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C Costa

Publications and source records attributed to C Costa.

At least 91 records · Page 5Linked to original sources
PubMed1998

The surface-charge asymmetry and dimerisation of cytochrome c550 from Paracoccus denitrificans--implications for the interaction with cytochrome c peroxidase.

The implications of the dimeric state of cytochrome c550 for its binding to Paracoccus cytochrome c peroxidase and its delivery of the two electrons required to restore the active enzyme during catalysis have been investigated. The amino acid sequence of cytochrome c550 of Paracoccus denitrificans strain LMD 52.44 was determined and showed 21 differences from that of strain LMD 22.21. Based on the X-ray structure of the latter, a structure for the cytochrome c550 monomer from strain 52.44 is proposed and a dipole moment of 945 debye was calculated with an orientation close to the exposed haem edge. The behaviour of the cytochrome on molecular-exclusion chromatography is indicative of an ionic strength-dependent monomer (15 kDa)/dimer (30 kDa) equilibrium that can also be detected by 1H-NMR spectroscopy. The apparent mass of 50 kDa observed at very low ionic strength was consistent with the presence of a strongly asymmetric dimer. This was confirmed by cross-linking studies, which showed that a cross-linked species of mass 30 kDa on SDS behaved with an apparent mass of 50 kDa on molecular-exclusion chromatography. A programme which carried out and evaluated molecular docking of two monomers to give a dimer generated a most probable dimer in which the monomer dipoles lay almost antiparallel to each other. The resultant dipole moment of the dimer is therefore small. Although this finding calls into question the possibility of preorientation of a strongly asymmetrically charged cytochrome as it collides with a redox partner, the stoichiometry of complex formation with cytochrome c peroxidase as studied by 1H-NMR spectroscopy shows that it is the monomer that binds.

Amino Acid Sequence↗
PubMed1998

Evidence from transgenic mice that interferon-beta may be involved in the onset of diabetes mellitus.

A number of cytokines have been shown to alter the function of pancreatic beta-cells and thus might be involved in the development of type 1 diabetes. Interferon-beta (IFN-beta) expression is induced in epithelial cells by several viruses, and it has been detected in islets of type 1 diabetic patients. Here we show that treatment of isolated mouse islets with this cytokine was able to alter insulin secretion in vitro. To study whether IFN-beta alters beta-cell function in vivo and leads to diabetes, we have developed transgenic mice (C57BL6/SJL) expressing IFN-beta in beta-cells. These mice showed functional alterations in islets and impaired glucose-stimulated insulin secretion. Transgenic animals presented mild hyperglycemia, hypoinsulinemia, hypertriglyceridemia, and altered glucose tolerance test, all features of a prediabetic state. However, they developed overt diabetes, with lymphocytic infiltration of the islets, when treated with low doses of streptozotocin, which did not induce diabetes in control mice. In addition, about 9% of the transgenic mice obtained from the N3 back-cross to outbred albino CD-1 mice spontaneously developed severe hyperglycemia and hypoinsulinemia and showed mononuclear infiltration of the islets. These results suggest that IFN-beta may be involved in the onset of type 1 diabetes when combined with either an additional factor or a susceptible genetic background.

Animals↗
PubMed1998

Temporal-spatial expression of two Paracentrotus lividus cell surface proteins.

The temporal expression of two cell surface proteins, called BEP1 and BEP4, during Paracentrosus lividus embryonic development was studied. These proteins are found in both monomeric and dimeric forms in egg and embryos and we have established that their specific form is related to their being in the cytoplasm or on the cell surface. The spatial distribution of BEP1 and BEP4 proteins in eggs and embryos was established by whole mount immunohistochemistry. These proteins are located in the animal part of unfertilized and fertilized eggs; thereafter they are much less represented in structures derived from the vegetal cells of the embryo such as the micromeres of the 16 cell stage, the primary mesenchyme of blastula and the gut of gastrula. At the prism stage BEP1 and BEP4 proteins are present to some ectodermal parts and thereafter, at the pluteus stage, to the oral region.

Animals↗
PubMed1998

Transglutaminase-synthesized gamma-(glutamyl5) spermidine derivative of substance P is a selective tool for neurokinin-2 receptors characterization.

