The expression and the nuclear activity of the caretaker gene Ku86 are modulated by somatostatin

Somatostatin is a peptide hormone that exerts antisecretory and antiproliferative activities on some human tumors. The Ku70/86 heterodimer acts as regulatory subunit of the DNA dependent protein kinase and its DNA binding activity mediates DNA double strands breaks repair that is crucial to maintain the genetic integrity of the genome. The activation of the heterodimer regulates cell cycle progression and the activity of nuclear transcription factors involved in DNA replication and cell proliferation. Moreover Ku86 behaves as a receptor for the growth inhibitory tetradecapeptide, somatostatin. Herein we report that somatostatin treatment to a colon carcinoma cell line (Caco-2) inhibits cell growth and, at same time, strongly modulates the activation of Ku70/86 heterodimer and the levels of Ku86 in the nucleus by increasing its specific mRNA level. Our findings are consistent with the hypothesis that somatostatin controls cell cycle progression and DNA repair through a new signalling pathway that involves the regulation of Ku86 level and modulates the Ku70/86 activity in the nucleus

Synchronized onset of nuclear and cell surface modifications in U937 cells during apoptosis

In this study we investigated the relationship between nuclear and cell surface modifications (i.e. blebbing, phosphatidylserine [PS] and sugar residues exposure) in a monocytic cell line, U937, during apoptosis induced by oxidative stress (1mM H2O2) or inhibition of protein synthesis (10 mg/ml puromycin). Dying cells were simultaneously observed for nuclear modifications, presence of superficial blebs and plasma membrane alterations. Morphological analysis performed by conventional fluorescence microscopy, or by transmission and scanning electron microscopy showed that the courses of nuclear and membrane alterations occured concomitantly, but the phenotype was dependent on the stage of the apoptotic process and the type of apoptogenic inducer used. The progression of apoptosis in U937 cells beyond early stages resulted in the extensive formation of blebs which concomitantly lost some typical markers of apoptosis, such as PS and sugar residues. Therefore, the modality by which the nucleus condenses, or the amount and the pattern of distribution of PS on the cell surface were, for each cell line, strictly related to the apoptogenic inducer. The morphological data reported in the present paper should lead to a more precise quantification of apoptosis by improving the detection of apoptotic cells in vivo (i.e. in tissue, organs), which is a crucial point in the evaluation of efficiency of antiproliferative drugs, such as antiblastic or immunosuppressive compounds

Morphometric analysis of gap junctions in regenerating arterial endothelium

Gap junctions may provide the structural basis for communication between arterial and endothelial cells and modulate their response to injury. We have utilized autoradiography and freeze fracture techniques to correlate proliferative activity with changes in the organization, density, and surface area of gap junctions in healing arterial endothelium. A well-circumscribed, reproducible area of endothelial loss was produced in the common carotid artery of the rabbit by desiccation of the intima. The lesion healed in 15 days by centripetal proliferation and migration of endothelial cells from adjacent uninjured areas. As controls, we used the uninjured contralateral artery. In parallel experiments, the vascular endothelium was sampled either for autoradiography after administration of 3H-thymidine or for freeze fracturing. Proliferative activity was measured by calculating the labeling index in autoradiographs of endothelium. The surface areas of gap junctions and that of the lateral endothelial membranes was measured by planimetry in electron micrographs of freeze fracture replicas. Two days after injury, cells at the growing edge of the endothelium revealed a marked decrease in the density and surface area of gap junctions, loss of tight junctions, and high labeling index (232 +/- 55 S.E.M.). At seven days, the labeling index was lower (61 +/- 31 S.E.M.), gap junctions were small but numerous, and short segments of tight junctions were present. At fifteen days, the endothelial integrity was restored, the labeling index was at control levels (3.32 +/- 3 S.E.M.), and both gap and tight junctions were well developed and indistinguishable from controls. The study shows that loss of junctions between endothelial cells is associated with high proliferative activity. As a corollary, well-developed gap junctions may prevent the response of the uninjured endothelium to circulating mitogens

Polyostotic fibrous dysplasia involving the sternum

The authors present a case of polyostotic fibrous dysplasia involving the sternum as well. The case is well supported the strumental and histological point of view

Lead brachial neuropathy in heroin addiction. A case report

The possible toxical effect of heavy metals in the pathogenesis of brachial and lumbar plexopathies during heroin addiction has been previously hypothesized by some authors, but never detected. A 24-year-old man, addicted to heroin showed the clinical picture of a symmetrical brachial neuropathy, without other neurological involvement. Lead poisoning was detected in this patient and the chelating therapy induced a marked improvement of the clinical symptoms

Age-related modifications of aorta and coronaries in the rabbit: A morphological and morphometrical assessment

Aging seems to be related to various vascular diseases, such as dissecting aneurysm and atherosclerosis. The nature of the relationship between aging and these vascular diseases has not been completely clarified. The goal of this study was to investigate, using morphological and morphometrical methods, the age related modifications of the arterial wall in rabbits of three different ages, evaluating separately two different vascular districts and the various aortic segments. Our results confirm that the most relevant age-related structural aortic changes were the increase of thickness, length, volume and diameter of the vessels, together with the development of an intimal thickening. The latter was diffuse in the aorta and focal in coronary vessels and it appears earlier in the aorta than in the coronaries, being absent in the coronaries of young rabbits. In addition, morphological and ultrastructural studies revealed the presence in aged rabbits of some marked intimal storage of a ground substance into intimal thickening of proximal aortic segments. Morphometric studies demonstrated an age-related decrease of aortic cellularity of tunica media and a parallel increase of the content of collagen and glycosaminoglycans, whereas elastin did not vary. The different relationships between cells and interstitial tissue occurring with aging are most probably a phenomenon of adaptation to the changing forces acting on the arterial wall and they might constitute the structural background of the increased arterial susceptibility to various noxae. Finally, the intimal storage of the ground substance, probably related to a functional disturbance of endothelium and or smooth muscle cells, may play an initiating role in atherogenesis

