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Biomedical subjects

A Vitale

Publications and source records attributed to A Vitale.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1989

Mannose analog 1-deoxymannojirimycin inhibits the Golgi-mediated processing of bean storage glycoproteins.

The asparagine-linked oligosaccharide chains of glycoproteins can be processed to form a wide variety of structures. The Golgi complex is the main compartment involved in this processing. In mammalian cells the first enzyme acting along the Golgi processing pathway is mannosidase I, whose action is a prerequisite for any further processing and which is inhibited by the mannose analog 1-deoxymannojirimycin (dMM). To have insights into the processing pathway in plant cells, we have studied the in vivo effect of dMM on the processing of the bean (Phaseolus vulgaris) storage proteins phaseolin and phytohemagglutinin, two well characterized plant glycoproteins. Cotyledons obtained from developing seeds were labeled with radioactive leucine, glucosamine, or fucose in the presence or absence of dMM. Treatment with dMM fully inhibited the acquisition of resistance to endo-beta-N-acetylglucosaminidase H by phaseolin and phytohemagglutinin and the incorporation of fucose into protein. Furthermore, the apparent molecular weight of the polypeptides of phaseolin and phytohemagglutinin synthesized in dMM-treated cotyledons was consistent with the exclusive presence of oligommanose oligosaccharide chains which had not been processed in the Golgi complex. The inhibition of processing did not prevent exit from the Golgi complex, and most probably the storage proteins were correctly targeted to the protein bodies as indicated by the post-translational polypeptide cleavage of phaseolin. These results indicate that the action of a mannosidase is the first obligatory step of Golgi-mediated processing also in a plant cell and, together with data obtained in other laboratories on the in vitro specificity of glycosidases and glycosyltransferases present in the Golgi complex of plant cells, support the hypothesis that the key early reactions in Golgi-mediated processing are similar if not identical in plants and mammals.

Journal Article↗
PubMed1989

Synthesis of Lectin-Like Protein in Developing Cotyledons of Normal and Phytohemagglutinin-Deficient Phaseolus vulgaris.

The genome of the common bean Phaseolus vulgaris contains a small gene family that encodes lectin and lectin-like proteins (phytohemagglutinin, arcelin, and others). One of these phytohemagglutinin-like genes was cloned by L. M. Hoffman et al. ([1982] Nucleic Acids Res 10: 7819-7828), but its product in bean cells has never been identified. We identified the product of this gene, referred to as lectin-like protein (LLP), as an abundant polypeptide synthesized on the endoplasmic reticulum (ER) of developing bean cotyledons. The gene product was first identified in extracts of Xenopus oocytes injected with either cotyledonary bean RNA or LLP-mRNA obtained by hybrid-selection with an LLP cDNA clone. A tryptic map of this protein was identical with a tryptic map of a polypeptide with the same SDS-PAGE mobility detectable in the ER of bean cotyledons pulse-labeled with either [(3)H]glucosamine or [(3)H]amino acids, both in a normal and in a phytohemagglutinin-deficient cultivar (cultivars Greensleeves and Pinto UI 111). Greensleeves LLP has M(r) 40,000 and most probably has four asparagine-linked glycans. Pinto UI 111 LLP has M(r) 38,500. Unlike phytohemagglutinin which is a tetramer, LLP appears to be a monomer by gel filtration analysis. Incorporation of [(3)H]amino acids indicates that synthesis of LLP accounts for about 3% of the proteins synthesized on the ER, a level similar to that of phytohemagglutinin.

Journal Article↗
PubMed1989

Interferon alpha-2b as treatment for Philadelphia-negative chronic myeloproliferative disorders with excessive thrombocytosis.

We treated 32 patients with Ph1-negative chronic myeloproliferative disorders (CMD) with excessive thrombocytosis with Interferon alpha-2b (IFN alpha-2b): 26 had essential thrombocythaemia, ET (18 previously untreated, eight pretreated); one thrombocythaemia after treatment for Hodgkin's disease (HD); two thrombocythaemia associated with non-Hodgkin's lymphoma (NHL); three stage II idiopathic myelofibrosis (IM). IFN was given at daily doses of 1-4 x 10(6) IU. Twenty-seven patients (84%) responded, 17 (53%) achieved complete haematologic response after a median time of 12 weeks, and 10 (31%) partial haematologic response. Median platelet levels declined in complete haematologic response patients from 1,190 to 335 x 10(9)/l. Normalization of megakaryocyte (MK) levels was observed in 8/17 complete haematologic response patients treated for 9-12 months, with decreased bone marrow (BM) cellularity. Side effects requiring dose reduction or discontinuation of treatment occurred in 28% of cases with IFN doses of 2 or 4 x 10(6) IU. After 1 year of continuous IFN treatment, responses were maintained with conventional chemotherapy or low-dose IFN. This study demonstrates that IFN has definite therapeutic activity in CMD with excessive thrombocytosis. This biological agent, either alone or in combination with other antineoplastic treatment, may represent a new therapeutic approach for these disorders.

