摘要:

Breast milk macrophages culturedin vitrosynthesized and secreted increasing amounts of protein, lysozyme, and prostaglandin E2(PGE2) into the extracellular medium. These cells were also shown to actively phagocytose labeled zymosan particles in culture. Morphologic characteristics, phagocytosis, and secretory responses of the macrophages were altered depending on the presence of various stimuli in the culture. Concanavalin A, endotoxin and zymosan particles, but not latex particles, all resulted in an increased PGE2secretion into the medium. Although total protein synthesis was not altered by any of these stimuli, Concanavalin A and endotoxin resulted in a decreased lysozyme concentration in the extracellular medium. Concanavalin A enhanced, whereas endotoxin and prior phagocytosis of latex particles inhibited phagocytosis of labeled zymosan particles. These findings indicate that phagocytosis and secretions of milk macrophages may be altered depending on the nature of the stimulating agent.

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

We examined autoregulation of cerebral blood flow (CBF) over the range of oxygen tension commonly observed in the chronic fetal lamb preparation. Seventeen animals were surgically prepared under general anesthesia for chronicin uterostudies. Based on measured resting arterial Po2and calculated % saturation 24–48 h after surgery, two groups were defined: a normoxic group of eight with saturation of 57% or higher (our laboratory normal for physiologically stable preparations) and an hypoxic group of nine with saturation less than 57%. Regional CBF was measured with radiolabeled 15-μm microspheres. Autoregulation of CBF was assessed by measuring the change in CBF when fetal mean arterial blood pressure (MABP) was acutely decreased and increased by withdrawal and reinfusion of fetal blood. In normoxic animals CBF was constant over an MABP range of 42–61 torr in all four areas of the brain examined: cerebral hemispheres, basal ganglia, cerebellum, and brain stem. In hypoxic animals CBF was pressure dependent in all areas over an MABP range of 46–73 torr,i.e., autoregulation was abolished. These studies demonstrate that the mechanism of autoregulation is functionally developed in the mature fetal lamb, but operationally dependent upon arterial oxygen concentration. Below a saturation of approximately 50–60% CBF varies directly with perfusion pressure.

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Red blood cell (RBC) geometry is a determinant of RBC deformability, survival time, osmotic resistance, and oxygen uptake. Because accurate information on the geometry of neonatal RBC appears lacking, a micropipette technique was employed to measure surface area and volume of individual neonatal and adult RBC. In addition, RBC diameter was determined microscopically. From these measurements, surface area index (actual surface area divided by area of sphere of same volume), swelling index (maximal volume divided by actual volume), minimum cylindrical diameter and mean thickness of RBC were calculated. Compared to adult cells, the volume of neonatal RBC was 21% larger, their surface area was 13% greater and their diameter 11% wider. The surface area-to-volume ratio of the neonatal RBC was 1.42 ± 0.08 and that of the adult RBC was 1.49 ± 0.06 (PP

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

To assess the effects of environmental temperature on responses to hypoxemia, we studied five unsedated lambs in the first week after birth. We catheterized the carotid artery and pulmonary artery (via the jugular vein). After recovery of at least 1 day, we measured pH, blood gases, arterial and mixed venous blood O2content, oxygen consumption (VO2), heart rate, carotid and pulmonary arterial pressures, and cardiac output in both warm (25°C) and cool (17.4 ± 1.1°C) environments. In the cool environment, with no shivering, VO2increased 40% (14.9 to 20.8 ml/kg/min). There were also increases of arteriovenous blood O2content difference of 19%, cardiac output of 18%, and heart rate of 14%. In four lambs, we studied the same variables during hypoxemia (FiO2= 0.09 for 1 h) at both temperatures. In the cool environment, hypoxemia produced a greater fall of VO2(26%versus6%) and arteriovenous oxygen differences (30%versus19%) and a smaller increase of cardiac output (8%versus14%) and heart rate (26%versus43%). Also in the cool environment, core temperature decreased more (2.1versus0.4°C), but base deficit was the same (-6versus−5 mEq/liter). Despite the greater fall in VO2during hypoxemia in the cool environment, the lowest value achieved was still higher than the level during normoxemia in the warm environment. Similarly, cardiac output during hypoxemia was greater in the cool than in the warm environment. These findings may explain the variability in reported normal resting values and responses to hypoxemia. Contrary to previous reports, they also indicate that during severe hypoxemia neonates have a decreased reserve of metabolic and cardiovascular responses in a cool compared with a warm environment.

