摘要:

The postnatal anemia in rabbits is accompanied by a marked rise in the plasma erythropoiesis stimulating factor(s) (ESF). The purpose of this study was to establish whether the increase in plasma ESF is only related to the anemia, or whether other mechanisms also are involved. Two matched groups of rabbits were studied from the 15th to the 36th day after birth. One group received iron parenterally and had no postnatal fall in hemoglobin concentration (Hb), the other developed the usual anemia. In both groups plasma ESF was undetectable on the 15th day, and also on the 22nd day, despite a marked fall in Hb in the untreated group and rise in the iron-treated group. Thereafter plasma ESF showed a slight, continuous rise in the nonanemic rabbits, in contrast to a marked, transient rise with maximum on the 29th day in the untreated group. On the 36th day there was no difference between the groups. In the iron-treated group the reticulocyte production rate remained unchanged, while the Hb mass rose continuously. In the untreated animals there was an initial decline in reticulocyte production rate, while Hb mass showed a slight increase. From the 29th day, however, reticulocyte production rate rose to the same level as in the iron-treated group and Hb mass rose markedly. In conclusion, the rise in plasma ESF during the postnatal anemia in rabbits is only in part related to the low Hb. Hypoxia-independent mechanisms, probably related to the growth and maturation per se also are involved. The lack of erythropoietic response to the rise in plasma ESF is due to lack of available iron.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Preparation by the developing alveolar epithelium for the transition to air breathing and surfactant secretion at birth are critical components of neonatal survival. We combined morphometric analysis and biochemical assays of lung phospholipids to measure the amount and redistribution of lung surfactant during the perinatal period of rats. Within 10 min of the start of air breathing, there was a small increase in type II cell lamellar body content by morphometric and biochemical estimates. By 24 h, the whole lung and alveolar extracellular pool surfactant lipid had substantially increased. Subfractionation of the alveolar surfactant pool obtained at four times, from birth to 24 h of life, demonstrated a 20-fold increase in the ratio of phospholipid in a tubular myelin-rich fraction compared to a unilamellar vesicle-rich fraction. We conclude that packaging of surfactant may be very active immediately postbirth. Our results also indicate a major shift in the physical forms of extracellular surfactant during the first hours of air breathing.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Leucine turnover was measured using [l-14C] L-leucine in three patients with classical maple syrup urine disease. There was measurable leucine oxidation although it was lower than in normal adults. Leucine production rate was greater than normal in all three patients with an increased rate of incorporation of leucine into protein and increased protein catabolism. These fluxes were both relatively insensitive to exogenous insulin.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Chronic sequelae of neonatal hyperoxia was studied in male rats exposed to 0.96-1.0 FiO2for the first 8 days of life. At 58 days of age functional and morphologic cardiopulmonary changes were compared with controls. Right ventricular systolic pressure was measured percutaneously under anesthesia and was increased in the O2group (29.5 mm Hg ± 3.1 versus 23.2 mm Hg ± 3.5,p< 0.001). Lung and heart weights were similar between groups. Right ventricular weights however were increased in the O2group (0.197 g ± 0.023 versus 0.175 g ± 0.020,p< 0.001). Air pressure-volume curves were similar but in the O2rats saline deflation curves were shifted left and maximal fluid lung volumes were greater (14.1 ± 1.2 versus 12.0 ± 0.7 ml,p<0.001). Pulmonary arteries were perfused at 100 cm H2O with a barium-gel mixture and lungs were fixed at 25 cm H2O with formalin. Microscopic examination of lungs revealed dysplastic changes of alveolar architecture which included irregularly enlarged alveoli and incomplete alveolar septation. Morphometric studies of the lungs showed that the O2rats had an increased volume proportion of parenchyma (0.865 ± 0.020 versus 0.850 ± 0.019,p<0.05), increased mean linear intercept (72.3 urn ± 9.5 versus 53.6 /tin ± 5.0,p<0.001), decreased number of alveoli per mm2(207 ± 34 versus 319 ± 39,p<0.001) and fewer small arteries (20-200 nm) per mm2(8.7 ±1.3 versus 14.9 ± 2.4,p<0.001). The number of small arteries/ 100 alveoli was similar. We conclude that limited and specifically timed neonatal hyperoxia is associated with chronic morphologic and functional cardiopulmonary changes in the adult rat. These changes include a decrease in the number of small pulmonary arteries, elevated right ventricular pressure, and emphysema-like changes in the air spaces.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

In 16 newborn infants (24 6-39 wk 6 days 830-3390g) at ages between 0-70 days, the skin's electrical resistance was measured. Over 30 min we sequentially measured direct current resistance between two skin electrodes placed on the abdomen. The resistance was found to be low in very premature infants with gestation ages of 30 wk or less. It increased with both gestational age and postnatal age. In these infants, the resistance measured at 30 min during the first 4 days of life (3.4 ± 0.3 KΩ; mean ± SD) was significantly less than that found at 20-70 days (8.8 ± 1.2 kΩ;p<0.001). The relationship between the infant's electrical skin resistance (y) and the gestational age (x) best fit the exponential formula: y=7.42 -e024k- 10-4+ 2.74. This formula shows that the electrical skin resistance increases exponentially during the last trimester. The measurement of electrical skin resistance is a quantitative method that can be utilized to evaluate the gestational age of infants. (Pediatr Res 21: 21-24, 1986)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

