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Biomedical subjects

M Canepa

Publications and source records attributed to M Canepa.

At least 19 recordsLinked to original sources
PubMed2006

Isolating the step contribution to the uniaxial magnetic anisotropy in nanostructured Fe/Ag(001) films.

We have investigated the possibility of isolating the step-induced in-plane uniaxial magnetic anisotropy in Fe/Ag(001) films on which nanoscale surface ripples were fabricated by the ion sculpting technique. For rippled Fe films deposited on flat Ag(001), the steps created along the ripple sidewalls are shown to be the only source of uniaxial anisotropy. Ion sculpting of ultrathin magnetic films allows one to selectively study the step-induced anisotropy and to investigate the correlation between local atomic environment and magnetic properties.

Journal Article↗
PubMed2004

Temperature driven reversible breakdown of pseudomorphism in ultrathin Fe/Cu3Au films.

We observe that ultrathin Fe/Cu(3)Au(001) films in the 6-13 A thickness range, beyond the thickness of pseudomorphism breakdown at room temperature, exhibit a temperature dependent structural phase transition in the range T(c) approximately 345-380 K. In the high temperature state the Fe film becomes pseudomorphic, while breakdown of pseudomorphism reversibly occurs as the system is cooled below the transition temperature. The difference between substrate and overlayer thermal expansion coefficient is highlighted as the driving force for the observed transition.

Journal Article↗
PubMed2004

Self-assembled monolayers of organosulphur molecules bearing calix[4]arene moieties.

We investigate the self-assembly of modified calix[4]arene on gold surfaces. Calix[4]arene was modified through a reaction sequence which led to assembling of the crown-5 moiety and to the insertion of two thioether groups into the starting molecule. The so-obtained calix[4]arene-crown-5 bis(7-thiatridecyloxy) (hereafter called calix[4]arene) was in the stable 1,3-alternate conformation. The calix[4]arene/gold interface was investigated by means of spectroscopic ellipsometry (SE), scanning tunneling microscopy (STM) and cyclic voltammetry (CV). SE data indicate a layer thickness compatible with the formation of a monomolecular layer. This result is confirmed by STM imaging which shows the formation of a high density of small pits, one gold layer deep, a typical feature of self-assembled organosulphur monolayers on gold. CV measurements performed in presence of the [Ru(NH(3))(6)(2+/3+)] redox couple indicate a passivation of the metal electrode, resulting in a reduction of the redox current, after the layer deposition. CV has also been used to investigate the selectivity properties of calix[4]arene-covered gold electrodes by measuring the redox current decrease in the presence of different salt solutions. It is found that calix[4]arene-covered electrodes are able to complex K(+) and Ba(2+), while no complexation is observed in the case of Li(+), Na(+), Cs(+), Mg(2+) and Ca(2+).

Adsorption↗
PubMed2001

Photochemistry and spectroscopy of "stable organic radicals": steric and electronic effects in intermolecular photoinduced electron transfer.

The intermolecular reactivities of amino-substituted perchlorotriphenylmethyl radicals 1-3 were studied, with particular emphasis on electron transfer (ET) reactions. The natural fluorescence lifetimes and the rates of the electron-transfer quenching were studied with several electron donors and acceptors. Fluorescence quenching studies demonstrate the importance of the redox potentials of the ET pair on the observed steric and electronic properties.

Journal Article↗
PubMed1999

Subacute measles encephalitis in a young man immunosuppressed for ankylosing spondylitis.

Subacute measles encephalitis occurred 1 month after measles onset in a 26-year-old HIV-negative man undergoing immunosuppressive treatment for ankylosing spondylitis. He had seizures, a decline in mental status, and progressive impairment of consciousness, with a fatal outcome. Despite severely deficient cellular immunity, the elevated antimeasles antibody titers and CSF findings indicated that humoral immunity was not impaired. Histologic, electron microscopic, and immunocytochemical studies revealed the typical intranuclear inclusions of paramyxovirus nucleocapsids, and measles virus antigen in neurons and oligodendrocytes.

Adult↗
PubMed1997

[Detection of Helicobacter pylori in 201 stomach biopsies using the polymerase chain reaction, histological staining (H&E/Giemsa) and immunohistochemistry].

