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Biomedical subjects

R Vicente

Publications and source records attributed to R Vicente.

At least 19 recordsLinked to original sources
PubMed2003

[Is the breath test reliable in primary care diagnosis of Helicobacter pylori infection?].

OBJECTIVE: To evaluate the reliability of the breath test urea 13C in the primary care for the diagnosis of Helicobacter pylori (Hp) infection. DESIGN: Descriptive, prospective and multicentric.Location. Urban area belonging to the Health Center Actur Sur of Zaragoza with participation of Miguel Servet Hospital. PARTICIPANTS: 87 patients with clinical diagnosis of functional dispepsia. In all of them was made a breath test with 13C urea as well as a gastroscopy with taking of samples for histology and ureasa fast test. MAIN MEASUREMENTS: Age, sex and the presence of positivity or negativity of infection by Hp were valued in the histology, ureasa test and in the breath test, considering the histology and the ureasa test like gold tests for this measurement, reason why it was demanded that the positive or outside negative result in both considering it nonambiguous. RESULTS: Two cases were excluded by ambiguous results. The 77.6% (66/85) were positive by histology and ureasa test, and these, 92.4% (61/66) were positives to the breath test. The sensitivity of this test was 92% and the specificity 100%. CONCLUSIONS: The breath test in primary care has a high value diagnosis of Hp infection, being able to avoid, in some cases, another invasives techniques like gastroscopy.

Adult↗
PubMed2003

Cardiopulmonary transplantation: experience of a lung transplant group.

Cardiopulmonary transplantation (CPT) is indicated for patients eligible for heart transplantation (HT) or lung transplantation (LT) who have severe concomitant lung or heart disease. Only 2 groups perform CPT in Spain. We report our experience with 18 CPTs representing 8.2% and 5% compared with LT (220) and HT (362), respectively, from February 13, 1990 to October 15, 2002. The mean time on a waiting list was 138 days. The current number of surviving patients is 7 (39%), with a mean follow-up of 602 days (range, 3 to 4627 days). They all remain asymptomatic with normal respiratory function in 4 patients. No cardiac graft rejection has been detected. Two patients experienced sustained gastroparesis during the first year with spontaneous resolution. Death occurred within the first 3 months in 9 patients. These outcomes contrast with the early mortality associated with LT and HT in our series, namely 10.6% and 11%, respectively. The different causes of death were as follows: sepsis and multiorgan failure in 5 patients, hemorrhagic shock in 3 patients, and suture dehiscence and fungal aortic perforation in 1 patient. Late mortalities were recorded in 2 cases. Overall patient survival in our series is lower than that reported by the International Registry (IR), with an early mortality rate of 50% (30% IR). Nevertheless, our survival rate at 10 years after transplantation is 30% (26% IR). We conclude that CPT should be considered despite the greater early morbidity and mortality.

Adolescent↗
PubMed2003

Lung transplantation in patients with x-linked agammaglobulinemia.

Lung transplantation is an established procedure to treat patients with end-stage lung disease. The criteria for recipient selection are broadening to include patients with congenital defects of the immune system, such as X-linked hypogammaglobulinemia (XLA). We report 2 cases of successful double lung transplantation in patients with XLA. The 2 men had developed bronchiectasis and end-stage lung disease despite early institution of intravenous immunoglobulin (IVIG) replacement therapy. Before transplantation, hypogammaglobulinemia was well controlled with IVIG in both patients. After transplantation, IVIG was administered every 48 hours during the first 10 days and then tapered slowly in the following weeks until returning to an every 3 weeks schedule. One patient has been followed up for 12 months and the other for 6 months. Lung function normalized in the first case and showed a restrictive pattern in the second one. Lung transplantation may be considered as a therapeutic option for patients with XLA and end-stage lung disease. Regular administration of IVIG overcomes the high risk of infections due to the severe immunodeficiency and the intensive immunosuppressive therapy.

Adult↗
PubMed2002

Different Kv2.1/Kv9.3 heteromer expression during brain and lung post-natal development in the rat.

