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Biomedical subjects

E Jimenez

Publications and source records attributed to E Jimenez.

At least 19 recordsLinked to original sources
PubMed1992

Characterization of postsynaptic alpha-adrenoceptors in the arteries supplying the oviduct.

1. In vitro experiments were designed to characterize postjunctional alpha-adrenoceptor subtypes in ring segments (1 mm length; outer diameter 300-500 microns) from arteries supplying the oviduct of the heifer. 2. Noradrenaline, adrenaline and phenylephrine evoked concentration-dependent contractile responses. The pD2 values were 5.67, 5.89 and 5.93, respectively. Medetomidine clonidine and B-HT 920 (2-amino-6-allyl-5,6,7,8-tetra-hydro-4H-(thiazo)-4,5-d-azepoine ) were ineffective. 3. The alpha-adrenoceptor selective antagonists, prazosin (1 nM-0.1 microM) and rauwolscine (0.1-10 microM) competitively antagonized the response to noradrenaline. The pA2 values were 9.38 and 6.83, respectively. 4. The dissociation constant (KD) for noradrenaline calculated by use of the irreversible antagonist, dibenamine, was 3.95 (2.09-5.81) microM. The occupancy-response relationship was non-linear. Half-maximal response to noradrenaline was obtained with 22% receptor occupancy while maximal response required 100% occupancy. 5. B-HT 920 evoked a biphasic contractile concentration-dependent response in preparations incubated in a physiological solution containing 20 mM K+, 0.1 microM prazosin and 1 microM propranolol. Rauwolscine 0.1 microM significantly (P less than 0.01) blocked the first component of the B-HT 920 concentration-response curve with an apparent pA2 value of 8.52 (7.86-9.18). 6. These results strongly suggest that alpha-adrenoceptors in oviductal arteries are mainly of the alpha 1 subtype, although a possible role for alpha 2-adrenoceptors cannot be excluded.

Acetylcholine↗
PubMed1992

Relationship of utero- and fetoplacental blood flow velocity wave forms with pathomorphological placental findings.

Pulsed Doppler examinations were performed in 143 risk pregnancies. The resistance index (RI) values of the uteroplacental vessels and umbilical artery on the last examination before delivery were correlated to specific patterns of morphological placental findings. The sensitivity and specificity of Doppler blood flow velocity wave forms to predict placental disease as well as the significant relationships were calculated. Impaired uteroplacental perfusion is correlated with: disturbances in growth, such as reduced weight and reduced basal area (p < 0.005, p < 0.05); disturbances in villous maturation, such as prematurity or a reduction in intermediate sized villi (p < 0.05, p < 0.01), and circulation disorders, such as acute or chronic infarcts (p < 0.05), villous fibrosis (p < 0.005) or microfibrin deposits (p < 0.05). Villous immaturity was not correlated to either pathological utero- or fetoplacental blood flow. Except for acute infarcts, all these findings as well as endangiopathy of truncal arteries are also combined with high RI values in umbilical arteries (p < 0.005) possibly reflecting the 'down-stream impedance' of the fetoplacental circulation.

Blood Flow Velocity↗
PubMed1992

Effect of aging on intracellular Ca2+, pHi, and contractility during ischemia and reperfusion.