Ultrastructural studies of spontaneous in vitro transformation of cultured marrow monocyte-macrophage cells from a patient with congenital hypoplastic anemia

The CM-S cell line was established from the bone marrow of a patient suffering from congenital hypoplastic anemia (syndrome of Diamond-Blackfan). The cells grew in suspension in liquid culture and were dependent for their continuous replication in vitro on growth factors produced by the same cells seeded at high density. Initially, undifferentiated blasts, immature myeloid, megakaryocytic and, rarely, erythroid cells were observed. Eventually, a population of cells with characteristics of monocyte-macrophage precursors predominated. These cells could be induced to terminal macrophage differentiation by incubation with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. During this period (over 150 continuous passages), the cells failed to form colonies in agar and to give rise to tumors when inoculated into athymic mice. On prolonged passages, however, the cells gradually increased their growth capacity in liquid culture and became capable of forming colonies in agar and tumors in animals. Ultrastructural studies revealed that the expression of differentiated traits markedly changed as a function of time: after 277 passages, the transformed cells, although displaying characteristics of monocyte precursors, appeared blocked at this stage and no longer responded to 12-O-tetradecanoylphorbol-13-acetate

Increased Expression and Activity of Matrix Metalloproteinases Characterize Embolic Cardiac Myxomas

Tumor embolism occurs in 30 to 50% of all cases of cardiac myxoma, but the causes are still uncertain. Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade the extracellular matrix (ECM) and play a crucial role in plaque instability and aortic aneurysm development, in addition to cancer and heart failure. To determine whether MMP activity contributes to tumor embolism, we examined 27 left atrium-sided myxomas, 10 of which showed clinical signs of peripheral embolism. Immunohistochemistry (in all cases) and Western blotting, and in situ and in-gel zymography (in four embolic and six nonembolic consecutive tumors) demonstrated higher expression and activity of MT1-MMP, pro-MMP-2, and pro-MMP-9 in embolic myxomas, whereas pro-MMP-1, MMP-3, and TIMP-1 levels were similar to those of nonembolic tumors. Reverse transcriptase-polymerase chain reaction demonstrated that increased MMP activity was due, at least in part, to increased transcription and that TIMP-2 transcripts increased in embolic myxomas. In vitro, embolic tumor cells retained higher MT1-MMP and pro-MMP-2 levels in basal conditions and after stimulation with interleukin-1β and interleukin-6. Increased MMP synthesis and release correlated with enhanced ECM degradation products containing glycosaminoglycan chains in embolic myxoma tissue. Our results strongly suggest that MMP overexpression may contribute to an excessive degradation of tumor ECM and increase the risk of embolism in cardiac myxomas

Radiolabeled native low-density lipoprotein injected into patients with carotid stenosis accumulates in macrophages of atherosclerotic plaque: Effect of vitamin E supplementation

Background-Accumulation of LDL within the arterial wall appears to play a crucial role in the initiation and progression of atherosclerotic plaque. The dynamic sequence of this event has not been fully elucidated in humans. Methods and Results-In 7 patients with previous transient ischemic attack or stroke and critical (>70%) carotid stenosis, autologous native [I-125]-labeled LDL or [I-125]-labeled human serum albumin were injected 24 to 72 hours before endarterectomy. Carotid specimens obtained at endarterectomy were analyzed by autoradiography and immunohistochemistry, Autoradiographic study showed that LDL was localized prevalently in the foam cells of atherosclerotic plaques, whereas the accumulation in the lipid core was negligible. Immunohistochemistry revealed that foam cells that had accumulated radiolabeled LDL were mostly CD68 positive, whereas a small number were alpha-actin positive. No accumulation of the radiotracer was detected in atherosclerotic plaques after injection of radiolabeled human serum albumin. In 3 patients treated for 4 weeks with vitamin E (900 mg/d), an almost complete suppression of radiolabeled LDL uptake by macrophages was observed. Conclusions-This study shows that circulating LDL rapidly accumulates in human atherosclerotic plaque. The prevalent accumulation of LDL by macrophages provides strong support to the hypothesis that these cells play a crucial role in the pathogenesis of atherosclerosis

[Occult carcinoma of the thyroid gland: an epidemiological study of autopsy material]

The occurrence of occult thyroid carcinoma at autopsy was examined in 507 consecutive autopsies performed over one-year in subjects without clinical evidence of thyroid cancer, from different regions of Italy, including areas of endemic goiter. We found 54 (10.65%) occult thyroid carcinomas. In 37 cases the histologic pattern was of the papillary type, with diameter ranging between 176 and 6000 microns, 12 of these cases showed a typical papillary pattern, 6 had a marked fibrosis, 2 had a cystic pattern, one showed a lymphoid stroma, and 17 had a follicular pattern. The remaining 17 cases were medullary carcinomas, with a diameter ranging from 50 to 1600 microns. The percentage of occult thyroid carcinomas reported in the present study may constitute real value of the occurrence of this tumor in the Italian population