The ability of transglutaminase-synthesized 1,3-diaminopropane, spermidine (Spd), spermine (Spm), and monodansylcadaverine gamma-(glutamyl5)derivatives of substance P (SP) to produce bronchoconstriction was investigated. In urethane-anaesthetized guinea pigs, intravenous injections of SP derivatives contracted differently bronchial smooth muscle and caused hypotension. The most effective bronchoconstrictor among SP analogs was the gamma-(glutamyl5)Spd derivative of SP (Spd-SP; EC50 = 5.3 nmol/kg), which was more potent than the native peptide (EC50 = 26.5 nmol/kg). In contrast, the gamma-(glutamyl5)Spm derivative of SP (Spm-SP) was found completely unable to cause bronchoconstriction and was significantly less effective than SP in determining hypotension. The contractile effect of Spd-SP and Spm-SP was investigated in vitro on rat isolated colon, a well-characterized preparation rich in NK2 receptors. In addition, Spd-SP was tested on the endothelium-denuded rabbit pulmonary artery (RPA) and the hamster isolated trachea (HT), both tissue preparations containing only a single functional receptor subtype (NK2A and NK2B, respectively). The results obtained showed that Spd-SP recognizes NK2 receptors occurring on rat isolated colon more effectively (EC50 = 11 nM) than the native peptide (EC50 = 45 nM). Conversely, Spm-SP evokes a contractile response less effective than that elicited by SP (EC50 = 312 nM). Furthermore, Spd-SP (0.1-10 microg kg(-1)) produced a concentration-dependent contraction of both HT and RPA, exhibiting a potency respectively 12 and 30 times higher than SP in contracting HT and RPA. Our results indicate that the introduction of a Spd moiety at the level of glutamine-5 of SP gives rise to an analog that possesses a different capability to recognize NK2 receptors than the parent peptide. Moreover, since Spd-SP seems to contract more effectively RPA than HT, we conclude that it preferentially recognizes the NK2A receptor subtype.

Animals↗
PubMed1998

Oral toxicity of bis(2-ethylhexyl) phthalate during pregnancy and suckling in the Long-Evans rat.

Bis(2-ethylhexyl) phthalate (DEHP) is a compound widely used in plastics technology to impart flexibility to rigid polymers. We sought to determine whether the oral exposure of female rats to DEHP during gestation and suckling produces alterations in the litter. Female rats were exposed to different concentrations of DEHP suspended in drinking water (32.5 and 325 microl/litre) from day 1 of pregnancy to day 21 after delivery. Pup body weight gain and kidney, liver and testes weight was measured at different times (21, 28, 35, 42 and 56 days) after birth. Plasma concentrations of DEHP and histopathological alterations in kidneys, liver and testes were also studied. In addition, the ability of female pups (1 month of age) to perform a learned avoidance test, the 'beam walking' test, was evaluated. Perinatal exposure to DEHP produced no statistically significant changes in the body weight gain of offspring. Conversely, it produced a significant decrease in kidney and testes relative weight (organ/body weight) with a significant increase in relative liver weight. Signs of histological damage in kidneys, liver, and particularly testes, were observed. Pups exposed perinatally to the highest concentration of DEHP elicited a significant increase in the time necessary to perform the beam walking test.

Administration, Oral↗
PubMed1998

Unrelated donor marrow transplantation for chronic myelogenous leukaemia.

Between January 1989 and July 1995 the search for an unrelated donor (UD) was started for 379 consecutive Italian patients with Philadelphia positive (Ph+) chronic myelogenous leukaemia (CML). 89 (23%) were transplanted. The overall probability of transplant before and after December 1991 was 16% and 49%, respectively (P=0.0001), and average interval between search activation and graft was 23 months and 13 months, respectively (P=0.0001). Disease-free survival (DFS) following 60 consecutive transplants performed before February 1996 was 41.5% at 48 months and was 64% for patients grafted after January 1993. In univariate analysis, five variables had a favourable effect on DFS: year of bone marrow transplantation (BMT) after 1993 (P=0.0002), HLA-DRB1 donor/recipient (D/R) match (P=0.0006), total body irradiation (TBI) containing regimen (P=0.0006), graft-versus-host disease (GvHD) prophylaxis including 'early' cyclosporin before the transplant, and a marrow cell dose > 3 x 10(8)/kg of recipient body weight (P=0.04). Multivariate analysis confirmed that HLA identity (P=0.006), TBI-containing regimen (P=0.0001) and 'early cyclosporin' (P=0.04) were associated with higher DFS. Transplant-related mortality (TRM) was 67% in patients grafted before January 1993 and 30% in patients grafted subsequently (P=0.002). Multivariate analysis confirmed DRB1 identity (P=0.03) and TBI-containing regimen (P=0.0005) to be independent factors predictive of low TRM. This suggests that the outcome of patients transplanted from an HLA DRB1 matched donor, after a TBI-containing preparative regimen, is similar to results recently reported in patients transplanted from geno-identical siblings. These results indicate that the search should be initiated at diagnosis for patients < 45 years of age and UD BMT should be considered early in the disease course for those with an available DRB1-matched unrelated donor.

