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Biomedical subjects

C Costa

Publications and source records attributed to C Costa.

At least 73 records · Page 4Linked to original sources
PubMed2000

EAAT1 is involved in transport of L-glutamate during differentiation of the Caco-2 cell line.

Little is known concerning the expression of amino acid transporters during intestinal epithelial cell differentiation. The transport mechanism of L-glutamate and its regulation during the differentiation process were investigated using the human intestinal Caco-2 cell line. Kinetic studies demonstrated the presence of a single, high-affinity, D-aspartate-sensitive L-glutamate transport system in both confluent and fully differentiated Caco-2 cells. This transport was clearly Na(+) dependent, with a Hill coefficient of 2. 9 +/- 0.3, suggesting a 3 Na(+)-to-1 glutamate stoichiometry and corresponding to the well-characterized X(A,G)(-) system. The excitatory amino acid transporter (EAAT)1 transcript was consistently expressed in the Caco-2 cell line, whereas the epithelial and neuronal EAAT3 transporter was barely detected. In contrast with systems B(0) and y(+), which have previously been reported to be downregulated when Caco-2 cells stop proliferating, L-glutamate transport capacity was found to increase steadily between day 8 and day 17. This increase was correlated with the level of EAAT1 mRNA, which might reflect an increase in EAAT1 gene transcription and/or stabilization of the EAAT1 transcript.

ATP-Binding Cassette Transporters↗
PubMed2000

Hepatotoxicity of camptothecin derivatives in a primary culture system of rat hepatocytes.

The topoisomerase I inhibitors are a new class of antineoplastic agents currently under clinical development. Among these compounds there are some camptothecin (CPT) derivatives with improved toxicity profiles and antitumor activity: irinotecan (CPT-11) and topotecan (TPT), particularly active against colon, lung and ovarian cancer. The aim of this study was to evaluate the cytotoxicity of CPT, CPT-11, its metabolite SN38 and TPT in a primary culture system of rat hepatocytes. Cytotoxicity was evaluated by measuring the leakage of lactate dehydrogenase (LDH) into the medium and by assessing cell viability in terms of tetrazolium salts (MTT) reduction by mitochondrial dehydrogenase activity. Our results showed that cytotoxicity was limited in the case of short drug exposure. There was a significant and time-dependent increase in LDH leakage and a significant time- and dose-dependent decrease in MTT reduction after 3 h of incubation (p<0.01). In the treatments with doses related to peak plasma levels, CPT-11 was less responsible for the observed in vitro hepatotoxicity than its metabolite SN38; TPT had lower LDH leakage compared to SN38 and CPT-11 but showed significant and early (3 h) decrease in MTT reduction: this may mean a different mechanism of cellular damage. These results demonstrate that CPT derivatives are directly toxic to liver cells in a distinct time- and dose-related response.

Animals↗
PubMed1999

Transglutaminase-mediated amine incorporation into substance P protects the peptide against proteolysis in vitro.

The in vitro metabolism of transglutaminase-synthesized substance P analogs has been characterized comparing their stability to that of the parent peptide. The major metabolites have been purified and their structures elucidated by mass spectrometry. Our results demonstrated that gln5 spermidine and spermine analogs of substance P possess an enhanced resistance to the action of proteases. Moreover spermine, a large size hydrophilic compound, specifically prevented the hydrolysis at Phe7-Phe8 bond.

Amines↗
PubMed1999

Microsatellite instability in medullary breast carcinomas.

Microsatellite instability (MSI) has been reported to occur in a wide variety of sporadic tumours, such as colorectal and gastric cancers. MSI positivity has been associated with a particular clinico-pathologic profile, including the presence of abundant lymphoid infiltration, poor differentiation and a relatively good outcome for the patients. Since medullary breast carcinomas (MBCs) share these clinico-pathologic features with the MSI-positive tumours described above, we evaluated MSI in this particular histologic type of breast cancer. DNA of 24 MBC cases was extracted from formalin-fixed, paraffin-embedded tissue. The presence of MSI was analysed using BAT-26. We also searched mutations in 2 target genes: TGF-beta RII and BAX. Five cases of the series were also analysed for 1 (CA) dinucleotide tandem repeat sequence (D1S158), 8 tetranucleotide repeat sequences (D3S1358, D5S818, D7S820, D8S1179, D13S317, D21S11, FGA and VWA) and 1 pentanucleotide repeat (dAAAAT), localized in intron 1 of p53 gene. We found 2 carcinomas (8.3%) with BAT-26 instability. None of the cases had mutations in the "target genes", TGF-beta RII and BAX, including the 2 cases with BAT-26 instability. No MSI was observed using the panel of tetra- and pentanucleotide markers. Loss of heterozygosity was found in some loci. No significant difference in mean MIB-1 index according to RER status was observed. The low frequency of MSI in MBC is similar to that of other histologic types of breast cancer. Although MBCs share some clinico-pathologic features with colorectal and gastric carcinomas, which exhibit a high frequency of MSI, the underlying genetic events leading to this breast tumour are different from those leading to tumours of the digestive tract.

