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Biomedical subjects

F A Guerra

Publications and source records attributed to F A Guerra.

At least 19 recordsLinked to original sources
PubMed2001

Motor-vehicle occupant injury: strategies for increasing use of child safety seats, increasing use of safety belts, and reducing alcohol-impaired driving.

The Task Force on Community Preventive Services has conducted systematic reviews of interventions designed to increase use of child safety seats, increase use of safety belts, and reduce alcohol-impaired driving. The Task Force strongly recommends the following interventions: laws requiring use of child safety seats, distribution and education programs for child safety seats, laws requiring use of safety belts, both primary and enhanced enforcement of safety belt use laws, laws that lower the legal blood alcohol concentration (BAC) limit for adult drivers to 0.08%, laws that maintain the minimum legal drinking age at 21 years, and use of sobriety checkpoints. The Task Force recommends communitywide information and enforcement campaigns for use of child safety seats, incentive and education programs for use of child safety seats, and a lower legal BAC for young drivers (in the United States, those under the minimum legal drinking age). This report provides additional information regarding these recommendations, briefly describes how the reviews were conducted, and provides information to help apply the interventions locally.

Accidents, Traffic↗
PubMed2000

Developing the Guide to Community Preventive Services--overview and rationale. The Task Force on Community Preventive Services.

When the GUIDE TO COMMUNITY PREVENTIVE SERVICES: Systematic Reviews and Evidence-Based Recommendations (the Guide) is published in 2001, it will represent a significant national effort in encouraging evidence-based public health practice in defined populations (e.g., communities or members of specific managed care plans). The Guide will make recommendations regarding public health interventions to reduce illness, disability, premature death, and environmental hazards that impair community health and quality of life. The Guide is being developed under the guidance of the Task Force on Community Preventive Services (the Task Force)-a 15-member, nonfederal, independent panel of experts. Subject matter experts, methodologists, and scientific staff are supporting the Task Force in using explicit rules to conduct systematic literature reviews of evidence of effectiveness, economic efficiency, and feasibility on which to base recommendations for community action. Contributors to the Guide are building on the experience of others to confront methodologic challenges unique to the assessment of complex multicomponent intervention studies with nonexperimental or nonrandomized designs and diverse measures of outcome and effectiveness. Persons who plan, fund, and implement population-based services and policies to improve health at the state and local levels are invited to scrutinize the work in progress and to communicate with contributors. When the Guide is complete, readers are encouraged to consider critically the value and relevance of its contents, the implementation of interventions the Task Force recommends, the abandonment of interventions the Task Force does not recommend, and the need for rigorous evaluation of the benefits and harms of promising interventions of unknown effectiveness.

Decision Making↗
PubMed2000

Use of free-hand three-dimensional ultrasound software in the study of the fetal heart.

OBJECTIVE: To propose a new approach to the study of the fetal heart using free-hand three-dimensional (3D) ultrasound software. METHODS: We studied a total of 28 fetuses, of which 26 were normal and two were known to have heart pathology. In all of them a B-mode scan was performed. After obtaining a four-chamber view, and keeping the transducer in the same position, the free-hand 3D-View software was activated. A sequence of frames was stored. Additional information was recorded looking from the four-chamber view towards the outflow tract, and also adding color Doppler. RESULTS: We obtained a multiplanar display of one B-mode and two perpendicular M-modes in all cases studied. In this multiplanar mode, Y and X axes represent distance and Z axis represents time. We were able to obtain M-modes and a variation of color-M-mode in any desired position. Moving the information along the Z axis, a frame sequence of the B-mode was obtained. Using this approach we observed one case of fetal supraventricular extrasystoles and other having an interventricular septum defect. CONCLUSIONS: This modality gives a new perspective of fetal heart scanning using the free-hand 3D-View software, in which there is benefit from many of the advantages of the 3D software, although the power of this procedure must be improved.

Fetal Diseases↗
PubMed1999

A randomized, controlled trial of a behavioral intervention to prevent sexually transmitted disease among minority women.