We examined the effect of inspiratory resistive loaded breathing (IRL) on the electromyographic (EMG) activity of the costal and crural diaphragm in nine anesthetized spontaneously breathing piglets (age 10-23 days, weight 2.8-4.4 kg). Bipolar wire electrodes were inserted into the anterior paratendinous costal diaphragm and the midportion of the crural diaphragm. EMG activity was quantified in arbitrary units (au) of peak moving time average while the animals breathed 50% O2/50% N2(baseline) and during 30 min of IRL. Thirty min of IRL increased the peak moving time average of both parts of the diaphragm, with the increase in the crural EMG activity (from baseline: 22 ± 2 to 30 min of IRL: 76 ± 22 au) exceeding that of costal (from baseline: 23 ± 2 to 30 min of IRL: 50 ± 24 au),p<0.05. These results 1) suggest that the inspiratory EMG activity of the diaphragm can be differentially distributed between its costal and crural components and 2) document that crural inspiratory EMG activity undergoes greater augmentation under the condition of IRL than does the costal activity in piglets. (Pediatr Res 21: 25-28,1987)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

In adults, exposure to prolonged hypercarbia results in a normalization of the extravascular brain pH associated with a reduction in brain blood flow (BBF). Following prolonged hypercarbia, sudden normalization of the arterial PCO2also produces a change in the extravascular brain pH to an alkaline state, resulting in a marked decrease in BBF. We examined these physiologic phenomena in newborn subjects by exposing seven awake, spontaneously breathing newborn piglets to 4 h of sustained hypercarbia (PaCO2: 60-70 mm Hg) followed by a 45-min normocarbic period. Total and regional BBF, cardiac output (radionuclide-labeled microsphere method), arterial blood pressure, plasma catecholamine and lactate concentrations, blood gases, oxygen contents, and hematocrits were measured during a baseline period, at V2, 2, and 4 h of sustained hypercarbia and V* and 3A h following an abrupt onset of normocarbia. The initial 2.5-fold increase in total BBF during hypercarbia persisted for 2 h and at 4 h decreased significantly below the level of the 30-min hypercarbic measurement, although the values still remained 2-fold above the baseline values. Brain tissue pH was reduced at the onset of hypercarbia, remaining unchanged throughout the hypercarbic period. Both total BBF and brain tissue pH returned to baseline values following the return to normocarbia. Changes in regional BBF were similar to that of total BBF with the exception of the boundary zone (periventricular area in the frontoparietal region of the cerebrum, adjacent to the caudate nucleus) and the parietal area (site of the brain tissue pH electrode), where a significant decrease from the peak hyperemia was not observed. Choroid plexus blood flow demonstrated a small initial increase over normocarbic baseline values. Plasma bicarbonate concentrations did not change during the studies. Following the onset of hypercarbia, heart rate and cardiac output increased significantly whereas plasma lactate concentrations decreased significantly. There was also an increase in the percentage of cardiac output distributed to the brain. The increase in cardiac output persisted throughout the hypercarbic period and returned to baseline levels during normocarbia. Mean arterial blood pressure increased significantly at the 4-h hypercarbic period and this increase persisted during normocarbia. We conclude that in newborn piglets 1) hypercarbia resulted in cerebral hyperperfusion, accompanied by marked fall in brain tissue

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

We report a girl with Cockayne syndrome (CS) with atypical cellular features. We studied the ultraviolet (UV)-sensitivity of cultured fibroblast cells derived from this case and male CS siblings as positive controls. Cells from this female with CS displayed normal unscheduled DNA synthesis and repair replication capacity. However, the cells also displayed a less depressed level of RNA synthesis after UV irradiation, compared to control CS cells, and showed normal UV survival. This CS case with early onset of abnormalities had more serious clinical manifestations than the control CS siblings. These cytological results suggest that there is considerable clinical and cellular heterogeneity in CS and that cellular sensitivity to UV might not be as essential for the diagnosis of CS as previously thought.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

It has been suggested that the substantial rise in fetal plasma arginine vasopressin (AYP) during intrauterine hypoxia/asphyxia reflects decreases in PaO2and/or pHa; however, the components of these “stresses,” i.e. PO2, PCO2, and pH, have not been controlled. Recently, only modest increases in fetal AVP secretion were seen during hypoxia independent of changes in pH and PCO2. Since the independent effects of metabolic acidosis on fetal AVP secretion are unknown, we induced acute metabolic acidemia in fetal sheep at 137 ± 4 (mean ± SD) days gestation with 1 M NH4C1, while monitoring mean arterial pressure, heart rate, PaO2, PaCO2, pHa, plasma osmolality, and blood concentrations of electrolytes, AVP, dopamine, norepinephrine, and epinephrine. Mean arterial pressure, PaO2, PaCO2, and plasma osmolality and sodium were unchanged; pHa decreased from 7.37 ± 0.01 to 7.04 ± 0.05 (p<0.05) during NH4C1 and did not return to control levels until 24 h later. AVP increased from 2.85 ± 0.23 to 5.26 ± 1. 1 1 µU/ml (p<0.05) at the time of maximum acidosis, correlating with the fall in pHa (r=-0.67,p=0.001); however, after stopping NH4C1, AVP returned to baseline levels although pHa remained <7.15. In control studies using the same osmolar load, volume, and rate of infusion, AVP levels were unchanged. Only epinephrine was significantly (p<0.05) elevated during acidosis, but did not correlate with pHa or plasma AVP. Marked metabolic acidemia appears to have little or no effect on fetal AVP secretion, and fetal catecholamine secretion is variable. (Pediatr Res 21: 38-43,1987)

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID