Biomedical subjects

A Porcellini

Publications and source records attributed to A Porcellini.

At least 37 records · Page 2Linked to original sources

PubMed1998

VACOP-B versus VACOP-B plus autologous bone marrow transplantation for advanced diffuse non-Hodgkin's lymphoma: results of a prospective randomized trial by the non-Hodgkin's Lymphoma Cooperative Study Group.

PURPOSE: The aim of this multicenter randomized study was to compare conventional therapy with conventional plus high-dose therapy (HDT) and autologous bone marrow transplantation (ABMT) as front-line treatment for poor-prognosis non-Hodgkin's lymphoma (NHL). PATIENTS AND METHODS: Between October 1991 and June 1995, 124 patients, aged 15 to 60 years, with diffuse intermediate- to high-grade NHL (Working Formulation criteria), stages II bulky (> or = 10 cm), III, or IV were enrolled. Sixty-one patients were randomized to receive etoposide, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin (VACOP-B) for 12 weeks and cisplatin, cytarabine, and dexamethasone (DHAP) as a salvage regimen (arm A), and 63 to receive VACOP-B for 12 weeks plus HDT and ABMT (Arm B). RESULTS: There was no significant difference in terms of complete remissions (CRS) in the two groups: 75% in arm A, and 73% in arm B. The median follow-up observation time was 42 months. The 6-year survival probability was 65% in both arms. There was no difference in disease-free survival (DFS) or progression-free survival (PFS) between the two groups. DFS was 60% and 80% (P = .1) and PFS was 48% and 60% (P = .4) for arms A and B, respectively. Procedure feasibility was the major problem. In arm B, 29% of enrolled patients did not undergo HDT and ABMT. A statistical improvement in terms of DFS (P = .008) and a favorable trend in terms of PFS (P = .08) for intermediate-/high- plus high-risk group patients assigned to HDT and ABMT was observed. CONCLUSION: In this study, conventional chemotherapy followed by HDT and ABMT as front-line therapy seems no more successful than conventional treatment in terms of overall results. However, our results suggest that controlled studies of HDT plus ABMT should be proposed for higher risk patients.

Adolescent↗

PubMed1998

Apolipoprotein A-I reverse transcriptase-polymerase chain reaction analysis for detection of hematogenous colon cancer dissemination.

Detection of systemic tumor dissemination in colon carcinoma patients might be important for selection of appropriate treatment modalities. It has been previously shown that Apolipoprotein A-I (Apo A-I) is expressed in human intestinal epithelial cells, and in some human colon carcinoma cell lines. We examined the expression of Apo A-I mRNA in 14 human primary colon carcinomas by Northern blot and/or reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. An Apo A-I specific transcript was found in up to 70% of the colon carcinomas. We developed an RT-PCR assay for Apo A-I transcripts, to identify circulating carcinoma cells in the peripheral blood of colon cancer patients. The Apo A-I RT-PCR assay was optimized using limiting dilution of an Apo A-I positive cancer cell line mixed with peripheral blood from healthy donor. In this system, up to 10 colon carcinoma cells were detected in 5 ml of peripheral blood. We examined Apo A-I mRNA expression in peripheral blood samples from 4 healthy donors, 20 colon carcinoma patients, and 11 individuals with tumor disease other than colon cancer. No Apo A-I mRNA was detected in the healthy donors and in the patients without colon cancer. Two out of 10 patients with metastatic colon carcinoma were positive by this assay, whereas Apo A-I mRNA was not found in any of the blood samples from the 10 radically resected colon carcinoma patients. These data suggest that Apo A-I RT-PCR assay is a highly specific and sensitive assay, although a low number of advanced colon carcinoma patients was found to be positive.

Apolipoprotein A-I↗

PubMed1997

Thyroid cell transformation inhibits the expression of a novel rat protein tyrosine phosphatase.

