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A Poletti

Publications and source records attributed to A Poletti.

At least 19 recordsLinked to original sources
PubMed1996

Characterization of rat 5alpha-reductases type 1 and type 2 expressed in Saccharomyces cerevisiae.

Two isoforms of the rat 5alpha-reductase (5alpha-R), the enzyme that converts testosterone into dihydrotestosterone (DHT), and other delta4-3-keto steroids (e.g. progesterone and corticoids) into their 5alpha-reduced metabolites, have been cloned. In this study, a convenient and efficient system was developed to overexpress the two isoenzymes in Saccharomyces cerevisiae by using the ubiquitin-fusion expression system. Two yeast expression vectors have been prepared, YEpR1 and YEpR2, which code for 5alpha-R type 1 and 5alpha-R type 2 respectively; they contain the copper-responsive yeast metallothionein promoter (CUP1) upstream of the ubiquitin coding sequence, and the full-length rat 5alpha-R type 1 or 5alpha-R type 2 cDNAs in frame to the 3' end of the ubiquitin cDNA. The activity of the two isoenzymes produced in yeast was determined in cell lysates at the enzyme pH optima (type 1, pH 7.5; type 2, pH 5.5) and a possible differential intracellular distribution was also evaluated. The kinetic parameters were: type 1, Km 4.6 microM, Vmax.100.6 micrograms/h per mg of protein; type 2, Km 68.6 nM, Vmax. 0.84 micrograms/h per mg of protein. Yeast cell lysates were fractionated by differential centrifugation and the 5alpha-R type 1 activity was maximal in fractions containing nuclei (1000 g and 2500 g), whereas the maximal activity of 5alpha-R type 2 was present in subcellular fractions sedimenting at higher speeds (20000g). The data indicate that yeasts overexpress the two 5alpha-R isoenzymes, maintaining their native biochemical properties, and that the two isoforms are probably differentially localized within the yeast cell.

Animals↗
PubMed1995

CD25-negative hairy cell leukaemia: intracytoplasmic detection of Tac antigen and interferon-induced surface expression.

Hairy cell leukaemia (HCL) is a chronic lymphoproliferative disease of B-cell lineage. One of the peculiar immunophenotypic markers is the strong expression of the p55 chain of the interleukin-2 receptor (IL2R), recognized by anti-CD25 (or anti-Tac) monoclonal antibody. However, it is known that in rare cases CD25 may not be detectable, even when variant forms of HCL are excluded. The possibility has not been investigated that in these situations CD25 is present in the cytoplasm of the neoplastic cells. This paper describes a case in which the clinical, histological, and electron microscopic features were consistent with a typical HCL. Immunophenotype analysis showed the whole spectrum of markers of HCL, except for the expression of IL2R. The soluble form of the molecule was, however, increased in the patient's serum. Cytospin staining of the neoplastic B cells with anti-CD25 clearly demonstrated the presence of IL2R in the cytoplasm of hairy cells. When the cells were cultivated in vitro in the presence of interferon-alpha 2b, CD25 was detectable at the membrane level. These findings suggest that at least some cases of CD25-negative HCL may express cytoplasmic IL2R.

Aged↗
PubMed1995

Phosphorylation and progesterone receptor function.

Four phosphorylation sites have been identified in the chicken progesterone receptor. Two of these sites exhibit basal phosphorylation which is enhanced upon treatment with hormone and two of the sites are phosphorylated in response to hormone. Mutation of one of these hormone dependent sites, Ser530 to Ala530, causes a decrease in transcriptional activation at low concentrations of hormone, but the activity is unaffected at high concentrations. However, the hormone binding of the mutant is unaffected suggesting that phosphorylation of Ser530 plays a role in facilitating the response of the receptor to low concentrations of hormone. The chicken progesterone receptor can be activated by modulators of kinases in the absence of hormone. The finding that signals initiated by tyrosine phosphorylation (through treatment with EGF) or through the dopamine receptor suggests that there are multiple means of activating chicken progesterone receptor. In contrast, the human progesterone receptor does not exhibit ligand independent activation; however, its activity in the presence of the agonist R5020 is enhanced by treatment with 8-Br-cAMP, an activator of protein kinase A, and treatment with 8-Br-cAMP causes the antagonist, RU486, to act as an agonist.

