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Biomedical subjects

M Barrera

Publications and source records attributed to M Barrera.

At least 19 recordsLinked to original sources
PubMed2005

Levels of 137Cs in muddy sediments of the seabed of the Bay of Cadiz, Spain. Part I. Vertical and spatial distribution of activities.

This is the first of a two-part paper. This first part describes a detailed study conducted of the spatial and vertical distribution of the concentration of the radionuclide (137)Cs, utilising columns of sediment extracted from the seabed of the Bay of Cadiz (Spain) as specimens. The activity concentrations have been measured by means of gamma spectrometry using a HPGe detector and (137)Cs is used as an indicator of the sedimentation and contamination processes in the zone. At the same time the relationship between the levels of activity found and other hydrodynamic and sedimentological variables characteristic of the zone have been studied. The experimental results obtained will also serve to develop a model of the distribution of (137)Cs, which will be presented in the second part of this paper.

Carbon↗
PubMed2005

Levels of 137Cs in muddy sediments on the seabed in the Bay of Cadiz (Spain). Part II. Model of vertical migration of (137)Cs.

This second part of the study reports the development of a model to describe the vertical migration of the artificial radioisotope (137)Cs in the sediment column on the seabed of the Bay of Cadiz. The application of the model provides an overall picture of the process of sedimentation in the Inner Bay of Cadiz. The spatial distribution of the rate of sedimentation enables us to study the sources of sediments and the means by which the sediments have been transported. A method has been derived from the rate of sedimentation to perform the dating of the layers of sediment. The model describes the behaviour of (137)Cs in the area under study, taking into account the time of residence in the zones that are the source of accumulation, the origin of the sedimentary material, together with the diffusion of the radionuclide in the sediment of the seabed.

Cesium Radioisotopes↗
PubMed2004

Environmental impact of unleaded gasolines in the bay of Cádiz (Spain).

Given the strategic situation of the José León de Carranza bridge, which spans the Bay of Cádiz (in the SW of Spain) and carries very heavy motor traffic, together with knowledge of the currents and tidal flows in the zone, we have used a technique of radioactive dating of sediments to study the temporal evolution presented by contamination from lead in the sediment column. This has allowed us to observe the environmental impact, in terms of the concentration of Pb in the sea bed sediments, that has been produced in the zone by the introduction of unleaded gasolines as substitutes for traditional automobile fuels that employ organic forms of tetra methyl lead as an antidetonant agent in the fuel.

Environmental Monitoring↗
PubMed2004

The relationship between social support, depression and treatment for depression in people with multiple sclerosis.

BACKGROUND: Studies have been fairly consistent in finding a relationship between social support and depression. However, little is known about the relationship between depression and social support in the context of treatment for depression. This study examined the effects of treatment for depression on social support among patients with multiple sclerosis (MS). METHOD: Sixty-three moderately depressed MS patients received 16 weeks of cognitive behaviour therapy (CBT), supportive expressive group psychotherapy (SEGP) or sertraline. Depression was measured using the Beck Depression Inventory and social support was measured using Arizona Social Support Interview Schedule. RESULTS: Treatment for depression was associated with significant increases in perceived social support, utilized social support and satisfaction with support, as well as reduction in need for emotional support. There were no significant changes in structural support or need for physical support. There were also no differences in change in social support across treatments. All changes in social support were fully explained by depression. Improvements in utilized social support and satisfaction with social support were fully mediated by improvements in depression. Baseline depression predicted improvements in perceived support and need for emotional support. CONCLUSIONS: These findings suggest that improvements in social support among MS patients during treatment for depression can be explained by depression. However, different domains of social support may be differentially sensitive to changes in depression.

Adult↗
PubMed2004

The role of emotional social support in the psychological adjustment of siblings of children with cancer.

BACKGROUND: Siblings of children with cancer are at risk for reduced emotional support. The role of emotional social support in the psychological adjustment of siblings of paediatric cancer patients was examined, in the context of age and gender. METHODS: The sample consisted of two groups of siblings of children being treated for cancer: siblings referred for behaviour problems (n = 47) and a comparison group of non-referred siblings (n = 25). Forty-two were female, and 30 were male. The mean age was 10.31 years (SD = 2.71). Siblings completed measures of depression, anxiety, behaviour, and emotional social support. One parent of each sibling completed measures of sibling's behaviour and anxiety. RESULTS: Siblings who reported more social support endorsed significantly fewer symptoms of depression, anxiety, and fewer behaviour problems, and their parents reported less anxiety and fewer behaviour problems than siblings who reported lower social support. Parents of referred siblings reported significantly more behaviour problems than parents of non-referred siblings. Referred adolescent females reported significantly higher depression scores and were perceived as more anxious than referred adolescent males and non-referred adolescent females. Non-referred younger siblings with high social support were perceived by their parents as having the fewest behaviour problems. CONCLUSIONS: High level of social support appears to play a protective role in psychological adjustment of siblings of paediatric cancer patients, with age and gender as modifying factors. Although not all siblings develop behaviour or emotional problems, it is critical to identify those who do in order to intervene accordingly.

