Biomedical subjects

I Papa

Publications and source records attributed to I Papa.

10 recordsLinked to original sources

PubMed2006

Leukotriene E(4) in urine in patients with asthma and COPD--the effect of smoking habit.

Leukotriene E(4) (LTE(4)) is implicated in asthma pathophysiology and possibly in chronic obstructive pulmonary disease (COPD) as one of the causes of persistent bronchoconstriction and mucus hypersecretion. Cigarette smoking stimulates cysteinyl leukotrienes (CysLTs) production. We investigated whether LTE(4) is equally increased in asthma and COPD and whether smoking significantly affects LTE(4) levels. Secondary outcomes involved correlations with inflammatory and functional parameters. We studied 40 patients with COPD [20 smokers], 40 asthmatics [20 smokers] and 30 healthy subjects [15 smokers]. Spirometry (FEV(1)% pred., FEV(1)/FVC) was performed, urine was collected for measurement of LTE(4) and creatinine, induced sputum was collected for differential cell counts and serum for ECP. LTE(4)/creatinine levels (pg/mg) [mean (sd)] were increased in asthmatic patients compared to COPD and controls, [125.6(54.5) vs. 54.5(19) vs. 55.9(18.9)pg/mg, respectively, P<0.0001 for asthma]. Smoking significantly affects LTE(4) levels only in asthmatic patients [164 (48) vs. 87 (26.3), P<0.0001 for smokers]. The only significant correlation was between eosinophils in induced sputum and LTE(4)/creatinine levels in asthmatics. In conclusion, patients with asthma presented higher LTE(4) values compared to normals and patients with COPD. Smoking significantly affects LTE(4) values only in asthmatics indicating a different underlying CysLTs inflammatory process in this condition.

Adult↗

PubMed2001

Neonatal aortic arch thrombosis as a result of congenital cytomegalovirus infection.

Thrombotic disease is rare in neonates. The main risk factors at this age are perinatal asphyxia, maternal diabetes, sepsis, polycythemia, dehydration, a low cardiac output, and in primis the catheterization of central lines. Another important risk factor is inherited thrombophilia. Arterial thrombosis is even more rare than venous thrombosis and less related to most of the risk factors listed above; it occurs more frequently in the iliac, femoral, and cerebral arteries but very rarely in the aorta. Most of the described cases of aortic thrombosis are associated with the catheterization of an umbilical artery and involve the descending tract and the renal arteries; very few relate to the ascending tract and the aortic arch. The possible role of virus-induced primary vascular endothelium damage in the etiopathogenesis of neonatal arterial thrombosis has been previously hypothesized. Herpesviruses, particularly human cytomegalovirus (HCMV), can infect endothelial cells and directly damage intact vascular endothelium, altering its thromboresistant surface as a result of procoagulant activity mediated by specific viral surface phospholipids, necessary for the coagulation enzyme complex assembly that leads to thrombin generation. We describe a case of congenital aortic arch thrombosis. The clinical, laboratory, and virologic pictures; the anatomopathologic findings (fully compatible with viral infection); the detection of HCMV in various tissues (including the aorta); and the absence of other causes of aortic thrombosis make it possible to attribute the case to a severe congenital HCMV infection with multiple organ involvement, after the primary infection of the mother. The hemostatic system disorders and hemodynamic disturbances related to viral cardiac damage explain the clinical features of the case and indicate that congenital HCMV infection should be included among the causes of neonatal aortic thrombosis.

Aorta, Thoracic↗

PubMed2001

[Neonatal sepsis].

Sepsis is still one of the most important causes of mortality and morbidity in the neonatal period. Infection is responsible for approximately 2 million neonatal deaths per year in developing countries. In Italy, as in other industrialized countries, the mortality rate has declined to 5.1 per 1000 livebirths. Progress in obstetrics and neonatal intensive care competence have improved survival particularly of preterm and low birth weight neonates. These neonates, for the immunological state and the invasive therapies they are subjected to, are extremely at risk for sepsis. Knowledge of neonatal risk factors, together with cytokines evaluation as early markers of sepsis and laboratory tests such as polymerase chain reaction, have allowed us to accelerate the diagnosis of sepsis with prognostic improvements. The frequent involvement of group B streptococci and coagulase-negative staphylococci requires empiric antibiotic therapy, effective for these pathogens, in all infants with suspected infection, waiting for blood cultures and antibiotic susceptibility results. Breast milk, carrier of immunologically active agents, is still the best prophylaxis for neonatal sepsis.