Adult↗
PubMed1989

Interaction of HIV and EBV at lymphoid tissue level: immunohistochemistry and in situ hybridization.

The presence of Epstein-Barr virus antigens and genome was studied in lymph nodes from HIV + patients affected by PGL. Cryostat sections from 50 lymph nodes of HIV + patients were immunostained with EBV-VCA (viral capsid antigen), EBV-EA (early antigen) and p24 HIV major core protein monoclonal antibodies. In situ hybridization was performed using a biotin conjugated EBV DNA probe; the reaction product was demonstrated by immunohistochemical method. As positive controls, EBV producer B95-8 and HIV infected H9 cell lines were used. The majority of patients had circulating EBV antibodies mainly directed against the viral capsid antigen and only in few cases against early antigens. Positivity for HIV p24 protein was detected in 43 out of 50 lymph nodes within the germinal centers with a reticular pattern. Only 2 out of 50 lymph nodes presented very few positive cells for EBV antigens and none expressed detectable EBV genome. Our results suggest that EBV cellular expression does not correlate with serum positivity; furthermore the absence of EBV antigens and genome at tissue level might indicate that EBV is not directly involved in the pathogenesis of PGL.

AIDS-Related Complex↗
PubMed1988

1-Deoxymannojirimycin inhibits Golgi-mediated processing of glycoprotein in Xenopus oocytes.

We prepared in vitro an mRNA transcript coding for the erythroagglutinating subunit of the kidney bean glycoprotein phytohemagglutinin, E-PHA. The mRNA, injected into Xenopus oocytes, synthesized E-PHA carrying two Asn-linked carbohydrate chains, one of which was processed and acquired resistance to endo-beta-N-acetylglucosaminidase H, as occurs in the native bean cells. When the mannose analog 1-deoxymannojirimycin, an inhibitor of mammalian Golgi mannosidase I, was included in the oocyte culture medium, the acquisition of endo-beta-N-acetylglucosaminidase H resistance was abolished, indicating that also in an amphibian cell the inhibitor blocks a key reaction in Golgi-mediated processing.

1-Deoxynojirimycin↗
PubMed1986

The position of the oligosaccharide side-chains of phytohemagglutinin and their accessibility to glycosidases determines their subsequent processing in the Golgi.

Phytohemagglutinin (PHA), the glycoprotein lectin of Phaseolus vulgaris has two types of asparagine-linked oligosaccharides per polypeptide: a high-mannose chain with the formula (Man)8-9(GlcNAc)2 on Asn12 and a modified chain with fewer mannose residues and additional fucose and xylose residues on Asn60. Glycosylation of PHA is a cotranslational process, which occurs in the endoplasmic reticulum, and newly synthesized PHA has two high-mannose chains. Transport of PHA to the protein bodies via the Golgi complex is accompanied by the modification of one of the two high-mannose chains. Why is only one chain modified, while the other remains in the high-mannose configuration? By determining the effect of digestion with various glycosidases (alpha-mannosidase, endo-beta-N-acetylglucosaminidase H and endo-beta-N-acetylglucosaminidase F) on native and denatured PHA we obtained evidence consistent with the interpretation that the accessibility of oligosaccharide chains to modifying enzymes is of major importance in determining whether a high-mannose chain becomes modified or not. The high-mannose chain of mature undenatured PHA is only partially accessible to glycosidases, while PHA obtained from the endoplasmic reticulum has one high-mannose chain, which is readily accessible to alpha-mannosidase and endoglycosidases H and F. We show that this readily accessible chain is in the same position on the polypeptide (Asn60) as the modified oligosaccharide on mature PHA. Thus, accessibility of the oligosaccharide side-chains to processing enzymes in the Golgi determines whether a particular oligosaccharide side-chain is processed or not.

Concanavalin A↗
PubMed1985

Each zein gene class can produce polypeptides of different sizes.

The family of zein proteins in maize consists of several prototypes whose amino sequence is characterized by a repetitive block structure. We have now isolated and characterized a new series of zein cDNA clones from a cDNA library made from protein-body polysomal mRNA. The nucleotide sequences and the hybrid-selected translation results indicate that anomalous zein genes with termination codons within the coding region are transcribed, translated and possibly accumulated into zein protein bodies. The sequence analysis of these new clones and their comparison with already characterized zein sequences, all from the same maize line, indicate a large variability in the amino acid sequence of the blocks both among the prototypes and within members of each prototype. Northern blot analysis of total RNA from endosperms at different maturation stages shows a differential expression of each prototype sequence with the production, within each family, of zein transcripts coding for discrete size classes of polypeptides. The results allow a better definition of the zein system, clarify the relationship between sequence types and polypeptide size classes, and suggest the possibility of inserting lysine codons to raise the nutritional value of the seed storage protein.