Amino Acid Sequence↗
PubMed1995

Identification of a group of Ser-Pro motif hormone-inducible phosphorylation sites in the human progesterone receptor.

The human progesterone receptor (PR) is a member of the steroid/thyroid hormone superfamily of nuclear receptors. The receptor is expressed as two forms, PR-B and the shorter PR-A, which lacks the NH2-terminal 164 amino acids of PR-B; whereas PR-B seems to be predominantly a transcriptional activator, PR-A also functions as a repressor. Our previous studies of PR expressed in T47D breast cancer cells have shown that PR is a phosphoprotein whose phosphorylation is enhanced in response to hormone. There is an initial rapid (minutes) increase in phosphorylation followed by a slower, less substantial increase, which results in decreased mobility of the receptor on sodium dodecyl sulfate gels. We now report the identification of three phosphorylation sites, which are predominantly phosphorylated during the later phase of the response to hormone. These sites, Ser102, Ser294, and Ser345, are all found in Ser-Pro consensus sequences. Whereas Ser294 and Ser345 are common to PR-A and PR-B, Ser102 is unique to PR-B. Finally, we demonstrate that phosphorylation of Ser345 is associated with the altered mobility on sodium dodecyl sulfate gels.

Amino Acid Sequence↗
PubMed1995

[SFAAT: the study of nonrheumatic chronic atrial fibrillation in the Trieste area. Results of an enrollment study].

BACKGROUND: Chronic atrial fibrillation unassociated with rheumatic valvular heart disease (NRAF) considerably increases the risk of thromboembolism. Recent studies have provided new evidence concerning the risk-benefit ratio of anticoagulant therapies in patients with AF. OBJECTIVE: To evaluate the incidence of primary end points (ischemic stroke, systemic embolism, bleeding complications to oral anticoagulant or antiplatelet therapy) and secondary end points (death, TIA) in patients with NRAF. METHODS AND RESULTS: Between November 1992 and June 1993, 694 patients with chronic NRAF were enrolled in the Trieste Area Study on Nonrheumatic Atrial Fibrillation (TASAF), an ongoing prospective community study with a follow-up period of 2 years. The preliminary results of the enrolled study population show: an elevated mean age (71 +/- 9 years), the prevalence of males (383/694), high prevalence of overt or previous heart failure (23%), of mitral regurgitation confirmed at echocardiography (30%) and of previous myocardial infarction (11%). Many of the enrolled patients had a history of hypertension (58%). With regard to the etiology of the underlying heart disease, the following should be emphasized: a high incidence of cardiac hypertrophy (with or without history of hypertension) (28%) and of degenerative cardiopathy (20%); unclassifiable cardiopathy (14%); and lone AF (13%). Echocardiographic findings: left ventricular dysfunction (17%); mitral annular calcification (27%); and good mean left ventricular function (EF 0.50 +/- 0.15). Retrospectively there were 96 clinically documented embolic events in 78 subjects while in 34 patients there were 38 episodes suspected for embolism or TIA. Nine patients suffered 1 recurrence of embolism; three patients suffered 2 recurrences; one patient had 3 recurrences; and 4 patients had one suspected recurrence of TIA. In 35 cases the embolic events clustered around the time of the onset of the arrhythmia. In the other 99 subjects the embolic complication appeared after the onset of AF: range 1-266 months. The group of patients with true embolic events in comparison with patients without embolism or with suspected embolism or TIA had same variables predictive of thromboembolic complications: arrhythmia duration (p = 0.09) and previous myocardial infarction (p = 0.03); in contrast mitral annular calcification (p = 0.06), history of hypertension (p = 0.09) and cardiac hypertrophy (with or without hypertension) (p = 0.07) demonstrated only a slight trend of statistical significance. Comparing the clinical characteristics and echocardiographic findings of patients without embolism with those of patients with tru embolism, or suspected embolism, or TIA the variables predictive of thromboembolic events were: arrhythmia duration (p = 0.007), history of hypertension (p = 0.01), cardiac hypertrophy (with or without hypertension (p = 0.02) and mitral annular calcification (p = 0.01), at the same time, age showed only a trend of statistical significance (p = 0.06). Among the 616 patients without a history of embolism only 3% were treated with oral anticoagulant agents and 28% with antiplatelet therapy, while among the 78 subjects with documented embolism only 28% were receiving anticoagulant therapy and 58% were receiving antiplatelet agents. CONCLUSIONS: NRAF is an important risk factor for thromboembolism. Some clinical characteristics and echocardiographic findings increase the risk. Physicians still hesitate to use oral anticoagulants and antiplatelet agents in their patients for the prevention of embolic complications.