BACKGROUND: African-American and Hispanic women are disproportionately affected by sexually transmitted diseases, including the acquired immunodeficiency syndrome (AIDS). In the effort to reduce infection rates, it is important to create and evaluate behavioral interventions that are specific to the target populations. METHODS: We enrolled women with nonviral sexually transmitted diseases in a randomized trial of a sex- and culture-specific behavioral intervention. The intervention consisted of three small-group sessions of three to four hours each designed to help women recognize personal susceptibility, commit to changing their behavior, and acquire necessary skills. The control group received standard counseling about sexually transmitted diseases. The design of the intervention was based on the AIDS Risk Reduction Model and ethnographic data on the study populations. Participants in both groups underwent screening, counseling, and an interview before randomization and at the 6- and 12-month follow-up visits. The principal outcome variable was subsequent chlamydial or gonorrheal infection, which was evaluated on an intention-to-treat basis by logistic-regression analysis. RESULTS: A total of 424 Mexican-Americans and 193 African-American women were enrolled; 313 were assigned to the intervention group and 304 to the control group. The rate of participation in the intervention was 90 percent. The rates of retention in the sample were 82 and 89 percent at the 6- and 12-month visits, respectively. Rates of subsequent infection were significantly lower in the intervention group than in the control group during the first 6 months (11.3 vs. 17.2 percent, P=0.05), during the second 6 months (9.1 vs. 17.7 percent, P=0.008), and over the entire 12-month study period (16.8 vs. 26.9 percent, P=0.004). CONCLUSIONS: A risk-reduction intervention consisting of three small-group sessions significantly decreased the rates of chlamydial and gonorrheal infection among Mexican-American and African-American women at high risk for sexually transmitted disease.

Adolescent↗
PubMed1997

The Pope, hot pavement, and public health.

The author recalls his first days and weeks as Director of Health for the City of San Antonio and Bexar County, Texas. The article details some of the observations made by the author as he developed a computerized immunization registry.

Computer Systems↗
PubMed1995

Effect of inhibition of prostaglandin synthesis on breathing movements and pulmonary blood flow in fetal sheep.

During transition from fetal to extrauterine life, respiration increases in incidence and magnitude as pulmonary blood flow dramatically increases. To determine whether alterations in pulmonary blood flow in utero are directly related to alterations in fetal breathing movements (FBM), we studied six chronically instrumented fetal sheep late in gestation to assess the effects of continuous FBM caused by a 4-h infusion of meclofenamate, a prostaglandin synthase inhibitor, on mean pulmonary blood flow to the fetus. We found a striking increase in FBM from 46 +/- 15% (SD) of the time during control to > 85% of the time by 1 h (P < 0.001), with the fetuses exhibiting continuous FBM by the last 1 h of infusion. The mean pulmonary blood flow also increased significantly during the first 90 min of the infusion as the incidences of FBM were increasing (26 +/- 14 and 56 +/- 23 ml.min-1.kg-1 for control and infusion, respectively; P < 0.01). Despite the simultaneous initial increase in FBM and mean pulmonary blood flow, the increase in left pulmonary artery blood flow was not sustained and decreased back to baseline by 2 h, even though the incidence of FBM continued to increase at this time. During the infusion, the mean pulmonary blood flow was not different between the presence or absence of FBM. There were no changes in fetal heart rate or pulmonary or systemic blood pressures during the infusion nor in arterial pH or blood gas tensions. We conclude that this increase in mean pulmonary blood flow in utero was not solely related to the increase in breathing movements.

Animals↗
PubMed1995

Prostaglandin E2 decreases fetal breathing movements, but not pulmonary blood flow, in fetal sheep.

