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Biomedical subjects

L Lopez

Publications and source records attributed to L Lopez.

At least 19 recordsLinked to original sources
PubMed2007

Indomethacin and cerebral autoregulation in severe head injured patients: a transcranial Doppler study.

OBJECTIVE: To assess the effect of indomethacin on cerebral autoregulation, systemic and cerebral haemodynamics, in severe head trauma patients. DESIGN: Prospective, controlled clinical trial, with repeated measurements. SETTINGS: A 12-bed adult general intensive care unit in a third level referral university hospital. PATIENTS: 16 severely head injured patients, 14 males, age range 17-60. INTERVENTIONS: Indomethacin was administrated as a load plus continuous infusion. Indomethacin reactivity was assessed as the estimated cerebral blood flow change elicited by the load. Dynamic and static cerebral autoregulation tests were performed before indomethacin administration, and during its infusion. MEASUREMENTS AND MAIN RESULTS: Systemic and cerebral haemodynamic changes were assessed through continuous monitoring of mean arterial pressure, transcranial Doppler cerebral blood flow velocity, intracranial pressure, cerebral perfusion pressure, and jugular venous oxygen saturation. Indomethacin loading dose was immediately followed by a cerebral blood flow median decrease of 36 or 29% (p = ns) evaluated by two different methods, by an ICP decrease and by an AVDO(2) increase from 3.52 to 6.15 mL/dL (p = 0.002). Dynamic autoregulation increased from a median of 28 to 57% (p<0.05) during indomethacin infusion; static autoregulation also increased, from a median of 72 to 89% (p = ns). CONCLUSIONS: Indomethacin decreased intracranial pressure and cerebral blood flow, and increased cerebral perfusion pressure, while maintaining tissue properties of further extracting O(2). The increase in both autoregulatory values reveals an enhancement of cerebral microvasculature reactivity under indomethacin, during hypertensive and--especially--during hypotensive situations.

Adolescent↗
PubMed2006

Observation of a new Ds meson decaying to DK at a mass of 2.86 GeV/c2.

We observe a new D_{s} meson with mass (2856.6+/-1.5_{stat}+/-5.0_{syst}) MeV/c;{2} and width (48+/-7_{stat}+/-10_{syst}) MeV/c;{2} decaying into D0K+ and D;{+}K_{S};{0}. In the same mass distributions, we also observe a broad structure with mass (2688+/-4_{stat}+/-3_{syst}) MeV/c;{2} and width (112+/-7_{stat}+/-36_{syst}) MeV/c;{2}. To obtain this result, we use 240 fb;{-1} of data recorded by the BABAR detector at the PEP-II asymmetric-energy e;{+}e;{-} storage rings at the Stanford Linear Accelerator Center running at center-of-mass energies near 10.6 GeV.

Journal Article↗
PubMed2006

RNA editing has been lost in the mitochondrial cox3 and rps13 mRNAs in Asparagales.

RNA editing in plant mitochondria alters the RNA sequence by converting C-to-U or U-to-C at a specific site. We investigated the requirement for RNA editing in the complete genomic sequences of the gene encoding the cytochrome oxidase subunit III (cox3) and the ribosomal protein S13 (rps13) in 59 closely related species within the Asparagales and Liliales (monocots). To obtain a comprehensive picture of the degree of variation in editing we explored the non-synonymous RNA editing sites within the newly sequenced cox3 and rps13 genes by a comparative phylogenetic approach. RNA editing is predicted to occur in all the surveyed species, but to different extents. Zero to one non-synonymous editing site is inferred in the cox3 mRNA in species from Amaryllidaceae and Iridaceae. No RNA editing of rps13 mRNAs is required in Amaryllidaceae, because all respective genomic sequences resemble the edited version of the mRNAs of other analysed land plants. The observed absence of cox3 and rps13 RNA editing in Iridaceae and Amaryllidaceae and the striking RNA editing reduction of ccb2 in the latter family is likely generated by recombination and reverse transcription mediated events involving edited mitochondrial transcripts.