BACKGROUND: To investigate the effect of aging on myocardial ischemic and reperfusion injury, cytosolic calcium (Ca2+), intracellular pH (pHi), and mechanical performance were measured in isolated perfused rabbit hearts. METHODS AND RESULTS: Hearts of mature (4-5-month-old) and aged (28-38-month-old) rabbits were loaded with 10 microM of fura-2 or 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) and subjected to 30 minutes of normothermic ischemia and reperfusion. Cytosolic Ca2+ levels ([Ca2+]) during the nonbeating ischemic period and end-diastolic Ca2+ levels ([EDCa2+]) during reperfusion were determined from the fura-2 fluorescence ratio of emission at 510 nm during excitation at 340 and 380 nm. pHi was obtained from the ratio of emission at 530 nm during excitation at 450 and 490 nm. [Ca2+] of the mature group (n = 8) increased from 188 +/- 19 nM (mean +/- SEM) to 373 +/- 32 nM during ischemia, and that of the aged group (n = 7) increased from 242 +/- 17 to 465 +/- 20 nM. The rise of [Ca2+] of the aged group was significantly greater (p < 0.05) than that of the mature group. Immediately after reperfusion, [EDCa2+] in both groups returned to the preischemic level. pHi decreased to the same extent (from 7.2 to 6.7) during ischemia and returned to preischemic values during reperfusion. The mature group recovered 84 +/- 3% of left ventricular peak pressure after ischemia, whereas the aged group recovered only 55 +/- 3% (p < 0.005). Functional recovery was inversely correlated to the increase of [Ca2+] during ischemia (r = 0.66). CONCLUSIONS: Aged hearts exhibit greater accumulation of [Ca2+] during ischemia and less functional recovery after ischemia than mature hearts. The greater rise of [Ca2+] in aged hearts is not a result of the difference of buffering capacity for ischemia-induced acidosis.

Aging↗
PubMed1992

Age-related differences in cardiac susceptibility to ischemia/reperfusion injury. Response to deferoxamine.

Age-related differences in susceptibility to ischemia/reperfusion injury and the response to the iron chelator deferoxamine during reperfusion were studied in isolated nonworking rabbit hearts subjected to 30 or 40 minutes of ischemia at 37 degrees C followed by 30 minutes of reperfusion. In the experimental group, hearts received a bolus of deferoxamine just before the moment of reflow, followed by a continuous infusion during the first 10 minutes of reperfusion. Isovolumic systolic (peak developed pressure) and diastolic (diastolic pressure versus balloon volume relationship) function was assessed with an intracavity balloon and incremental volume changes. In separate groups of hearts, adenine nucleotide content (adenosine triphosphate, diphosphate, and monophosphate) was measured before ischemia, at end-ischemia, and 30 minutes after reperfusion. The cardiac function measurements showed that after 30 minutes of ischemia and 30 minutes of reperfusion, peak developed pressure in newborn hearts recovered to 89% +/- 5% of preischemic levels; this recovery was significantly better than that of adult hearts, which exhibited 67% +/- 6% (p less than 0.01) recovery. Deferoxamine significantly improved cardiac function only in adult hearts (p less than 0.01). However, after 40 minutes of ischemia and 30 minutes of reperfusion, peak developed pressure in newborn hearts was reduced to 61% +/- 3% and was not significantly better than that of adult hearts (54% +/- 5%). Deferoxamine significantly improved systolic function in both newborn and adult hearts (p less than 0.01) exposed to 40 minutes of ischemia. Myocardial adenosine triphosphate content fell markedly by the end of 30 and 40 minutes of ischemia in both groups. After 30 minutes of ischemia, newborn but not adult hearts were able to completely recover adenosine triphosphate content by 30 minutes of reperfusion. This advantage was lost after 40 minutes of ischemia. Deferoxamine had no effect on recovery of adenosine triphosphate content in any group. We conclude that (1) newborn hearts recover postischemic function and metabolism faster than adult hearts after shorter periods of ischemia; (2) this advantage is lost as the ischemic period is prolonged; (3) deferoxamine improved postischemic cardiac function after longer ischemic periods, in both age groups, but failed to improve the recovery of myocardial adenosine triphosphate content.

Adenine Nucleotides↗
PubMed1991

Long-term developmental outcome of infants with iron deficiency.

