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Biomedical subjects

F Ronchetto

Publications and source records attributed to F Ronchetto.

At least 19 recordsLinked to original sources
PubMed1998

[Genetic alterations and molecular mechanisms underlying colorectal tumorigenesis].

Tumor cells are cells that have acquired damage to genes that directly regulate their cell cycles. In the multistep process leading to colorectal carcinoma, the adenoma-carcinoma sequence is characterized by progressive accumulation of genetic abnormalities (K-ras oncogene mutation, allelic deletion on chromosome 5q, 18q, 17p). In a hereditary non-polyposis syndrome (Lynch syndrome II) and in about a quarter of the cases of sporadic colorectal cancer there is a DNA micro-instability which contributes to the acquisition of mutations that cause loss of tumor-suppressor function. The p53 tumor-suppressor gene is the most frequently mutant gene in human cancer. In colorectal cancer cells missense p53 mutations and allelic deletion on chromosomal locus 17p13.1 are found with very high frequency. One of biological roles of p53 gene is to ensure that, in response to genotoxic damage, cells arrest in G1 and attempt to repair their DNA before it is replicated. In addition, p53 is required for apoptosis in response to severe DNA damage, included the damage induced by chemotherapeutics drugs and ionizing radiation. The loss of p53 function results in genomic instability and has been implicated in the evolution of normal cells into cancer cells.

Alleles↗
PubMed1998

[Genes, molecules, and mechanisms regulating programmed cell death].

Apoptosis is a morphologically distinct form of programmed cellular death that plays a central role during embryogenesis, tissue homeostasis, and to remove not necessary or potentially dangerous cells. Moreover, disregulation of genes mediating or modulating apoptosis contributes to the pathogenesis of a number of human diseases, including cancer, autoimmune diseases, neurodegenerative disorders, viral infections and acquired immunodeficiency syndrome. A number of genes and molecules promoting or protective against cell death is at present-day known and an important information about the external and internal signals involved in stimulation and suppression of apoptosis is also emerging. In the intracellular pathway of the death deregulation of [Ca2+](i) plays a pivotal role. Increased ionized intracellular calcium stimulates both the activation of enzymes (protein kinases, endonucleases, proteases and phospholipases) and plasma membrane K+ channels. This calcium-mediated activation leads to morphostructural changes, such as cell shrinkage, cytoplasmatic blebbing, nuclear chromatin condensation and DNA degradation into oligonucleosomal fragments. At least some genes of the cell death pathway have been conserved throughout animal evolution; ced-3 e ced-9 that regulate the initiation of cellular suicide in the nematode Caenorhabditis elegans are homologous to genes that in mammalian cells are thought to play a similar role (interleukin-1 beta converting enzyme [ICE] family, Bcl-2). It is possible to suppose that these regulators could constitute a target for treatment of disorders related with disregulation of apoptosis.

Apoptosis↗
PubMed1998

[Findings on standard electrocardiograms of elderly in-patients with diagnosis other than cardiac].

OBJECTIVE: To investigate the frequency of cardiac arrhythmias, conduction disturbances and other electrocardiographic abnormalities in elderly in-patients without clinical evidence of heart disease, and in relation to different age groups. DESIGN: Retrospective analysis of the standard 12-lead electrocardiogram recordings. METHODS: Resting electrocardiograms of 595 in-patients aged 65 years and older, without cardiac diagnoses, over a period of one year were examined. There were 148 subjects aged from 65 to 69 years (group I of age), 258 from 70 to 79 (group II), 189 older than 80 (group III). RESULTS: Abnormal ECGs were in 108 (73%) subjects of group I of age, 199 (77%) of group II, 174 (92%) of group III (between group I and III, and group II and III: p-value < 0.01). Conduction disturbances were observed in 200 (33.6%) patients: 65 (10.9%) had right bundle branch block, 59 (9.9%) first-degree atrioventricular block. Supraventricular arrhythmias were found in 117 (19.6%) patients: 65 (11%) had atrial premature beats, 40 (6.7%) atrial fibrillation. Ventricular arrhythmias were seen in 65 (10.9%) patients: simplex ventricular premature beats in 55 (9.2%), complex in 10 (1.7%). CONCLUSIONS: The variation of frequency of ventricular premature beats between age group I and III, and of first-degree AV block between age group II and III was at p-value < 0.05. Our results indicate that the prevalence of electrocardiographic abnormalities in elderly subjects without other clinical manifestations of heart disease is very high and some of these increase significantly with the age.

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PubMed1996

[What posttreatment monitoring in Whipple's disease? A case report].

The authors--which publish an overview about Whipple's disease in this issue, pages 609-611--report the case of a 67-year-old man admitted to the hospital because of migratory arthralgia, low-grade fever, lymphadenopathy, diarrhea, and impaired intestinal absorption. The microscopical examination of the intestinal mucosa showed an infiltration of the lamina propria by foamy PAS-positive macrophages. The patient was treated with antibiotics for 1 year and obtained clinical remission. The authors discuss if it is opportune, in subjects with this disease, to repeat the small-bowel biopsies at the end of the antibiotic treatment in absence of clinical manifestations of relapse or not.

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PubMed1995

[Strongyloides stercoralis in a region of northwestern Italy. An epidemiological note and presentation of a case of eosinophilic infiltration of the lung].

The Authors report a case of Strongyloides stercoralis infection in an autochthonous farmer from Piedmont (Northern Italy) presenting as an eosinophilic lung disease. After having briefly considered the epidemiological and clinical characteristics of the Strongyloides stercoralis infection, the Authors conclude by affirming that the appearance of migratory pulmonary infiltrates in autochthonous subjects or resident in Canavese area (Piedmont), especially if blood and sputum eosinophilia is present, should raise the possibility of Strongyloides-induced lung disease and lead to appropriate examination of sputum, feces, and eventually duodenal contents.

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PubMed1994

Occlusion of a branch of the central retinal vein as a manifestation of hypercoagulability in a patient with lung cancer. A possible paraneoplastic event.

The author describes the case of a patient with occlusion of a branch of the retinal central vein associated with lung carcinoma. He attributes the occlusive event, at the level of the retinal venous microcirculation, to a condition of hypercoagulability induced by cancer in coexistence with a slowing down of the blood flow as a result of a slight increase of serum viscosity. In the clinical discussion the author first considers the pathogenesis of the clinical and laboratory alterations concerning the coagulation observed in patients with cancer, and then hypothesises that the retinal vein thrombosis in the patient under question might be produced by way of a mechanism of interaction between tumor cells, plasmatic systems of the coagulation, leucocytes, platelets and endothelial cells.

Aged↗