Helicobacter Pylori is believed to be an essential etiologic agent of type B chronic gastritis and peptic ulcer disease in humans. Recent reports have also suggested a role for these organisms in the development of gastric carcinoma and MALT-Lymphoma. A variety of diagnostic procedures are used for the identification of Helicobacter Pylori in clinical samples. 201 gastric biopsy (164 antral and 37 body biopsy specimens) were obtained from 164 patients with endoscopic abnormalities. These samples were studied for the detection of the presence of Helicobacter Pylori by histological staining (EE/Giemsa), immunohistochemistry and PCR by using a primer pair derived from the nucleotide sequence of the Urease A gene of Helicobacter Pylori. Specific amplification of a 411 base pair DNA fragment from all strain of Helicobacter Pylori tested was achieved. Of the 201 gastric biopsy analyzed, 63 (31%) were infected with Helicobacter Pylori on the basis of both histological and immunohistochemical staining, and 81 (41%) were positive with PCR (P < 0.001). Our results support a role for PCR in the rapid and highly sensitive and specific identification of Helicobacter Pylori in gastric biopsy specimens.

Azure Stains↗
PubMed1996

Isolated lung perfusion with platinum in the treatment of pulmonary metastases from soft tissue sarcomas.

A multimodality approach including operation and isolated lung perfusion with platinum was used in six patients with lung metastases from soft tissue sarcomas. Staged thoracotomies were used in two patients with bilateral lesions. The inclusion criteria generally applied for surgical excision were adopted in this study. The pulmonary artery and a portion of the left atrium were isolated from systemic circulation and cannulated. The cannulas were then connected to a perfusion circuit and normothermic isolated lung perfusion was done for 60 minutes. The lung was then flushed and metastasectomy was done. Serial blood (systemic and pulmonary), tissue (normal lung and tumor), and urine samples were obtained for platinum content measurement by flameless atomic absorption spectroscopy. Lung damage was assessed by light and electron microscopy examination and by serial respiratory tests. Isolated lung perfusion was accomplished in all patients without any death, operative complication, or systemic toxicity. After operation, interstitial and alveolar edema developed in two patients (48 hours after treatment), necessitating respiratory support in one case. Total platinum concentrations in pulmonary plasma were about 43 times greater than those in systemic plasma. No differences in platinum concentrations between normal lung and metastatic tissue were found. Thus the proposed isolated lung perfusion technique is feasible and safe enough to be offered as a valid model to study combined chemosurgical approaches in the treatment of lung metastases.

Adult↗
PubMed1995

Impairment of vitamin A uptake by rat hepatocytes and fat storing cells determined by Monensin--morphological observations.

The action of the Na+/H+ antiport monensin on vitamin A uptake by rat liver has been studied in vivo. The quickfading autofluorescence of vitamin A has been used for the determination of vitamin A uptake by the liver. Pretreatment of rats intraperitoneally with monensin decreases the uptake of vitamin A by hepatocytes and its transfer for storage to fat storing cells. Pretreatment of rats intraperitoneally with vitamin A for a short time, then with monensin, shows that the hepatocytes no longer transfer vitamin A to fat storing cells for storage. These results might indicate that monensin impairs the uptake of vitamin A by the hepatocytes and might also impair the transport of vitamin A from parenchymal to perisinusoidal cells.

Adipocytes↗
PubMed1995

[Perisinusoidal stellate cells in a model of experimental liver cirrhosis].

The association of the common bile duct (CBD) ligation followed by CCl4 and progesterone treatment leads to liver cirrhosis in rats in 28 days. The resulting cirrhosis shows mixed aspects: it starts as biliary cirrhosis and goes on to nodular and periportal pseudolobular form of cirrhosis. Because Ito cells are the main source of extracellular matrix components, changing their phenotype from quiescent Ito cells to myofibroblast like cells, the purpose of this study was to evaluate the behaviour of Ito cells by the immunohistochemistry technique of desmin and alpha-SM-actin after these treatments. After CBD ligation alone, positive Ito cells for desmin remarkably proliferate around adenomateous areas; after treatment with CCl4 alone desmin positive stellate cells are more numerous. Desmin positive Ito cells in CBD ligation and CCl4 treatment were even larger than those of the previous lots. Significant differences were not observed after progesterone and for the alpha-SM-actin positive cells.