Breast Neoplasms↗
PubMed1999

Evaluation of an intervention to reduce sun exposure in children: design and baseline results.

The Kidskin Study is a 5-year intervention study (1995-1999) involving 1,776 5- and 6-year-old children attending 33 primary schools in Perth, Western Australia. The aim of the study is to design, implement, and evaluate an intervention to reduce sun exposure in young children. There are three study groups: a control group, a "moderate intervention" group, and a "high intervention" group. The control schools receive the standard Western Australian health education curriculum, while the moderate and high intervention schools receive a specially designed curricular intervention. In addition, children in the high intervention group receive program materials over the summer holidays, when exposure is likely to be highest, and are offered sun-protective swimwear at low cost. The main outcome measure is the number of nevi on the back. Other outcomes include nevi on the chest (boys only), face, and arms, levels of suntanning, degree of freckling, and sun-related behaviors. At baseline, the three groups were similar with respect to nevi and freckling after adjustment for observer and month of observation. Sun exposure was slightly higher in the high intervention group. The groups were also similar with respect to most potential confounders, although they differed with respect to Southern European ethnicity and parental education.

Back↗
PubMed1999

The structure of an electron transfer complex containing a cytochrome c and a peroxidase.

Efficient biological electron transfer may require a fluid association of redox partners. Two noncrystallographic methods (a new molecular docking program and 1H NMR spectroscopy) have been used to study the electron transfer complex formed between the cytochrome c peroxidase (CCP) of Paracoccus denitrificans and cytochromes c. For the natural redox partner, cytochrome c550, the results are consistent with a complex in which the heme of a single cytochrome lies above the exposed electron-transferring heme of the peroxidase. In contrast, two molecules of the nonphysiological but kinetically competent horse cytochrome bind between the two hemes of the peroxidase. These dramatically different patterns are consistent with a redox active surface on the peroxidase that may accommodate more than one cytochrome and allow lateral mobility.

Animals↗
PubMed1999

Direct measurement of sun protection in primary schools.

BACKGROUND: "Kidskin" is an intervention study involving children at 33 primary schools in Perth, Western Australia. This study includes measurement of changes in implementation of schools' sun protection policies. This paper reports on measurement of observable aspects of sun protection. METHODS: Hat use was assessed from videos of children in the playground. Shade use was measured using UVR-sensitive polysulfone badges worn by a random sample of children. Shade provision was measured from aerial photographs of the schools. Principals were surveyed about school policies and practices. RESULTS: Eighty-seven percent of children wore a hat during lunch time at school, although only 14% wore the most protective styles of hats. The mean proportion of ambient UVR exposure received by Year 1 children was 15.5%; children spent less time in the sun on sunnier days. On average, 14.5% of the playground was shaded; this was not associated with children's sun exposure. Correlations between these results and the principals' estimates were poor. CONCLUSIONS: Children should be encouraged to wear more protective styles of hats and to avoid sun exposure, even on less sunny days during spring and summer. Principals' estimates of shade provision and children's sun protection behavior at school are of little value.

Analysis of Variance↗
PubMed1999

Environmental assessment in an industrial area of Portugal.

The region of Lisbon and south of Lisbon (Sado estuary) is densely industrialized, and, therefore, air pollution should be studied in a more detailed scale there. The topography of the Sado estuary region and the predominant wind direction from the northwest contribute to the influence in this region of the industries located in the north. The region selected includes a fuel-fired power station. Transplants of the lichen Parmelia sulcata Taylor were suspended in nylon bags within a rectangle 15 km wide and 25 km long on a grid 2.5 km x 2.5 km, centered in the power station. In each of the 47 sites, 2 sets of 4 transplants each were hung. Care was taken (1) in covering the two sets with a polyethylene roof to prevent leaching of elements in the lichen, (2) in building a hanging system that could rotate according to the wind direction, and (3) in orienting one set toward the wind and the other set opposite the wind. For a 1-yr period and every 3 mo, one transplant of each set is collected. In this work, the results of the first campaign (after 3 mo suspension) obtained by instrumental neutron activation analysis and proton-induced X-ray emission are shown. Some elemental contents are mapped and discussed.