The Kv2.1/Kv9.3 heteromer generates an O2 sensitive potassium channel and induces a slow deactivation that has important consequences for brain and lung physiology. We examined the developmental regulation of Kv2.1 and Kv9.3 mRNAs in brain and lung. Both genes followed parallel expression patterns in brain, increasing progressively through post-natal life. In lung, however, the expression of the two genes followed opposite trends: Kv2.1 transcripts decreased, while Kv9.3 mRNA increased. The Kv9.3/Kv2.1 ratio shows that while in brain the expression of both genes followed a similar pattern, the relative abundance of Kv9.3 increased steadily through post-natal life in lung. Furthermore, there is selective regulation of gene expression during the suckling-weaning transition. Our results suggest that different Kv9.3/Kv2.1 ratios could have physiological implications in both organs during post-natal development, and that diet composition and selective tissue-specific insulin regulation modulate the expression of Kv2.1 and Kv9.3.

Animals↗
PubMed2002

One-step reverse transcription polymerase chain reaction for semiquantitative analysis of mRNA expression.

Analysis of mRNA expression is one of the main targets of scientific research. However, its quantification can be difficult, especially when dealing with low-expression mRNAs (ionic channels, carriers, receptors, etc.) or when only small samples are available (human biopsies). Here we suggest an easy, rapid and reliable method to assess semiquantitative changes in mRNA that combines several technical improvements: i) one-step reverse transcription polymerase chain reaction (RT-PCR) from total RNA; ii) addition of ethidium bromide to the gel, which provides a more homogeneous binding to DNA; iii) direct capture of the gel image using a charged-coupled device camera and then saving the image on computer before quantification, which increases resolution and thus improves and shortens the analysis; and iv) the use of 18S rRNA as a control, which is especially useful when samples from activation, differentiation and proliferation models are used. The technique was validated by checking the system conditions of image capturing and quantification. This was corroborated by a study of Kvl.3 ion channel expression in the brain. In these conditions, the wide range of PCR cycles and total RNA allows us to correlate relative gene expression and direct input of the target gene.

Animals↗
PubMed2002

[Lung transplantation in patients in mechanical ventilation before transplantation].

Mechanical ventilation before lung transplantation has been identified as a risk factor for early death after surgery. However, several studies have reported patient series in which ventilation assistance was given preoperatively without increasing the rates of postoperative complications and death, apart from increasing time of postoperative intubation. The present retrospective analysis of the postoperative course of patients who had been mechanically ventilated before transplantation encompasses a period of 5 years in our hospital. Eight transplants (7 double- and 1 single-lung procedures) were performed. Six patients (75%) required extracorporeal oxygenation during surgery. Three patients (37.5%) died within 30 days of receiving the transplanted lung. The mean time of intubation after the operation was 10.3 days and the mean stay in the postoperative recovery and intensive care unit was 27.5 days. The most common postoperative complications were respiratory colonization (100%), with infection in 3 patients, and reimplantation injury (50%). Pretransplant mechanical ventilation was associated with high risk in the patient series we report; however, the survival rate observed suggest that such patients should be considered acceptable candidates to receive grafts if indicated.

Adolescent↗
PubMed2001

Synthesis of ferrocene-substituted 2-azetidinones.

The photochemical reaction of alkoxychromium(0)carbene complexes and ferrocene mono- and disubstituted imines formed 2-azetidinones having one or two ferrocene moieties in good yields. Yields decrease when the carbene moiety bears an aminoferrocene moiety attached to the carbene carbon, while complex 9 having the ferrocene directly bonded to the carbene carbon was totally inert in these reactions. Access to beta-lactams with the ferrocene tethered to the C3 position through a methylene group was gained using the lithium enolate derived from ethyl 3-ferrocenylpropanoate. The reaction of this enolate produced two unexpected processes. Thus, 2-azetidinone 15 having an hydroxyl group at the C3 position was obtained together with the expected beta-lactam 14, by reaction of the lithium enolate of ethyl 3-ferrocenylpropenoate and imine 1. Additionally, unsaturated amide 17 was obtained by base-promoted Hoffmann-like breakage of the beta-lactam ring formed in the reaction of the same enolate and imine 2. Oxidation of the anion at the C3 of the 2-azetidinone ring on compound 14, as well as the sterically driven ring-breakage of the C3 anion derived from the nonisolated 2-azetidinone 18, should be responsible for this behavior.