BACKGROUND: Iron-deficiency anemia has been associated with lowered scores on tests of mental and motor development in infancy. However, the long-term developmental outcome of infants with iron deficiency is unknown, because developmental tests in infancy do not predict later intellectual functioning. METHODS: This study is a follow-up evaluation of a group of Costa Rican children whose iron status and treatment were documented in infancy. Eighty-five percent (163) of the 191 children in the original group underwent comprehensive clinical, nutritional, and psychoeducational assessments at five years of age. The developmental test battery consisted of the Wechsler Preschool and Primary Scale of Intelligence, the Spanish version of the Woodcock-Johnson Psycho-Educational Battery, the Beery Developmental Test of Visual-Motor Integration, the Goodenough-Harris Draw-a-Man Test, and the Bruininks-Oseretsky Test of Motor Proficiency. RESULTS: All the children had excellent hematologic status and growth at five years of age. However, children who had moderately severe iron-deficiency anemia as infants, with hemoglobin levels less than or equal to 100 g per liter, had lower scores on tests of mental and motor functioning at school entry than the rest of the children. Although these children also came from less socioeconomically advantaged homes, their test scores remained significantly lower than those of the other children after we controlled for a comprehensive set of background factors. For example, the mean (+/- SD) adjusted Woodcock-Johnson preschool cluster score for the children who had moderate anemia in infancy (n = 30) was 448.6 +/- 9.7, as compared with 452.9 +/- 9.2 for the rest of the children (n = 133) (P less than 0.01); the adjusted visual-motor integration score was 5.9 +/- 2.1, as compared with 6.7 +/- 2.3 (P less than 0.05). CONCLUSIONS: Children who have iron-deficiency anemia in infancy are at risk for long-lasting developmental disadvantage as compared with their peers with better iron status.

Anemia, Hypochromic↗
PubMed1991

Hormonal changes associated with bleeding during low dose progestogen contraception delivered by Norplant subdermal implants.

The main side effect associated with the use of Norplant contraceptive implants is a disruption of the menstrual bleeding pattern. To explore the relationship between bleeding and hormonal changes, we analyzed the estradiol (E2) and progesterone (P) patterns that preceded bleeding episodes or that corresponded to periods of amenorrhea in 103 cycles observed among 82 women using Norplant subdermal implants. Five different bleeding patterns were defined: 'normal' (24-45 day cycles), oligomenorrhea (46-90 day cycles), amenorrhea (over 90 day cycles), irregular/frequent bleeding (less than 25 day cycles), and prolonged bleeding (continuous bleeding/spotting for more than 10 days). All 'normal' cycles were associated with a rise followed by a fall in E2 levels preceding bleeding. In half of the 'normal' cycles (28/54), a rise and fall of P was also observed. The same pattern was found in oligomenorrheic cycles, but only two of 12 cycles had a rise and fall of both E2 and P. None of the subjects with amenorrhea had luteal activity. Six of the nine amenorrheic cycles displayed persistently low E2 levels (below 75 pg/ml). The remaining three had a moderate elevation in E2 levels during the sampling period. Sixty percent of the subjects who showed irregular/frequent bleeding (15/25) had low E2 levels (less than 75 pg/ml), without luteal activity, and bleeding occurred without clear evidence of a further drop in E2 levels. In the remaining 40%, bleeding was preceded by a rise and drop of E2 without luteal activity, with the exception of one women, who exhibited a rise and fall of both E2 and P. Samples were obtained in only three subjects during continuous bleeding. One had low E2 levels, and the remaining two bled continuously, in spite of having E2 levels in the normal range. We conclude that ovarian hormones continue to influence endometrial shedding during the use of Norplant contraceptive implants.

Amenorrhea↗
PubMed1991

Multiple forms of angiotensin II receptors in rat tissues.

Angiotensin II (AII) receptors were identified in rat tissue membranes by specific binding of 125I-labelled AII. Using an isoelectric focusing technique, two forms of the high-affinity AII receptor were identified in rat adrenal zona glomerulosa and liver membranes. These migrated to isoelectric points (pI) 6.8 and 6.7. Two low-affinity forms migrated to pI 6.5 and 6.3. The two high-affinity forms were in greatest abundance in the zona glomerulosa, while the low-affinity pI 6.5 isoform was predominant in liver membranes. In uterine membranes both low-affinity isoforms were observed, but there was only one of the high-affinity forms (pI 6.7). Concentrations of AII receptor isoforms were increased in the zona glomerulosa of sodium-deprived rats. Reduction of disulphide bridges with dithiothreitol (DTT) had different effects on the various AII receptor isoforms. Thus 1 mmol DTT/1 caused a twofold increase in 125I-labelled AII binding in zona glomerulosa membranes. DTT produced no appreciable differences in specific AII binding in uterine membranes, whereas there was a 50% reduction of binding in liver membranes. At 20 mmol/l, DTT greatly decreased AII binding in all tissues. The data suggest the existence of multiple forms of AII receptors which may have different functions.