Humans↗

PubMed2000

Interaction of actin with the capping protein, CapZ from sea bass (Dicentrarchus labrax) white skeletal muscle.

We have compared the functional properties of CapZ from fish white skeletal muscle with those of CapZ from chicken muscle. CapZ is a heterodimer, which enhances actin nucleation and inhibits the depolymerization process by binding to the barbed ends of microfilaments. Here, we report the interaction of CapZ not only with F-actin, but also with monomeric actin. The affinity of sea bass CapZ for G-actin estimated by enzyme-linked immunosorbent assay (ELISA) was in the microM range. This association was PIP2 dependent. Binding contacts with the barbed end of actin were delimited by both ELISA and fluorescence approaches. One site (actin sequence 338-348) was located in a helical region of the subdomain 1, region already implicated in the interaction with other actin binding proteins such as gelsolin. Another site implicates the C-terminal region (sequence 360-372) of actin. Finally, the partial competition of antibodies directed against CapZ alpha or beta-subunits towards CapZ interaction with actin filaments suggests both subunits participate in the complex with actin.

Actins↗

PubMed1999

Use of a chaotropic anion iodide in the purification of Z-line proteins: isolation of CapZ from fish white muscle.

In the present study, we have described an improved method allowing the isolation of proteins which form tightly associated complexes in organized structures such as Z line in skeletal muscle. This procedure is based on both extraction and chromatography in the presence of a chaotropic agent. KI at medium concentration (0.6 M) was selected, taking into account its dissociating activity and mild effect on the native state of proteins. This procedure was applied to purify and to characterize for the first time a CapZ from fish white muscle, a protein involved in the stabilization of the filaments in Z line. The alpha and beta CapZ subunits were identified using anti-synthetic peptide antibodies directed against conserved sequences derived from chicken CapZ. The protocol can be also used for the isolation of other muscular proteins such as alpha-actinin and actin. Finally this technique may be utilized to obtain a good amount of capping protein which could be employed in experiments of microfilament dynamics.

Acetone↗

PubMed1999

Alpha actinin-CapZ, an anchoring complex for thin filaments in Z-line.

CapZ is a widely distributed and highly conserved, heterodimeric protein, that nucleates actin polymerization and binds to the barbed ends of actin filaments, preventing the addition or loss of actin monomers. CapZ interaction with actin filaments was shown to be of high affinity and decreased in the presence of PIP2. CapZ was located in nascent Z-lines during skeletal muscle myofibrillogenesis before the striated appearance of thin filaments in sarcomers. In this study, the stabilization and the anchorage of thin filaments were explored through identification of CapZ partners in the Z-line. Fish (sea bass) striated white muscle and its related Z-line proteins were selected since they correspond to the simplest Z-line organization. We report here the interaction between purified CapZ and alpha-actinin, a major component of Z filaments and polar links in Z-discs. Affinity of CapZ for alpha-actinin, estimated by fluorescence and immunochemical assays, is in the microM range. This association was found to be independent of actin and shown to be weakened in the presence of phosphoinositides. Binding contacts on the alpha-actinin molecule lie in the 55 kDa repetitive domain. A model including CapZ/alpha-actinin/titin/actin interactions is proposed considering Luther's 3D Z-line reconstruction.

Actin Cytoskeleton↗

PubMed1997

Analysis of long-range structural effects induced by DNase-I interaction with actin monomeric form or complexed to CapZ.