Adolescent↗
PubMed1998

Transgenic rabbits overexpressing growth hormone develop acromegaly and diabetes mellitus.

Transgenic rabbits expressing the bovine growth hormone (bGH) gene in liver and kidney were obtained to study the long-term effects of chronic exposure to GH in nonrodent animals. These rabbits presented high levels of bGH and insulin-like growth factor I in serum. In spite of chronic exposure to bGH, transgenic rabbits had similar body weight to controls. However, enlargement of the head and limbs and reduction of visceral fat were observed in these animals. They also showed marked hyperinsulinemia, hyperglycemia, and hypertriglyceridemia, indicating that they developed insulin resistance. Furthermore, serious histopathological alterations, including marked fibrosis, were observed in liver, kidney, and skeletal muscle. These anatomical, metabolic, and histological alterations closely resemble those found in patients with acromegaly. Thus, transgenic rabbits overexpressing GH may be a good model of the human disease.

Acromegaly↗
PubMed1998

[Oxygen consumption during cardiovascular surgery conducted under extra-corporeal circulation].

Whole-body oxygen consumption (VO2) is universally considered both a measure of the metabolic activity of the body and an indicator of the adequacy of tissue perfusion during cardiopulmonary bypass as well. There is little agreement in the literature about the main determinants of oxygen consumption during CPB, except for the role of temperature in reducing the metabolic activity of the body. Many studies, which have been performed both on animals and in humans, have reached some contradictory conclusions about the role of delivery and perfusion flow rates, of haemodynamic variables, of the acid-base status, and of drugs influencing the variations of oxygen consumption during CPB. Aim of this paper is to review the evidences in literature about the determinants of whole-body oxygen consumption during cardiopulmonary bypass in man.

Cardiopulmonary Bypass↗
PubMed1997

The primary structure of the split-Soret cytochrome c from Desulfovibrio desulfuricans ATCC 27774 reveals an unusual type of diheme cytochrome c.

The complete amino acid sequence of the unusual diheme split-Soret cytochrome c from the sulphate-reducing Desulfovibrio desulfuricans strain ATCC 27774 has been determined using classical chemical sequencing techniques and mass spectrometry. The 247-residue sequence shows almost no similarity with any other known diheme cytochrome c, but the heme-binding site of the protein is similar to that of the cytochromes c3 from the sulphate reducers. The cytochrome-c-like domain of the protein covers only the C-terminal part of the molecule, and there is evidence for at least one more domain containing four cysteine residues, which might bind another cofactor, possibly a non-heme iron-containing cluster. This domain is similar to a sequence fragment of the genome of Archaeoglobus fulgidus, which confirms the high conservation of the genes involved in sulfate reduction.

Amino Acid Sequence↗
PubMed1997

Centrifugation does not alter spatial distribution of 'BEP4' mRNA in paracentrotus lividus EGG.

Paracentrotus lividus unfertilized eggs were centrifuged in a sucrose gradient, so to split each into two parts: a nucleated light fragment and an anucleated heavy fragment. Northern blot analyses utilizing a bep4 probe as animal marker and H2A histone gene and 12S-mit RNA as controls indicate that the eggs are elongated along the animal-vegetal axis during centrifugation and thereafter split into an animal and a vegetal half. Treatment of the eggs with colchicine before centrifugation abolishes the animal localization of bep4 mRNA.

Animals↗
PubMed1997

Prevalence, risk factors, and genotype distribution of hepatitis C virus infection in the general population: a community-based survey in southern Italy.