Animals↗
PubMed1991

Potassium-induced contraction in the lamb proximal urethra: involvement of norepinephrine and different calcium entry pathways.

The purpose of this work was to investigate the mechanisms involved in the peculiar biphasic response of the lamb urethral smooth muscle to high K+ solutions. The relative amplitude of the phasic and tonic components of the contraction and its reproducibility were dependent on the concentration of K+ used. Only concentrations higher than 80 mM (i.e., 120 mM) showed a tonic component greater in amplitude than the phasic one and manifested a tachyphylactic effect. Phentolamine (10(-6) M), prazosin (10(-6) M) and chemical denervation with 6-hydroxydopamine significantly inhibited the tonic component of the K+ (120 mM)-induced contraction, modifying its morphology. Reproducible contractions to K+ (120 mM) could be obtained in the presence of prazosin (10(-6) M) or cocaine (10(-6) M). The preparations were also shown to accumulate [3H]noradrenaline and release it upon depolarization with K+ (60 and 120 mM). Calcium removal inhibited the K+ (120 mM)-induced contraction. After addition of calcium (0.5-5 mM) the contractile activity was restored. Nifedipine (10(-6) M) and verapamil (10(-6) M) but not sodium nitroprusside (10(-6) M) significantly blocked the contractile response for calcium as well as the phasic component of the K+ contraction in calcium-containing medium. In preparations treated with prazosin (10(-6) M) the tonic component of the K+ (120 mM) contraction was more sensitive to nifedipine and removal of extracellular calcium than the phasic one.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1990

Long-term contraception with the levonorgestrel 20 mcg/day (LNg 20) and the copper T 380Ag intrauterine devices: a five-year randomized study.

An intrauterine device, releasing approximately 20 micrograms/day of levonorgestrel (LNg 20), used by 1124 women, was studied in a randomized trial of five years duration in comparison with the Copper T, model TCu 380Agm in 1121 women. At five years, the gross cumulative pregnancy rate of 1.1 +/- 0.5 per 100 among users of the LNg 20 devices was not significantly different from the rate of 1.4 +/- 0.4 per 100 experienced by users of the Copper T 380Ag. The steroid-releasing IUD had significantly higher termination rates for expulsion and amenorrhea, a significantly lower termination rate for other menstrual problems and pain, and a lower continuation rate. The five-year continuation rate among women using the TCu 380Ag was 40.6 per 100 as compared with that of 33.0 per 100 among women randomized to the LNg 20 device (P less than .001). Terminations attributed to amenorrhea with the LNg device primarily account for differences in continuation. These two intrauterine devices are the most effective long-term, reversible IUDs yet reported in the literature. No other contraceptive methods have exhibited such low long-term pregnancy rates in randomized comparative trials.

Adolescent↗
PubMed1990

Effects of low extracellular calcium on cytosolic calcium and ischemic contracture.

We have shown that myocardial cytosolic calcium [Cai] rises during ischemia. Simultaneously membrane bound stores are depleted. The [Cai] rise precedes the onset of irreversible ischemic contracture. We found that a low extracellular calcium [Cao] (100 microM) perfusate decreased peak contracture pressure and delayed the time to onset and to peak of ischemic contracture in the isolated retroperfused rabbit heart subjected to 37 degrees C ischemia. [Cai] was measured with the intracellular [Cai] fluorescent indicator Fura-2 AM (10 microM) in a separate group. In the group exposed to 2.45 mM Ca2+ there was a significant rise (P less than 0.05) in [Cai] to above 50% of preischemic value after 30 min of ischemia. The [Cai] in the low [Cao] perfused group at 30 min of ischemia was 30% below the preischemic value. The peak of the [Cai] rise in the low [Cao] perfusate group was markedly attenuated and delayed to 40 min. Taken together it appears that low calcium perfusate (100 microM) prior to ischemia attenuates the ischemia-induced [Cai] rise, delays the onset, and decreases the force of contracture with irreversible ischemic injury.