We have isolated a rat thyroid cDNA encoding a novel rat receptor-type tyrosine phosphatase protein. This gene, on the basis of its homology to another tyrosine phosphatase, the recently isolated human DEP-1/HPTPeta, has been named r-PTPeta. In rat thyroid cells the r-PTPeta gene acts as a differentiation marker. Indeed, the block of thyroid cell differentiation induced by viral and cellular oncogenes is associated with the inhibition or marked reduction of the expression of this gene, and its expression is positively regulated by thyrotropin, the physiological stimulator of thyroid cell growth.

Amino Acid Sequence↗

PubMed1997

Mutations of thyrotropin receptor isolated from thyroid autonomous functioning adenomas confer TSH-independent growth to thyroid cells.

TSH receptor mutants in the VI transmembrane segment, found in thyroid autonomously functioning adeonomas, have been expressed in differentiated thyroid cells. All mutant receptors constitutively stimulated adenylyl cyclase. The biological activity, measured as cAMP production relative to the wild type receptor, was specific for each mutant in transient and stable transfection assays. Cells expressing these mutants proliferated in the absence of TSH. The rate of growth in the absence of TSH paralleled basal cAMP production for each mutant receptor. Low TSH concentrations stimulated the growth of mutant receptor-expressing cells, and not of the cells expressing the wild type receptor. Also, the entry in the cell cycle and the plating efficiency were markedly stimulated by the expression of the mutant receptors. These data provide a molecular link between the occurrence of TSH receptor mutations and thyroid autonomously functioning adenomas.

Adenoma↗

PubMed1997

Mutations of thyrotropin receptor gene.

Thyrotropin is the primary pituitary hormone which stimulates the growth and differentiation of thyroid cells. TSH binds a specific receptor present in the plasma membrane of thyroid cells and signals the G protein transducers, which activate different effectors, mainly adenyl cyclase and phospholipase C. The TSH receptor belongs to a broad class of receptors known as seven-loop receptors because they contain a long stretch of amino acids which cross the plasma membrane seven times. Mutations in the TSH receptor gene have been found in hyperfunctioning thyroid adenomas. These mutations are: (a) somatic (present only in the tumor), (b) dominant (only one copy of the gene is affected), and (c) lead to the constitutive activation of the cAMP signaling cascade. Most mutations which have been identified occur in the intracellular loop III and in the transmembrane domain VI. Germline mutations in the same regions of the receptor have been found in congenital nonautoimmune hyperthyroidism. In addition, germ line mutations have been described in the extracellular domain of the receptor leading to increased TSH levels. The clinical implications of these findings are discussed.

Adenoma↗

PubMed1997

Opposite feedback control of renin and aldosterone biosynthesis in the adrenal cortex by angiotensin II AT1-subtype receptors.

The aims of this study were to identify whether tissue renin is regulated by a negative-feedback mechanism produced by locally generated angiotensin (Ang II) in the adrenal cortex and to detect the pathway of Ang II modulation. For this purpose, in 36 12-week old, salt-restricted, nephrectomized Sprague-Dawley rats, we studied the effects of the Ang II AT1-subtype receptor antagonist losartan and of the Ang II AT2-subtype receptor antagonist PD123319 on renin mRNA and activity, aldosterone synthase mRNA, and AT1a-, AT1b-, and AT2-subtype receptor expression in the adrenal cortex. Ten additional rats, kept on a regular diet and then nephrectomized, were also studied. In salt-restricted, nephrectomized rats, losartan administration caused increases of adrenal renin mRNA (P<.05) and activity (P<.05) and a concomitant reduction of aldosterone synthase mRNA (P<.05). In addition, after losartan AT1b, receptor mRNA was reduced (P<.05), AT1a receptor mRNA was unchanged, and AT2 mRNA was increased (P<.05). PD123319 did not significantly modify any of these parameters. In conclusion, in salt-restricted, nephrectomized rats, selective antagonism of AT1-subtype receptors stimulates the expression and the activity of renin in the adrenal cortex. This observation demonstrates that Ang II locally formed in the adrenal cortex exerts a modulatory negative-feedback action on adrenal renin biosynthesis independent of the influence of the circulating renin-Ang system; this action is largely mediated through the AT1b-subtype receptors.