Azetidines↗
PubMed2001

Reactivity in polynuclear transition metal chemistry as a means to obtain high-spin molecules: substitution of mu 4-OH- by eta 1,mu 4-N3- increases nine times the ground-state S value of a nonanuclear nickel(II) cage.

The reaction of di-2-pyridyl ketone, (2-py)2CO, with Ni(O2CMe)(2).4H2O yields the cage [Ni9(OH)2(O2CMe)8((2-py)2CO2)4], which reacts further with N3- ions to give the structurally similar cluster [Ni9(N3)2(O2CMe)8((2-py)2CO2)4] containing extremely rare eta 1,mu 4-N3- groups; magnetic studies reveal that the spin ground state of the latter is nine times the ground state of the former.

Journal Article↗
PubMed2000

Topological ferrimagnetic behavior of two new [Mn(L)2(N3)2]n chains with the new AF/AF/F alternating sequence (L = 3-methylpyridine or 3,4-dimethylpyridine).

The reaction of manganese(II) and pyridine derivatives such as 3-methylpyridine (3-Mepy) and 3,4-dimethylpyridine (3,4-Dmepy) led to the new one-dimensional systems trans-[Mn(3-Mepy)2(N3)2]n (1) and trans-[Mn(3,4-Dmepy)2(N3)2]n (2). Compound 1 crystallizes in the monoclinic system, space group P2(1)/n, a = 11.201(3) A, b = 14.499(4) A, c = 14.308(4) A, Z = 6, and compound 2 crystallizes in the triclinic system, space group P1, a = 11.502(4) A, b = 14.246(5) A, c = 16.200(8) A, Z = 6. The two compounds show the same general one-dimensional arrangement of double azido bridges between neighboring manganese atoms with the unprecedented -Mn-(mu(1,3)-N3)2-Mn-(mu(1,3)-N3)2-Mn-(mu(1,1)-N3)2-Mn- sequence. Susceptibility and magnetization measurements reveal a ferrimagnetic-like behavior derived from the topology of the chain. A model of the Heisenberg chain, comprising classical spins coupled through alternating exchange interactions J1J1J2... is proposed to describe the magnetic behavior.

Journal Article↗
PubMed2000

Synthesis, structural characterization, and Monte Carlo simulation of the magnetic properties of two new alternating MnII azide 2-D honeycombs. Study of the ferromagnetic ordered phase below 20 K.

Reaction of MnII and pyridine derivatives such as 4-methylpyridine (4-Mepy) and 4-ethylpyridine (4-Etpy) led to the new two-dimensional systems trans-[Mn(4-Mepy)2(N3)2]n (1) and trans-[Mn(4-Etpy)2(N3)2]n (2). Compound 1 crystallizes in the triclinic system, P1 group (a = 9.269(2) A, b = 9.635(3) A, c = 18.860(4) A, Z = 4), and compound 2 crystallizes in the monoclinic system, P2(1)/c group (a = 14.416(3) A, b = 8.515(2) A, c = 15.728(4) A, Z = 4). The two compounds show honeycomb structures based on dinuclear Mn-(mu-N3)2-Mn subunits linked to the four nearest-neighbor similar subunits by four end-to-end single azido bridges, but whereas the subunits of compound 1 show the end-to-end Mn-(mu 1,3-N3)2-Mn kind of bridges, compound 2 prefers the end-on Mn-(mu 1,1-N3)2-Mn fragment. Magnetically, compound 1 is an alternating 2-D system with two different antiferromagnetic interactions, whereas compound 2 corresponds to a two-dimensional ferro-antiferromagnetic system showing spin canting and permanent magnetization below 20 K. The coupling constant parameters J1 = -10.1 cm-1, J2 = -4.7 cm-1, and g = 2.019 for 1 and J1 = -5.3 cm-1, J2 = 2.9 cm-1, and g = 2.016 for 2 have been obtained from calculations using the Monte Carlo method based on the Metropolis algorithm.