Air Pollutants↗
PubMed1999

Modifications in the metabolic pathways of benzene in streptozotocin-induced diabetic rat.

Benzene is a ubiquitous environmental pollutant primarily metabolized by a cytochrome P-450 (CYP-450) isoenzyme, CYP-450 IIE1. A consistent induction of CYP450 IIE1 has been observed in both rat and human affected by diabetes mellitus. The aim of this study was to evaluate whether streptozotocin (STZ)-induced diabetes determines modifications in the metabolic pathways of benzene in rat. Benzene (100 mg/kg per day, dissolved in corn oil) was administered i.p. once a day for 5 days. Urine samples were collected every day in STZ-treated and normoglycaemic animals, treated and untreated with benzene (n = 10). Urinary levels of trans,trans-muconic acid and of phenol, catechol and hydroquinone (free and conjugated with sulphuryl and glucuronic group) were measured by high-performance liquid chromatography (HPLC). In normoglycaemic rats during the 5 days of treatment with benzene we observed a progressive and significant decrement in the urinary excretion of phenol, phenyl sulphate and glucuronide, catechol, catechol glucuronide, hydroquinone, hydroquinone glucuronide and t,t-muconic acid (P < 0. 05). In the diabetic animals, conversely, the same metabolites showed progressively increasing urinary levels (P < 0.05). Catechol sulphate and hydroquinone sulphate levels were below the instrument's detection limit. In the comparison between diabetic and normoglycaemic benzene treated rats, the inter-group difference was significant (P < 0.05) from day 3 of treatment for t,t-muconic acid, and from day 1 for free and conjugated phenol, free and glucuronide catechol and free hydroquinone. In the normoglycaemic rat exposed to benzene the decreasing trend observed in urinary excretion of free and conjugated metabolites may be due to their capability to reduce cytochromial activity. Conversely, in the diabetic rat, urinary levels of benzene metabolites tended to increase progressively, probably due to the consistent induction of CYP-450 IIE1 observed in diabetes, which would overwhelm the inhibition of this isoenzyme caused by phenolic metabolites. Furthermore, the metabolic switch towards detoxification metabolites observed after administration of high doses of benzene is not allowed in the diabetic because of reduced glutathione-S-transferase activity. As a consequence, higher levels of hydroquinone, phenol and catechol, considered the actual metabolites responsible for benzene toxicity, will accumulate in the diabetic rat. Extrapolating these data to human, we may thus suggest that occupational exposure to benzene of a diabetic subject poses a higher risk level, as his metabolism tends to produce and accumulate higher levels of reactive benzene catabolites.

Animals↗
PubMed1999

Cardiopulmonary bypass and oxygen consumption: oxygen delivery and hemodynamics.

BACKGROUND: This study was undertaken to investigate the relations between whole body oxygen consumption (VO2), oxygen delivery (DO2), and hemodynamic variables during cardiopulmonary bypass. METHODS: One hundred one patients were studied during cooling, hypothermia, and rewarming. Oxygen consumption, DO2, hemodynamics, and DO2crit were measured at these times. RESULTS: There was a direct linear relation between DO2 and VO2 during all three times. No relation between VO2 and hemodynamics was detected during cooling; during hypothermia, an inverse linear relation with peripheral arterial resistance was found. Finally, during rewarming, there was a direct relation with pump flow rate, and an inverse relation with arterial pressure and arterial resistance. The same relations among the variables were found at delivery levels above or below DO2crit. CONCLUSIONS: During cardiopulmonary bypass there is a direct linear relation between DO2 and VO2; the relations with hemodynamic variables depend on the phases of cardiopulmonary bypass. This suggests that increasing delivery levels may recruit and perfuse more vascular beds, and higher delivery levels are advisable during perfusion. During rewarming and hypothermia, lower arterial resistances are also desirable to optimize VO2.

Aged↗
PubMed1999

Isolation of a trans-acting factor involved in localization of Paracentrotus lividus maternal mRNAs.