Fetal breathing movements are vital for normal fetal lung growth. Inhibition of these fetal breathing movements is associated with pulmonary hypoplasia. Pulmonary hypoplasia also occurs subsequent to alterations in other factors, such as a significant decrease in pulmonary blood flow. The prostaglandin system is known to have profound effects on both fetal breathing movements and on the pulmonary vascular system. We studied six late-gestation chronically instrumented fetal sheep by using an electromagnetic flow transducer around the left pulmonary artery to determine whether a decrease in fetal breathing movements, subsequent to a continuous infusion of prostaglandin E2 (PGE2), is associated with a decrease in pulmonary blood flow. A continuous PGE2 infusion of 0.88 +/- 0.11 microgram.kg-1.min-1 over 120 min led to a significant decrease in fetal breathing movements (control 40.5 +/- 3.6%, infusion 3.3 +/- 1.6%; P < 0.001). In contrast, the PGE2 infusion had no effect on mean left pulmonary artery blood flow (control 27.7 +/- 9.3 ml.min-1.kg-1, infusion 23.8 +/- 7.0 ml.min-1.kg-1. The PGE2 infusion demonstrated central effects in the percentage of time the fetus was in high-voltage electrocortical activity (control 41.9 +/- 2.5%, infusion 56.5 +/- 5.4%; P < 0.05) and in the amount of time spent in low-voltage electrocortical activity without fetal breathing movements (control 17.5 +/- 2.7%, infusion 40.2 +/- 4.8%; P < 0.05). A significant decrease in the fetal heart rate during the infusion was seen with no effect on either the systemic or pulmonary blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The effect of fetal breathing movements on pulmonary blood flow in fetal sheep.

In the fetus, normal lung growth requires both fetal breathing movements (FBM) and adequate pulmonary blood flow. We postulated that FBM intermittently increase pulmonary blood flow and may stimulate lung growth through that effect. To test the hypothesis that normal intermittent FBM cause associated intermittent increases in pulmonary blood flow, we studied eight chronically instrumented fetal sheep (gestational ages 125-143 d) on 34 occasions (total study time = 65.7 h). Each fetus had a cuff electromagnetic flow transducer around the left pulmonary artery, electrocortical electrodes, and catheters in the trachea, main pulmonary artery, carotid artery, and amniotic cavity. Mean blood flow though the left pulmonary artery averaged 59 +/- 8 mL/min (mean +/- SEM; per kg: 25 +/- 4 mL/kg/min) and was similar in both the presence (61 +/- 9 mL/min) and absence (57 +/- 7 mL/min) of FBM and during both high and low voltage electrocortical activity. In contrast, in utero phasic pulmonary blood flow varied with FBM, increasing during the inspiratory phase and decreasing during the expiratory phase. Both pulmonary and systemic vascular pressures showed changes in the opposite directions. Arterial pH and blood gas tensions were normal and did not change with FBM or electrocortical activity. We conclude that FBM do not increase mean blood flow through the left pulmonary artery; thus, it is unlikely that FBM stimulate lung growth through changes in pulmonary blood flow.

Animals↗
PubMed1993

[Effect of arginine-vasopressin infusion on the secretion of tracheal fluid in sheep fetuses].

Timely evacuation of alveolar fluid, release of surfactant and the beginning of continuous breathing, are key processes for an adequate adaptation of the fetus to the extrauterine life. Fetal vasopressin increases during labor and inhibit the secretion of tracheal fluid through a mechanism still unknown. The aim of this study was to elucidate the mechanism whereby vasopressin inhibit the secretion of lung fluid. We used fetal sheep chronically catheterized and infused either with vasopressin, vasopressin agonist (V2; dDAVP) or vasopressin antagonist (V1). Tracheal flow was measured during basal and infusions periods of 2 hours, monitoring fetal blood pressure, heart rate and blood pH and gases. Vasopressin and the V1 vasopressin antagonist caused a significant reduction in tracheal fluid flow, effect that was potentiated when both peptides were infused together. The V2 vasopressin agonist had no effect on the secretion of lung fluid. We concluded that vasopressin causes a significant inhibition of lung liquid secretion through a mechanism different to the activation of V1 and V2 receptors, and we propose the existence of other (s) kind of receptors (or receptors) for vasopressin that is (are) active during fetal life.