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

At the Bone Mineral Laboratory of the University of Wisconsin a microcomputer-based digital read-out system was designed specifically for determining bone mineral content (BMC) and bone width (BW) in newborn infants with the following features: (1) high accuracy and precision; (2) high reproducibilityin vivo; (3) direct read-out of BMC and BW; (4) automatic data calibration; and (5) use of a low activity [125I] source (r= 0.99). Short-term precision (weekly, coefficient of variation 1.7%) and long-term precision (monthly, coefficient of variation 2.1%) for measuring BMC were determined by multiple determinations on a four-chambered bone phantom calibrated with the bone sections. Immediate reproducibility (without repositioning the arm) for the 4–6 scans performed for each determination of BMC and BW was good with a mean coefficient of variation of 3.9% for BMC and 3.6% for BW. In 84 infants, repositioning error was determined by repeating the measurement of BMC and BW after repositioning the arm. The correlation coefficients between measurements before and after repositioning the arm were 0.97 for BMC and 0.95 for BW. BMC correlated well with gestational age (r= 0.92), birth weight (r= 0.89) and bone width (r= 0.92). BW also correlated with gestational age (r= 0.84) and birth weight (r= 0.85). A multiple linear regression analysis of BMC versus BW, gestational age, and birth weight was done. The correlation coefficient between the predicted BMC from these variables and measured BMC was 0.95. Photon absorptiometry can be used with high accuracy, precision, and reproducibilityin vivoin newborn infants. BMC correlates with gestational age, birth weight, and bone width.

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Manganese balance studies have been performed on 16 infants, aged 3 days to 8 months, in the period following operation for the correction of congenital heart defects. Samples were analyzed by flameless atomic absorption spectroscopy or by solvent extraction with 8-hydroxyquinoline followed by flame atomic absorption spectroscopy. A higher manganese content was found in either whole blood (710 ± 320 nmole·litre-1) or purified plasma protein (1130 ± 770 nmole·litre-1) compared with fresh frozen plasma (215 ± 35 nmole·litre-1) used in intravenous drips. The manganese content of the milks used in oral feeding was 200–300 nmole·litre-1.

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Cystic fibrosis (CF) is characterized by high sweat sodium and chloride concentrations. CF patients have long been assumed to be at risk for heat illness, but there has been no quantitative documentation that CF patients actually have a greater loss of sodium and chloride than normals when under environmental stress. We compared thermoregulatory responses of eight CF patients with five normal controls during 90-min exposures to exercise and heat stress. Both groups reached similar peak rectal temperatures and peak heart rates; they had similar sweat volumes and rates. CF patients showed the normal rise in renin and aldosterone and the normal fall in urine sodium excretion; however, CF patients lost significantly more sodium (48.8 ± 23.4 mEq/liter/m2versus20.2 ± 11.2 mEq/liter/m2) and chloride (46.6 ± 21.6 mEq/liter/m2versus18.5 ± 11.3 mEq/liter/m2) per unit of surface area than the controls. Serum sodium and chloride concentrations fell in the CF patients but not in the normals. After exercise/heat stress, CF serum chloride was significantly less than normals' (99 ± 3 mEq/literversus104 ± 1 mEq/liter,PCF patients have normal temperature, heart rate, hormonal, and renal responses to exercise and heat stress, yet still lose significantly more sodium and chloride than normal. These losses are reflected in part in lower serum concentrations of these ions. There may be important effects of these losses on respiratory tract secretions.

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

In order to study the role of thyroid releasing hormone (TRH) in the control of thyroid stimulating hormone (TSH) secretion during the neonatal period, we measured the binding of [3H]-TRH to pituitary homogenate of rats at various stages of development. In 2-day-old animals, the number of [3H]-TRH binding sites were similar to that of adult male animals (23 ± 8 fmole/mg proteinversus21 ± 7 fmole/mg protein, respectively). Between 5–21 days of age, the number of [3H]-TRH binding sites was significantly higher than that of adult animals (P3H]-TRH binding sites in all the age groups studied. This effect was reversed by administration of L-T4(0.4 μg/g body weight for 3 days). These studies thus indicate that TRH binding sites are present during the neonatal period in the rat and suggest that TRH may be an important modulator of TSH secretion during this period in the rat and that these effects are mediated by postreceptor mechanisms.

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The action of beta-adrenergic agonists on pulmonary surfactant secretion requires lung cell membrane beta-adrenergic receptors. In the fetus, the density of beta-adrenergic receptors in lung increases in the latter stages of gestation. The increase in density can also be induced by maternal glucocorticoid treatment. In this study, we measured beta-adrenergic receptors in developing rat lung by (-) [3H]-dedydroalprenalol (DHA) binding and confirmed the increase in beta-adrenergic receptors late in gestation. To determine if glucocorticoids have a direct effect on fetal lung to regulate beta-adrenergic receptors, we cultured fetal lung explants with dexamethasone. Treated explants had increased DHA binding compared with controls (138.0 ± 8.8versus63.2 ± 5.0 fmole/mg membrane protein). Scatchard analysis revealed that the increased DHA binding was due to an increase in maximum receptor number. There was also a significant difference in the dissociation constant of the treated and control explants (0.85 ± 0.07 nMversus0.43 ± 0.08 nM, respectively;P

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Adult rats infected with group B streptococci (GBS) develop neutrophilia and display a marked increase in granulocytic stem cells (CFUc). In contrast, infected neonatal rats develop a profound neutropenia and their CFUc do not increase. In order to better understand this phenomenon, we assessed the CFUc pro-liferative rate in control and infected adult and neonatal rats using the technique of [3H]-thymidine suicide. Beginning only 3 h after GBS inoculation, adult rats increased CFUc proliferative activity, as illustrated by an increase in thymidine suicide, from 38 ± 2% cell kill in control animals to 70 ± 2% when infected (mean + S.E.,P

ISSN:0031-3998    

出版商:OVID    

年代:1983

数据来源: OVID