In 1996 the prevalence, risk factors, and genotype distribution of hepatitis C virus (HCV) infection were assessed in the general population of a town in southern Italy. The sample was selected from the census by a systematic 1:4 sampling procedure. The participation rate was 96.6%. Among the 1,352 subjects enrolled, 195 (14.4%) tested reactive to antibody to HCV (anti-HCV) with enzyme immunoassay (EIA 3). When further tested with recombinant immunoblot assay (RIBA 3), 170 subjects (87.2%) tested positive, 23 subjects (11.8%) had indeterminate results, and 2 subjects (1%) tested negative. Thus, the overall anti-HCV EIA-positive RIBA-confirmed prevalence was 12.6% (170 of 1,352 subjects) and increased from 1.3% in subjects younger than 30 years to 33.1% in those > or =60 years of age. This latter age group accounted for 72.3% of all anti-HCV-positive subjects. Females tested positive more frequently than males (14.1% vs. 10.5%; P < .05). Alanine transaminase (ALT) concentrations were abnormal in only 4.1% (7/170) of anti-HCV EIA-positive RIBA-confirmed subjects. This suggests that ALT screening is not useful in the detection of anti-HCV-positive subjects in a general population. The results of multiple logistic regression analysis showed that an age of less than 45 years, the use of glass syringes, and dental therapy were all independent predictors of anti-HCV positivity. HCV RNA was detected by polymerase chain reaction in 75.9% of the 195 anti-HCV EIA-positive subjects: in 84.7% (144/170) of the RIBA-confirmed subjects; in 17.4% (4/23) tested as RIBA indeterminate; and in neither of the two subjects who tested RIBA negative. HCV type 1b was detected in 75 subjects (50.7%), type 2b in 1 subject (0.7%), type 2c in 66 subjects (44.6%), type 3a in 4 subjects (2.7%), and type 4 in two subjects (1.3%). These figures differ from those of Italian patients with chronic liver disease in whom genotype 2 is more rare. None of the individuals was infected with more than one genotype. The distribution of the two most common HCV viral types (1b and 2c) was not statistically different in terms of mean age, sex, or risk factors and suggests that they may have had a parallel spread in this community. These findings provide one of the highest overall anti-HCV prevalence rates in a general population with a likely cohort effect, i.e., decreased risk of infection along generations. These observations may indicate an epidemic or focus of hepatitis C that occurred several years earlier. The majority of anti-HCV-positive subjects in the oldest age group and with no clinical evidence suggests that HCV infection is a very prolonged and indolent disease.

Adolescent↗
PubMed1997

Transglutaminase-synthesized spermine derivative of substance P recognizes rat portal vein neurokinin-3 receptors.

The effects of the transglutaminase-synthesized polyamine derivatives of Substance P (SP) have been further characterized by their ability to contract in vitro the rat portal vein strip (RPV), a pharmacological preparation particularly rich in NK-3 receptors. The effects of selective agonists of NK-1, NK-2 and NK-3 receptors [Sar9,Met(O(2))11]SP, beta-Ala8 NKA(4-10), and senktide respectively, were also evaluated by measuring RPV concentration-response curves. Peptide [GR-82334 (NK-1) and MEN-10,376 (NK-2)] and nonpeptide [WIN 51,708 (NK-1) and SR 142801 (NK-3)] NK receptor antagonists were used to confirm the participation of the different NK receptors to contractile response. Our results demonstrated that the spermine derivative of SP (Spm-SP), previously shown to be unable to recognize NK-1 and NK-2 receptors in some bioassays, contracts RPV (EC50 = 588 nM) better than the native neuropeptide (EC50 = 1120 nM). A pretreatment with thiorphan, an inhibitor of neutral endopeptidases, significantly reduced such a difference. While this inhibitor shifts the SP concentration-response curves to the left (EC50 = 720 nM) the action of Spm-SP and [Sar9,Met(O(2))11]SP were completely thiorphan-resistant. In the absence of thiorphan we found the following rank order of potency: senktide > > beta-Ala8 NKA(4-10) > [Sar9,Met(O(2))11]SP = Spm-SP > SP. Among the mentioned NK receptor antagonists, only the selective NK-3 receptor antagonist, SR 142801, shifted to the right Spm-SP and [Sar9,Met(O(2))11]SP concentration-response curve, showing pKB values of 5.84 and 5.88, respectively. Therefore, the reported results suggest that the introduction of a Spm moiety into the SP alters the parent peptide molecule by increasing its affinity for NK-3 receptors and/or by preventing its degradation by some proteolytic enzymes.

Androstanes↗
PubMed1997

Prevalence of human retroviral infection in Quillabamba and Cuzco, Peru: a new endemic area for human T cell lymphotropic virus type 1.