Adaptation, Psychological↗
PubMed2004

Effect of telmisartan 80 mg once daily on 24-h blood pressure profile in patients with mild-to-moderate hypertension failing to respond to prior antihypertensive therapy.

Blood pressure is not adequately controlled in almost 50% of patients with hypertension who are in receipt of antihypertensive therapy. This multicentre, prospective, open-label trial was designed to determine whether or not once-daily telmisartan 80 mg reduced blood pressure during the last 6 h of the 24-h dosing interval in patients with mild-to-moderate hypertension who were unresponsive to previous antihypertensive therapy. The study comprised 100 patients (47 males, 53 females) who had failed to respond satisfactorily to prior treatment given for a minimum of 3 months. At screening, 24-h ambulatory blood pressure monitoring (ABPM) was conducted after the patient had been treated with the currently prescribed antihypertensive medication. Following 5 weeks of telmisartan 80 mg treatment, ABPM was repeated. Telmisartan significantly reduced mean systolic blood pressure, diastolic blood pressure (DBP) and pulse pressure compared with previous antihypertensive therapy over each time interval (24-h, morning, night-time and the last 6 h of the dosing interval [2.00 a.m.-8.00 a.m.]) analysed. In addition, more than 90% of patients responded successfully (clinic DBP <90 mmHg or a >10 mmHg reduction in clinic DBP) at the end of telmisartan treatment. In conclusion, telmisartan provides effective blood pressure control throughout the 24-h dosing interval in patients with mild-to-moderate hypertension who were unresponsive to previous antihypertensive medication.

Adolescent↗
PubMed2004

Ileal amino acid digestibility and performance of growing pigs fed wheat-based diets supplemented with xylanase.

Two experiments were conducted to determine the effect of supplementation of xylanase to a wheat-based diet on the apparent ileal digestibility (AID) of AA and the performance of growing pigs fed diets limiting in AA. In Exp. 1, eight pigs (average initial BW = 20.5+/-1.2 kg) fitted with a simple T-cannula at the distal ileum, were fed four diets according to a repeated 4 x 4 Latin square design. Diet 1 was a basal diet that contained 97.6% wheat. Diets 2, 3, and 4 were the basal diet supplemented with xylanase at rates of 5,500, 11,000, and 16,500 units of xylanase activity (XU), respectively (as-fed basis). There were linear and quadratic effects (0.062 < P < 0.001) of xylanase supplementation on the AID of CP and most of the AA. The largest increases in AID of CP and AA were obtained when xylanase was supplemented at a rate of 11,000 XU; no further increases were observed with xylanase supplementation at a rate of 16,500 XU. In Exp. 2, 30 pigs (average initial BW 21.4+/-1.8 kg) were randomly allotted to six dietary treatments. Diets 1 to 4 were similar to those used in Exp. 1. Diet 5 was the same as Diet 1, but supplemented with 0.53% lysine, 0.12% threonine, and 0.05% methionine. Diet 6 (positive control diet) was a wheat-soybean meal diet that contained 18.2% CP (as-fed basis). The total contents of lysine, threonine, and methionine were similar for Diets 5 and 6. There was a linear effect of xylanase supplementation on ADG (P = 0.093) and feed:gain ratio (P = 0.089), and a quadratic effect on ADG (P = 0.067) and feed:gain ratio (P = 0.074). But, the greatest response was obtained with the supplementation of 11,000 XU. The supplementation of lysine, threonine, and methionine to Diet 1 increased (P = 0.001) ADG and ADFI and improved (P = 0.01) feed:gain ratio. There was no difference (P = 0.508) in the performance of pigs fed the AA-supplemented or control diet. In conclusion, the supplementation of xylanase to a diet in which wheat provided the sole source of protein and energy improved the AID of AA, ADG, and feed:gain ratio; however, this improvement was very small compared with that obtained with the supplementation of synthetic amino acids.

Amino Acids↗
PubMed2003

Effect of proinflammatory cytokines (IL-6, TNF-alpha, IL-1beta) on hemodynamic performance during orthotopic liver transplantation.