Animals↗
PubMed1994

AgNORs in ductal breast cancer: correlation with ploidy and S-phase fraction by DNA flow cytometry.

Silver-binding nucleolar organizer regions (AgNORs) have been counted in sections of routinely processed paraffin embedded material. The AgNOR score has been correlated with proliferative activity of various neoplasms. An increase in the AgNOR score can be related to cellular growth fractions or DNA-ploidy. We have examined 301 invasive ductal breast carcinomas by this method. The AgNOR counts were also compared with DNA Ploidy and the S-phase fraction flow cytometry. A positive correlation has been found between the AgNOR score and the S-Phase fraction. These data show cell proliferation. We conclude that AgNOR counting may provide information on breast carcinoma in addition to that obtained from flow cytometric analysis.

Breast Neoplasms↗
PubMed1994

Comparative DNA analysis of breast cancer by flow cytometry and image analysis.

Measurement of DNA ploidy can be performed either with Flow Cytometry (FCM) and Image-Analysis (IA); both methods provide prognostic information in primary breast cancer. We compared the results of quantitative DNA analysis of formalin fixed, paraffin embedded tissue from 62 invasive ductal breast cancers. For FCM nuclear suspensions from disaggregated tumor were stained with Propidium Iodide and analyzed by means of Ortho Cytoron Absolute. For IA nuclear suspensions were stained by the Feulgen method and analyzed by means of Vidas system. We found a good correlation between flow cytometry DNA Index and Histogram Type, according to Auer classification (rs = 0.65, p < 0.001) and between DNA Index and Grading of Malignancy (MG) which had been measured by Bocking's algorithm (rs = 0.38, p < 0.05). Concerning to disease free survival (DFS), flow cytometric DNA Index showed a better correlation (rs = 0.56, p < 0.001). We concluded that the two methods provide comparable results, but offer individual advantages and are complementary for analyzing DNA ploidy in breast cancer.

Algorithms↗
PubMed1994

Human breast cancer: prognostic significance of DNA ploidy compared with c-erbB2 expression, Cathepsin D and silver-binding nucleolar organizer regions (AgNORs).

We evaluated breast cancer specimens from 150 patients after a follow-up more than 10 years, by means of DNA flow cytometry, immunohistochemistry (cerbB2 and Cathepsin D) and argyrophilic (AgNORs) methods. In univariate analysis all indexes studied provide prognostic information about the disease free survival, whereas in the multivariate Cox model the DNA Index is the most important prognostic factor. We conclude that the data obtained from DNA flow cytometry, associated with other parameters, can be of greatest importance for the decision an the level of aggressiveness of adjuvant therapy for the decision an the level of aggressiveness of adjuvant therapy for a individual patients.

Aneuploidy↗
PubMed1994

[Perisinusoidal stellate cells or Ito cells and their role in hepatic fibrosis].

In this review on stellate cells, discovered by Kupffer more than 100 years ago, morphological and ultrastructural aspects, origin and differentiation are described through also a comparative analysis in some animal species. Many methods used from different laboratories for isolation, identification and in vitro culture of these heterogeneous cells are reported and discussed regarding advantages and disadvantages. The normal Ito cells functions, that are metabolism and storage of vitamin A, extracellular matrix (ECM) synthesis under cytokines control, and sinusoidal tonus through its reversible contraction are discussed. Then an update description is reported about fibrogenesis and all the factors involved in liver fibrosis, from cytokines to the adhesion molecules. Stellate cells being the main source of ECM in chronic liver injury, can play different and primary roles by shifting its functions toward fibrosis. The role of metalloproteinases and their inhibitors on the balance of the ECM synthesis and degradation are also evaluated. When liver is injured, Ito cells became activated and change their phenotype from fat-storing cells to cells to cell devoid of retonoid droplets. They express the smooth muscle-like features, including a-SM-actin. The role of vitamin A in liver fibrosis is not yet clear: current data and hypothesis about this topic are discussed. Contractile behaviour of the perisinusoidal stellate cells seems also important in influencing portal blood pressure during fibrosis and cirrhosis. Diagnostic methods for hepatic fibrosis and Ito cells activation are also briefly reported. The review is supplied with more than three hundred references updated to August 1994.

Cell Differentiation↗