Stefano Bacci

Cerebellar liponeurocytoma : Morphological, immunohistochemical, and ultrastructural study of a relapsed case

Cerebellar liponeurocytoma is a rare and newly identified neoplasm  found  in  adults  which  is  reputed  to  be benign. Its salient morphological characteristics are advanced neuronal/neurocytic differentiation, the presence of lipomatous areas, low mitotic rate, and the absence of necrosis, pleomorphism and vascular hyperplasia. Reported is a case of relapsing liponeurocytoma which occurred 3 and a half years after the radical excision of the primary lesion. Histopathological aggressive features (mitoses and a high proliferation index as evaluated by MIB‐1) were shown in the primary lesion and recurrence of the tumor. We suggest that liponeurocytoma is an uncertain malignant potential lesion when mitoses are present and the MIB‐1 positive cells are more than 10%.

Smooth muscle cells, dendritic cells and mast cells are sources of TNFalpha and nitric oxide in human carotid artery atherosclerosis ☆

INTRODUCTION In atherogenesis, dendritic cells, beside presenting antigens, may be sources of tumour necrosis factor (TNF)alpha and nitric oxide (NO), together with mast cells and smooth muscle cells. MATERIAL AND METHODS We have looked at the expression of TNFalpha and inducible NO synthase (iNOs) by these cells by affinity cytochemistry in autoptical specimens from normal carotid arteries and not ruptured, hemorrhagic or calcified atheromata. RESULTS Round to dendritic, major histocompatibility complex class II molecules (MHC-II+) cells and avidin-labeled mast cells were rare in normal arteries and significantly more numerous in atheromata. Many MHC-II+ cells expressed S-100 antigen; while a few were positive for phalloidin; appreciable fractions of these cells were immunoreactive for TNFalpha and iNOs, both in control specimens and atheromata. The fraction of mast cells labeled for iNOs was significantly lower in atheromata than in controls. Phalloidin positive cells were the most abundant cell type in the normal intima and atheromata; the fractions of these cells labeled for TNFalpha and iNOs were significantly higher in atheromata than in controls. Very few of these cells were also labeled for MHC-II. Computerized image analysis confirmed that the amounts of iNOs and TNFalpha were higher in atheromata than in controls. The increase in TNFalpha in atheromata was also confirmed by western blot. CONCLUSIONS Dendritic cells and mast cells can participate to the generation of TNFalpha and NO in the normal arterial wall and in atheromata, but myointimal cells are candidates as major sources of these molecules.

Distribution of mast cells in human ileocecal region

The number and histochemistry of mast cells were analyzed in surgical specimens of the ileocecal junction and neighboring intestinal segments. All the basophilic cells contained tryptase and some were immunoreactive for chymase, vasoactive intestinal polypeptide, or nitric oxide synthase. The medium density of mast cells per square millimeter was 31.90, 110.38, 72.83, 29.80, and 32.70, in the mucosa, submucosa, inner circular, outer circular, and longitudinal muscle layers, respectively. Mast cell density was higher at the ileocecal junction (for all layers together, 79.29 mast cells/mm2) than elsewhere (mast cells/mm2: ileum, 52.29; cecum, 59.22; cecocolonic junction, 54.65; ascending colon, 48.63). The differences among layers and among segments were significant and might be due to layer- and region-specific mast cell roles. Mast cell richness in the muscle coat, especially in the inner circular muscle layer, might be important in regulating its motility.

Inflammatory events in a vascular remodeling model induced by surgical injury to the rat carotid artery.

The aim of our study was to gain insight into the molecular and cellular mechanisms of the inflammatory response to arterial injury in a rat experimental model. Rats (five for each experimental time) were subjected to brief clamping and longitudinal incision of a carotid artery and monitored for 30 days. Subsequently, Nuclear Factor‐kappaB (NF‐κB) expression was measured by electrophoretic mobility shift assay. Heat shock protein (HSP) 27, HSP47 and HSP70 were evaluated by Western blot. Morphological changes of the vessel wall were investigated by light and electron microscopy. In injured rat carotid artery NF‐κB activity started immediately upon injury, and peaked between 2 and 3 weeks later. Western blot showed a significant increase of HSP47 and HSP70 7 days after injury. At 2 weeks postinjury, HSP27 expression peaked. Ligth microscopy showed a neointima formation, discontinuity of the media layer and a rich infiltrate. Among infiltrating cells electron microscopy identified dendritic‐like cells in contact with lymphocytes. Our model of surgical injury induces a significant inflammatory process characterized by enhanced NF‐κB activity and HSPs hyperexpression. Dendritic‐like cells were for the first time identified as a novel component of tissue repair consequent to acute arterial injury.

Nitric oxide synthase immunoreactivity in the human ileocecal region

The nitric oxide (NO) producing neurons in the human ileocecal region (pre-junctional ileum, ileocecal and cecocolonic junctions, cecum and post-junctional colon) have been evaluated by immunocytochemistry. The percentage of NO synthase-positive neurons was higher at the myenteric plexus than at the submucous plexus, independently of the levels examined. The inner portion of the circular muscle layer, except at the ileal level, was devoid of immunoreactive nerve fibers. Data obtained suggest that neuronal-released NO at the ileocecal region has a greater role in the relaxation of the muscle coat, except for the inner circular muscle layer, than in the regulation of blood flow, absorptive and secretory processes.