BACKGROUND: Proinflammatory cytokines (IL-6, IL-1beta, TNF-alpha) released during liver transplantation may affect hemodynamic stability. The aim of the present study was to analyze the association between IL-6, TNF-alpha, and IL-1beta and systemic vascular resistance during the phases of liver transplantation. MATERIAL AND METHODS: The proinflammatory cytokines IL-6, IL-1beta, and TNF-alpha were analyzed in the blood of 20 consecutive patients who underwent transplantation. Blood samples were drawn from the pulmonary artery at serial times during surgery. Hemodynamic parameters were determined using a cardiac output monitor. Correlations between parameters were analyzed using the Spearman's rho and Kendall's tau-b methods. RESULTS: Both in the vena cava and the pulmonary artery, significant association was observed between basal values of IL-6 during hepatectomy and systemic vascular resistance during the phases of liver transplantation: hepatectomy phase (r=.76, P=.02), anhepatic phase (r=.78, P=.03) and reperfusion phase (r=.87, P=.005). CONCLUSIONS: Basal values of IL-6 may be considered a prognostic factor for hemodynamic performance during the phases of liver transplantation.

Biomarkers↗
PubMed2003

Association between anatomopathologic graft disorders during reperfusion and vena cava sIL-2r in orthotopic liver transplantation.

UNLABELLED: Graft ischemia-reperfusion injury during orthotopic liver transplantation (OLT) is associated with anatomic and pathologic disorders in the graft, which may cause initial dysfunction. The object of this paper was to evaluate sIL-2r as an indicator of liver damage during graft reperfusion. MATERIAL AND METHODS: Blood samples were drawn from 20 consecutive patients who required OLT secondary to chronic end-stage insufficiency various sites (portal vein, vena cava, pulmonary artery) and during different surgical phases. Following centrifugation and storage at -70 degrees C, sIL-2r was quantitated by chemiluminescence (Immulite, EURO/DPC). In addition biopsies were graded from 0 to III according to the anatomic and pathologic findings. Base excess and ammonia were measured to evaluate the function of the new liver. STATISTICAL ANALYSES: Parameter associations were explored using Spearman's Rho and Kendall's Tau-b methods. RESULTS: There was a correlation between the degree of graft preservation and sIL-2R both during vena cava reperfusion (r=.0591, P=.05) and for the initial 2 hours after reperfusion (r=0.61, P=.062). CONCLUSION: sIL-2r levels drawn from the vena cava after graft reperfusion are associated with its degree of injury.

Drug Therapy, Combination↗
PubMed2002

Dating of marine sediments and time evolution of heavy metal concentrations in the Bay of Cádiz, Spain.

In this paper the time evolution of heavy metal concentration of Pb, Zn, Cd and Hg, in the sediments of the Bay of Cádiz (southwest of Spain) is studied during the past century, as a result of the industrial influence in the zone. The study has been performed using sedimentary profiles that have been extracted from the seabed. The measurement of 210Pb and 137Cs radionuclides has provided the dating of the sediment layers, up to a depth corresponding to the age of 115 years. The relative sedimentation rates obtained are around 0.2 cm/year. The 137Cs activity profile reflects the concentration of this radionuclide in the atmosphere and into aquatic systems during the second half of the twentieth century. This profile has been used to ratify the results provided by the 210Pb dating method.

Cesium Isotopes↗
PubMed2001

Relationships between sea-bed radionuclide activities and some sedimentological variables.

Natural radionuclides (232Th, 226Ra, 40K) and 137Cs, coming from atmospheric radioactive fallout, have been measured in sea-bed sediments of the Bay of Cádiz (South Western Spain). In this report, multivariate analysis methods have been employed to study the relationships between the activities of the radionuclides and some sedimentological variables like granulometric facies, organic content and apparent density. The correlation functions found show that it is possible to determine, with a satisfactory degree of approximation, the granulometric facies of the sediments using only radiometric information.

Geologic Sediments↗
PubMed2001

The psychological sense of economic hardship: measurement models, validity, and cross-ethnic equivalence for urban families.

Poverty is a community stressor that disproportionally affects ethnic minority families. One aspect of programmatic research on poverty focuses on the psychological sense of economic hardship. In a study of 319 African American, European American, and Mexican American urban families, parents completed objective measures of economic status and scales of perceived economic hardship that were adapted from previous research. Measurement models identified a coherent construct of psychological sense of economic hardship that was essentially equivalent for mothers and fathers, English- and Spanish-speaking Mexican Americans, and the 3 ethnic groups. In support of the validity of this construct, relations between objective indicators of economic status and perceived economic hardship showed equivalence across these same groups.

