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Biomedical subjects

M Di Giacomo

Publications and source records attributed to M Di Giacomo.

11 recordsLinked to original sources
PubMed2002

Two novel mutations and a new STK11/LKB1 gene isoform in Peutz-Jeghers patients.

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominantly inherited disorder with variable expression and incomplete penetrance characterized by mucocutaneous pigmentation, predisposition to hamartomatous intestinal polyposis, and various other neoplasms. It occurs in approximately 1 in 8,300 to 29,000 live births. In nearly 50% of patients PJS is caused by germ line mutations in the STK11/LKB1 serine/threonine kinase gene, the only kinase gene currently known to act as a tumor suppressor. We have performed a mutation search in the STK11/LKB1 gene in 8 sporadic cases and 3 PJS families using a combination of different screening techniques. We have identified four mutations, two of which I177N and the IVS2+1A->G, were previously unreported. We have also evaluated the presence of cDNA alterations by means of RT-PCR analysis and direct cDNA sequencing and have found two aberrant transcripts in a single PJS case despite the lack of any apparent genomic alteration. Finally, we report the presence of a novel STK11/LKB1 cDNA isoform observed in all the normal subjects studied as well as in the majority of the PJS patients.

AMP-Activated Protein Kinase Kinases↗
PubMed2002

Micrometastasis in colorectal cancer.

Colorectal cancer is one of the most common malignancies in the word and can be usually cured if diagnosed at an early stage. In the European area the estimated number of new cases of cancer in 1995 were approximately 334.000 and 189.000 died of cancer in that year. Despite recent progress in early detection and surgical therapy, the mortality remained unchanged over the past decades. The major reason for this disturbing discrepancy is that occult dissemination of viable cancer cells can occur at any stage of tumorigenesis. Occult dissemination of the tumor cells in patients with operable cancer may be considered a determinant of subsequent metastasis formation. Several groups have therefore designed immunocytochemical and molecular assays to identify such minimal amounts of residual tumor cells that have successfully invaded secondary organs. The question whether circulating tumor cells represent metastatic dissemination or are merely cancer cells without metastatic potential that have detached from the primary tumor, has been debated for over half a century.

Colorectal Neoplasms↗
PubMed2001

Control of mouse cumulus cell-oocyte complex integrity before and after ovulation: plasminogen activator synthesis and matrix degradation.

During the preovulatory period, cumulus cells (CCs) form a hyaluronan-protein extracellular matrix (cumulus expansion) that positively influences oocyte fertilization. Degradation of this matrix and CC-oocyte complex (COC) dissociation occurs within a few hours of ovulation and parallels the aging of oocytes. Modulation of CC proteolytic activity by gonadotropins and oocyte soluble factors has been hypothesized to determine such cumulus matrix changes. In the present study, we investigated plasminogen activator (PA) synthesis by COCs during the expansion and disassembly processes. Our results show that the secretion of tissue type PA and urokinase type PA (uPA) by oocytes and CCs, respectively, does not change significantly during expansion but dramatically increases thereafter. Compact COCs were isolated from immature mice, primed 48 h earlier with 5 IU PMSGs, and were induced to expand in vitro with 100 ng/ml FSH in the presence of 1% FCS. Full expansion was achieved at 16 h, when hyaluronan synthesis ceased. Release of hyaluronan and CCs from the COC matrix began between 18 and 20 h of culture, which indicates that matrix degradation started at this time. PA activities in culture media were determined by SDS-PAGE, followed by a zymography at various time intervals between 4 and 32 h of culture. Secreted tissue type PA and uPA activity abruptly increased between 16 and 20 h after FSH stimulation. Slot blot hybridization of CC messenger RNA showed that uPA messenger RNA levels correlated with the increase in uPA activity. Similar temporal patterns of PA synthesis and matrix degradation were found in COCs induced to expand in vivo by injection of 5 IU human CG into PMSG-primed mice. Cultures of CCs, both in the presence and absence of oocytes, revealed that uPA synthesis is repressed in FSH-stimulated CCs by an oocyte-soluble factor for the first 16 h of culture, whereas CC responsiveness to this factor is lost thereafter. In conclusion, the data show that a sophisticated interplay between oocyte and CCs causes the two cell types to simultaneously secrete PA activity after ovulation. The fact that matrix degradation parallels PA production strongly supports the hypothesis that these enzymes may destabilize the expanded COC matrix.