Localization of Paracentrotus lividus bep maternal mRNAs at the animal pole occurs by association with the cytoskeleton and involves a 54-kDa protein, called LP54, that is able to bind to the 3' untranslated regions (UTRs) of bep mRNAs. We describe here the isolation and purification of this protein. Antibodies raised against purified LP54 allowed us to establish its localization in P. lividus eggs and embryos. This localization coincides with the mRNAs with which it is associated, that is, the animal pole in the egg, and, after fertilization, the regions derived from this part of the egg, and finally the oral ectoderm of the pluteus. Association with the cytoskeleton was shown by the copurification of LP54 in a microtubule preparation. Involvement in bep mRNA localization was demonstrated by microinjection of anti-LP54 antibodies in P. lividus eggs, which caused alteration of spatial distribution of bep3 mRNA.

3' Untranslated Regions↗
PubMed1999

Defects in activation and transport of fatty acids.

The oxidation of long-chain fatty acids in mitochondria plays an important role in energy production, especially in skeletal muscle, heart and liver. Long-chain fatty acids, activated to their CoA esters in the cytosol, are shuttled across the barrier of the inner mitochondrial membrane by the carnitine cycle. This pathway includes four steps, mediated by a plasma membrane carnitine transporter, two carnitine palmitoyltransferases (CPT I and CPT II) and a carnitine-acylcarnitine translocase. Defects in activation and uptake of fatty acids affect these four steps: CPT II deficiency leads to either exercise-induced rhabdomyolysis in adults or hepatocardiomuscular symptoms in neonates and children. The three other disorders of the carnitine cycle have an early onset. Hepatic CPT I deficiency is characterized by recurrent episodes of Reye-like syndrome, whereas severe muscular and cardiac signs are associated with episodes of fasting hypoglycaemia in defects of carnitine transport and translocase. Convenient metabolic investigations for reaching the diagnosis of carnitine cycle disorders are determination of plasma free and total carnitine concentrations, determination of plasma acylcarnitine profile by tandem mass spectrometry and in vitro fatty acid oxidation studies, particularly in fresh lymphocytes. Application of the tools of molecular biology has greatly aided the understanding of the carnitine palmitoyltransferase enzyme system and confirmed the existence of different related genetic diseases. Mutation analysis of CPT II defects has given some clues for correlation of genotype and phenotype. The first molecular analyses of hepatic CPT I and translocase deficiencies were recently reported.

Adult↗
PubMed1999

Comparative analysis of three genetic modifications designed to inhibit human serum-mediated cytolysis.

Hyperacute rejection (HAR) remains a critical immunologic hurdle in the development of xenogeneic organs for human transplantation. Strategies that simultaneously eliminate both natural antibody reactivity and complement activation on the xenogeneic cell surface may be the best approach to achieve clinical application of xenogeneic vascularized organ transplantation. We have developed multiple lines of genetically manipulated mice to evaluate the combination of different genetic approaches aimed at inhibiting antibody and complement-mediated cell lysis. We utilized transgenic mice expressing the human complement inhibitor, CD59, the human 1,2-fucosyltransferase (H-transferase, HT) and the alpha1,3-galactosyltransferase (alpha1,3-GT) knock-out mouse line (Gal KO). Our data show that expression of hCD59 in combination with HT expression or the null phenotype of alpha1,3-GT are equally effective at preventing human serum-mediated cytolysis. Interestingly, the triple combination affords no additional protective effect. Therefore, coexpression of HT and a complement inhibitor is the most immediate strategy to genetically engineer transgenic pigs to be used as xenogeneic donors.

Animals↗
PubMed1999

The use of observational methods for monitoring sun-protection activities in schools.

Evaluation of health promotion interventions aimed at behavioural or environmental change involves assessing change that occurs as a result of the program. Direct observational methods can be used for this purpose and this paper describes three such methods that we pilot tested for use in a 5-year intervention study aimed at reducing sun exposure in primary school children. (1) Monitoring 'No hat, no play' policies. This method involved video taping children in selected school play areas during lunch time and analysing the content of the videos to assess the proportion of children wearing various types of hats. (2) Assessing shade provision in the playground. This method involved taking aerial photographs of each school and using them to estimate the proportion of shade in play areas available to children at lunchtime. (3) Shade use. This involved children wearing polysulphone film badges to measure the amount of UV-B exposure they received during one lunch period, relative to the total possible dose registered on index badges. Each method was implemented successfully, and we demonstrated that the video and aerial photography methods produced highly reproducible results and that all three methods were feasible. These three methods will be used in our intervention study to assess longitudinal change in schools' sun-protection policy and practice.

