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Biomedical subjects

E B Olson

Publications and source records attributed to E B Olson.

At least 55 records · Page 3Linked to original sources
PubMed1982

Uptake and metabolism of prostaglandin E1 in isolated perfused fetal, newborn and adult rabbit lungs.

PGE1 has been used to maintain the patency of the ductus arteriosus in newborns with pulmonary hypertension. However, it is known that adult lungs avidly take up and metabolize circulating PGE1. We compared the ability of isolated perfused lungs from previable, 26-day gestation, fetal rabbits; newborn rabbits (within 12 hours of birth) and 3 month old adult rabbits to metabolize a 20-second bolus of PGE1. The concentration of PGE1 infused was approximately 2 orders of magnitude below the Km for the PGE1 uptake process so that first order uptake kinetics are assured. The retention time of a vascular marker dye was monitored as an index of pulmonary vascular surface area. In all three sizes of lungs perfusate flow was adjusted to produce an approximately 7 second dye retention time. At these flows the adult lungs inactivate about 45 percent of the infused PGE1. In contrast, fetal and newborn rabbit lungs both inactivate about 22 percent of the infused PGE1. We conclude that the ability of the lung to take up and metabolize circulating PGE1 is markedly reduced in premature and term newborns.

Aging↗
PubMed1982

A rat model of psychopathology for use in exercise science.

Exploratory behavior, defecation, urination, and a subjective psychophysical rating system were evaluated in a series of four experiments designed to assess rat psychopathology. In every case, individual rats were studied for 5-min periods in an open field consisting of 49 7.5-inch squares. We find that the open-field test can be scored in a highly objective manner (r = 0.93-0.98) by two observers. The reproducibility (r = 0.79-0.85) of the assessment using total squares traversed is not improved using any of the other parameters evaluated. Use of total squares alone was also found to be in agreement with a subjective behavioral rating procedure (r = 0.96-0.98). Fifty percent of overall variability occurs in a rat's first trial. Therefore, the average of total squares traversed on the second and third (not necessarily consecutive) days provides a reliable and objective index of a rat's emotional status. Using this criterion, we find that a random group of 30 adult, male Sprague-Dawley rats exhibit a range of psychopathologies. We propose that this method of assessment provides a rat model of emotionality which should theoretically be modifiable by experimental paradigms involving exercise and pharmacological or dietary intervention.

Animals↗
PubMed1979

Serotonin and the control of ventilation in awake rats.

In awake, unrestrained, intact rats, reserpine, para-chlorophenylalanine, 6-fluorotryptophan, and para-chloroamphetamine depleted whole brain serotonin and produced a substantial and sustained hyperventilation as evidenced by a 5--9 torr drop in PaCO2. Administration of 5-hydroxytryptophan to rats treated with para-chlorophenylalanine partially alleviated the hyperventilation. No change in ventilation was observed after alpha-methyltyrosine. 5,7-Dihydroxytryptamine produced contradictory results. On the basis of these pharmacological studies, we propose that some serotonin-mediated nerve transmissions might function under physiological conditions to inhibit the central nervous system output which controls normal breathing.

5,7-Dihydroxytryptamine↗
PubMed1979

The brain's role in exercise hyperpnea.

Three aspects concerning the role of the central nervous system in the control of exercise hyperpnea are reviewed. First, the integration of sensory input stresses the concept of multiple sites of integration--with the end result that both adequate gas exchange and near-optimal mechanical response of the lung and chest wall are achieved during exercise. Secondly, the potential role of the "central" [H+] chemoreceptor is discussed--in terms of the mechanisms available for the protection of brain ECF [H+] and the stimulus-response characteristics of this important chemical sensor and a critical analysis of how it may be evaluated. Finally, the question of forebrain influences on exercise hyperpnea and the "sensation" of ventilatory effect is discussed, with particular emphasis on the multi-purpose regulation of breathing in athletic endeavors.

Brain↗
PubMed1978

Rat as a model for humanlike ventilatory adaptation to chronic hypoxia.

