The cerebral microvasculature of the rat: structure and luminal surface properties during early development

The development of the cerebral microvasculature of the rat was studied during three successive postnatal periods, namely: 1) neonatal period, i.e., 1 to 9 days after birth (capillary sprouting period); 2) myelinization period, i.e., 10 to 20 days; and 3) young adult period, i.e., 2 to 3 months. The survey covered structural aspects and distribution of binding sites for anionic or cationic probes and for albumin-gold complexes on the luminal surface of the microvascular endothelium. The salient results are: a) an extensive development of the endoplasmic reticulum of endothelial cells during the first period (presumably in relation with the production of basement membrane components); b) the high surface density of coated pits and coated vesicles that peaks during the myelinization period; c) the paucity of plasmalemmal vesicle and their differential distribution (their volume density is higher in the endothelium of arterioles than in that of capillaries and venules); d) the existence of an extensive smooth surface tubular system in the cytoplasm of endothelial cells, whose structural connections and functional significance remains to be established; and e) the presence of pericytes with elaborate interactions with endothelia in the early developmental periods. Labeling by perfused tracers indicates an uneven patchy distribution of binding sites for cationic ferritin (generally limited to the plasmalemma proper) and a more even distribution of binding sites for cationic and anionic hemeundecapeptides. Binding patterns did not change during the developmental periods studied. No binding sites were detected for albumin-gold complexes.     

Changes in the organization of membrane lipids during human platelet activation. Study by fluorescent and freeze-fracture cytochemistry

Modifications in the membrane lipid organization of human platelets activated with different agents (adenosine 5'-diphosphate, thrombin, collagen type I, and monosaccharides such as fucose, mannose, and galactose) were analyzed in vitro by using three lipid markers. Cholesterol was detected upon interaction with filipin, the anionic phospholipids were reacted with polymyxin B, and alterations in the degree of lipid packing were evaluated with the lipophilic fluorescent probe merocyanine 540, which reportedly inserts into bilayer domains whose lipids are more disordered. Filipin-sterol complexes and polymyxin B-anionic phospholipid complexes form characteristic membrane deformations which were examined in freeze-fracture preparations, whereas the merocyanine 540 binding to platelet membrane was recorded by fluorescent microscopy. In contrast to the resting cells, thrombin-stimulated platelets displayed an uneven distribution of filipin-sterol complexes which occurred in much higher density on the cell body than on pseudopods: on the latter, apparently cholesterol-free domains were very common. Unlike the non-stimulated cells, the platelets aggregated with the various agents employed showed characteristic polymixin B-anionic phospholipid complexes deformations of plasmalemma suggesting the appearance in uneven concentration of anionic phospholipids in the outer membrane leaflet. Incubation with merocyanine 540 did not result in staining of resting platelets when these were maintained in plasma, but a slight fluorescence was observed when platelets were kept in Tyrode buffer. However, platelets stimulated with thrombin, collagen type I, and monosaccharides bound very heavily the fluorescent dye; platelets aggregated with adenosine-5'-diphosphate bound only small amounts of merocyanine 540. The results showed that, during activation by different agents, modifications in lipid membrane organization include alterations in cholesterol and anionic phospholipid distribution, transbilayer movement of anionic phospholipids accompanied by more disordered membrane.     

Growing skull fractures of childhood. A particular form of posttraumatic encephalopathy

Summary The authors describe the findings in 12 cases of growing skull fracture of childhood as revealed by clinical and paraclinical investigations. Based on these findings the authors regard this pathological entity as a separate form of posttraumatic encephalopathy.

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Zusammenfassung Die Autoren beschreiben die klinischen und paraklinischen Befunde bei 12 Fällen von wachsender Schädelfraktur des Kindesalters. Auf Grund dieser Befunde betrachten die Autoren dieses Krankheitsbild als eine besondere Form der posttraumatischen Enzephalopathie.

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Resumen Los autores describen los hallazgos obtenidos en 12 casos de fractura de craneo en niños con el hueso craneal en crecimiento, como revelan sus estudios clínicos y paraclínieos. Estos hallazgos permiten al autor considerar esta entidad patológica como una forma particular de la encefalopatía postraumética.

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Résumé Les auteurs exposent leurs constatations dans douze cas de fracture progressive du crâne chez l'enfant, ceci à la lumière d'investigations cliniques et para-cliniques. Il leur est ainsi possible de considérer cette entité pathologique comme une forme particulière d'encéphalopathie post-traumatique.

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Riassunto Gli AA. descrivono i risultati di indagini cliniche e paracliniche di 12 casi si accrescimento delle fratture craniche infantili. Essi sono d'avviso che detta entità patologica debba essere considerata corne una forma particolare di encefalopatia posttraumatica.

     

Bilateral struma ovarii: a case mimicking an ovarian neoplasm

We present a case of bilateral struma ovarii which developed postoperatively and was histopathologically diagnosed after the patient was hospitalized for investigation and treatment of tumoral anexal bilateral formations. There was no evidence of clinical malignancy or metastases. Data from the literature, together with histopathologic, diagnostic and therapeutic aspects of the disease were checked again taking into account the scarcity of this lesion, especially bilaterally.     