Child↗
PubMed1999

Expression of the human alpha1,2-fucosyltransferase in transgenic pigs modifies the cell surface carbohydrate phenotype and confers resistance to human serum-mediated cytolysis.

Hyperacute rejection (HAR) is the first critical immunological hurdle that must be addressed in order to develop xenogeneic organs for human transplantation. In the area of cell-based xenotransplant therapies, natural antibodies (XNA) and complement have also been considered barriers to successful engraftment. Transgenic expression of human complement inhibitors in donor cells and organs has significantly prolonged the survival of xenografts. However, expression of complement inhibitors without eliminating xenogeneic natural antibody (XNA) reactivity may provide insufficient protection for clinical application. An approach designed to prevent XNA reactivity during HAR is the expression of human alpha1, 2-fucosyltransferase (H-transferase, HT). H-transferase expression modifies the cell surface carbohydrate phenotype of the xenogeneic cell, resulting in the expression of the universal donor O antigen and a concomitant reduction in the expression of the antigenic Galalpha1,3-Gal epitope. We have engineered various transgenic pig lines that express HT in different cells and tissues, including the vascular endothelium. We demonstrate that in two different HT transgenic lines containing two different HT promoter constructs, expression can be differentially regulated in a constitutive and cytokine-inducible manner. The transgenic expression of HT results in a significant reduction in the expression of the Galalpha1,3-Gal epitope, reduced XNA reactivity, and an increased resistance to human serum-mediated cytolysis. Transgenic pigs that express H-transferase promise to become key components for the development of xenogeneic cells and organs for human transplantation.

ABO Blood-Group System↗
PubMed1999

Hepatoprotective properties in the rat of Mitracarpus scaber (Rubiaceae).

The effect of Mitracarpus scaber on carbon tetrachloride-induced acute liver damage in the rat has been evaluated. Results showed that treatment with Mitracarpus scaber decoction resulted in significant hepatoprotection against CCl4-induced liver injury both in-vivo and in-vitro. In-vivo, Mitracarpus scaber pretreatment reduced levels of serum glutamate-oxalate-transaminase (P < 0.01 for 250, 500 and 1000 mg kg(-1)) and serum glutamate-pyruvate-transaminase (P < 0.05 for 250 mg kg(-1) and P < 0.01 for 1000 mg kg(-1)) previously increased by administration of CCl4. In-vitro results indicated that addition to the culture medium of Mitracarpus scaber extracts significantly reduced glutamate-oxalate-transaminase (P < 0.05 for 100 microg mL(-1) and P < 0.01 for 10 and 1000 microg mL(-1)) and lactate dehydrogenase activity (P < 0.05 for 10 microg mL(-1)). Mitracarpus treatment also resulted in a good ( > 93%) survival rate for the CCl4-intoxicated hepatocytes as demonstrated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Moreover, as in the in-vitro assay, Mitracarpus scaber had radical-scavenging properties, shown by its reaction with the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (EC50, the extract concentration resulting in a 50% reduction in the absorbance of DPPH blank solution, = 41.64+/-1.5 microg mL(-1)). The results of this study showed that Mitracarpus scaber had antihepatotoxic potential, a finding which supports the validity of traditional usage of this drug in Mali for the treatment of liver diseases.

Animals↗
PubMed1999

[The Italian Registry of Bone Marrow Donors].

Following a synthetic statement of the scientific, genetic and practical assumptions of the bone marrow transplantation (BMT) from marrow unrelated donor (MUD), which, in turn, have represented the basis for the establishment of the Italian Bone Marrow Donor Registry (IBMDR), the paper reports the registry activity on 30 November 1998. At that date, Italian volunteers were 232,876, number which put the IBMDR as the fourth registry all over the world and as the third in Europe. The mean age of the donors is 34 years, and this means that IBMDR is one of the youngest among international registries. Using Italian donors, 426 BMT, altogether, have been performed, (248 for Italian patients and 178 for foreign patients). Donor search activations performed by national and international transplant centres have been, at the same date, 5729 (1821 for Italian patients and 3908 for foreign patients). Operating standards and guidelines for all centres participating in the IBMDR are reported in this issue.

Age Distribution↗