Journal Article↗
PubMed1985

Abnormal processing of the modified oligosaccharide side chains of phytohemagglutinin in the presence of swainsonine and deoxynojirimycin.

Phytohemagglutinin, the glycoprotein lectin of the common bean, Phaseolus vulgaris, has both high-mannose (Man(8-9)GlcNAc(2)) and modified oligosaccharide side chains. The modified side chains have glucosamine, mannose, fucose, and xylose in the molar ratios 2:3.8:0.6:0.5, and are resistant to hydrolysis by endoglycosidase H. Synthesis and processing of side chains in the presence of 1-deoxynojirimycin, an inhibitor of alpha-glucosidase, results in the formation of chains which are all alike. They are sensitive to endoglycosidase H, do not contain fucose, and are largely resistant to alpha-mannosidase. This indicates that they are probably high-mannose chains blocked by terminal glucose residues. Synthesis and processing of side chains in the presence of swainsonine, an inhibitor of alpha-mannosidase II, results in the formation of normal high-mannose chains, and of modified chains which contain fucose residues, are resistant to endoglycosidase H, and can be distinguished from normal modified chains only by the presence of extra mannose residues.Processing of the phytohemagglutinin modified chains of PHA under normal conditions involves the attachment of peripheral N-acetylglucosamine residues in the Golgi complex and their subsequent removal in the protein bodies. The attachment of the N-acetylglucosamine residues is largely inhibited by deoxynojirimycin but still occurs in the presence of swainsonine. The results presented in this work show that processing of the asparagine-linked oligosaccharides is under the control of several glycosidases and glycosyltransferases and involves the formation of intermediate products.

Journal Article↗
PubMed1985

Lymphocyte subpopulations and cell mediated cytotoxicity in acute non-lymphoid leukemia (ANLL) patients in complete remission (CR) and off-therapy.

An assessment of the lymphocyte sub-populations and cell mediated cytotoxicity was made in 12 adults with acute non-lymphoid leukemia after stopping chemotherapy. No significant differences were found between ANLL and controls, for absolute lymphocyte count, %SIg/+ cells, Fc gamma + cells and ERFC. The OKT4+/OKT8+ was reduced in ANLL. Leu-7+ cells were significantly higher in ANLL. Moreover it appears that in ANLL lymphocyte function is restored early after stopping chemotherapy.

Acute Disease↗
PubMed1985

[Drug metabolism in the septic liver: conclusions about the pharmacokinetics of chloramphenicol].

In nine patients in anaerobic septic shock, five of them with hepatic injury compatible with sepsis liver failure, hematic chloramphenicol concentration was determined at 5 minutes, 1, 2, 3 and 6 hours after intravenous administration of the first of three daily dose (50 mg/k/day); in the hepatic failure group the procedure was repeated with the next dose, previous attempt of haemodynamic compensation with two hours dopamine (3-10 mcg/k/min.) infusion. Starting from experimental data computation adjustment of time-concentration curve and lineal regression with a p = 0.0001 adjustment was done, determining half live (HL), distribution volume (DV), constant of elimination (K) and clearance (CL). In septic shock without hepatic injury patient group, there was noticed a uniform behavior in time-concentration graphic, withdrawn from chloramphenicol bone-marrow depression levels and pharmacokinetics parameters quite near the normal ones, with a reasonable extension of (DV). When attempting hepatic injury patient group, though an individual variability, drug concentration reach bone marrow depression levels and there was a significant lowering of Cl (p = 0.001) and a reasonable one of DV. Dopamine haemodynamic compensation attempt results in an increase of chloramphenicol hematic concentration in the sepsis liver group and the pharmacokinetics levels bear new deterioration. Practical meaning of the methodology used in drug handling in severe hepatic failure is stressed, to allow mathematic valuation of different pathogenic compounds. Though each patient should be individually evaluated, in septic shock without liver injury chloramphenicol dosification should not been any changes but in presence of sepsis liver doses should be diminished to half and administration interval extended to 11.5 hours.

Chloramphenicol↗
PubMed1984

Biosynthesis and processing of phytohemagglutinin in developing bean cotyledons.