Animals↗
PubMed1992

Effects of acute oligohydramnios on respiratory system of fetal sheep.

Prolonged oligohydramnios, or a lack of amniotic fluid, is associated with pulmonary hypoplasia and subsequent perinatal morbidity, but it is unclear whether short-term or acute oligohydramnios has any effect on the fetal respiratory system. To investigate the acute effects of removal of amniotic fluid, we studied nine chronically catheterized fetal sheep at 122-127 days gestation. During a control period, we measured the volume of fluid in the fetal potential airways and air spaces (VL), production rate of that fluid, incidence and amplitude of fetal breathing movements, tracheal pressures, and fetal plasma concentrations of cortisol, epinephrine, and norepinephrine. We then drained the amniotic fluid for a short period of time [24-48 h, 30.0 +/- 4.0 (SE) h] and repeated the above measurements. The volume of fluid drained for the initial studies was 1,004 +/- 236 ml. Acute oligohydramnios decreased VL from 35.4 +/- 2.9 ml/kg during control to 22.0 +/- 1.6 after oligohydramnios (P less than 0.004). Acute oligohydramnios did not affect the fetal lung fluid production rate, fetal breathing movements, or any of the other measured variables. Seven repeat studies were performed in six of the fetuses after reaccumulation of the amniotic fluid at 130-138 days, and in four of these studies the lung volume also decreased, although the overall mean for the repeat studies was not significantly different (27.0 +/- 5.2 ml/kg for control vs. 25.5 +/- 5.5 ml/kg for oligohydramnios). Again, none of the other measured variables were altered by oligohydramnios in the repeat studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1992

Synergistic effect of cortisol and thyrotrophin releasing hormone on lung maturation in the fetal sheep entails connective tissue maturation.

Pressure-volume relationships and collagen and elastin contents were measured in the lungs of fetal sheep infused either with saline (n = 4), thyrotrophin-releasing hormone (TRH; n = 6), cortisol (n = 9) or TRH plus cortisol (n = 10) at 128 days of gestation (term = 149 days) for 7 days. Lung distensibility (V40 = 1.8 +/- 0.1 ml/g wet wt; mean +/- SD) and stability (V5 = 0.6 +/- 0.1) increased along with collagen (C) (10.1 +/- 2.7 micrograms/mg) and elastin (E) contents (128 +/- 35 ng/mg) in the animals infused with TRH plus cortisol and were significantly higher (p < 0.05) than those observed in TRH (V40 0.62 +/- 0.07; V5 0.32 +/- 0.04; C 3.53 +/- 1.3; E 38.2 +/- 8.3), cortisol (V4 0.66 +/- 0.6; V5 0.27 +/- 0.03; C 4.27 +/- 0.8; E 41.02 +/- 12.7) or saline infused fetuses (V40 0.40 +/- 0.1; V5 0.20 +/- 0.06; C 3.28 +/- 0.9; E 31.5 +/- 9.2). Plasma concentrations of prolactin (PRL), triiodothyronine (T3) and cortisol (F) were also higher in the group of fetuses infused with both hormones in comparison with the other groups. In fetuses treated with TRH plus cortisol, PRL (32 +/- 8.3 ng/ml) and T3 (308.3 +/- 36 micrograms/dl) were significantly higher than in those infused with cortisol alone (PRL 3.7 +/- 2.3; T3 128 +/- 30) or with saline (PRL 4.2 +/- 1.6; T3 < 5 micrograms/dl). In the group treated with TRH alone, PRL also increased significantly (37 +/- 6.4), but T3 increased only slightly (18 +/- 3.4).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Meclofenamate increases ventilation in lambs.