Aged↗
PubMed1995

Hemangiopericytoma of the skull base and Collet-Sicard syndrome: a case report.

Hemangiopericytoma (HP) is a mesenchymal tumor that originates from the pericytes of the capillary walls. This is a rare neoplasm, particularly in the head and neck; the skull base is involved exceptionally. We report a case of a large HP located in the jugular foramen. The last four cranial nerves were involved, causing a Collet-Sicard syndrome associated with facial palsy. Only one case of HP and Collet-Sicard syndrome is reported in the literature. The clinical course of the disease is described, emphasizing the long period of elapsed time between onset of the complaints and the final diagnosis. Diagnostic procedures and immunohistochemical evaluation are analyzed, along with the possible differential diagnosis with other pathological processes that more frequently involve the jugular foramen.

Aged↗
PubMed1994

Identification of phosphorylation sites unique to the B form of human progesterone receptor. In vitro phosphorylation by casein kinase II.

The human progesterone receptor (PR), a member of the steroid/thyroid receptor superfamily of ligand-activated transcription factors, is expressed in most tissues as two forms that exhibit differential transcriptional activation potentials, full-length PR-B and NH2-terminally truncated PR-A. In human breast cancer cells (T47D) both forms of PR are constitutively phosphorylated but phosphorylation is increased in response to hormone treatment, suggesting that this modification has a role in regulating the activation state of the receptor. To more directly define the functional role of phosphorylation in the action of A and B receptors requires knowledge of the phosphorylated amino acid residues and the protein kinase(s) involved. Toward this end we have developed a strategy that combines isolation of PR phosphotryptic peptides by reverse phase high performance liquid chromatography, secondary analytical protease digestion, manual Edman degradation, and release of 32P that resulted in identification of two major phosphorylation sites, Ser81 and Ser162. Both sites are located in the amino-terminal region unique to PR-B, and one of these sites (Ser81) is encompassed in a casein kinase II (CKII) consensus sequence. Although human PR contains 11 potential CKII consensus sequences, CKII in vitro phosphorylated purified PR-B only at Ser81 suggesting that this may be an authentic site for CKII in vivo.

Amino Acid Sequence↗
PubMed1994

Sudden death in the young. Is acute coronary thrombosis the major precipitating factor?