Oxygen uptake (VO2), expired volume (VE), and arterial blood gases were studied in awake, unrestrained rats over 14 days of hypobaric hypoxia (4,300 m altitude) and upon return to acute normoxia. Control data (at 250 m) showed (mean +/- 95% confidence limits (CL)) arterial oxygen pressure (Pao2) = 85.5 +/- 1.1; arterial carbon dioxide pressure (PaCO2) = 39.8 +/- 0.5; arterial pH pHa) = 7.430 +/- 0.009; VE = 78 +/- 3; VO2 = 2.36 +/- 0.09 ml.min-1.100 g-1; and dead space volumetidal volume ratio (VD/VT) = 0.37 +/- 0.04. During 14 days at 4.300 m the rat showed: a) a constant PaO2 (50-52 Torr); b) a time-dependent hyperventilation (e.g., PaCO2 = 30.2 +/- 1.1 at 1 h of hypoxia, 24.7 +/- 1.3 at day and 21.9 +/- 1.0 at 14 days); c) an increase in VE (85% of control) due to both frequency (33%) and VT (40%); d) a continued but reduced hyperventilation upon acute return to normoxia after 5 h to 14 days at 4,300 m; e) a 24% fall in VO2 after 1 h of hypoxia which returned to control by 4 days at 4,300 m; and f) a rise in pHa to 7.52 after 5 h of hypoxia, which fell to 7.45 by 14-day hypoxia. The rat's marked ventilatory response and changing VO2 during acute hypoxia clearly differs from the human response to sojourn at 4,300 m. However, the progressive and sustained hypocapnia during hypoxic exposure and the continued hyperventilation with acute normoxia in the rat provided essential, perhaps unique characteristics for an animal model of human ventilatory acclimatization.

Adaptation, Physiological↗
PubMed1977

Effect of maternal isoxsuprine on fetal rabbit lung biochemical maturation.

Isoxsuprine was given intramuscularly for 24 hours to pregnant rabbits at 26 to 27 days' gestation. There was no effect on fetal weight within one day of the last injection. Fetuses of isoxsuprine-treated mothers had higher lung lecithin (6.67 micron per gram +/- 2.81) and higher tracheal wash lecithin/sphingomyelin (L/S) ratios (5.85 +/- 4.5) than did untreated fetuses--lung lecithin (5.35 micron per gram 1.23) and tracheal wash L/S (4.08 +/- 2.3). In contrast, phosphorylcholine glyceride transferase activity of the fetal lung was less in isoxsuprine-treated fetal lung tissue.

Animals↗
PubMed1977

Isolated, ventilated, perfused newborn rabbit lung preparation and its assessment.

To achieve an isolated, ventilated, perfused newborn rabbit lung preparation, newborn rabbits are anesthetized and ventilated. The pulmonary vasculature is perfused with a Krebs-Ringer bicarbonate solution containing glucose and plasma expanders, and the lungs are isolated in a 37 degrees C chamber at 100% humidity. The success of a perfusion is evaluated on three levels. 1) Visual. 2)mechanical: a, drop in flow of greater than 20% indicates failure; b, an increase of more than 25% of the initial lung weight indicates fluid accumulation and failure. 3) Biochemical: a, the endogenous ATP concentration after perfusion; b, the level of the enzyme choline phosphotransferase (CPT) after perfusion. Isolated, perfused, ventilated newborn rabbit lungs maintained for 4 h with no changes in the monitored physical and mechanical parameters have an endogenous ATP level of 1.06 +/- 0.06 (2 SD) mumol ATP/mg wet weight and a CPT level of 1.34 +/-0.15 (2 SD nmol [14C]CDP-choline per milligram protein in 30 min. These values are stable at a level lower than observed in intact, hypoxic, newborn rabbit's lungs. In constrast, if perfusion is maintained after any of the monitored criteria indicate failure, the endogenous ATP concentration and CPT activity are significantly depressed.

Adenosine Triphosphate↗
PubMed1976

Production of cortisol from cortisone by the isolated, perfused fetal rabbit lung.

Perfusion of the isolated 26 day fetal rabbit lung with 3H-cortisone resulted in its conversion to 3H-cortisol and release into the perfusate. Little conversion of 14C-cortisol to 14C-cortisone occurred. Quantitative study of homogenized fetal rabbit lung revealed the development of both the cofactor and the enzyme for 11beta-hydroxy steroid dehydrogenase activity between 21 and 29 days gestation. These results suggest increasing production of cortisol from cortisone by the fetal rabbit lung as a function of gestational age. This conversion may be of significance with respect to both lung development and parturition, both events being accelerated by cortisol treatment.

Animals↗
PubMed1976

The effect of hepatectomy on the synthesis of 25-hydroxyvitamin D3.