An epidemiologic study was conducted to determine the prevalence of retroviral infections among people of Qucchua origin in Cuzco and Quillabamba, Peru. The study volunteers included individuals at low and at high risk for retroviral infections. Each volunteer was interviewed to obtain clinical and epidemiologic data, and to identify risk behaviors for infection. The serum was tested for human immunodeficiency virus type 1 (HIV-1) and human T cell lymphotropic virus types 1/2 (HTLV-1/2) by standard enzyme-linked immunosorbent and Western blot assays. Among a total of 370 volunteers enrolled in the study, 276 were women and 94 were men whose ages ranged between 15 and 49 years. Infection with HTLV-1 was demonstrated in 5.1% (19 of 370), and one of these, a homosexual, was also positive for HIV-1; none had HTLV-2. Overall, the rate of HTLV-1 infection was 5.3% (5 of 94) for males and 5% (14 of 276) for females. Among the low risk group of 211 healthy pregnant women, five (2.3%) were positive for HTLV-1. The rate of HTLV-1 infection in this group was significantly correlated with a history of dental surgery, as well as other surgical procedures, and a history of jaundice. Among the volunteers who practiced risk behavior(s) for retroviral infections, the positive rates for HTLV-1 were 13.7% (7 of 51) for female sex workers, 6.2% (3 of 48) for homosexuals and/or bisexuals, 8.5% (4 of 47) for patients with sexually transmitted diseases (STDs), and 0.0% (0 of 13) for promiscuous heterosexual males. In female sex workers. HTLV-1 infection was found to be significantly associated with age, a history of STDs or genital ulcers, sexual intercourse during menses, and vaginal douching (P < 0.05). A low prevalence of HIV-1 infection indicates that the virus has not yet spread significantly in these areas.

Adolescent↗
PubMed1996

Preliminary crystallographic analysis and further characterization of a dodecaheme cytochrome c from Desulfovibrio desulfuricans ATCC 27774.

Dodecaheme cytochrome c has been purified from Desulfovibrio (D.) desulfuricans ATCC 27774 cells grown under both nitrate and sulfate-respiring conditions. Therefore, it is likely to play a role in the electron-transfer system of both respiratory chains. Its molecular mass (37768 kDa) was determined by electrospray mass spectrometry. Its first 39 amino acids were sequenced and a motif was found between amino acids 32 and 37 that seems to exist in all the cytochromes of the c(3) type from sulfate-reducing bacteria sequenced at present. The midpoint redox potentials of this cytochrome were estimated to be -68, -120, -248 and -310 mV. Electron paramagnetic resonance spectroscopy of the oxidized cytochrome shows several low-spin components with a g(max) spreading from 3.254 to 2.983. Two crystalline forms were obtained by vapour diffusion from a solution containing 2% PEG 6000 and 0.25-0.75 M acetate buffer pH = 5.5. Both crystals belong to monoclinic space groups: one is P2(1), with a = 61.00, b = 106.19, c = 82.05 A, beta = 103.61 degrees, and the other is C2 with a = 152.17, b = 98.45, c = 89.24 A, beta = 119.18 degrees. Density measurements of the P2(1) crystals suggest that there are two independent molecules in the asymmetric unit. Self-rotation function calculations indicate, in both crystal forms, the presence of a non-crystallographic axis perpendicular to the crystallographic twofold axis. This result and the calculated values for the volume per unit molecular weight of the C2 crystals suggest the presence of two or four molecules in the asymmetric unit.

Journal Article↗
PubMed1996

Redox properties of cytochrome c nitrite reductase from Desulfovibrio desulfuricans ATCC 27774.

The dissimilatory nitrite reductase from Desulfovibrio desulfuricans ATCC 27774 catalyzes the reduction of nitrite to ammonia. Previous spectroscopic investigation revealed that it is a hexaheme cytochrome containing one high spin ferric heme and five low spin ferric hemes in the oxidized enzyme. The current study uses the high resolution of Mössbauer spectroscopy to obtain redox properties of the six heme groups. Correlating the Mössbauer findings with the EPR data reveals the pairwise spin-spin coupling among four of the heme groups. The other two hemes are found to be magnetically isolated. Reduction with dithionite and reaction with CO further indicate that only the high spin heme is capable of binding small exogenous ligands. These results confirm our previous finding that Desulfovibrio desulfuricans nitrite reductase contains six heme groups and that the high spin ferric heme is the substrate and inhibitor binding site.

Carbon Monoxide↗