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Biomedical subjects

G Leone

Publications and source records attributed to G Leone.

At least 325 records · Page 18Linked to original sources
PubMed1991

Vasoactive intestinal peptide fluctuates in human blood with a circadian rhythm.

The vasoactive intestinal peptide (VIP) may be radioimmunoassayed in systemic venous blood. The plasma concentrations of VIP were investigated in human blood according to a chronobiological design. The study documented a circadian rhythmicity in time-qualified concentrations of VIP. Accordingly, VIP may be ascribed to biological variables characterized by periodicity in their physiological attributes. The rhythmic physiology of VIP is, however, highly disturbed in its tonic and phasic properties during senescence.

Adult↗
PubMed1991

Apparent isolated skin relapse in acute monocytic leukemia. A case report.

A case of acute monocytic leukemia with an apparent isolated skin relapse is reported. The cutaneous involvement was associated with a morphological bone marrow remission but a cytogenetic relapse was present. Regression of the skin lesions was obtained with a protocol including daunoblastine, aracytin and thioguanine, but the patient relapsed and died a few months later without achieving another remission. The relation between cutaneous and medullary disease is discussed.

Adult↗
PubMed1991

Hepatocarcinoma in cirrhosis. Is antithrombin III a neoplastic marker?

It has been reported that hepatoma (HCC) cells produce abnormal proteins such as erytropietin, fibrinogen, prothrombin, and, recently, antithrombin III (AT III). In a preliminary report, we reported increased AT III levels in patients bearing HCC independent of their clinical liver status. The present study was performed to assess antithrombin III levels and other serological data present in patients with cirrhosis and in patients with cirrhosis and clinical findings of neoplastic disease. In 70 well-matched patients (47 with cirrhosis and 23 with cirrhosis and proven HCC) serum total cholesterol, albumin, prothrombin, alkaline phosphatase, AFP, aminotransferases, and AT III were determined. Together with AFP and alkaline phosphatase, patients with HCC had higher values of AT III (88 +/- 7%) and total cholesterol (184 +/- 17 mg/100 ml), as compared with cirrhotic patients (AT III 56 +/- 3.6%; total cholesterol 113 +/- 5 mg/100 ml) (P less than 0.001). No difference was observed between these two groups for albumin, prothrombin, and aminotransferases. In HCC patients, AT III levels were related to the total cholesterol level (R2 = 0.317), whereas in the cirrhotic patients it correlated with the prothrombin level (R2 = 0.274). These data suggest that in HCC patients a greater rate of synthesis of AT III occurs, whereas in cirrhotic patients lower levels of AT III occur due to impaired synthesis or increased catabolism of the protein. The serial determination of AT III in cirrhotic patients as a means of detecting neoplastic transformation is suggested.

Adult↗
PubMed1991

Arterial thrombosis as clinical manifestation of congenital protein C deficiency.

A 49-year-old man was hospitalized for slight paresis of the upper left limb. Thrombosis of the right internal carotid artery was documented by arteriography and digital angiography, which showed evidence of an anastomotic blood flow. He went on anticoagulation treatment. Five years later, after an uneventful period, he was referred to our center for the occurrence of a superficial thrombophlebitis: diagnosis of congenital protein C deficiency was possible in the patient as well as in two of his relatives. Two other subjects with congenital protein C deficiency belonging to two different kindreds, whose illness was diagnosed in our center, suffered from myocardial infarction and TIA, respectively, as the only clinical manifestation; a fourth case, previously described, with recurrent superficial thrombophlebitis, suffered from a TIA when on treatment with stanozolol. These cases indicate that arterial thrombosis or TIA is not an uncommon event in congenital protein C deficiency, even in patients without other risk factors for arterial thrombosis.

Adult↗
PubMed1991

Trimerization of the reovirus cell attachment protein (sigma 1) induces conformational changes in sigma 1 necessary for its cell-binding function.

The implications of reovirus sigma l protein trimerization on its cell-binding function were investigated. Both monomeric and trimeric forms of sigma l were found to be present when full-length type 3 reovirus Sl transcripts prepared in vitro were translated in rabbit reticulocyte lysates. Pulse-chase experiments demonstrated that monomers were precursors of trimers. However, only the trimeric form was capable of binding to cell surface receptors. Protease and antibody recognition analyses revealed significant structural differences between these two sigma l forms at both the N- and C-termini. Our results suggest that trimerization of protein sigma l is accompanied by extensive conformational changes necessary for its cell attachment function.