Journal Article↗
PubMed2000

Three new polynuclear copper(II) complexes with the symmetric [Cu(mu1,1-N3)2Cu]2+ core and pyridine derivatives: syntheses, structure, and magnetic behavior.

Three new polynuclear copper(II) complexes, derived from the end-on azido bridging ligand and pyridine derivatives, have been synthesized, and their crystal structures have been determined by X-ray diffraction methods; they are the dinuclear compounds [Cu2(mu 1,1-N3)2(4-Etpy)4(mu-NO3)2] (1), and [Cu2(mu 1,1-N3)2(3-ampy)4(mu-NO3)2]. C2H5OH (2), and the trinuclear [Cu3(mu 1,1-N3)4(N3)2(Meinic)2(DMF)2] (3). 4-Etpy is 4-ethylpyridine, 3-ampy is 3-aminopyridine, and Meinic is methylisonicotinate. Compound 1, C28H36Cu2N12O6, crystallized in the monoclinic system, space group P2(1)/n, with a = 12.355(9) A, b = 12.474(4) A, c = 12.854(6) A, beta = 117.68(4) degrees, and Z = 2. Compound 2, C22H30Cu2N16O7, crystallized in the triclinic system, space group P1, with a = 9.695(2) A, b = 10.895(2) A, c = 7.909(2) A, alpha = 96.81(3) degrees, beta = 96.40(3) degrees, gamma = 96.56(3) degrees and Z = 1. Compound 3, C20H28-Cu3N22O6, crystallized in the monoclinic system, space group P2(1)/n, with a = 7.755(2) A, b = 14.680(5) A, c = 15.810(5) A, beta = 102.81(2) degrees, and Z = 2. 1-3 have the symmetric [Cu(mu 1,1-N3)2Cu]2+ core and structural parameters outside the previously reported range. Magnetic susceptibility data, measured from 2 to 300 K, show strong ferromagnetic coupling for the dinuclear end-on compounds 1 and 2 and bulk moderate ferromagnetic coupling for the trinuclear compound 3. These data were fitted to the appropriate equations derived from the Hamiltonian H = -JS1S2 for 1 and 2 and from the Hamiltonian H = -J1(SA1SB + SA2SB) - J2SA1.SA2 for 3, giving the parameters J = 230.1(1) cm-1, g = 2.17(0.01) for 1, J = 223.2(2) cm-1, g = 2.16(0.01) for 2, and J1 = 47.3(2) cm-1, J2 = -22.5(1) cm-1, gA = 2.26(0.02), gB = 2.07(0.03) for 3. The magnetic susceptibility data can be correlated with the structural parameters.

Journal Article↗
PubMed2000

Two new one-dimensional compounds with end-to-end dicyanamide as a bridging ligand: syntheses and structural characterization of trans-[Mn(4-bzpy)2(N(CN)2)2]n and cis-[Mn(Bpy)(N(CN)2)2]n, (4-bzpy = 4-benzoylpyridine; bpy = 2,2'-bipyridyl).

Two new one-dimensional compounds, trans-[Mn(4-bzpy)2(N(CN)2)2]n (1) and cis-[Mn(bpy)(N(CN)2)2]n (2), have been synthesized and studied from a magnetic point of view (4-bzpy = 4-benzoylpyridine; bpy = 2,2'-bipyridyl). The crystal structures of 1 and 2 have been solved. Compound 1 crystallizes in the monoclinic system, P2(1)/n group, a = 6.374(2) A, b = 7.584(2) A, c = 26.766(5) A, beta = 91.87 degrees, and Z = 2, whereas compound 2 crystallizes in the monoclinic system, C2/c group, a = 6.707(2) A, b = 17.188(5) A, c = 13.096(5) A, beta = 90.54 degrees, and Z = 4. The two compounds consist of chains with double mu 1,5-dicyanamide bridges between neighboring manganese(II) atoms. The weak antiferromagnetic coupling found for the two compounds (J = -0.3 cm-1 for 1 and -0.4 cm-1 for 2) has been studied by MO analysis, and the superexchange pathway through the mu 1,5-(NCNCN-) bridge has been compared with the shorter mu 1,3-(NNN-).