Adolescent↗
PubMed2001

Efficacy, safety and predictive factors of therapeutic success with sildenafil for erectile dysfunction in patients with different spinal cord injuries.

STUDY DESIGN: Multicenter, open, prospective, before-after study. OBJECTIVE: To assess the efficacy and safety of sildenafil therapy for erectile dysfunction in patients with spinal cord injury, and the association between the response to sildenafil and factors such as causes and levels of spinal cord injury, grade of ASIA deficit, time since injury, orgasmic perception, and degree of baseline erection. SETTING: Homes of outpatients of 16 spinal cord injury units in Spain. METHOD: One hundred and seventy patients with erectile dysfunction secondary to spinal cord injury, from whom baseline data were collected on their sexual function, and who started treatment with sildenafil 50 mg. An efficacy assessment was made by the patient and his partner, and the score of the International Index of Erectile Function (IIEF) was recorded. RESULTS: It was reported by 88.2% of the patients and 85.3% of their partners that treatment with sildenafil had improved their erections, regardless of the baseline characteristics of the spinal cord injury and erectile function. In responders, this improvement was confirmed by an increase from 12.5 to 24.8 points (P<0.001) of the Erectile Function Domain of IIEF. A significant improvement was also seen in patients' satisfaction with sexual activity and general satisfaction derived from sexual life. Preservation of orgasmic perception and a baseline degree of erection of 3 or 4 (P=0.006) were predictors of therapeutic success. No serious adverse events occurred. CONCLUSION: Sildenafil is an effective, well-tolerated treatment for erectile dysfunction caused by spinal cord injury, regardless of the cause, neurological level, ASIA grade, and time since injury. SPONSORSHIP: Spanish Society of Paraplegia.

Adult↗
PubMed2000

Quality of life and behavioral adjustment after pediatric bone marrow transplantation.

The purpose of this study was two-fold: to describe the quality of life and behavioral adjustment of survivors of pediatric bone marrow transplantation (BMT) prior to and 6 months post-BMT; and, to identify correlates of survivors' quality of life and behavioral adjustment. Participants were 26 children and adolescents who underwent BMT, and their mothers. At pre- and 6 months post BMT, mothers completed standardized measures of their children's behavioral adjustment, quality of life, and adaptive functioning. Self-report questionnaires were completed to determine levels of maternal anxiety and depression, and family functioning. Information was also gathered about demographic variables, medical history, and symptom severity. Children's overall quality of life improved 6 months post BMT and was most strongly associated with pre-BMT levels of family cohesion. Children's behavioral adjustment remained within the normal range across time and was associated with pre-BMT levels of family cohesion and child adaptive functioning. Mothers' psychological adjustment improved over time and was associated with quality of life, but unrelated to children's behavioral adjustment. Pre-BMT levels of family cohesion and child adaptive functioning appear to be important in understanding quality of life and behavioral adjustment of pediatric BMT survivors.

Adaptation, Psychological↗
PubMed2000

Brief clinical report: procedural pain and anxiety management with mother and sibling as co-therapists.

OBJECTIVE: To describe a multidimensional family-focused intervention for pain and anxiety management during port-access with a Spanish-speaking preschool child being treated for acute lymphoblastic leukemia, using the patient's mother and one sibling as co-therapists. METHODS: Assessment procedures included interviews with mother, sibling, and primary nurse and behavioral observations during port-access, and during a medical examination. Intervention consisted of two training and two "in-vivo" sessions, using behavioral and cognitive behavioral techniques. RESULTS: Physical resistance was eliminated and anxiety responses reduced during port-access sessions. Maternal anxiety and sibling distress were also reduced. CONCLUSIONS: This case study illustrates an empirically supported child and family focused in the clinical care context and highlights cultural factors that may influence the success of such interventions.

Anxiety↗
PubMed1999

Ethnicity, substance use, and development: exemplars for exploring group differences and similarities.

Epidemiological research shows some ethnic-group differences in the prevalence of substance use. This approach does not address the question of whether there are ethnic-group differences in the models that are needed to understand the development of substance use. For this question we need to understand the relations between psychological constructs and their trajectories over time. In this paper we describe some approaches to studying ethnic-group differences in the predictors of substance use that illustrate probing for mediators, multisample analyses of structural models, and an experimental trial of a preventive intervention. Our studies found some ethnic-group differences in the structure of constructs and the relations between variables, but many similarities. The challenge for researchers is using appropriate research methods for studying ethnicity, uncovering the basis for ethnic-group differences when they occur, knowing when statistical differences are meaningful, and acknowledging when developmental models are comparable.

Adolescent↗