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Biomedical subjects

L Castro

Publications and source records attributed to L Castro.

At least 73 records · Page 4Linked to original sources
PubMed1992

Serum concentrations of cefepime (BMY-28142), a broad-spectrum cephalosporin, in dogs.

Serum concentrations of cefepime (BMY-28142) were determined for four dosing regimes, 10 mg/kg or 20 mg/kg, given as single subcutaneous (SC) or intramuscular injections (IM) to dogs. Serial serum samples were analyzed for the presence of cefepime by high-performance liquid chromatography. In experiment 1, the overall mean (+/- SEM) serum concentration (for a 12-hour period) after a dose of 20 mg/kg for SC and IM routes (4.9 +/- 0.74 micrograms/ml and 5.5 +/- 0.63 micrograms/ml, respectively) was twice that for the 10 mg/kg dose given either SC or IM (2.2 +/- 0.31 micrograms/ml and 2.8 +/- 0.47 micrograms/ml, respectively). There was no significant difference (p greater than 0.05) in mean serum concentrations for SC and IM routes of administration at the same dosage. In subsequent experiments, 5 doses of cefepime (20 mg/kg) were administered IM at 12-hour (experiment 2) or 24-hour (experiment 3) intervals. The mean (+/- SEM) peak serum concentration was 12.1 +/- 1.59 micrograms/ml, 2 hours after the 2nd injection in experiment 2. In experiment 3, the mean (+/- SEM) peak serum concentration was 10.9 +/- 1.34 micrograms/ml, 4 hours after the 1st injection. Mean trough concentrations in experiment 2 were greater than or equal to 0.5 microgram/ml and less than or equal to 0.5 in experiment 3. Multiple IM doses produced transient edema at the injection site and mild lameness in all dogs. Cefepime was highly active against single canine isolates of Staphylococcus intermedius, Pseudomonas aeruginosa and Escherichia coli, with minimum inhibitory concentrations of 0.125 microgram/ml, 1 microgram/ml and 0.3 microgram/ml, respectively.

Animals↗
PubMed1991

The genetic properties of homosexual copulation behavior in Tribolium castaneum: diallel analysis.

The rate of homosexual copulation has been defined as the ratio between the number of homosexual mountings and the total number of mountings (homo and heterosexual) performed by a Tribolium castaneum male during a period of 30 min. In a laboratory population, the average rate when a number of males (m) and females (k x m) are tested together has been estimated in each of the six situations defined by m = 2 and 10 and k = 0.5, 1, and 2, k being the sex ratio among scored individuals. Good agreement was found between the observed rates of homosexual copulation and those expected assuming random contacts between pairs of individuals totally indiscriminate with respect to sex. The genetic properties of the trait have been investigated by means of a diallel analysis of six highly inbred lines derived from the same population and their F1 crosses. Significant general and specific combining ability effects were detected. When noninbred females were used for testing, the rate of homosexual copulation is expected to be higher for inbred than for noninbred males. This prediction, implying the existence of inbreeding depression for the trait, also was confirmed by the data.

Alleles↗
PubMed1991

Fetal and maternal plasma atrial natriuretic factor responses to angiotensin II infusion.

Plasma atrial natriuretic factor and angiotensin II have opposing actions in the regulation of body fluid homeostasis and systemic blood pressure. Angiotensin II infusions stimulate atrial natriuretic factor release in some, but not all, studies in adult mammals. To examine the response during the perinatal period, graded intravenous angiotensin II infusions were administered to four chronically instrumented pregnant ewes and fetuses (132 +/- 1 days of gestation). Fetuses received successive 20-minute intravenous angiotensin II infusions at 25, 50, and 100 ng/kg/min. After a 90-minute recovery, maternal ewes received successive 20-minute angiotensin II infusions (5, 10, and 25 ng/kg/min). During the fetal infusions, mean (+/- SEM) fetal arterial blood pressure (47 +/- 2 to 61 +/- 2 mm Hg, p less than 0.05) and heart rate (155 +/- 16 to 196 +/- 36 beats/min, p less than 0.05) increased, although there was no change in maternal measured parameters. In response to the maternal infusion, maternal mean arterial blood pressure increased (92 +/- 7 to 110 +/- 8 mm Hg, p less than 0.05) and maternal heart rate decreased (136 +/- 4 to 125 +/- 2 beats/min, p less than 0.05) without change in fetal parameters. Fetal plasma atrial natriuretic factor levels (210 +/- 27 to 664 +/- 250 pg/ml, p less than 0.05) significantly increased during the fetal angiotensin II infusions in spite of no change in maternal plasma atrial natriuretic factor (85 +/- 21 to 124 +/- 22 pg/ml) during the maternal angiotensin II infusions. These findings indicate that similar increases in systemic blood pressure in response to angiotensin II infusions stimulate increased fetal, but not maternal, plasma atrial natriuretic factor.