Adrenal Cortex↗

PubMed1997

Role of tissue renin in the regulation of aldosterone biosynthesis in the adrenal cortex of nephrectomized rats.

The aim of the study was to investigate whether the adrenal renin-angiotensin system plays an independent role in the regulation of mineralocorticoid biosynthesis in the adrenal gland and to explore the mechanisms of this action. Twelve-week-old male Sprague-Dawley rats were studied: 22 rats were maintained on a regular diet; 27 and 22 rats received a low salt diet with and without treatment, respectively, with the angiotensin II (Ang II) AT1-subtype receptor antagonist losartan (10 mg/kg per day). A fraction of each group of rats underwent bilateral nephrectomy (n = 12, 15, and 10, respectively) and was killed 48 hours later. In an additional group of 24 (12 intact and 12 nephrectomized) rats, the effects of the Ang II AT2-subtype receptor antagonist PD123319 were investigated. In intact rats, plasma renin activity (PRA) and adrenal renin activity and expression were progressively raised by salt restriction and losartan, whereas aldosterone synthase mRNA and plasma aldosterone (PA) levels were increased by salt restriction and reduced by losartan. Forty-eight hours after nephrectomy, PRA fell to undetectable levels; in contrast, adrenal renin expression, assessed by semiquantitative reverse-transcriptase polymerase chain reaction (using GAPDH as a standard for gene expression), showed an 18-fold increase and was further increased after salt restriction and losartan (all P < .05). Also, adrenal renin activity was raised after nephrectomy and further increased after salt restriction (P < .05) and losartan. Cytochrome P450 aldosterone synthase expression in the adrenal cortex was stimulated by nephrectomy alone and by nephrectomy combined with low salt intake (P < .05), with consequent increases in PA concentrations. In losartan-treated salt-restricted nephrectomized rats, cytochrome P450 aldosterone synthase expression (P < .05 versus nephrectomy alone and nephrectomy plus salt restriction) and PA concentrations were diminished (P < .05) in spite of the observed increases of adrenal renin expression. The AT2-receptor antagonism did not significantly affect PRA, adrenal renin, and aldosterone biosynthesis and production in either intact or nephrectomized salt-restricted rats. These results demonstrate that the adrenal renin-angiotensin system plays an independent role in the regulation of mineralocorticoid biosynthesis in vivo. This action is mediated primarily via the Ang II AT1-subtype receptors.

Adrenal Glands↗

PubMed1996

Membrane localization of cAMP-dependent protein kinase amplifies cAMP signaling to the nucleus in PC12 cells.

The A126 cell line, in contrast to its PC12 parent, does not differentiate, accumulate nuclear cAMP-dependent protein kinase A (PKA) catalytic subunit, or transcribe cAMP-dependent promoters in response to cAMP. Total PKA is reduced by 50% and is partly resistant to cAMP-induced dissociation in vivo. Unlike PC12, where PKAII is membrane-associated, PKAII is exclusively cytosolic in A126. Cotransfection with the RII anchor protein (AKAP75) and the PKA catalytic subunit (C-PKA) restored cAMP-induced transcription to levels found in PC12. These data indicate that membrane-bound PKAII amplifies cAMP signaling to the nucleus and suggest that cAMP-mediated responses are specified by the type and cellular localization of the PKA isoform.

A Kinase Anchor Proteins↗

PubMed1996

The v-Ki-Ras oncogene alters cAMP nuclear signaling by regulating the location and the expression of cAMP-dependent protein kinase IIbeta.