Amino Acid Sequence↗
PubMed2006

Expectant care versus surgical treatment for miscarriage.

BACKGROUND: Miscarriage is a common complication of early pregnancy that can have both medical and psychological consequences like depression and anxiety. The need for routine surgical evacuation with miscarriage has been questioned because of potential complications such as cervical trauma, uterine perforation, hemorrhage, or infection. OBJECTIVES: To compare the safety and effectiveness of expectant management versus surgical treatment for early pregnancy loss. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (December 2005), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2004, Issue 3), PubMed (1966 to March 2005), POPLINE (inception to March 2005), and LILACS (1982 to March 2005) and reference lists of reviews. SELECTION CRITERIA: Randomized trials comparing expectant care and surgical treatment (vacuum aspiration or dilation and curettage (D & C)) for miscarriage were eligible for inclusion. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. We contacted study authors for additional information. MAIN RESULTS: Five trials were included in this review with 689 total participants. The expectant-care group was more likely to have an incomplete miscarriage (RR 5.37; 95% CI 2.57 to 11.22). However, the time frames for declaring the process incomplete varied across the studies. The need for unplanned surgical treatment (such as vacuum aspiration or D&C) was greater for the expectant-care group (RR 4.78; 95% CI 1.99 to 11.48). The expectant-care group had more days of bleeding (WMD 1.59; 95% CI 0.74 to 2.45) and a greater amount of bleeding (WMD 1.00; 95% CI 0.60 to 1.40). Post-procedure diagnosis of infection was lower in the expectant-care group (RR 0.29; 95% CI 0.09 to 0.87). Information on psychological outcomes and pregnancy was too limited to draw conclusions. AUTHORS' CONCLUSIONS: Expectant management led to a higher risk of incomplete miscarriage, need for surgical emptying of the uterus, and bleeding. None of these were serious. In contrast, surgical evacuation was associated with a significantly higher risk of infection. Given the lack of clear superiority of either approach, the woman's preference should play a dominant role in decision making. Medical management has added choices for women and their clinicians, but these were not reviewed here.

Abortion, Incomplete↗
PubMed2006

Strategies to improve adherence and acceptability of hormonal methods for contraception.

BACKGROUND: Worldwide, hormonal contraceptives are among the most popular reversible contraceptives in current use. Despite their high theoretical effectiveness, typical use results in much lower effectiveness. In large part, this disparity reflects difficulties in adherence to the contraceptive regimen and low rates for long-term continuation. OBJECTIVES: To determine the effectiveness of ancillary techniques to improve adherence to, and continuation rates of, hormonal methods of contraception. SEARCH STRATEGY: We searched computerized databases for randomized controlled trials (RCTs) comparing client-provider interventions with standard family planning counseling. Sources included CENTRAL, MEDLINE, EMBASE, POPLINE, LILACS, and PsycINFO. SELECTION CRITERIA: Randomized controlled trials (RCTs) of an intensive counseling technique or client-provider intervention versus routine family planning counseling. Interventions included group motivation; structured, peer, or multi-component counseling; and intensive reminders of appointments. Outcome measures were discontinuation, reasons for discontinuation, number of missed pills and on-time injections, and pregnancy. DATA COLLECTION AND ANALYSIS: The primary author evaluated all titles and abstracts from the searches to determine eligibility. Two authors independently extracted data from the included studies. With RevMan 4.2, we calculated the odds ratio for all dichotomous outcomes and the weighted mean difference for continuous data. The studies were so different that we could not conduct a meta-analysis. MAIN RESULTS: We found six RCTs; only one showed a statistically significant benefit of the experimental intervention. In that trial, women who received repeated, structured information about the injectable contraceptive depo-medroxyprogesterone acetate (DMPA) were less likely to have discontinued the method by 12 months (OR 0.27; 95% CI 0.16 to 0.44) than were women who had routine counseling. The intervention group was also less likely to discontinue due to menstrual disturbances. In another study, the intervention group was less likely to discontinue due to dissatisfaction with the contraceptive method, but overall continuation was not affected. AUTHORS' CONCLUSIONS: Most studies to date have shown no benefit of strategies to improve adherence and continuation. These trials have important limitations, however. Two had small sample sizes, several had high losses to follow-up, and the intervention and its intensity varied across the studies. High-quality research is a priority, since adherence and continuation are fundamentally important to the successful use of hormonal contraceptives.