Angiotensin II↗
PubMed1991

Characterization of enzymes of catecholamine synthesis and metabolism in human fetal membranes at birth.

We looked for the presence of the enzymes monoamine oxidase, catechol-O-methyltransferase, and phenylethanolamine-N-methyltransferase in human fetal membranes at term. The activity of all three enzymes was detected via highly sensitive and selective radiometric enzyme assays. The most novel finding was the extremely high level of monoamine oxidase activity in the chorion compared with that in the amnion. The other enzyme of catecholamine metabolism, catechol-O-methyltransferase, did not show any difference in activity between the two layers. In addition, we observed that the enzyme phenylethanolamine-N-methyltransferase, which is primarily located in the adrenal medulla, was also present in appreciable levels in the two layers of fetal membranes. These results suggest that fetal membranes, like the placenta, possess the enzymatic machinery to metabolize catecholamines and have the capacity to synthesize epinephrine.

Amnion↗
PubMed1989

What is the significance of the presence of MHC molecules on the surface of parasites in human neurocysticercosis?

Sixteen cysticerci excised from 15 surgery patients were examined for the presence of HLA molecules on their surface, to confirm the role of these molecules in parasite damage and to investigate if HLA products are host specific or perhaps host-like antigens synthesized by the parasite. MoAbs against monomorphic and polymorphic HLA were chosen according to the patients HLA phenotypes. MoAbs against host and non-host antigens were selected and tested on cyst slides by indirect immunofluorescence assays. Host molecules were present in 43.7% of the cysts, but non-host antigens were also apparent in 62.5%. These results suggest mimicry as a possible mechanism to explain the presence of MHC products on the surface of the parasite; inflammation may also induce the expression of HLA that could become associated with the parasite. In vitro cellular immune response to specific antigens was also performed and positive responses correlated with the presence of HLA molecules on the cyst's surface. Moreover, damaged parasites had host molecules as well. Parasites from responder patients had all kind of HLA molecules or at least, antigenic determinants while the cysts from non-responders did not have molecules on their surface. These data support the role of HLA in cyst destruction.

Adult↗
PubMed1988

The efficacy of starting postterm antenatal testing at 41 weeks as compared with 42 weeks of gestational age.

Postterm antenatal fetal surveillance has traditionally begun at 42 completed weeks of gestation. However, recent data have shown that a significant percentage of cases of perinatal asphyxia occurs between 40 and 42 weeks of gestation. We compared the perinatal outcome of fetuses with antenatal surveillance beginning at 41 weeks to those starting at 42 weeks of gestation. The study groups consisted of 908 patients who began antenatal testing at 41 weeks and 352 who began testing at 42 weeks. Antenatal testing consisted of twice-weekly amniotic fluid assessments and nonstress tests (including evaluation for late and variable decelerations). Between 41 and 42 weeks, the group whose testing started at 41 weeks had an overall incidence of intrapartum fetal distress of 2.7%, no stillbirths, and no infants with major neonatal morbidity. Patients without antenatal testing who delivered between 41 to 42 weeks did not have a significantly increased incidence of fetal distress (3.3%; p = 0.07). However, this group had a significantly increased incidence of adverse outcomes (p less than 0.05), including three stillbirths and seven cases of major neonatal morbidity. Beyond 42 weeks, the group whose testing started at 41 weeks had a 2.3% overall incidence of fetal distress. This was significantly less (p less than 0.01) than the group whose testing started at 42 weeks (5.6%). Neither of the groups had any stillbirths or infants with major neonatal morbidity. These findings suggest that starting antenatal testing at 41 weeks of gestation may result in decreased postterm perinatal mortality and morbidity as well as a decreased incidence of intrapartum fetal distress.

Female↗
PubMed1988

Ovine fetal and adult atrial natriuretic factor metabolism.

