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A Vitale

Publications and source records attributed to A Vitale.

At least 19 recordsLinked to original sources
PubMed1992

Sorting of proteins to the vacuoles of plant cells.

The secretory system of plant cells sorts a large number of soluble proteins that either are secreted or accumulate in vacuoles. Secretion is a bulk-flow process that requires no information beyond the presence of a signal peptide necessary to enter the endoplasmic reticulum. Many vacuolar proteins are glycoproteins and the glycans are often modified as the proteins pass through the Golgi complex. Vacuolar targeting information is not contained in glycans as it is in animal cells; rather, targeting information is in polypeptide domains as it is in yeast cells. Several such domains have now been identified, but these show little or no amino acid sequence homology. We discuss the possibilities that targeting of protein to plant vacuoles may involve receptors as well as aggregation of protein at low pH.

Amino Acid Sequence↗
PubMed1992

A single mRNA, transcribed from an alternative, erythroid-specific, promoter, codes for two non-myristylated forms of NADH-cytochrome b5 reductase.

Two forms of NADH-cytochrome b5 reductase are produced from one gene: a myristylated membrane-bound enzyme, expressed in all tissues, and a soluble, erythrocyte-specific, isoform. The two forms are identical in a large cytoplasmic domain (Mr approximately 30,000) and differ at the NH2-terminus, which, in the membrane form, is responsible for binding to the bilayer, and which contains the myristylation consensus sequence and an additional 14 uncharged amino acids. To investigate how the two differently targeted forms of the reductase are produced, we cloned a reductase transcript from reticulocytes, and studied its relationship to the previously cloned liver cDNA. The reticulocyte transcript differs from the liver transcript in the 5' non-coding portion and at the beginning of the coding portion, where the seven codons specifying the myristoylation consensus are replaced by a reticulocyte-specific sequence which codes for 13 non-charged amino acids. Analysis of genomic reductase clones indicated that the ubiquitous transcript is generated from an upstream "housekeeping" type promoter, while the reticulocyte transcript originates from a downstream, erythroid-specific, promoter. In vitro translation of the reticulocyte-specific mRNA generated two products: a minor one originating from the first AUG, and a major one starting from a downstream AUG, as indicated by mutational analysis. Both the AUGs used as initiation codons were in an unfavorable sequence context. The major, lower relative molecular mass product behaved as a soluble protein, while the NH2-terminally extended minor product interacted with microsomes in vitro. The generation of soluble reductase from a downstream AUG was confirmed in vivo, in Xenopus oocytes. Thus, differently localized products, with respect both to tissues and to subcellular compartments, are generated from the same gene by a combination of transcriptional and translational mechanisms.

Amino Acid Sequence↗
PubMed1992

Bean homologs of the mammalian glucose-regulated proteins: induction by tunicamycin and interaction with newly synthesized seed storage proteins in the endoplasmic reticulum.

Treatment of developing bean cotyledons with the inhibitor of N-glycosylation tunicamycin enhanced the synthesis of at least two polypeptides with molecular mass 78 kDa and 97 kDa. Pulse-chase experiments and subcellular fractionation indicated that these are endoplasmic reticulum (ER) residents. The 78 kDa protein is a major component of the ER protein fraction and, by N-terminal sequencing, was identified as a bean homolog of the mammalian 78 kDa glucose-regulated protein (GRP78). This is a molecular chaperone that is probably involved in the folding and oligomerization of several animal and yeast proteins in the ER. When newly synthesized storage glycoproteins phaseolin, phytohemagglutinin or alpha-amylase inhibitor were immunoprecipitated from an ER preparation of tunicamycin-treated tissue, the GRP78 homolog was always co-precipitated. Bound GRP78 homolog could be released by ATP treatment. These results suggest that, at least when glycosylation is inhibited, this protein plays a role in the early stages of the synthesis of vacuolar storage proteins.

Amino Acid Sequence↗
PubMed1992

Sleep patterns in acute ischemic stroke.

We studied polysomnographic recordings using an Oxford Medilog 9000 System in 18 patients with ischemic stroke in the middle cerebral artery territory. All patients underwent neurologic examination and brain CT scan within 5 h after the onset of symptoms. Polysomnographic recordings were started immediately thereafter and went on for three nights. Clinical and polysomnographic follow-up were performed 3 weeks after admission. The number and duration of REM phases were significantly reduced in the acute phase. This reduction correlated with the severity of neurological deficit at outcome and with the anatomical site of the lesion on CT scan. Our data provide evidence that polysomnographic recording is useful to detect symptoms of patients with different clinical outcomes during the acute phase of ischemic stroke.

Aged↗
PubMed1991

Expression of the wild-type and mutated vacuolar storage protein phaseolin in Xenopus oocytes reveals relationships between assembly and intracellular transport.