Animals↗
PubMed1998

Cytochemical localization of adenylate cyclase in the limb buds of Bufo bufo.

The importance of cyclic nucleotides in the regulation of the processes of differentiation and embryonic development is known. The possible role that cyclic adenosine monophosphate (cAMP) plays during the development of the posterior limb of Bufo bufo is studied by the cytochemical localization of adenylate cyclase (AC), an enzyme that catalyzes the synthesis of the cyclic nucleotide. The method is based on the reaction between the enzyme AC and its specific substrate AMP-PNP (5'-adenylylimidodiphosphate) in the presence of lead. The lead precipitates that form as secondary reaction products are evidence of enzymatic activity. Reaction products are present only at the epithelial level in the limb bud; initially, such products are visible only at the base of the bud, particularly on the epithelial fascia located at the boundary with the body. During successive elongation and toe formation, AC activity is only present on the cells of the proximal portion of each new segment. Enzymatic activity is never present in correspondence to the ectodermal apical crest. cAMP is probably not involved in the processes of cellular proliferation but, rather, in the processes of inducing differentiation of the internal mesenchymal cells.

Adenylyl Cyclases↗
PubMed1996

Duodenal obstruction following elective abdominal aortic aneurysm repair.

A case where duodenal obstruction complicated elective repair of abdominal aortic aneurysm is reported. A review of the literature shows that the incidence of this rare complication has probably been underestimated. Patients should be treated expectantly, regardless of the pathogenesis of the obstruction.

Aged↗
PubMed1995

[Not Available].

Explore the source record for details and available documents.

Dental Prosthesis↗
PubMed1992

Synthesis of a 11-deoxyprostanoid in the area of preclavulones: (+-)-8,12-trans-(5Z-14Z)-9-oxo-prosta-5,14-dienoic acid from 2-allyl-2-cyclopenten-1-one.

Following our research on the arachidonic acid metabolites and their derivatives with potential biological activity, we describe the synthesis of the (+-)-8,12-trans-(5Z, 14Z)-9-oxo-prosta-5,14-dienoic acid, a 11-deoxyprostanoid correlated to the class of Preclavulones, one of the unusual families of marine eicosanoids from the coral Clavularia Viridis with considerable biological interest.

Animals↗
PubMed1984

Conversion of longstanding atrial flutter to sinus rhythm and transient complete A-V block following oral administration of verapamil. Report of a case.

In a patient with ischaemic heart disease chronic atrial flutter reverted to sinus rhythm during treatment with oral Verapamil, given at dosage of 240 mg once a day in order to prevent spontaneous angina. Such an unexpected event was accompanied by a remarkable sinus node depression and by a transient complete a-v block, that gradually subsides leaving a slight permanent a-v conduction delay. Either a higher bioavailability of the drug or an extremely increased sensitivity of the receptors can explain such a marked electrophysiological effect at a moderate drug dosage.

Aged↗
PubMedDate not supplied

Hyaluronan and proteoglycans in ovarian follicles.

Proteoglycans are macromolecules formed by a protein backbone to which one or more glycosaminoglycan side chains are co-valently attached. They can be secreted by the cells, retained at the cell surface, or stored in intracellular vacuoles. Hyaluronan is an extremely long glycosaminoglycan which, at variance with other glycosaminoglycans, is released into the extracellular matrix as a free polysaccharide not co-valently linked to a core protein. Both proteoglycans and hyaluronan influence many aspects of cell behaviour by multiple interactions with other molecules. They are involved in matrix formation, cell-cell and cell-matrix adhesion, cell proliferation and migration, and show co-receptor activity for growth factors. Both proteoglycan and hyaluranon synthesis change significantly during ovarian follicle development and atresia. This review describes the structure of these molecules and their possible function in ovarian physiology.

Animals↗
PubMedDate not supplied

Benign fibrous mesothelioma: report of a case.

A case of fibrous benign mesothelioma is reported, together with some considerations on the diagnosis and the treatment of this rare tumour. Preoperative diagnosis is often impossible and so surgery is of great value both for treatment and diagnosis.

Aged↗