Phytohemagglutinin (PHA) is a family of tetrameric isolectins which accumulate in the protein bodies of developing Phaseolus vulgaris cotyledons. Each tetramer contains erythroagglutinating (E) or lymphocyte-mitogenic (L) subunits, or a combination of both. The subunits have Mr around 33000, E being slightly larger than L. Phytohemagglutinin is a glycoprotein, and its carbohydrate moiety contains N-acetylglucosamine, mannose, fucose and xylose, indicating that this protein has complex oligosaccharide sidechains. Several steps in the biosynthesis and in the cotranslational and post-translational processing of the glycopolypeptides of PHA have been identified. The polypeptides of PHA are synthesized by polysomes attached to the endoplasmic reticulum. The glycosylation of the polypeptides is a cotranslational process, in which each PHA polypeptide usually acquires two oligosaccharide sidechains. The oligosaccharides of PHA isolated from the endoplasmic reticulum are susceptible to digestion with alpha-mannosidase and endo-beta-N-acetylglucosaminidase H indicating that they are of the high-mannose type. In the presence of tunicamycin two unglycosylated polypeptides of PHA are synthesized, indicating that the differences in Mr between the E and L subunits of PHA are not due to differences in glycosylation alone. Transport of PHA to the protein bodies is mediated by the Golgi apparatus where at least part of the oligosaccharide chains of PHA are modified [ Chrispeels , M. J. (1983) Planta ( Berl .) 157, 454-461, and 158, 140-151]. The modified oligosaccharide chains of PHA are then gradually trimmed to a smaller size when the protein is already in the protein bodies. This processing results in an increase in the mobility of the PHA subunits in denaturing polyacrylamide gels.

Endoplasmic Reticulum↗
PubMed1984

Transient N-acetylglucosamine in the biosynthesis of phytohemagglutinin: attachment in the Golgi apparatus and removal in protein bodies.

Cotyledons of the common bean (Phaseolus vulgaris L.) synthesize large amounts of the lectin phytohemagglutinin (PHA) during seed development. The polypeptides of PHA are synthesized by endoplasmic reticulum-bound polysomes and co-translationally glycosylated, pass through the Golgi complex, and accumulate in protein bodies, which constitute the lysosomal compartment in these cells. Some of the high-mannose sidechains of PHA are modified in the Golgi complex, and in mature PHA they contain N-acetylglucosamine, mannose, fucose, and xylose in the molar ratios 2, 3.8, 0.6, and 0.5. The results reported here show that the Golgi complex is also the site of additional N-acetylglucosamine incorporation into the modified sidechains. When developing cotyledons are labeled with [3H]glucosamine and glycopeptides of PHA present in the Golgi complex isolated, the radioactivity can be released as [3H]N-acetylglucosamine by digestion of the glycopeptides with beta-N-acetylglucosaminidase, indicating that the residues are in a terminal position. Arrival of PHA in the protein bodies is followed by the slow removal of these terminal N-acetylglucosamine residues, resulting in a decrease in the Mr of the modified sidechains. The biosynthetic intermediates of the glycoproteins destined for the lysosomal compartments of animal cells contain high-mannose sidechains modified by phosphate groups covered by N-acetylglucosamine that is labile to mild acid treatment. When cotyledons are labeled with [32P]orthophosphate, there is no radioactivity in PHA obtained from any of the subcellular fractions. There is also no release of radioactivity when [3H]glucosamine-labeled glycopeptides obtained from PHA in the Golgi complex are subjected to mild acid hydrolysis. These results indicate that the sorting-signals and posttranslational processing steps for proteins that are transported to the lysosomal compartment are different in plant cells and animal cells.

Acetylglucosamine↗
PubMed1984

Gene Expression and Synthesis of Phytohemagglutinin in the Embryonic Axes of Developing Phaseolus vulgaris Seeds.

Phytohemagglutinin (PHA), the major seed lectin of the common bean (Phaseolus vulgaris), is found largely in the cotyledons, but is also present in the embryonic axis. At mid-maturation, the percentage of total protein synthesis which is directed towards making PHA is 5 to 10 times greater in the cotyledons than in the axes. This lower rate of synthesis in the axes is correlated with a lower abundance of mRNA for PHA, as determined by dot blot hybridization using a cDNA clone for PHA. Manen and Pusztai (Planta 1982 155: 328-334) have claimed on the basis of immunocytochemical evidence that, in the axis, PHA is found in the cytosol although it is present in protein bodies in the cotyledons. In the cotyledons, PHA is synthesized on rough endoplasmic reticulum, and its transport to the protein bodies via the Golgi complex is associated with specific posttranslational processing steps (Vitale and Chrispeels, J Cell Biol 1984 In press). A cytosolic localization of axis PHA would be an indication of a different site of synthesis and transport pathway. The results presented here indicate that the site of synthesis of PHA and the posttranslational modifications of PHA are the same in the axes as in the cotyledons. Since in the cotyledons these modifications take place in the endoplasmic reticulum, the Golgi, and the protein bodies, it appears that the transport pathway and the site of accumulation of PHA in the axes is similar to that in the cotyledons. On the basis of our evidence, we suggest that the subcellular localization of PHA in the axes should be reexamined.

Journal Article↗