Contraception↗
PubMed2005

Spermicide used alone for contraception.

BACKGROUND: Spermicides have been used as contraceptives for thousands of years. Despite this long use, only recently have studies examined the comparative efficacy and acceptability of these vaginal medications. Spermicides contain an active ingredient (most commonly nonoxynol-9) and a formulation used to disperse the product, such as foam or vaginal suppository. OBJECTIVES: This review examined all known randomized controlled trials of a spermicide used alone for contraception. SEARCH STRATEGY: We searched the following computerized databases from inception to July 2004 for randomized controlled trials of spermicides for contraception: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, POPLINE, LILACS, and EMBASE. We examined the reference list of each trial found as well as that of review articles and textbook chapters. SELECTION CRITERIA: We included any trial of a commercial product used alone for contraception. Each included trial must have provided sufficient information to determine pregnancy rates. We located reports from 14 trials. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted information from the trials identified. We did not conduct a meta-analysis, since most trials had large losses to follow-up. We entered the data into tables and presented the results descriptively. MAIN RESULTS: In the largest trial to date, the gel (Advantage S) containing the lowest dose of nonoxynol-9 (52.5 mg) was significantly less effective in preventing pregnancy than were gels with higher doses of the same agent (100 mg and 150 mg). Probabilities of pregnancy by six months were 22% for the 52.5 mg gel, 16% for the 100 mg dose, and 14% for the 150 mg dose. In the same trial, the three different vehicles with 100 mg of nonoxynol-9 had similar efficacy. Interpretation of these figures is limited, since 39% of participants discontinued the method or were lost from the trial. Few important differences in efficacy emerged in other trials. AUTHORS' CONCLUSIONS: The probability of pregnancy varied widely in reported trials. A gel containing nonoxynol-9 52.5 mg was inferior to two other products tested in the largest trial. Aside from this finding, personal characteristics and behavior of users may be more important than characteristics of the spermicide products in determining the probability of pregnancy. Gel was liked more than the film or vaginal suppository in the largest trial. Spermicide trials have the dual challenges of difficult recruitment and high discontinuation rates; the latter threatens trial validity.

Contraception↗
PubMed2005

Lymphocyte subpopulations and intima media thickness in primary antiphospholipd syndrome.

The aim of this study was to evaluate a possible association between lymphocyte subsets and intima media thickness (IMT) of carotid arteries in primary antiphospholipid syndrome (PAPS). We used a cross-sectional study on PAPS patients (n = 18) and healthy controls (n = 16). IgG anti-cardiolipin antibody (aCL), IgG anti-beta2glycoprotein-I (anti-beta2GPI), IgG anti-beta2glycoprotein-I complexed to oxidized low-density lipoprotein (oxLDL) and to a specific oxidized moiety of LDL (oxLig1), and beta2GPI-oxLDL were measured by ELISA. Lymphocyte immunophenotyping was performed using pairs of monoclonal antibodies directly labelled with fluorescein isothiocyanate, or phycoerythrin or phycoerythrin-Texas-red-X. Intima media thickness (IMT) of carotid arteries was determined by high-resolution sonography. Total peripheral blood lymphocytes did not differ between PAPS and controls. Memory CD4+/CD45RO + T cells were lower in PAPS than controls (P = 0.0007) as well as CD16+56+ natural killer cells (P = 0.02). In PAPS memory T CD45RO + cells positively correlated with IgG anti-beta2GPI-oxLigl (P = 0.002) and to IMT of carotid arteries (common carotid P = 0.02, bifurcation P = 0.007). Naive CD4+/CD45RA+ T cells inversely correlated with beta2GPI-oxLDL (P = 0.009). The relation between IgG anti-beta2GPI-oxLig1 and IMT of carotid arteries with memory CD45RO + T lymphocytes suggests a role for the latter in PAPS related atherogenesis.