The v-Ki-Ras oncoprotein dedifferentiates thyroid cells and inhibits nuclear accumulation of the catalytic subunit of cAMP-dependent protein kinase. After activation of v-Ras or protein kinase C, the regulatory subunit of type II protein kinase A, RIIbeta, translocates from the membranes to the cytosol. RIIbeta mRNA and protein were eventually depleted. These effects were mimicked by expressing AKAP45, a truncated version of the RII anchor protein, AKAP75. Because AKAP45 lacks membrane targeting domains, it induces the translocation of PKAII to the cytoplasm. Expression of AKAP45 markedly decreased thyroglobulin mRNA levels and inhibited accumulation of C-PKA in the nucleus. Our results suggest that: 1) The localization of PKAII influences cAMP signaling to the nucleus; 2) Ras alters the localization and the expression of PKAII; 3) Translocation of PKAII to the cytoplasm reduces nuclear C-PKA accumulation, resulting in decreased expression of cAMP-dependent genes, including RIIbeta, TSH receptor, and thyroglobulin. The loss of RIIbeta permanently down-regulates thyroid-specific gene expression.

A Kinase Anchor Proteins↗

PubMed1996

Requirement for cAMP-PKA pathway activation by M phase-promoting factor in the transition from mitosis to interphase.

Cell cycle progression in cycling Xenopus egg extracts is accompanied by fluctuations in the concentration of adenosine 3',5'-monophosphate (cAMP) and in the activity of the cAMP-dependent protein kinase (PKA). The concentration of cAMP and the activity of PKA decrease at the onset of mitosis and increase at the transition between mitosis and interphase. Blocking the activation of PKA at metaphase prevented the transition into interphase; the activity of M phase-promoting factor (MPF; the cyclin B-p34cdc2 complex) remained high, and mitotic cyclins were not degraded. The arrest in mitosis was reversed by the reactivation of PKA. The inhibition of protein synthesis prevented the accumulation of cyclin and the oscillations of MPF, PKA, and cAMP. Addition of recombinant nondegradable cyclin B activated p34cdc2 and PKA and induced the degradation of full-length cyclin B. Addition of cyclin A activated p34cdc2 but not PKA, nor did it induce the degradation of full-length cyclin B. These findings suggest that cyclin degradation and exit from mitosis require MPF-dependent activation of the cAMP-PKA pathway.

Animals↗

PubMed1996

The differential response of protein kinase A to cyclic AMP in discrete brain areas correlates with the abundance of regulatory subunit II.

We analyzed the expression and relative distribution of mRNA for the regulatory subunits (RIalpha, RIIalpha, and RIIbeta) and of 150-kDa RIIbeta-anchor proteins for cyclic AMP (cAMP)-dependent protein kinase (PKA) into discrete brain regions. The subcellular distribution of both holoenzyme and free catalytic subunit was evaluated in the same CNS areas. In the neocortex and corpus striatum high levels of RIIbeta paralleled the presence of specific RII-anchoring proteins, high levels of membrane-bound PKA holoenzyme, and low levels of cytosolic free catalytic activity (C-PKA). Conversely, in brain areas showing low RIIbeta levels (cerebellum, hypothalamus, and brainstem) we found an absence of RII-anchoring proteins, low levels of membrane-bound holoenzyme PKA, and high levels of cytosolic dissociated C-PKA. Response to cAMP stimuli was specifically evaluated in the neocortex and cerebellum, prototypic areas of the two different patterns of PKA distribution. We found that cerebellar holoenzyme PKA was highly sensitive to cAMP-induced dissociation, without, however, a consistent translocation of C-PKA into the nucleus. In contrast, in the neocortex holoenzyme PKA was mainly in the undissociated state and poorly sensitive to cAMP. In nuclei of cortical cells cAMP stimulated the import of C-PKA and phosphorylation of cAMP-responsive element binding protein. Taken together, these data suggest that RIIbeta (whose distribution is graded throughout the CNS, reaching maximal expression in the neocortex) may represent the molecular cue of the differential nuclear response to cAMP in different brain areas, by controlling cAMP-induced holoenzyme PKA dissociation and nuclear accumulation of catalytic subunits.

Animals↗

PubMed1996

Rhabdomyosarcoma presenting as acute leukemia.