To investigate the effects of the prostaglandin synthetase inhibitor, meclofenamate, on postnatal ventilation, we studied 11 unanaesthetised, spontaneously-breathing lambs at an average age of 7.9 +/- 1.1 days (SEM; range 5-14 days) and an average weight of 4.9 +/- 0.5 kg (range 3.0-7.0 kg). After a 30-min control period we infused 4.23 mg/kg meclofenamate over 10 min and then gave 0.23 mg/h per kg for the remainder of the 4 h. Ventilation increased progressively from a control value of 515 +/- 72 ml/min per kg to a maximum of 753 +/- 100 ml/min per kg after 3h of infusion (P less than 0.05) due to an increased breathing rate; the effects were similar during both high- and low-voltage electrocortical activity. There were no significant changes in tidal volume, heart rate, blood pressure, arterial pH or PaCO2, the increased ventilation resulted from either an increase in dead space ventilation or an increase in CO2 production. This study indicates that meclofenamate causes an increase in ventilation in lambs but no changes in pH of PaCO2. The mechanism and site of action remain to be defined.

Analysis of Variance↗
PubMed1988

Prostaglandin E2 causes hypoventilation and apnea in newborn lambs.

To test the hypothesis that prostaglandin (PG) E2 is a respiratory depressant in the newborn lamb, 12 chronically catheterized, unanesthetized lambs (age 2-6 days) were infused with progressively increasing doses of PGE2 (0.1, 0.5, 1.0, and 5.0 micrograms.kg-1.min-1; 30 min for each dose) into the ascending aorta. PGE2 caused significant progressive decreases in ventilation (due to decreased tidal volume and breathing rate), heart rate, blood pressure, and percent of the time spent in low-voltage electrocortical activity (LVA). PGE2 also caused respiratory acidosis, hypoxemia, and increased frequency and duration of apneic events (greater than 3 s). During the infusion there was a dose-related increase in plasma concentration of PGE2. At 30 min postinfusion, all measured variables showed recovery, although arterial pH, CO2 tension, and plasma PGE2 remained significantly different from control values, and the percent time in LVA was even higher than during control. Infusion of the vehicle alone (n = 5) caused no significant changes in any of the measured variables. The results, taken in combination with previous fetal studies, indicate that PGE2 has marked inhibitory effects on breathing movements both before and after birth.

Animals↗
PubMed1986

Effects of cholic acid infusion in fetal lambs.

The effects of prolonged intravenous infusions of cholic acid into fetal lambs are described in this study. The ewes (n = 10, 11 fetuses) were operated on at 114 days of gestation (term = 150 days) by placing plastic catheters in maternal and fetal vessels and in the amniotic cavity. Gestational ages were confirmed after delivery by radiographic examination of the ossification centers of the fetal legs. Infusions of cholic acid (1.6 mumoles/min-1) started 8 to 10 days after surgery in 5 fetuses (including one twin). The remaining 6 fetuses (also including one twin) were infused with 5% dextrose in water. Total plasma bile acids at the beginning of the experiment were similar in both groups (23.8 +/- 6.6 vs. 24.3 +/- 5.7 microM). No significant changes in fetal heart rate, blood pressure, blood gases or pH were detected during the infusion. Meconium-stained amniotic fluid was observed during the third day of infusion in all the fetuses infused with cholic acid and in one control fetus. Fetuses infused with cholic acid were delivered alive 19-26 days before term. The concentration of plasma bile acids in the experimental group at delivery was 829 +/- 305 microM, i.e. significantly higher than that of the control group (24.4 +/- 5.7 microM). Control fetuses (except one twin) were delivered at term. We concluded that cholic acid, even at the high dose infused, is neither lethal nor severely harmful for the fetus. Meconium passage of the fetuses infused with cholic acid, in our experiment, appeared to be related to the stimulatory effect of cholic acid on fetal colonic motility rather than to fetal hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Deletion 2q: two new cases with karyotypes 46,XY,del(2)(q31q33) and 46,XX,del(2)(q36).

We describe the clinical and cytogenetic findings of two patients with deletions of the long arm of chromosome 2. One has an interstitial deletion identical to that found in a previously reported patient, although they are phenotypically dissimilar. The other patient has a terminal deletion, the first such deletion reported to date.

Chromosome Deletion↗