Adult↗
PubMed2003

Isolation and characterization of a novel insect defensin from Rhodnius prolixus, a vector of Chagas disease.

An antimicrobial peptide belonging to the defensin family of small cationic peptides associated with innate immunity in insects was isolated from the hemolymph of Rhodnius prolixus, a vector of Chagas disease. This peptide, designated R. prolixus defensin A, was purified and sequenced. The active peptide contains 43 residues and aligns well with other insect defensins. However the pre-pro region of the sequence has little shared identity with other insect defensins. We have identified 3 isoforms of R. prolixus defensin from cDNA clones obtained from RNA isolated from the whole bodies of immune activated insects. Northern analysis and Real-Time Quantitative PCR indicate that there is a very low baseline transcription of this peptide in naïve insects, and that transcription increases significantly in the fat body of immune activated insects. In addition there is a delayed induction of transcription of this peptide in the intestine 24 h post activation suggesting that the midgut/intestine of this species is active in the immune response against pathogens.

Amino Acid Sequence↗
PubMed2003

Phase-locked oscillatory approximately 15- to 30-Hz response to transient visual contrast stimulation: neuromagnetic evidence for cortical origin in humans.

We present neuromagnetic evidence that the human oscillatory (-15-30 Hz; "gamma band") mass response to transient visual (contrast) stimulation originates from cortical areas also generating the conventional pattern-evoked response (VERs). The oscillatory response has shorter latency from stimulus and earlier temporal evolution than the VERs, with different orientation of the source currents. These results suggest the activation of (partly) distinct generating neuronal assemblies with contributions to the development of the VER response. A functional role in stimulus-related cortical synchronization during early visual processing is further suggested and appears consistent with the results of single-unit/multiunit animal research.

Adult↗
PubMed2003

MCP-1 (CCL2) protects human neurons and astrocytes from NMDA or HIV-tat-induced apoptosis.

Acquired immunodeficiency syndrome (AIDS)-associated dementia is often characterized by chronic inflammation, with infected macrophage infiltration of the CNS resulting in the production of human immunodeficiency virus type 1 (HIV-1) products, including tat, and neurotoxins that contribute to neuronal loss. In addition to their established role in leukocyte recruitment and activation, we identified an additional role for chemokines in the CNS. Monocyte chemoattractant protein-1 (MCP-1 or CCL2) and regulated upon activation normal T cell expressed and secreted (RANTES) were found to protect mixed cultures of human neurons and astrocytes from tat or NMDA-induced apoptosis. Neuronal and astrocytic apoptosis in these cultures was significantly inhibited by co-treatment with MCP-1 or RANTES but not IP-10. The protective effect of RANTES was blocked by antibodies to MCP-1, indicating that RANTES protection is mediated by the induction of MCP-1. The NMDA blocker, MK801, also abolished the toxic effects of both tat and NMDA. Tat or NMDA treatment of mixed cultures for 24 h resulted in increased extracellular glutamate ([Glu]e) and NMDA receptor 1 (NMDAR1) expression, potential contributors to apoptosis. Co-treatment with MCP-1 inhibited tat and NMDA-induced increases in [Glu]e and NMDAR1, and also reduced the levels and number of neurons containing intracellular tat. These data indicate that MCP-1 may play a novel role as a protective agent against the toxic effects of glutamate and tat.