PURPOSE: We describe a case of a very unusual presentation of rhabdomyosarcoma. PATIENT AND METHODS: An 18-year-old woman presented with symptoms and signs compatible with acute leukemia. The bone marrow picture showed diffuse involvement sustained by undifferentiated blasts that turned out to be of striated muscle origin by immunochemistry. While it is well known that rhabdomyosarcoma may metastasize to the bone marrow, extensive marrow involvement with leukemic spread as a unique clinical manifestation is extremely rare. CONCLUSION: Our observation further confirms the need to consider rhabdomyosarcoma among the possible differential diagnoses in patients who present with a leukemic picture and atypical blasts lacking all hematopoietic markers.

Acute Disease↗

PubMed1996

The role of anthracyclines in adult acute lymphoblastic leukaemia.

The role of anthracyclines (ANT) in the treatment of adult acute lymphoblastic leukaemia (ALL) is poorly defined as regards drug dosage, schedule, preferable compound, and indications for use in specific treatment phases or disease subset. We therefore reviewed ANT treatment results in adult ALL. Altogether, an early and intensive use of ANT would improve both initial response rate and long-term disease-free survival; idarubicin (IDR) exhibits a considerable antileukaemic activity deserving further evaluation as possible reference drug; and the prognosis of CD10+ t(9;22)/BCR-ABL- ALL can be particularly good following an early dose-intensive ANT consolidation program.

Adolescent↗

PubMed1996

Increased plasma level of vascular endothelial glycoprotein thrombomodulin as an early indicator of endothelial damage in bone marrow transplantation.

We investigated the nature of hemostatic alterations occurring after bone marrow transplantation. In 45 patients, we evaluated the coagulation parameters, naturally occurring anticoagulants and thrombomodulin at days +15 and +22 after conditioning therapy. It was observed that endothelial cell damage is a central pathogenetic mechanism in some BMT complications. The increased plasma level of thrombomodulin after conditioning therapy is therefore discussed as a marker of endothelial cell injury. At day +15 a significant increase of fibrinogen from 276.1 mg/dI to 389.1 mg/dI was observed, while the natural anticoagulants all decreased significantly. Eleven patients with clinical complications related to endothelial damage had a significant thrombomodulin increase which, in uncomplicated patients, remained unchanged or resulted in lower than baseline values. Analysis of the data shows a strong correlation between clinical findings, reflecting endothelial cell injury and thrombomodulin increase when the increment is > or = 30%. We found a significant elevation in thrombomodulin in 70% of clinical complications related to endothelial cell damage namely: septicemia, GVHD, VOD. There were four cases (or 9%) of false positive data, and only two (or 4.5%) of false negative results. We therefore propose thrombomodulin assessment as a valid parameter to monitor chemotherapy toxicity-related complications.

Adolescent↗

PubMed1995

Somatic mutations in the VI transmembrane segment of the thyrotropin receptor constitutively activate cAMP signalling in thyroid hyperfunctioning adenomas.

We have discovered two somatic mutations in the VI transmembrane domain of the thyrotropin receptor gene in thyroid hyperfunctioning adenomas. The mutated amino acid residues are phenylalanine 631 (to cysteine) and threonine 632 (to isoleucine). Cloning and expression of the mutated versions of the receptor in COS cells increased significantly the basal and the TSH-induced cAMP levels compared to the wild type receptor. Moreover, the expression of a reporter gene under the control of the cAMP-inducible promoter, was likewise constitutively activated in cells expressing the 631 and 632 TSH receptor mutants relative to the wild type. These data indicate that the VI transmembrane segment in the TSH receptor and presumably in the other G-protein coupled receptors is a critical domain for the activation of G-protein signalling and that the mutations described here may be the cause of the thyroid hyperfunctioning adenoma.

Adenoma↗

PubMed1995

Smooth muscle cell proliferation is proportional to the degree of balloon injury in a rat model of angioplasty.