The role played by subunit assembly in the intracellular transport of the bean storage protein phaseolin, a soluble trimeric glycoprotein, was investigated using Xenopus oocytes injected with RNA. We show that phaseolin assembly is dependent upon the level of synthesis of the protein and is required for intracellular transport out of the endoplasmic reticulum. We also show that a fraction of the assembled phaseolin is permanently retained in a post-endoplasmic reticulum compartment. Deletion of the C-terminal alpha-helical domain fully prevents in vivo assembly but not endoplasmic reticulum retention. This indicates that this domain is necessary for trimerization but not for interactions of unassembled subunits with endoplasmic reticulum components. The truncated phaseolin has high in vivo stability. The potential implications of these findings on the possibility to improve the nutritional value of phaseolin through genetic engineering are discussed.

Animals↗
PubMed1991

A Saporin-6 cDNA containing a precursor sequence coding for a carboxyl-terminal extension.

Saporin-6 is a single-chain ribosome inactivating protein (RIP) from the seeds and the leaves of Saponaria officinalis (Caryophyllaceae). Here we have identified the COOH-terminal end of mature Saporin-6 and, by cDNA sequencing, the predicted carboxyl-terminal sequence of a leaf Saporin-6 primary translation product. Our data indicate that the characterized cDNA codes for a precursor containing a 22 amino acid carboxyl-terminal extension, not present in mature Saporin-6, that shows similarity to carboxyl-terminal propeptides of vacuolar proteins, suggesting that it may be involved in protein trafficking.

Amino Acid Sequence↗
PubMed1991

Heterologous in vivo processing of human preproendothelin 1 into bioactive peptides.

Endothelin (ET) is an extremely potent vasoconstrictor peptide of 21 amino acids, originally found in the supernatant of cultured vascular endothelial cells. To gain insights into its biosynthetic pathway, we expressed a synthetic RNA coding for the 212-amino acid precursor of human ET-1 (preproET-1) in Xenopus oocytes. Cell homogenates and oocyte incubation medium were tested by RIA using an anti-ET-1 serum. ET-1-like immunoreactivity was detected in oocytes injected with preproET-1 synthetic RNA but not in control oocytes and was much higher in medium than in cell homogenates. When preproET-1 was expressed in oocytes treated with monensin, a dramatic decrease in secretion of immunoreactive material was observed, indicating that secretion is mediated by the Golgi complex. ET-1-like immunoreactive material present in oocyte incubation medium was fractionated by reverse-phase HPLC into two main peaks, corresponding to the retention times of human big ET-1 and ET-1. Incubation medium of oocytes expressing the synthetic preproET-1 RNA elicited a characteristic vasoconstrictor response on rabbit vena cava, consistent with the biological activity that would be predicted from the amount of ET-1-like immunoreactivity measured. These results suggest that common pathways of ET maturation exist in widely different cells and that Xenopus oocytes may represent a useful tool in studying the cell biology of ET-1 synthesis.

Animals↗
PubMed1991

The signal peptide of human preproendothelin-1.

Synthetic mRNAs were produced using either the complete coding sequence of a human preproendothelin-1 cDNA clone or a truncated form in which the portion encoding the first 17 amino acids, representing a putative signal peptide for insertion into the endoplasmic reticulum, was replaced with a methionine codon. The mRNAs were translated in vitro in the presence or in the absence of microsomal membranes. Protection from trypsin digestion demonstrated that the full-length polypeptide, but not the truncated form, could be inserted into the membranes. Sequence analysis revealed that membrane insertion is accompanied by removal of the first 17 amino acids. These results indicate that the first 17 amino acids of human preproendothelin-1 are a functional signal peptide which allows the protein to enter the secretory pathway.

Amino Acid Sequence↗
PubMed1991

Studies of von Willebrand factor in essential thrombocythemia patients treated with alpha-2b recombinant interferon.

The crucial role of the von Willebrand Factor (vWF) and its interaction with platelets in myeloproliferative disorders (MPD) have emerged in recent years. Recently, many authors have reported the therapeutical efficacy of interferon (IFN) in MPD with thrombocytosis in decreasing platelet number. The purpose of our report is to study the modifications of vWF in a series of 20 patients affected by essential thrombocythemia (ET) or MPD with thrombocytosis, treated with alpha 2b recombinant IFN (alpha 2b-rIFN). Patients were studied before treatment and after complete or partial response: vWF-related properties, bleeding time (BT) and ristocetin-induced platelet aggregation (RIPA) were evaluated. Before treatment, we found prolonged BT in 5 patients (25%), abnormal RIPA in 8 (40%), reduced factor VIII coagulant activity (VIII:C) in 2 (10%), reduced vWF-related antigen (vWF:Ag) in 5 (25%) and low vWF:ristocetin cofactor (vWF:Ricof) in 5 (25%). Twelve subjects were evaluated after hematologic remission: in all patients, BT, VIII:C, vWF:Ag and vWF:Ricof were within normal range or upper normal limits. RIPA was abnormal in 7 subjects. Multimer patterns of vWF were performed in 3 patients before and after treatment: 2 of them showed loss of high-molecular-weight multimers that seemed to recover at remission. IFN seems to induce improvement of platelet number and their functions in MPD with thrombocytosis.