AIDS Dementia Complex↗
PubMed2002

Intrinsic changes on automatism, conduction, and refractoriness by exercise in isolated rabbit heart.

We have studied the intrinsic modifications on myocardial automatism, conduction, and refractoriness produced by chronic exercise. Experiments were performed on isolated rabbit hearts. Trained animals were submitted to exercise on a treadmill. The parameters investigated were 1) R-R interval, noncorrected and corrected sinus node recovery time (SNRT) as automatism index; 2) sinoatrial conduction time; 3) Wenckebach cycle length (WCL) and retrograde WCL, as atrioventricular (A-V) and ventriculoatrial conduction index; and 4) effective and functional refractory periods of left ventricle, A-V node, and ventriculoatrial retrograde conduction system. Measurements were also performed on coronary flow, weight of the hearts, and thiobarbituric acid reagent substances and glutathione in myocardium, quadriceps femoris muscle, liver, and kidney, to analyze whether these substances related to oxidative stress were modified by training. The following parameters were larger (P < 0.05) in trained vs. untrained animals: R-R interval (365 +/- 49 vs. 286 +/- 60 ms), WCL (177 +/- 20 vs. 146 +/- 32 ms), and functional refractory period of the left ventricle (172 +/- 27 vs. 141 +/- 5 ms). Corrected SNRT was not different between groups despite the larger noncorrected SNRT obtained in trained animals. Thus training depresses sinus chronotropism, A-V nodal conduction, and increases ventricular refractoriness by intrinsic mechanisms, which do not involve changes in myocardial mass and/or coronary flow.

Animals↗
PubMed2001

Ecological meltdown in predator-free forest fragments.

The manner in which terrestrial ecosystems are regulated is controversial. The "top-down" school holds that predators limit herbivores and thereby prevent them from overexploiting vegetation. "Bottom-up" proponents stress the role of plant chemical defenses in limiting plant depredation by herbivores. A set of predator-free islands created by a hydroelectric impoundment in Venezuela allows a test of these competing world views. Limited area restricts the fauna of small (0.25 to 0.9 hectare) islands to predators of invertebrates (birds, lizards, anurans, and spiders), seed predators (rodents), and herbivores (howler monkeys, iguanas, and leaf-cutter ants). Predators of vertebrates are absent, and densities of rodents, howler monkeys, iguanas, and leaf-cutter ants are 10 to 100 times greater than on the nearby mainland, suggesting that predators normally limit their populations. The densities of seedlings and saplings of canopy trees are severely reduced on herbivore-affected islands, providing evidence of a trophic cascade unleashed in the absence of top-down regulation.

Animals↗
PubMed2001

Secretion pattern, ultrastructural localization and function of extracellular matrix molecules involved in eggshell formation.

The chicken eggshell is a composite bioceramic containing organic and inorganic phases. The organic phase contains, among other constituents, type X collagen and proteoglycans (mammillan, a keratan sulfate proteoglycan, and ovoglycan, a dermatan sulfate proteoglycan), whose localization depends on a topographically defined and temporally regulated deposition. Although the distribution of these macromolecules in the eggshell has been well established, little is known about their precise localization within eggshell substructures and oviduct cells or their pattern of production and function during eggshell formation. By using immunofluorescent and immuno-ultrastructural analyses, we examined the distribution of these macromolecules in oviduct cells at different post-oviposition times. To understand the role of proteoglycan sulfation on eggshell formation, we studied the effects of inhibition of proteoglycan sulfation by treatment with sodium chlorate. We showed that these macromolecules are produced by particular oviduct cell populations and at precise post-oviposition times. Based on the precise ultrastructural localization of these macromolecules in eggshell substructures, the timing of the secretion of these macromolecules by oviduct cells and the effects on eggshell formation caused by the inhibition of proteoglycan sulfation, the putative role of mammillan is in the nucleation of the first calcite crystals, while that of ovoglycan is to regulate the growth and orientation of the later forming crystals of the chicken eggshell.