BACKGROUND: A variable degree of smooth muscle cell (SMC) proliferation after balloon injury has been reported in previous rat studies. It is unknown whether balloon injury induces c-fos expression and whether it is related to the degree of vascular injury in vivo. Therefore, we tested the hypothesis that proportional increases in neointimal formation and c-fos expression might be present after different degrees of balloon dilation. METHODS AND RESULTS: Angioplasty of the carotid artery was performed with a balloon catheter. Vascular injury was evaluated at 0, 0.5, 1.0, 1.5, and 2 atm (n = 6 for all). In 40 additional rats, total RNA dot blots were performed to assess the effect of various degrees of balloon injury on c-fos expression. SMC proliferation proportional to the increases of inflation pressure was found between 0 and 2 atm with neointimal areas of 0.002 +/- 0.002, 0.069 +/- 0.014, 0.128 +/- 0.043, 0.190 +/- 0.010, and 0.255 +/- 0.041 mm2, respectively. When the degree of SMC proliferation (neointima and neointima/media ratio) was plotted against balloon inflation pressure, a linear relation was observed (r = .733, P < .001 and r = .755, P < .001, respectively). An increase in c-fos expression proportional to the degree of injury was found 30 minutes after injury. CONCLUSIONS: Neointimal proliferation produced by balloon injury is related to balloon inflation pressure, supporting the concept of an SMC proliferative response proportional to the degree of injury. The increase in SMC proliferation is associated with a proportional increase in the early expression of the c-fos nuclear proto-oncogene.

Angioplasty, Balloon↗

PubMed1995

Differential expression of the asialoglycoprotein receptor in discrete brain areas, in kidney and thyroid.

The asyaloglycoprotein receptor is a dimer formed by two polypeptide chains abundantly expressed in the liver (RHL-1 and RHL-2). Using specific primers for the two polypeptide chains we measured, by semiquantitative reverse PCR (RT-PCR), the corresponding mRNAs in different rat tissues. We found that both RHL-1 and RHL-2 mRNAs are expressed in the liver, kidney, brain and thyroid. Under the same conditions we did not detect any specific mRNA in the spleen. In the brain these sequences are expressed along a posterior-anterior gradient. Cerebellum and brainstem display the highest expression of the brain RHL-1 and RHL-2 mRNAs. Tissues and regional distribution of this receptor suggest that other body districts besides liver may participate in the clearance of serum glycoproteins.

Animals↗

PubMed1995

Apolipoprotein AI-CIII-AIV genetic polymorphisms and coronary heart disease in type 2 diabetes mellitus.

The aim of this study was to verify whether or not the increased prevalence of coronary heart disease (CHD) commonly observed in patients with type 2 diabetes mellitus is related to a genetic background involving restriction fragment length polymorphisms (RFLPs) of apolipoproteins. On the basis of a case-control design, 62 type 2 diabetic patients with CHD (confirmed by clinical history and electrocardiogram) and 62 age- and sex-matched diabetic subjects without CHD were enrolled. In each of them RFLPs of the apolipoprotein CIII gene (S1 or S2 allele) and AI promoter region (A or G allele), together with fasting plasma lipids and apolipoproteins levels, were assessed. The rare S2 allele was found significantly (P = 0.05) more frequently in patients with CHD, and its related S1S2 genotype was associated with higher plasma levels of total cholesterol (P = 0.01), triglycerides (P = 0.007) and apo B (P = 0.001) than the S1S1 genotype. The A allele was more frequent (P = 0.004) in patients without CHD and was associated with lower plasma cholesterol (P = 0.0001), low-density lipoprotein (LDL)-cholesterol (P = 0.0001) and apo B (P = 0.005). The S1/A haplotype was more frequent (P = 0.05) in patients without CHD and was associated with the lowest plasma lipid levels. These results suggest that genetic factors, related to the apo AI-CIII-AIV gene cluster, could play a role in the development of CHD in type 2 diabetic patients, probably through modification of their plasma lipid pattern.

Alleles↗