Animals↗
PubMed1991

Conformational and functional analysis of the C-terminal globular head of the reovirus cell attachment protein.

We have been investigating structure-function relationships in the reovirus cell attachment protein sigma 1 using various deletion mutants and protease analysis. In the present study, a series of deletion mutants were constructed which lacked 90, 44, 30, 12, or 4 amino acids from the C-terminus of the 455-amino acid-long reovirus type 3 (T3) sigma 1 protein. The full-length and truncated sigma 1 proteins were expressed in an in vitro transcription/translation system and assayed for L cell binding activity. It was found that the removal of as few as four amino acids from the C-terminus drastically affected the cell binding function of the sigma 1 protein. The C-terminal-truncated proteins were further characterized using trypsin, chymotrypsin, and monoclonal and polyclonal antibodies. Our results indicated that the C-terminal portions of the mutant proteins were misfolded, leading to a loss in cell binding function. The N-terminal fibrous tail of the proteins was unaffected by the deletions as was sigma 1 oligomerization, further illustrating the discrete structural and functional roles of the N- and C-terminal domains of sigma 1. In an attempt to identify smaller, functional peptides, full-length sigma 1 expressed in vitro was digested with trypsin and subsequently with chymotrypsin under various conditions. The results clearly demonstrated the highly stable nature of the C-terminal globular head of sigma 1, even when separated from the N-terminal fibrous tail. We concluded that: (1) the C-terminal globular head of sigma 1 exists as a compact, protease-resistant oligomeric structure; (2) an intact C-terminus is required for proper head folding and generation of the conformationally dependent cell binding domain.

Amino Acid Sequence↗
PubMed1991

The N-terminal heptad repeat region of reovirus cell attachment protein sigma 1 is responsible for sigma 1 oligomer stability and possesses intrinsic oligomerization function.

The oligomerization domain of the reovirus cell attachment protein (sigma 1) was probed using the type 3 reovirus sigma 1 synthesized in vitro. Trypsin cleaved the sigma 1 protein (49K molecular weight) approximately in the middle and yielded a 26K N-terminal fragment and a 23K C-terminal fragment. Under conditions which allowed for the identification of intact sigma 1 in the oligomeric form (approximately 200K) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the N-terminal 26K fragment was found to exist as stable trimers (80K) and, to a less extent, as dimers (54K), whereas the C-terminal fragment remained in the monomeric form. A polypeptide (161 amino acids) containing the N-terminal heptad repeat region synthesized in vitro was capable of forming stable dimers and trimers. Using various criteria, we demonstrated that the stability of the intact sigma 1 oligomer is conferred mainly by the N-terminal heptad repeat region. Our results are summarized in a model in which individual heptad repeats are held together in a three-stranded alpha-helical coiled-coil structure via both hydrophobic and electrostatic interactions.

Amino Acid Sequence↗
PubMed1991

The incorporation of reovirus cell attachment protein sigma 1 into virions requires the N-terminal hydrophobic tail and the adjacent heptad repeat region.

The N-terminal portion of the reovirus cell attachment protein sigma 1 has recently been shown to possess intrinsic oligomerization and virion-anchoring functions. Sequence analysis of the sigma 1 proteins of the three reovirus serotypes has revealed the presence of distinct structural domains within this region: a terminal hydrophobic tail, a hinge, and an extended coiled-coil. To probe the inter-relationship between the virion-anchoring function and the oligomerization function, we constructed two serotype 3 (T3) sigma 1 deletion mutants in SV40 expression vectors, one lacking the hydrophobic tail and the hinge, and the other lacking an adjacent region which constituted part of the coiled-coil. These mutants were (i) expressed in uninfected COS-1 cells and assayed for their ability to form oligomers, and (ii) expressed in type 1 (T1) reovirus-infected COS-1 cells and assayed for their incorporability into progeny T1 virions. It was found that, whereas both truncated sigma 1 proteins were capable of forming stable oligomers, neither could be incorporated into virions. These observations, coupled with structural characteristics deduced from sequence analysis, are compatible with a model in which the hydrophobic tail is the bona fide sigma 1 anchorage domain and whose precise association with the virion spikes is dictated by an adjacent heptad repeat region linked to the former structure via a flexible hinge region.