The metabolism of [3H]vitamin D3 in hepatectomized vitamin D-deficient rats has been studied. Hepatectomy drastically disrupts vitamin D3 metabolism as revealed by prolonged high levels of [3H] vitamin D3 in the plasma compartment even 12 h after dose in contrast to sham-operated controls. Some conversion of [3H] vitamin D3 to [3H]25-hydroxyvitamin D3 was detected in hepatectomized rats, but the amount was small in spite of the high circulating levels of [3H]vitamin D3. Since the liver initially takes up much of an administered dose in normal animals and the conversion of [3H]vitamin D3 to [3H]25-hydroxyvitamin D3 is small in hepatectomized rats in spite of high circulating [3H]-vitamin D3, it is concluded that the liver plays a major role in the metabolism of vitamin D3 to 25-hydroxy-vitamin D3.

Animals↗
PubMed1975

The use of amniotic fluid bubble stability, L/S ratio, and creatinine concentration in the assessment of fetal maturity.

Amniotic fluid bubble stability and creatinine concentration are analyzed in relation to the L/S ratio and clinical outcome. Bubble stability by the standard method showed 20.5 per cent (31/151) initial disagreement between two laboratories, 53.6 per cent (81/151) correlation with L/S ratio, and did not correlate well with patient outcome. However, a "foamy" test, i.e., foam noticeable at a distance, in both 1:1 and 1:2 dilutions, indicated an elevated L/S ratio and mature pulmonary outcome. Amniotic fluid creatinine levels showed an estimated 5 to 6 per cent risk for RDS at levels we formerly thought to be safe (greater than or equal to 2.0 mg. per 100 ml. with maternal serum less than or equal to 0.9 mg. per 100 ml.), and has many false-negative values. Fetal maturity can be estimated with clinical data and amniotic fluid analysis. Amniotic fluid sampling is necessary in all instances where the clinical data leave a reasonable doubt of actual gestational age and in all cases for elective preterm delivery. We recommend a sequential approach to amniotic fluid analysis. First a bubble stability test (a "foamy" at both 1:1 and 1:2 dilutions indicates pulmonary maturity). If the bubble stability test is not "foamy", an L/S ratio. The risk of RDS associated with creatinine concentration makes this test unacceptable in any case of elective delivery; however, it may be useful as a weighing factor in emergency situations where phospholipid analysis is unavailable.

Amniocentesis↗
PubMed1975

Amniotic fluid lecithin to sphingomyelin ration of 3.5 and fetal pulmonary maturity.

The clinical outcome of 118 pregnancies assessed by amniotic fluid lecithin to sphingomyelin concentration (L/S) ratio within 2 days of delivery is presented. It has been observed that the critical L/S ratio for pulmonary function is 3.5 in that no infant born with an L/ S ratio greater than 3.5 has had respiratory distress syndrome (RDS). Below an L/S ratio of 3.5, the risk and severity of RDS is inversely related to the L/S ratio. An L/S ratio smaller than 3.5 has the same prognostic value in infants born between 30 and 34 weeks gestation as it has in infants born between 35 and 38 weeks gestation. Under these conditions the relation between L/S ratio and RDS is independent of gestational age.

Amniocentesis↗
PubMed1975

Oxygen consumption in fetal rabbit ductus arteriosus (38590).

Oxygen consumption in fetal rabbit ductus arteriosus and descending aorta was studied after human umbilical artery tissue was used to standardize the technique. A steady state of oxygen consjmption persisted for 90-100 min after dissection, and a tissue dry weight of greater than 15 mg was necessary to obtain reliable data, necessitating pooling of rabbit fetal tissue from 25.75-26.5 day gestation had an oxygen consumption of 2.05 plus or minus 0.22 (4) mul oxygen/10 mg dry wt/hr, and at 27.5-29.5 it was 5.69 plus or minus 0.28 (7) (P less than 0.001). There was no change with gestational age in the oxygen consumption in the descending aorta (2.15 plus or minus 0.23 mul oxygen/10 mg dry wt/hr).

Animals↗
PubMed1969

25-hydroxycholecalciferol: direct effect on calcium transport.

The perfused small intestine from a vitamin D deficient rat exhibits about one-half the calcium transport of the intestine from a rat given vitamin D. These levels of calcium transport can be maintained for at least 4 hours. Addition of 2.5 micrograms of 25-hydroxycholecalciferol added to the vitamin D deficient intestine via the arterial blood perfusate induces a rise in calcium transport to +D levels within 2 hours. In contrast, 250 micrograms of vitamin D(3) given in the same manner has no effect on the calcium transport level overa 4-hour period. These data provide strong evidence that 25-hydroxycholecalci ferol represents the metabolically active form of vitamin D(3).

Animals↗