Capillary and aortic endothelia interact in situ with nonenzymatically glycated albumin and develop specific alterations in early experimental diabetes

Diabetic mice (6 weeks duration) were studied to assess the interaction of advanced glycation endproduct-modifed albumin (AGE-Alb) with micro- and macrovascular endothelium, and to evaluate the alterations induced in the ultrastructure of the lung, kidney, and aorta. [¹²⁵I]-AGE-Alb and AGE-Alb-Au were perfused in situ in the vasculature; the total uptake was quantitated by spectrometry, and the endothelial pathways of AGE-Alb-Au and the morphological alterations of the vascular beds were examined by electron microscopy. The results showed that [¹²⁵I]-AGE-Alb (0.567 μM) was taken up specifically and saturably by all organs studied, and particularly by the lung. AGE-Alb-Au endocytosis and transcytosis occurred in the pulmonary and aortic endothelia, and were enhanced in diabetic animals. Also in diabetic animals, AGE-Alb-Au was detected throughout the kidney glomerular basement membrane (GBM) and within open filtration slits of podocytes, suggesting altered barrier function. The structural modifications progressed, and at the end of the experimental period, in the lung ∼28% of the capillaries and ∼25% of the alveoli became compressed or even collapsed, due to the hyperplasia of extracellular matrix and interstitial connective tissue. The presence of adherent intravascular macrophages suggests the development of an inflammatory immune process. The structural modifications observed in kidney glomeruli included thickening (∼30%) of the GBM and the disappearance of diaphragms between the cellular processes of podocytes. The aortic endothelium displayed luminal foldings, increased number (2.8-fold) of Weibel-Palade bodies, and proliferation of basal lamina. Together, the results show that in diabetes there is enhanced vascular uptake of AGE-Alb and significant pathomorphological changes of micro- and macrovessels. Received: 28 June 1996 / Accepted in revised form: 8 May 1997     

Transcatheter mitral valve replacement: tissue in-growth after 4 weeks

Open in a separate window OBJECTIVESTissue reaction to transcatheter mitral valve replacement in the mitral annulus remains to be elucidated.METHODSTrileaflet porcine pericardial valves were sewn onto self-expanding d-shaped nitinol stents, which were delivered transapically and in an off-pump fashion into the mitral position of 10 pigs. After at least 4 weeks of follow-up, gross pathological assessment and histological examination were performed. The specimens were stained with Movat’s pentachrome, Elastica-van-Gieson and von Kossa staining. The leucocytes, B cells, T cells or macrophages were detected by specific immunohistochemical staining.RESULTSProper stent positioning in the mitral annulus was achieved in 9/10 animals. Nine of 10 animals survived the desired observation period. In all but one, the mitral valve stent was well integrated into the left atrium and perpendicularly embedded into the annulus by 85 ± 24%. One animal had minor fractures in the nitinol struts and another animal showed tearing of 1 of 4 tethers. Histological examination demonstrated no major tissue reaction with the nitninol struts but well-preserved overall structures around the mitral annulus in 8/9 cases.CONCLUSIONSThis is the first report demonstrating good in-growth of transcatheter-delivered anatomically shaped mitral valve stents after at least 4 weeks of follow-up. Histological examination demonstrated progressive healing and neointimalization.     

VEGF expression and angiogenesis in oral squamous cell carcinoma: an immunohistochemical and morphometric study

Angiogenesis is involved in tumor progression of oral squamous cell carcinoma (OSCC). In this study, we have investigated by immunohistochemistry vascular endothelial growth factor (VEGF) expression in tumor cells and we have correlated VEGF expression to microvessel area, evaluated by using CD105 as a marker of endothelial cells, in bioptic specimens of 54 human OSCC. Results demonstrated that VEGF is highly expressed in OSCC tumor specimens when compared to pre-neoplastic and normal tissues, without differences between the edge and inside the tumor. Moreover, VEGF expression is reduced in poor differentiated OSCC tumors when compared to moderate and good differentiated forms, and tumor microvessel area is higher in tumors when compared to pre-neoplastic lesions and normal tissues. Finally, VEGF and CD105 may be considered as reliable markers of tumor angiogenesis and progression in OSCC, even if we did not demonstrate any correlation between VEGF expression, tumor microvascular area, clinical stage, and lymph node status.     

Structural and Optical Properties of Polyhydrosilanes

This work presents a study of the optical properties of polyhydrosilanes in relation with their specific chemical structure. For this purpose, poly[methyl(H)silane‐co‐diphenylsilane] copolymers with a different content of methylhydrosilyl‐segments have been investigated. Steady‐state fluorescence analysis and X‐ray photoelectron spectrometry showed that polyhydrosilanes possess a specific emission profile due to the presence of both methylhydrosilyl segments and silicon nanoparticles within the polymeric matrix. Polyhydrosilanes are capable of generating singlet oxygen reactive species at room temperature. This unusual property was investigated by analyzing the morphological changes in biological systems during Hek293 cell cultures growth in the presence of polyhydrosilanes.