Adenosine Triphosphate↗
PubMed1990

The effect of cardiac hypertrophy on changes in cytosolic free calcium concentration during ischemia.

Chronic ventricular hypertrophy caused by pressure overload is a common associated risk factor in congenital cardiac surgery. Because calcium controls contractile protein interaction, we postulated that inducing ventricular hypertrophy from birth alters the way myocytes are able to regulate free cytosolic calcium (Cai) during ischemia. In this study we measured Cai with a recently developed intracellular fluorescent probe trapped inside myocytes by deesterification. The probe shifts its fluorescence spectra (from 380 to 340 nm; fluorescence measured at 510 nm) when it binds to calcium in direct relation to Cai. We studied the effects of ischemia at 37 degrees C (up to 50 minutes) on Cai in newborn (3 to 5 days), adult control (2 to 4 months old), and hypertrophied (2 months old; aortic banding done at 10 days) isolated retroperfused rabbit hearts loaded with Fura-2. In a separate group of hearts (n = 6 per group) we measured isovolumic peak developed pressure with an intracavity balloon in hearts subjected to 30 minutes of ischemia at 37 degrees C and 30 minutes of reperfusion. The recovery of peak developed pressure (percent of preischemic control) was 101% +/- 6% in control, 85% +/- 4% (p less than 0.05 vs control) in newborn, and 67% +/- 7% (p less than 0.05 vs control) in hypertrophied hearts. Cai-dependent fluorescence rose to 160% +/- 30% of preischemic baseline levels by 30 minutes of ischemia in control versus a decline to 55% +/- 7% (p less than 0.05 vs control) in newborn and 51% +/- 2% (p less than 0.05 vs control) in hypertrophied hearts by 30 minutes of ischemia. We conclude that hypertrophied and newborn hearts have a lower Cai during ischemia compared with adult hearts, and this is associated with a worse recovery of cardiac function. The lower Cai may be the result of irreversible binding of calcium to contractile proteins.

Animals↗
PubMed1990

Deferoxamine fails to improve postischemic cardiac function in hypertrophied hearts.

Myocardial hypertrophy is a well-recognized risk factor in congenital cardiac surgery. Hypertrophied hearts have been demonstrated to have an increased vulnerability to ischemia/reperfusion injury. We studied the effects of the iron chelator and hydroxyl radical scavenger deferoxamine given during early reperfusion in a model of isolated retroperfused rabbit hearts made hypertrophic by aortic banding early in life (1 week of age). The rabbits were studied at 6-8 weeks of age, and the hearts were subjected to 30 minutes of 37 degrees C ischemia followed by 30 minutes of reperfusion. Postischemic recovery of isovolumic developed pressure was measured by using an intracavitary balloon in both the untreated (n = 6) and the deferoxamine-treated (n = 6) groups and compared with normal age-matched controls. Deferoxamine (50 mumol/kg) was given to one group with the hypertrophied hearts during the first 10 minutes of reperfusion. The left ventricular weight/body weight ratio in the hypertrophied hearts was 2.9 +/- 0.4 x 10(-3) (n = 14) versus 2.0 +/- 0.1 x 10(-3) in the age-matched controls (p less than 0.05). Postischemic peak developed pressure recovered to 102 +/- 6% of the preischemic value in the normal hearts after 30 minutes of reperfusion compared with 75 +/- 5% for the untreated and 71 +/- 4% for the deferoxamine-treated hearts (p less than 0.05 vs. control). We conclude that chronic hypertrophy from early in life leads to increased susceptibility to ischemia and that the iron chelator deferoxamine is not effective in preventing the injury of reperfusion in hypertrophied hearts.