Two fundamental properties of monomeric actin were examined in this study, ie its interaction with DNase-I, and the inhibition of endonuclease activity consecutive to the association of the two molecules. In particular, the topological independence between catalytic site of DNase-I and interface with actin, structural changes in actin monomer and the absence of conformational changes in DNase-I were described. We demonstrated a loss of flexibility of antigenic structures in actin subdomain I (ie epitopes 18-28 and 95-105) as well as modification in the exposure of Cys10 and Cys374 after DNase-I binding. Furthermore, the conformational changes induced by DNase-I into the actin molecule weakened the interaction of CapZ to its binding site located in the C-terminal region of actin monomer. These structural changes were time-dependent. When actin was cleaved in the DNase-I binding loop (sequence 38-52) at position 42 by E coli A2 strain protease, a tight DNase-I binding to split actin and the conformational changes were still observed, whereas the DNase-I inhibition activity was completely abolished. Finally, when we substitute Ca2+ by Mg2+ (ATP-Mg2+ monomeric actin) which induces a tighter conformation of actin and partially restores the inhibitory ability of split actin, long-range conformational effects of DNase-I are prevented and the ternary complex DNase-I-actin-CapZ is obtained.

Actins↗

PubMed1997

Fish muscle cytoskeleton integrity is not dependent on intact thin filaments.

Striated muscle cytoskeleton was studied by ultrastructure and electrophoresis. Treatment of sea bass white muscle myofibrils and glycerinated fibres with calpain caused disruption of costameres, intermediate filaments, and Z-line, without altering sarcomeres. V8 protease also caused loss of costameres and Z-line, and disrupted sarcomeres without affecting the intermediate filaments. Recombinant lipase caused loss of Z-lines and also sarcolemma detachment, without changing sarcomeres or intermediate filaments. DNase-1 removed thin filaments and partially removed Z-lines while leaving intact the sarcolemma attachments and intermediate filaments. Calpain, V8 protease, lipase and DNase-1 treatments induced extensive loss of alpha-actinin from the Z-line, which could be related to titin cleavage (calpain, V8), phosphoinositide hydrolysis (lipase), and actin depolymerisation (DNase-1). These results show that the cytoskeletal components are independent of intact thin filaments.

Actinin↗

PubMed1996

Quantitative analysis of the expression of the HLA-DRB genes at the transcriptional level by competitive polymerase chain reaction.

In addition to polymorphism of the peptide-binding site, the density of the MHC class II molecules expressed on the membrane of APC could well play a significant role in the MHC-peptide-TCR interaction during the immune response. We therefore investigated the regulation of the expression of the HLA-DRB genes at the transcriptional level. A competitive PCR approach was used to estimate the quantities of the HLA-DRB transcripts in peripheral blood B cells. When comparing the amounts of steady-state mRNAs among the different DRB1 alleles, the DRB1 transcripts in the DR52 haplotype group were found to be 2.5 to 3.5 times more abundant than the DRB1*01 transcripts, 1.5 to 2 times more abundant than the DRB1*04 transcripts, and 7 times more abundant than the DRB1*08 transcripts. Within the DR52 haplotype group, the DRB1 and DRB3 transcripts had the same abundance. Taken together, these results are in good agreement with the previously reported transcriptional activities of the DRB promoters except for DRB1*04, thus suggesting a differential post-transcriptional regulation among the DRB1 mRNAs.

Alleles↗

PubMed1995

Isolation and properties of white skeletal muscle alpha-actinin from sea-trout (Salmo trutta) and bass (Dicentrarchus labrax).

Fish alpha-actinin purified from sea-trout and bass white muscle by means of two different extraction procedures was used to investigate the eventual presence of different muscle isoforms in Z-disks. These fish alpha-actinins have the same apparent molecular weight (100 kDa) and the same isoelectric point (pI = 5.6), and also have a total antigenic identity towards anti-bass and anti-chicken alpha-actinin antibodies, suggesting a single molecular species. The role of fish alpha-actinin as an anchorage site for thin actin filaments and elastic titin filaments in Z-bands was studied. Despite conservation of the actin-binding site, fish alpha-actinin has a better actin-binding ability (kD = 0.3 microM) than chicken smooth muscle alpha-actinin (kD = 1.6 microM). Several other structural and functional characteristics of fish alpha-actinin were also studied: conservation of sequence and domain structure, the role of divalent ions (Ca2+, Mg2+) and the dielectric constant of the medium in alpha-actinin-actin interaction. Although the reason for fish white muscle alpha-actinin's close affinity to actin was not clearly established, our results suggested that the physicochemical environment of the Z-filaments in Z-disks might be crucial.

Actinin↗