Gastric mucosal histamine storing cells

Gastric mucosal histamine content, enterochromaffin-like cell density, and mast cell density were studied in 13 subjects under omeprazole therapy, 13 partially gastrectomized subjects with a Billroth II reconstruction, 10 partially gastrectomized subjects with a Roux-en-Y reconstruction, and 9 control subjects. Histamine content was significantly greater both in the subjects with higher gastrinemic levels (omeprazole-treated subjects) and those with more abundant enterogastric reflux (Billroth II subjects) than in controls. Enterochromaffin-like cell density was significantly greater in the omeprazole subjects than in each of the other groups. Mast cell density was significantly greater in Billroth II subjects than in controls. Serum gastrin levels, mucosal histamine content, and enterochromaffin-like cell density were positively correlated. Gastrin was not correlated to mast cell densilty. These results support the existence of different control pathways for enterochromaffin-like and mast cells. Moreover, they suggest that enterochromaffin-like cells and mast cells are involved in the regulation of gastric secretion and in gastric mucosal injury-repair mechanisms, respectively, due to histamine release.

Distribution of VIP-immunoreactive nerve cells and fibers in the human ileocecal region

VIP-containing nerve cells and fibers in the human ileocecal region (pre-junctional ileum, ileocecal and cecocolonic junctions, post-junctional cecum and colon) have been evaluated by immunocytochemistry. A high density of VIP-positive neurons and nerve fibers was found in all layers of the ileum. At all colonic levels examined and at both junctions, the percentage of VIP-containing cells was higher in the submucous plexus than in the myenteric plexus. At both junctions, the muscle wall was devoid of, and the myenteric plexus extremely poor in VIP-positive nerve fibers and cells. These data suggest that motility of these junctions is not--or only to a minor extent--regulated in man by VIP-containing nerves, at variance with other gut sphincteric areas.

Immunohistochemical analysis of dendritic cells in skin lesions: correlations with survival time

The response to wounds until healing requires the activity of many cell types coordinate in space and time, so that the types of cells in a wound and their localization may be of help to date lesions with respect to death, which would be useful in forensic pathology. Cells reacting to injury include dendritic cells; the early reaction of these cells to skin wounding has not yet been investigated in humans, which was the aim of this study. Samples of wounded and control skin were taken at autopsy and analyzed by affinity histochemistry. Both epidermal and dermal MHC-II+ cells increased transiently in number within the first hour after wounding, then decreased. In the epidermis the increase affected also CD1a+ cells, i.e. well differentiated Langherhans cells, which however increased less, earlier and for a shorter time period than MHC-II+ cells. Dermal MHC-II+ cells became part of a perivascular mononuclear cell infiltrate visible in the subpapillary dermis by 60 min after wounding, which contained also mast cells. The immediately perivascular MHC-II+ cells were DC-SIGN- and CD11c-, while MHC-II+, DC-SIGN+, CD11c+ dendritic cells were predominantly located at the periphery of infiltrates and some were near the epidermis. Mast cells underwent degranulation, besides increase in number, in the first hours after wounding. The results suggest that skin dendritic cells, including Langerhans cells, participate to the early response to wounding in concert with mast cells, and that subpapillary blood vessels are primary sites of cell infiltration during that response in humans. The results show that the ratio between CD1a positive and MHC-II positive cells in the epidermis, the degranulation index of mast cells and the relative volume of MHC-II positive cells in the dermis can be added to the tools useful to distinguish vital from post mortem lesions and, the first two of them, to estimate the interval between a lesion and death.

Gravitational stress on germinating Pinus pinea seeds.

In the germination of lipid-rich seeds, the glyoxylate cycle plays a control role in that, bypassing the two decarboxylative steps of the Krebs cycle; it allows the net synthesis of carbohydrates from lipids. The activity of isocitrate lyase, the key enzyme of the glyoxylate cycle, is an indicator of the state of seed germination: stage of germination, growth of embryo, activation and progress of protein synthesis, depletion of lipidic supplies. In order to investigate the effects of gravity on seed germination, we carried out a study on the time pattern of germination of Pinus pinea seeds that were subjected to a hypergravitational stress (1000 g for 64 h at 4 degrees C), either in a dry or in a wet environment, before to be placed in germination plates. During the whole time of germination, we monitored the state of embryo growth and the most representative enzymes of the main metabolic pathways. In treated wet seeds, we observed an average germination of only 20% with a slowdown of the enzyme activities assayed and a noticeable degradation of lipidic reserves with respect to the controls. These differences in germination are not found for dry seeds.

Blue led treatment of superficial abrasions

A compact and easy-to-handle photocoagulation device was used for inducing an immediate coagulation effect in skin large superficial abrasions, reducing the recovering time and improving the wound healing process. The handheld illumination device consists of a high power LED, emitting in the blue region of the spectrum, mounted in a suitable and ergonomic case, together with power supply, electronics, and batteries. The working principle of the LED-based photocoagulator is a photothermal effect: the blue light is selectively absorbed by the haemoglobin content of the blood and then converted into heat. Here we present an in vivo study performed on animal models. 10 Sprague Dawley rats (Harlan, Italy, weighing 200-250 g) were used to study the wound healing process. On the back of each rat, four large abrasions were mechanically produced: two of them were used as a control, while the other two were treated with the photocoagulator, keeping it at a constant distance (2 mm) from the target, in continuous slow motion (treatment time: tens of seconds). The induced photothermal effect was monitored by an infrared thermocamera in order to avoid accidental thermal damage and to control the temperature dynamics during treatment. Objective observations, histopathological analysis and non-linear microscopy performed in a 8 days follow-up study showed no adverse reactions and no thermal damage in the treated areas and surrounding tissues. Moreover, a faster healing process and a better recovered morphology was evidenced in the treated tissue.