BACKGROUND: Atherosclerotic coronary artery disease, complicated by acute thrombosis, is the usual cause of sudden death in adults. This study addresses the pathology of coronary arteries in sudden death in the young (< or = 35 years old). METHODS AND RESULTS: Among 200 consecutive cases of sudden death in youth in the Veneto region of Italy, 37 (33 men and 4 women, age 18 to 35 years; mean, 29.4 years) showed obstructive atherosclerotic coronary artery disease in the absence of other cardiac pathological conditions and causes of death. No patient had previous angina pectoris or myocardial infarction. Cardiac arrest occurred at rest in 30 subjects and was related to effort in 7. A histological study was carried out on the obstructive coronary plaques. Degree of lumen stenosis and extension of lipid core and intimal fibrocellular hyperplasia facing the lumen were calculated morphometrically. Immunohistochemistry and electron microscopy were used to further characterize the plaque cell population. Single-vessel disease was found in 33 patients and triple-vessel disease in 4, with an overall total of 45 obstructive plaques, 34 of which were located in the proximal left anterior descending coronary artery. At histological study, only 10 plaques from 10 patients showed acute thrombosis (occlusive in 5 and subocclusive in 5); the remaining 35 were uncomplicated. Thirty-one plaques were fibrous in nature, while the other 14 were atheromatous. Compared with the atheromatous lesions, the fibrous plaques were rarely complicated by thrombosis (3% versus 64%; P < .001) and distinctly exhibited a fairly well-preserved tunica media (81% versus 21%; P < .001) as well as a stratum of neointimal fibrocellular hyperplasia (68% versus 7%; P < .001), which on immunohistochemistry and electron microscopy appeared to be proliferating smooth muscle cells. CONCLUSIONS: In our study population, sudden death was precipitated by acute coronary thrombosis in only 27% of patients with obstructive coronary atherosclerotic plaque. Most of the young victims of sudden death with obstructive coronary atherosclerosis showed single-vessel disease that affected the left anterior descending coronary artery and was due to fibrous plaques with neointimal smooth muscle cell hyperplasia and a preserved tunica media in the absence of acute thrombosis.

Acute Disease↗
PubMed1994

Bronchocentric granulomatosis and central diabetes insipidus successfully treated with corticosteroids.

Bronchocentric granulomatosis (BCG) is a rare chronic granulomatous lung disease that leads to destruction of the airway walls. It has been observed in association with various conditions, but never, so far, been reported to involve the central nervous system. We report a case of histologically confirmed pulmonary bronchocentric granulomatosis temporally associated with a partial central diabetes insipidus (CDI). Although the pathological basis of the posterior pituitary gland involvement was not ascertained, the temporal association of bronchocentric granulomatosis and central diabetes insipidus, as well as the fact that corticosteroid treatment provided stable remission of both conditions after a 10 month follow-up, strongly suggest that central diabetes insipidus was aetiologically related to bronchocentric granulomatosis in this patient.

Diabetes Insipidus↗
PubMed1994

Steroid binding and metabolism in the luteinizing hormone-releasing hormone-producing neuronal cell line GT1-1.

LHRH synthesis and release are modulated in vivo by gonadal steroids. Although immunocytochemical and autoradiographic studies failed to detect appreciable amounts of estrogen or androgen receptor in LHRH-producing neurons, the recent finding that the promoter region of the LHRH gene contains several steroid hormone-responsive elements indicates a possible direct effect of sex steroids on these specialized neurons. The immortalized LHRH-producing neuronal cell line, GT1, which became recently available, may allow the study of LHRH dynamics. The presence of specific binding sites for estrogen and androgens as well as the presence of the two major enzymatic pathways involved in modulation of androgen action (the 5 alpha-reductase/3 alpha-hydroxysteroid dehydrogenase and the aromatase) have been studied in the GT1-1 clone. High affinity, low capacity binding sites for [3H]estradiol (Kd, 0.11 nM; binding capacity, 6.2 fmol/mg protein) and for a ligand of the androgen receptor, [3H]R1881 (Kd, 0.054 nM; binding capacity, 9.58 fmol/mg protein), have been identified in this cell line. A 2-fold induction of androgen-binding sites has been observed after 3 days of treatment of GT1-1 cells with estradiol (1 microM), indicating that the estradiol binding is probably linked to a functional estrogen receptor. Aromatase and 5 alpha-reductase/3 alpha-hydroxysteroid dehydrogenase activities have been also tested in GT1-1 cells. Under the culture conditions adopted, no detectable aromatization of [1 beta 3H]delta 4-androstenedione to estrone was observed using the tritiated water method. On the other hand, GT1-1 cells efficiently converted testosterone into dihydrotestosterone and subsequently into 5 alpha-androstan-3 alpha,17 beta-diol. In conclusion, GT1-1 cells possess several elements of the machinery through which sex steroids may influence LHRH dynamics.

3-Hydroxysteroid Dehydrogenases↗
PubMed1994

[Isolated double orifice mitral valve].