Adult↗
PubMed1990

Therapy of essential thrombocythemia with alpha-interferon: results and prospects.

Conventional treatment of symptomatic essential thrombocythemia (ET) consists of long-term administration of myelosuppressive cytotoxic agents which, although efficacious in most cases, are associated with leukemogenic potential. Alpha-interferon (IFN) exerts a dose-dependent inhibitory influence on thrombopoiesis through a direct antiproliferative effect on megakaryocytic precursors. Therefore, it may provide a biologic, potentially non-mutagenic alternative to conventional cytotoxic treatments. At daily doses ranging from 1 to 5 M.U., alpha-IFN is efficacious in inducing a hematologic response in most patients with ET. Response to IFN is a gradual process. The median time to hematologic response varies from 1 to 3 months and a significant proportion of patients reach and maintain normal platelet counts with low doses (1-3 M.U./d). Normalization of marrow megakaryocytosis requires longer treatment (9-12 months). Also patients resistant to cytotoxic drugs may respond to alpha-IFN, suggesting a lack of cross-resistance between the two treatment modalities. Side-effects, although not severe, represents a limit to the administration of adequate doses of IFN in about 25% of cases. Once hematologic response has been obtained, both low-dose IFN and cytotoxic drugs are effective as maintenance. The full potentialities of alpha-IFN in ET in combination with cytotoxic drugs or with other cytokines need to be further investigated.

Humans↗
PubMed1978

[Still's disease. Review of the literature and considerations on a case].

Following an extensive review of all the most recent literature on primary chronic rheumatism in infants or the young, a personal case of Still's disease is reported. Special attention is paid to the good results obtained associating an antitubercular therapy, even though no clinical or laboratory findings suggest any specific tubercular condition: no definitive conclusions are reached but an aspect of the problem which is undoubtedly worth further study is stressed.

Adolescent↗
PubMed1978

Effects of prostaglandin E2 and DL204 IT, an inhibitor of prostaglandin degradation, on ovulation and ovum transport in the hamster.

The effects of 2(3-ethoxyphenyl)-5,6-dihydro-s-triazole-[5,1-a]isoquinoline (L-11204 or DL 204 IT and PGE2 on ovulation and ova transport were studied. DI 204 IT was administered in doses of 0.2-25 mg/kg s.c. on the day of estrus. A smal reduction in ovulating follicles was observed 96 hours later, but only at the 5 mg/kg dose level. At all dose levels, however, DL 204 IT caused a dose-related reduction in the number of ova in the oviducts. PGE2 at a total dose of 2 mg/animal s.c., administered in 4 divided doses over the second and third day of the cycle did not affect ovulation or ova transport. PGE2 plus DL 204 IT (5 mg/kg), however, completely blocked ovulation in all but one animal. That animal had one ovulated follicle and a single ova was recovered from its oviduct.

Animals↗
PubMedDate not supplied

Surgical treatment of immune thrombocytopenic purpura.

The role of surgery in the treatment of immune thrombocytopenic purpura (ITP) is still discussed. The aim of this study was to verify our criteria of patient selection for splenectomy, to analyze the results of a protocol for the evaluation of the hemorrhagic risk, and to discuss long-term results of 70 patients with ITP who underwent surgical treatment from 1984 to 1990. All patients received steroid therapy. Sixty-two patients were given high doses of IgG (600 mg/kg/iv bolus) pre-operatively in order to obviate the need for intra-operative platelet transfusions. Forty-three patients showed a significant increase in the platelet count, 8 a moderate increase, while 11 patients did not respond. No operative mortality was observed, however postoperative minor complications occurred in 14 (20%) patients. Accessory spleens were found in 11 (15.7%) patients. Mean follow-up was 21 months. Response to splenectomy was considered as complete (platelets greater than 150,000 mm3 with no need for medical treatment) in 63 (90%) patients. No response was observed in 7 patients. In 2 of the non-responders postoperative indium-111 scan revealed accessory spleens and ITP remitted after accessory splenectomy. All non-responders were in the group of patients who did not respond to the pre-operative infusion of high dose IgG. It can be concluded that splenectomy is a safe and effective treatment for ITP and that response to pre-operative infusion of IgG may be considered as predictive for the outcome after splenectomy.

Adolescent↗
PubMedDate not supplied

Essential thrombocythemia: a retrospective study on the clinical course of 100 patients.

We report a study concerning 100 patients affected by essential thrombocythemia: 90 adult (age greater than 20 years) and 10 pediatric subjects. The diagnosis was made by chance (78%), because of hemorrhages (10%), thrombosis (9%), vasomotor symptoms (29%). In the adult group, single-agent chemotherapy was performed with good remission using pipobroman or interferon. Antiaggregant agents were used in all patients at diagnosis. During the clinical course only a few complications occurred.

Adolescent↗