Animals↗
PubMed2001

Cutaneous hyperpigmentation following venous sclerotherapy treated with deferoxamine mesylate.

BACKGROUND: Cutaneous hyperpigmentation after venous sclerotherapy is an adverse sequelae of difficult management. OBJECTIVE: To evaluate the degree of depigmentation with the use of deferoxamine mesylate (DM) in patients with postsclerotherapy hyperpigmentation treated with polydocanol (POL) for telangiectasias and reticular veins (0.2-5 mm diameter) and varicose veins (5-8 mm diameter). METHODS: The experimental group of 36 female patients (mean age 37 years) was divided in two groups. Group I consisted of 30 patients who were treated with POL at 0.25-0.50% concentration for telangiectasias and reticular veins. Group II consisted of six patients with prolonged postsclerotherapy hyperpigmentation (more than 6 months after treatment) in varicose veins that had been treated with POL at 1.5% concentration each week. Groups I and II were injected with DM 500 mg subcutaneously once a week until 81-100% depigmentation was reached. In group I, DM was injected at the time of sclerotherapy. These groups were compared to their respective control groups with similar conditions but allowing spontaneous depigmentation without DM. Evaluation was undertaken clinically and photographically, and the number of days required to reach the desired depigmentation of 81-100% was determined. RESULTS: When DM was used, depigmentation of 81-100% was observed in group I at 27 days, and for group II in 46 days. In each control group, similar depigmentation was seen at 150 +/- 19 and 255 +/- 11 days, respectively. Comparing results, there was a reduction in the time to depigmentation of 82% for each group (P <.0001). CONCLUSION: The weekly subcutaneous administration of DM 500 mg reduces the time to depigmentation by 82% in patients with postsclerotherapy cutaneous hyperpigmentation treated for telangiectasias and reticular veins and prolonged postsclerotherapy hyperpigmentation in varicose veins. In this study we could not explain why such variability exists in the length of time to spontaneous depigmentation.

Adult↗
PubMed2001

RNA editing of the ribosomal protein S13 transcripts in magnolia and sunflower mitochondria.

To obtain information on ribosomal protein gene content and RNA editing in plant mitochondria, we investigated the conservation of the gene for ribosomal protein S13 (rps13) in the mitochondrial genomes of Magnolia spp. and Helianthus annuus. A complete rps13 open reading frame was identified in the mitochondrial genome of Magnolia and Helianthus. Comparison of genomic and cDNA sequences revealed that transcripts from the mitochondrial rps13 locus in both Magnolia and Helianthus undergo RNA editing suggesting the functionality of the related gene. Six and four editing events in the rps13 transcript population of Magnolia and Helianthus mitochondria, respectively, cause critical changes of codons and, consequently, induce 5 and 3.4% amino acid modifications in the respective genomically-encoded S13 polypeptides. Both editing pattern and efficiency of RNA editing differ in the reverse transcription (RT)-PCR-derived cDNA populations from the rps13 locus from the analyzed plant species with only the Magnolia rps13 being fully edited.

Amino Acid Sequence↗
PubMed2001

Latino AIDS immigrants in the Western Gulf states: a different population and the need for innovative prevention strategies.

Immigrant HIV infected Latinos, and those at highest risk for infection, demonstrate strikingly different patterns of risk behaviors and origins. This complicates the already complex acculturation process impacting their lives. By weaving together immigration and AIDS epidemiological patterns, the impact of tightening immigration policy, and masked sexual behaviors, the authors express concern for a lack of communication with, and lack of health care access for, Latinos in the Western Gulf Coast. To combat this deficit, health care and social workers need to be aware of different social, cultural, and behavioral contexts in Latino populations. Policy makers should support efforts to provide health care workers with skills through appropriate language and cultural sensitivity workshops. HIV prevention strategies specific to Latinos are also discussed.

Acculturation↗