Animals↗
PubMed1990

Subxiphoid pericardiotomy versus echocardiography: a prospective evaluation of the diagnosis of occult penetrating cardiac injury.

Diagnostic subxiphoid pericardiotomy (SP) is presently advocated for the diagnosis of occult cardiac injuries in patients with stable vital signs with juxta-cardiac-penetrating chest wounds. This approach, however, results in a reported 80% negative pericardial exploration rate. To investigate the reliability of bedside two-dimension echocardiography (2-D echo) in predicting cardiac injury as compared to SP, a prospective study was undertaken of patients with stable vital signs who were admitted with penetrating chest wounds that were located within the space bounded by the manubrium, nipples, and subcostal line. Initial evaluation of the patients with bedside 2-D echo was found to have a 96% accuracy, 97% specificity, and 90% sensitivity in predicting cardiac injury. The only false-negative findings were in a patient who consented to SP 18 hours after bedside 2-D echo was performed. The reliability of bedside 2-D echo compared to SP was not significantly different according to the kappa measure of reliability. These data suggest that bedside 2-D echo is an expeditious and reliable method to diagnose occult cardiac injuries during the initial assessment of a patient with stable vital signs who had penetrating chest trauma. This approach may allow for the selective use of SP on patients with positive bedside 2-D echo and could eliminate unnecessary surgical procedures.

Echocardiography↗
PubMed1988

Human immunodeficiency virus-related lymphoreticular malignancies and peripheral neurologic disease. A report of four cases.

The most common human immunodeficiency virus-related (HIV) malignancies to date include Kaposi's sarcoma and the high-grade non-Hodgkin's lymphomas. There also appears to be an association between HIV and an aggressive form of Hodgkin's disease. In addition, there is a spectrum of HIV-related central and peripheral neurologic syndromes. This article documents four patients with HIV-associated lymphoma who presented with peripheral neurologic syndromes as part of their neoplastic process. Autopsy results obtained from two of these patients showed direct nerve infiltration by lymphoma. All patients had an elevated serum lactate dehydrogenase (LDH). It is recommended that HIV-related lymphoma be considered in a high-risk patient who presents with a peripheral neurologic syndrome especially if there is an elevated serum LDH.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Ranitidine prophylaxis in acute gastric mucosal damage in critically ill pediatric patients.

We determined the ranitidine dosage necessary to maintain gastric pH at or above 4 in 40 critically ill children. The patients were divided into four groups of ten patients each. They were treated with ranitidine in the following dosages: a) 2 mg/kg by NG tube every 12 h; b) 4 mg/kg by NG tube every 12 h; c) 0.75 mg/kg iv every 6 h; d) 1.5 mg/kg iv every 6 h. The fourth group had a higher median pH than the other groups, in spite of also having the highest risk of acute gastric mucosal damage (AGMD). Eight (80%) of ten patients in the fourth group had a pH greater than or equal to 4 or more than 80% of the study period. We recommend 1.5 mg/kg iv every 6 h for gastric acid inhibition in AGMD prophylaxis in children.

Adolescent↗
PubMed1988

Obstetrical characteristics of a loss of end-diastolic velocities in the fetal aorta and/or umbilical artery using Doppler ultrasound.

In 30 of 137 high-risk pregnancies we observed absent end-diastolic velocities indicating a high downstream impedance, which could be proved by histomorphological findings of the placenta. On the average the loss of end-diastolic velocities occurred 2-3 days before suspicious and nearly 8 days before pathological cardiotocographic findings. The perinatal mortality was high when absent velocities had been observed before the 32nd week, a cesarean section was obligatory in all but 1 case. All fetuses were growth-retarded. In 9 cases we were able to determine the ratio of blood flow volume in the common carotid arteries to that of the fetal aorta. The values were significantly increased as compared to values of undisturbed pregnancies, demonstrating a redistribution of fetal blood in favor of cerebral circulation.

Aorta↗