Amino Acid Sequence↗
PubMed1991

Biochemical and biophysical characterization of the reovirus cell attachment protein sigma 1: evidence that it is a homotrimer.

The oligomerization state of the reovirus cell attachment protein sigma 1 (49K monomeric molecular weight) was determined by biochemical and biophysical means. Full-length (protein product designated A) and C-terminal truncated (protein product designated B) serotype 3 reovirus S1 mRNA transcripts synthesized in vitro were cotranslated in a rabbit reticulocyte lysate, and the products were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under conditions which allowed for the identification of oligomeric forms of sigma 1. A total of four oligomeric protein bands (corresponding to A3, A2B1, A1B2, and B3, respectively) was consistently observed, which suggests that the protein is made up of three monomeric subunits. Biophysical characterization of purified sigma 1 using column filtration and sucrose gradient sedimentation analysis confirmed the highly asymmetric shape of sigma 1 and allowed us to determine the molecular weight of the native protein to be approximately 132K (a trimer). Similar biophysical analysis on the two tryptic fragments of the sigma 1 [N-terminal fibrous tail (26K monomeric molecular weight) and the C-terminal globular head (23K monomeric molecular weight)] yielded molecular weights of 77K and 64K, respectively, both again corresponding to trimers. We therefore conclude that protein sigma 1 is a homotrimer and provide, with supportive experimental evidence, a rationale for the anomalous behavior of the oligomeric protein in SDS-polyacrylamide gels, which, coupled with chemical cross-linking studies, has in part led to the previous suggestion that sigma 1 might be a higher order oligomer.

Capsid Proteins↗
PubMed1991

Novel point mutations leading to type 1 antithrombin deficiency and thrombosis.

Direct sequencing of antithrombin III (AT) gene fragments specifically amplified by the polymerase chain reaction was utilized to identify the molecular basis of type 1 AT deficiency in two unrelated kindreds, both with thrombotic disease. Two novel point mutations were identified, deletion of a T from the second position of codon 81 in one propositus and insertion of a G in codon 424 in the second kindred. The AT 81(-T) frameshift mutation leads to a premature stop signal in codon 89, while the AT 424(+G) allele has a premature stop only one codon short of the normal gene. The latter mutation changes the eight carboxy terminal residues of AT, including 429Cys, and increases the proportion of polar amino acids in this region. We suggest that altered folding of the mutant protein may explain the AT deficiency.

Adult↗
PubMed1991

Antiproliferative activity of quercetin on normal bone marrow and leukaemic progenitors.

We used an in vitro clonogenic assay in semi-solid medium to test the sensitivity of normal bone marrow and acute myeloid and lymphoid leukaemia progenitors to the flavonol quercetin. We have studied 14 acute myeloid (AML) and four acute lymphoid (ALL) leukaemias. All ALL and the vast majority of AML (12/14) had a high sensitivity to quercetin with more than 50% growth inhibition at 2 x 10(-6) M quercetin. One M3-AML was partially quercetin-sensitive displaying 60% surviving AML-colony forming units (CFU-AML) at a quercetin concentration of 10(-5) M. One M1-AML was resistant to the growth inhibitory effect of quercetin at a concentration of 2 x 10(-5) M. The clonogenic efficiency of both AML and ALL positively correlated with leukaemic colony-forming unit (CFU-L) sensitivity to quercetin suggesting that this parameter can be useful in predicting quercetin responsiveness of leukaemic cells. We have also studied the effect of various quercetin concentrations on colony formation by normal bone marrow cells. At a quercetin concentration of 10(-5) M, we observed (in five different experiments) a mean recovery of 53% and 65% of erythroid blast-forming units (BFU-E) and granulocyte-macrophage colony-forming units (CFU-GM), respectively. Thus, normal bone marrow appeared partially resistant to quercetin, being inhibited less than 50% by quercetin concentration higher than 2 x 10(-5). When normal bone marrow were deprived in CD34+ haematopoietic progenitors the resultant population became highly sensitive to quercetin, with a mean recovery of BFU-E and CFU-GM of 5% and 12% of controls respectively in the presence of 2 x 10(-5) M quercetin. Furthermore, CD34 progenitors, positively selected, appeared fully resistant to quercetin concentrations as high as 2 x 10(-5) M. Thus, CD34+ progenitors are a quercetin-resistant component in normal bone marrow. In conclusion, our results further provide a biological basis for the therapeutic use of quercetin, considering that this compound could inhibit leukaemic cell growth without suppressing normal haematopoiesis.