Studies were conducted to quantify ovine fetal and adult atrial natriuretic factor (ANF) metabolism. A total of 14 pregnant ewes with singleton fetuses were prepared with vascular catheters. In protocol 1, six fetuses (mean gestation, 131 +/- 1 days) received intravenous infusions of synthetic human ANF (hANF, 100 ng.min-1.kg-1) for 60 min. Mean basal fetal plasma ANF levels increased from 180 +/- 44 pg/ml to a steady-state level of 1,233 +/- 192 pg/ml. In protocol 2, five fetuses (mean gestation, 130 +/- 1 days) received successive 40-min infusions of hANF at 5, 25, and 100 ng.min-1.kg-1. Although basal fetal plasma ANF levels (522 +/- 135 pg/ml) were greater than those observed in protocol 1, fetal plasma ANF levels increased to 1,580 +/- 295 pg/ml at the highest infusion rate. In both protocols 1 and 2, basal fetal plasma ANF levels were three- to fourfold greater than maternal levels. The fetal plasma ANF clearance rates calculated from protocol 1 and from the 25- and 100-ng.min-1.kg-1 infusions from protocol 2 were similar (89 +/- 10, 120 +/- 31, and 116 +/- 38 ml.min-1.kg-1, respectively) and were combined to yield a mean estimated fetal plasma ANF clearance rate of 102 +/- 11 ml.min-1.kg-1. In protocol 3, adult plasma ANF levels increased from 137 +/- 36 to 4,142 +/- 776 pg/ml in response to ANF infusion at 200 ng.min-1.kg-1. The mean plasma ANF clearance rate calculated for the adult animals was 59 +/- 12 ml.min-1.kg-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Pharmacokinetics and body fluid and endometrial concentrations of trimethoprim-sulfamethoxazole in mares.

Six healthy adult mares were each given a single IV injection of trimethoprim (TMP)-sulfamethoxazole (SMZ) at a dosage of 2.5 mg of TMP/kg of body weight and 12.5 mg of SMZ/kg. Serum concentrations of each drug were measured serially over a 24-hour period. For TMP, the mean overall elimination rate constant (K) was 0.43/hr and the elimination half-life (t1/2) was 1.9 hours. The apparent volume of distribution (at steady state) was 1.62 L/kg and TMP clearance was 886 ml/hr/kg. For SMZ, K was 0.22/hr and t1/2 was 3.53 hours. The apparent volume of distribution at steady state was 0.33 L/kg and SMZ clearance was 78.2 ml/hr/kg. Each mare was then given 5 consecutive oral doses of TMP-SMZ at a rate of 2.5 mg of TMP/kg and 12.5 mg of SMZ/kg at 12-hour intervals. Trimethoprim and SMZ concentrations were measured in serum, synovial fluid, peritoneal fluid, CSF, urine, and endometrium. Although both mean TMP and SMZ serum concentrations were higher after the 5th dose than after the 1st dose, only the mean TMP concentration was significantly (P less than 0.05) different. After the 5th oral dose, concentrations of TMP and SMZ attained in body fluids (except CSF) and endometrial tissue were equal to or exceeded reported minimum inhibitory concentrations for Corynebacterium pseudotuberculosis, Staphylococcus sp, Streptococcus zooepidemicus, and several obligate anaerobes. Absorption of both drugs was variable after oral administration.

Administration, Oral↗
PubMed1987

[Coronary heart disease and heart valve diseases in patients with terminal kidney insufficiency].

Cardiac catheterisation and coronary angiography were performed in 100 patients preceding a planned renal transplantation. Coronary heart disease was revealed in 64 patients: stenoses of 50-70% in 28, 71-90% in 16, over 90% in 20 patients. For stenoses above 50% the sensitivity of clinical symptoms was 0.52, their specificity 0.64. For stenoses over 70% the specificity was 0.58; over 90% it was 0.70. Typical symptoms of angina were less common in dialysis patients with coronary heart disease than is usual in other patients with coronary heart disease. Total duration of dialysis as well as frequency and severity of coronary heart disease did not correlate. In 19 of the 100 patients valvar disease was also present, with a discrepancy between the severity of clinical and of hemodynamic findings. Incidence and severity of valvar disease increased with the duration of dialysis. Transplantation was postponed in 11 patients (bypass operation in 3, balloon dilatation in 2, valve replacement in 6). Transplantation was advised against in four (severe coronary heart disease in 2, cardiomyopathy in 2).

Adult↗
PubMed1987

Early third-trimester ultrasound screening in gestational diabetes to determine the risk of macrosomia and labor dystocia at term.