Journal Article↗
PubMed2000

Synthesis, structural characterisation, and Monte Carlo simulation of the magnetic properties of the 3D-stacked honeycomb Cs(n)

Two new polymeric manganese-azido systems with formula Cs(n)-[[Mn(N3)3]n] (1) and [[N(C2H5)4]n][[Mn2-(N3)5(H2O)]n] (2) were synthesised and structurally characterised. Compound 1 crystallises in the P2(1)/n group and consists of a three-dimensional system with end-to-end and end-on azido bridges with the caesium atoms in the holes of the net. Magnetically, compound 1 is a rare case of a three-dimensional network with alternate ferro-antiferromagnetic interactions. Compound 2 crystallises in the P1 group and consists of double chains of manganese atoms bridged by end-on and, the exceptional, (mu-1,1,1)-azido bridges. Magnetically, compound 2 shows net ferromagnetic behaviour. Exact fit of the magnetic data was performed for the two compounds by means of Monte Carlo simulations based on the Metropolis algorithm on sets of 10 x 10 x 10 (1) and 1 x 1 x 320 (2) S = 5/2 classical spin centres.

Journal Article↗
PubMed2000

Statistical physics of regular low-density parity-check error-correcting codes

A variation of Gallager error-correcting codes is investigated using statistical mechanics. In codes of this type, a given message is encoded into a codeword that comprises Boolean sums of message bits selected by two randomly constructed sparse matrices. The similarity of these codes to Ising spin systems with random interaction makes it possible to assess their typical performance by analytical methods developed in the study of disordered systems. The typical case solutions obtained via the replica method are consistent with those obtained in simulations using belief propagation decoding. We discuss the practical implications of the results obtained and suggest a computationally efficient construction for one of the more practical configurations.

Journal Article↗
PubMed2000

[Lesion caused by ischemia-reperfusion in lung transplantation].

OBJECTIVES: To assess the existence or not of a relation between the characteristics of lung donor and/or recipient and the development of ischemia-reperfusion injury (IRI). We also review the latest experimental findings on the biophysical conditions pf graft preservation. PATIENTS AND METHOD: A retrospective study of 74 lung transplants performed in our hospital from 1993 to 1998. Donor and recipient screening and anesthetic and surgical techniques were performed following established protocols. Various degrees of IRI were determined according to hemodynamic and gasometric criteria. We analyzed the statistical relation between donor and recipient variables and IRI. Statistical significance was set at p < 0.05. RESULTS: The incidence of IRI was 70.2% (52 cases), with 12 cases categorized as mild, 22 as moderate and 18 as severe. IRI was significantly related only to the start of extracorporeal circulation. CONCLUSIONS: The development of IRI in lung transplantation is linked to such donor and/or recipient characteristics as the biophysical conditions of graft preservation. At present, greater prevention of this type of early dysfunction of the lung graft requires not only use of adequate screening criteria for donors and receivers but also adequate measures for graft preservation with the use of drugs and handling that have been shown to be effective.

Adolescent↗
PubMed2000

[Lung transplantation and hemophilia. Preoperative considerations].

Lung transplantation is indicated in certain patients with terminal pulmonary disease. We report a case in which a single lung (left) was transplanted to a 16-year-old girl with hemophilia B; she also suffered idiopathic pulmonary fibrosis and had a history of malnutrition, osteoporosis, severe scoliosis, hepatitis C positivity and recurrent bilateral pneumothorax. Treatment with pure factor IX was started the moment the donor lung was available and was continued for 37 days after surgery. Plasma levels of factor IX were kept at 100% during surgery and in the early postoperative period, and over 40% after that time. Correct hemostasis was thus achieved throughout the procedure, with no need for blood products. Patient outcome was satisfactory. The stay in the intensive care recovery ward was 17 days and discharge was 40 days after transplantation. We discuss aspects of hemophilia and lung transplantation, and the influence on malnutrition, chronic steroid treatment and osteoporosis.

Adolescent↗