Acute Disease↗
PubMed1991

Semiautomated autologous bone marrow processing for transplantation.

This paper describes the development of a semiautomated procedure for autologous bone marrow processing, prior to ex vivo manipulation and/or cryopreservation. This procedure was employed with a pediatric bowl (125 ml Latham bowl) and the automated DuPont Stericell processor. We have obtained a mononuclear cell recovery of 85% and a hemopoietic progenitor cell recovery of 81% (CFU-GM; BFU-E), with a red cell removal of 84%. We believe that a reliable and standardized bone marrow processing procedure is the basic necessity for a bone marrow transplantation program.

Automation↗
PubMed1991

Autologous peripheral blood stem cell transplantation in malignancies involving bone marrow.

Six patients suffering from refractory malignancies (3 NHL, 1 MM, 1 AML, 1 neuroblastoma) received high dose of chemotherapy and autologous peripheral blood stem cell transplantation (APBSCT). The recruitment of PBSC was performed using conventional salvatage schedules of therapy. The patients received a median of 8.69 MNC/kg bw and 20.87 CFU-GM x 10(4)/kg bw. Prompt engraftment occurred in all patients and the median number of days to achieve WBC greater than 1 x 10(9)/l was 16.5 (range 7-26), PMN greater than 0.5 x 10(9)/l was 21.5 (range 6-37) and PLTs greater than 50 x 10(9)/l was 17.5 (range 4-31). Four patients achieved a complete remission. One patient (neuroblastoma) died of progressive disease after a partial response. One patient died in relapse because of drug related toxicity.

Adolescent↗
PubMed1991

ProMACE-cytaBOM versus MACOP-B in intermediate and high grade NHL. Preliminary results of a prospective randomized trial.

One hundred seventy-nine patients with intermediate or high-grade non-Hodgkin's lymphoma were randomized to receive either ProMACE-CytaBOM (P-C) or MACOP-B (M-B). At last follow-up 71 patients in the P-C arm and 78 in the M-B arm were assessable for response. Forty-one patients treated with P-C (58%) and 49 patients treated with M-B (63%) achieved a CR. Moreover 18 and 22 patients achieved PR with P-C and M-B, respectively. Twenty-five patients relapsed, 12 in the P-C arm and 13 in the M-B arm. Thirty-nine patients died, 32 from disease progression, 5 from treatment related causes, and 2 from other causes. No differences between the two treatment groups were observed as regard to relapse or death-rate. At 27 months the survival rate was of 71.9% for patients treated with P-C and 70.7% for those treated with M-B. At 2 years the RFD rate was 64% and 60% for patients in P-C and M-B arm, respectively. Patients treated with M-B experienced an high rate of methotrexate-related toxicity. ProMACE-CytaBOM and M-B seem provided with similar activity. However P-C seem less toxic and more manageable in an outpatient setting.

Adolescent↗
PubMed1991

[24-hour blood pressure: effects of sports in aged subjects].

The present study deals with the blood pressure (BP) and heart rate (HR) 24-h pattern in aged people of both sexes ranging in age from 66 to 75 years. 20 subjects were active in agonistic sports (running and swimming), 20 others had sedentary habits. BP and HR were studied by non-invasive monitoring along with chronobiometric analysis. The BP and HR 24-h pattern was seen to preserve its circadian rhythm in both aged athletes and sedentary elderly. The analysis reveals that the aged athletes show a higher mesor for systolic BP and a lower mesor for diastolic BP and HR. The daily pressure load, as the integral of the BP 24-h values multiplied by the HR mesor, is lower in aged people practising sport as compared to age-matched individuals with sedentary habits. The spectral analysis reveals that physical exercise acts to change the time structure of BP and HR 24-h patterns. The conclusion is drawn that active sport plays beneficial effects in aged people because of a lower pressure load.

Aged↗