The purpose of this study was to determine whether an early third-trimester fetal abdominal circumference measurement can be used in patients with gestational diabetes to predict the presence or absence of macrosomia and labor dystocia at term. The predictive accuracy of a 30- to 33-week abdominal circumference measurement was tested, using the ninetieth percentile as the discriminant point. The study consisted of 201 patients with gestational diabetes who maintained weekly fasting glucose levels less than 100 mg/dl and 2-hour postprandial glucose levels less than 120 mg/dl with dietary management alone. The predictive accuracy of a 30- to 33-week fetal abdominal circumference measurement was 96.4% for ruling out macrosomia and 56.3% for predicting macrosomia. Patients with fetal abdominal circumference measurements greater than the ninetieth percentile at 30 to 33 weeks had a significantly increased incidence of cesarean section for failure to progress, shoulder dystocia, and birth trauma, whereas patients with abdominal circumference measurements less than or equal to the ninetieth percentile were at no greater risk than the general population. These results suggest that patients with non-insulin-dependent gestational diabetes with fetal abdominal circumference measurements less than or equal to the ninetieth percentile at 30 to 33 weeks are not at increased risk for macrosomia, cesarean section, or birth trauma at term, as long as their weekly glucose testing remains within normal limits. Efforts to decrease the incidence of macrosomia and its attendant risks should focus on those gestational diabetic patients whose fetal abdominal circumference greater than the ninetieth percentile at 30 to 33 weeks.

Adult↗
PubMed1987

Plasma atrial natriuretic peptide response to volume expansion in the ovine fetus.

Atrial natriuretic peptide is a potent diuretic and vasorelaxant peptide secreted from the cardiac atria of adult mammals in response to increased intravascular volume. In sheep, fetal plasma levels of atrial natriuretic peptide are significantly greater than maternal levels, but the factors that control fetal release of atrial natriuretic peptide have not been defined. The present studies were conducted to determine whether the fetus responds to increased intravascular volume by atrial natriuretic peptide secretion. The mean (+/- standard error of the mean) atrial natriuretic peptide of basal fetal plasma (115 +/- 24 pg/ml) in chronically catheterized ovine fetuses (131 +/- 1 days' gestation) was significantly greater than atrial natriuretic peptide levels of basal maternal plasma (56 +/- 12 pg/ml). In response to successive 30-minute intravenous infusions of 0.9% saline solution at 0.5 and 1.0 ml/kg/min, fetal plasma atrial natriuretic peptide significantly increased to a maximum of 409 +/- 72 pg/ml during the high-dose saline infusion and returned to 234 +/- 83 pg/ml during a 30-minute recovery period. The increase in fetal plasma atrial natriuretic peptide was significantly correlated with the volume of saline solution infused (r = 0.68). During the saline infusion, a significant increase in fetal blood volume and heart rate was noted. Fetal blood pressure, maternal plasma levels of atrial natriuretic peptide, and fetal and maternal plasma osmolality remained unchanged. Despite elevated basal levels of plasma atrial natriuretic peptide, the third-trimester ovine fetus responds to increases in intravascular volume with a further increase in atrial natriuretic peptide secretion.

Animals↗
PubMed1985

Progression of coronary and valvular heart disease in patients on dialysis.

Coronary heart disease and end-stage renal disease: Coronary heart disease is frequent in patients with end-stage renal disease. Without invasive procedures coronary heart disease is often not diagnosed in patients with end-stage renal disease. We have no evidence for accelerated progression of coronary heart disease under conditions of dialysis. Valvular heart disease and end-stage renal disease: Valvular heart disease shows an increasing frequency depending on the period of dialysis. Valvular heart disease is often unnoticed and constantly underestimated without invasive investigation. Valvular heart disease often indicates a bad prognosis in our patients with end-stage renal disease.

Adult↗
PubMed1984

Digital subtraction angiography in the diagnosis of arterial complications after renal transplantation.

Digital subtraction angiography (DSA) was used to study arterial complications following renal transplantation in 33 patients. The results were compared with clinical follow-up and in three cases with conventional angiography. In 9 per cent using DSA (3 cases) we experienced inadequate visualization of the renal arteries of the graft; in 91 per cent, the visualization was diagnostically sufficient. In 53 per cent, we discovered an arterial stenosis of the main artery or segmental artery and in one case an AV-fistula. No morbidity resulted during the procedure. We consider DSA to be the best non-invasive method in the evaluation of patients with suspected renal artery stenosis following kidney transplantation.

Adolescent↗