spherical body and numerous, large rods. In conclusion, these data indicate that both contractile and mitochondrial modifications might be signs of an altered muscle function and seem to indicate that oculomotor congenital nystagmus should be included among the list of oculomotor myopathies.

Extraocular muscles in congenital strabismus: muscle fiber and nerve ending ultrastructure according to different regions.

The ultrastructure of the extraocular muscles of patients affected by congenital strabismus is not completely known, and the structures responsible of the pathogenesis of this condition are still to be determined. Specimens obtained from patients suffering from congenital strabismus were studied and compared with specimens obtained from patients enucleated for various pathologies and not affected by any disorder in the oculomotor system. The scleral myotendinous junction, where the occurrence of an altered proprioceptive innervation was already reported, was examined, and findings obtained were compared with those observed in the muscle body (venter), where motor innervation is prominent and usually described as normal. Only a small number of damaged muscle fibers was found everywhere. The damage consisted in alterations of both contractile structures and mitochondria and resulted in severer lesions in the scleral myotendinous junction rather than in the muscle body. The normal muscle fibers were innervated by motor nerve endings with normal features and by few altered proprioceptors. The less damaged muscle fibers were innervated by normal motor nerve endings and severely damaged proprioceptors. The most severely damaged muscle fibers did not receive any type of innervation. These data seem to imply that the most important functional alteration in strabismus regards the scleral myotendinous junction. It is the authors' opinion that these findings might have a clinical importance in choosing the treatment to be pursued in patients with a squint.

The zona glomerulosa of the adrenal gland in rats with portacaval shunt. An ultrastructural and morphometric study.

The zona glomerulosa of the adrenal glands was studied histologically, ultrastructurally and morphometrically in portacaval shunt (PCS)-bearing rats 4 weeks after surgery. Compared with controls, the zona glomerulosa of rats with PCS showed an increase in thickness and a reduction in the number of lipid droplets in the cells of its inner portion, adjacent to the intermediate zone. Moreover, electron microscopy and morphometry of the cells of the inner portion revealed that qualitative and quantitative changes occur, consisting in a decrease in lipid droplets, an increase in the amounts of smooth endoplasmic reticulum and mitochondria, enlargement of the Golgi apparatus, and the appearance of numerous dense bodies at the vascular cell poles. All the above findings indicate that PCS induces an enhanced activity of the fully differentiated cells of the zona glomerulosa, which may be considered as an adaptive response--mediated by an activation of the renin-angiotensin system--to the lowering of the systemic pressure taking place in this experimental condition.