A 58-year old woman with paroxysmal atrial fibrillation and isolated double orifice mitral valve is presented. This congenital abnormality is usually discovered by autopsy or surgery. In this case it was diagnosed by echocardiography.

Atrial Fibrillation↗
PubMed1993

Chicken progesterone receptor expressed in Saccharomyces cerevisiae is correctly phosphorylated at all four Ser-Pro phosphorylation sites.

This study describes the phosphorylation of chicken progesterone receptor (cPR) produced in yeast, Saccharomyces cerevisiae, and examines the dependence of specific phosphorylations on hormone and DNA binding. The chicken progesterone receptor is expressed in vivo as two forms, cPRB and a smaller form, cPRA. Characterization of the phosphorylation sites in the cPRB form expressed in yeast shows that progesterone receptor is phosphorylated on the three serines (Ser211, Ser260, and Ser530) reported previously in chicken oviduct. An additional site which was phosphorylated in response to hormone was also detected and was subsequently identified as Ser367. Although cPRB and cPRA are phosphorylated identically in chicken oviduct, cPRA expressed in yeast is phosphorylated on Ser211, Ser260, and Ser367, but phosphorylation of Ser530 is almost undetectable. In contrast, cPRB expressed in yeast is phosphorylated on all four sites. No phosphorylations were found in or near the region required for hormone binding, indicating that phosphorylation is not required for hormone binding. In order to determine whether any of the phosphorylations were DNA-dependent, phosphorylation was also studied using cPRA containing a partial deletion of the DNA binding domain. Two of the sites, Ser211 and Ser367, showed reduced phosphorylation in this mutant, suggesting a possible requirement for DNA binding activity for the phosphorylation of these sites. To our knowledge, this is one of the first demonstrations that a eucaryotic protein expressed in yeast is correctly phosphorylated.

Amino Acid Sequence↗
PubMed1993

Necrosis of a phaeochromocytoma associated with spontaneous remission of diabetes and hypertension.

The diagnosis of phaeochromocytoma is sometimes difficult since its clinical presentation is quite variable. We report a 52-year-old woman who presented with acute diabetes mellitus and severe hypertension, which spontaneously disappeared. MIBG-scintigraphy and urine and plasma catecholamines were normal. At surgery, a largely necrotic phaeochromocytoma was found. Pathological examination demonstrated extensive avascular necrosis, which had occurred spontaneously without any major symptoms.

Adrenal Gland Neoplasms↗
PubMed1993

Identification of a hormone-dependent phosphorylation site adjacent to the DNA-binding domain of the chicken progesterone receptor.

We have previously identified three phosphorylation sites in chicken progesterone receptor (PR) isolated from the cytosol of chicken oviducts. Several lines of evidence suggested that there might be additional phosphorylations that occur only in the nuclear compartment. We have reexamined the phosphorylation of the PR using whole cell extracts and have identified a second hormone-dependent phosphorylation site (Ser367) which is located on the amino-terminal side of the DNA-binding domain. This site also contains a Ser-Pro consensus sequence, as do the three previously reported sites. There are four Ser-Pro sequences in chicken PR, and all four are phosphorylated. Two of the sites showed substantial phosphorylation in the absence of hormone, with some enhancement in response to hormone, whereas two of the sites showed very little phosphorylation in the absence of hormone. This suggests either that despite the Ser-Pro consensus sequences, the sites are phosphorylated by different enzymes, or that binding hormone changes the conformation of the protein sufficiently to expose the two hormone-dependent phosphorylation sites.

Amino Acid Sequence↗
PubMed1993

Cardiac fibroma and heart transplantation.

Successful orthotopic heart transplantation was performed in a 38-day-old child with a fetal echocardiographic diagnosis of a left ventricular mass and in a 40-year-old woman with cardiac murmur since childhood and an echocardiographic diagnosis of asymmetric septal hypertrophy. Pathologic examination of the removed hearts, consisting of gross, histologic, immunohistochemical, and ultrastructural studies, led to the final diagnosis of cardiac fibroma. Both patients were alive and in good condition at 35 and 28 months, respectively, after operation.

Adult↗