摘要:

Saliva, whether taken from patients with cystic fibrosis or from normal subjects, caused an increase in red blood cell Na+efflux (in the presence or absence of ouabain) of 19–29% as compared with non-saliva controls. However, there was no significant difference between the effects of cystic fibrosis saliva and normal saliva.SpeculationSaliva, and possibly other body fluids as well, contain substances which influence Na+transport across cell membranes, and which are, as yet, uncharacterized. Further investigation of such substances may be relevant to the transport abnormality of cystic fibrosis.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Free myoinositol (henceforth called inositol) levels were measured in cord blood from newborns, as well as in sera from healthy infants during the first 6 months of life. Renal excretion of inositol by a group of premature infants during their first 2 months of life was also studied. Inositol was measured by a microbiologic assay, using an inositol-requiring yeast,Saccha***omyces carlsbergensis.Inositol concentration in pooled cord ***amples of full term normal newborns was 25 ± 5.3 μg/ml. These levels dropped progressively, reaching adult levels (6.9 μg/ml) by the eighth week of life. Mean concentration of inositol in cord blood of premature neonates was 30 μg/ml.In premature infants, the inositol content in the urine was always higher than that of the blood; the average urine concentration was 198 μg/ml. Inositol clearance values of premature infants ranged from 0.10–0.79 ml/min and averaged 0.34 ml/min, and were thus lower than the mean inositol clearances of nonuremic normal adults (2.8 ml/min). The total amounts of inositol excreted per day by the premature infants were considerably higher than the amounts ingested. The blood inositol concentrations in infants in this study are similar to those found in adults with unpaired renal function.The inositol status of the neonate appears to be determined by a balance between the two factors which tend to increase the amount of inositol available, that is, biosynthesis of inositol and ingestion with the formula; and the two factors which decrease the blood level,i.e.,kidney maturation with resultant increased inositol clearance and, possibly, renal enzymatic catabolism of inositol.SpeculationThe rat kidney regulates blood inositol concentration via catabolism by an inositol oxidase. Impaired renal function in man is accompanied by raised serum levels of inositol, as well

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Plasma concentrations of 17α-hydroxyprogesterone (OHP) were measured by a specific and sensitive radioimmunoassay in 348 blood specimens of male and female infants from birth to 2 years of age. Total corticoids levels were assayed by a competitive protein binding technique.OHP levels were higher in the cord than in the peripheral blood of both the mother and the newborn. At term OHP cord levels were higher in female than in male infants. Mean peripheral concentrations of OHP were 419 ± 217 in boys and 431 ± 175 ng/dl in girls in the first day of life and decreased during the first week of life to 70 ± 37.5 and 95 ± 39 ng/dl in male and female infants, respectively. Thereafter, a sex-linked difference in the pattern of OHP plasma concentrations was observed during infancy and, moreover, this dimorphism varied with age, values being higher in boys at 1–2 months but higher in girls at 6–9 months of age. Total corticoids values did not vary significantly with either sex or age.The pattern of OHP in boys closely parallels that which we described previously for testosterone and further documents the postnatal endocrine activity of the testis. The pattern of OHP in girls suggests that in human infant the ovaries exhibit a moderate and rhythmic endocrine activity which lasts at least until the end of the first year of life.SpeculationIt has been shown that in human infant the testis has a marked and transient (for about 4 months) endocrine secretion (OHP and testosterone) after the postnatal activation of the hypothalamopituitary function. In contrast, in female infants, the ovaries exhibit a moderate, rhythmic, but more prolonged endocrine secretory activity (OHP and estradiol). This could result from a pulsatile secretion with great amplitudes but a low tonic gonadotrophin activity in infancy. It is speculated that in the ovary a more sustained luteinizing hormone (LH) (or LH + follicle-stimulating hormone (FSH)) stimulation could be necessary to achieve full maturation of its steroidogenic enzymes, in particular, of the aromatase.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Injection of 11-ketoprogesterone into fetal rats at day 17 of gestation reduced the pulmonary C-11 activation index (an indicator of net gain or loss of glucocorticoid activity) as measured at day 21 (P< 0.001) and resulted in elevated levels of the inactive hormone 11-dehydrocorticosterone (P< 0.001), but unchanged corticosterone levels. Adrenal weight was significantly increased (P< 0.001). 11-Ketoprogesterone-injected fetuses had considerably larger lungs (P< 0.001) with reduced saturated phosphatidylcholine content (P< 0.001).SpeculationPrenatal glucocorticoid treatment to accelerate fetal lung maturation is an attempt to mimic a physiologic process. Further understanding of that process should provide means to enhance the safety and efficacy of such therapeutic intervention.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Ultrastructural and cytochemical observations indicate that both cystic fibrosis (CF) sera and calcium ionophore A23187 induce a swelling or an increase in the size and possibly the number of secondary lysosomes and an increase in mucus secretion in epithelium of the rabbit tracheal bioassay system. Extended incubation of the rabbit tracheal explants with either CF or control sera produces a cytotoxic effect on the tracheal epithelium, but only after the termination of the normal bioassay time period. Comparative ultrastructural study of the effect of both CF sera and calcium ionophore A23187 on the rabbit tracheal bioassay system indicates that increased membrane permeability to calcium may be important in the production of the ciliary dyskinesia response by CF serum factor(s) in the rabbit tracheal bioassay system.SpeculationCF serum factor(s) may be acting on the cultured rabbit tracheal explant epithelial membranes to produce altered membrane permeability to ions and to calcium in particular. This alteration in membrane function may be promoting the observed ultrastructural changes in the epithelial cells which include a swelling or increase in the number and size of secondary lysosomes and an increase in mucus secretion as well as ciliary dyskinesia. Alterations in membrane function and permeability may be related to the pathophysiology of this genetic disorder.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

The intestinal osmolal physiology and absorption of comparable preparations of polymerized glucose and glucose were evaluated in isolated segments of rat duodenum. The acute rise in the osmolality of the succus entericus after 5% polymer injections (298 mOsm/kg at 3 min, 311 mOsm/kg at 30 min) was significantly less than that noted after 5% glucose (387 mOsm/kg at 3 min, 351 mOsm/kg at 30 min). At 60 min a steady state had been established and no significant difference was found. Ten percent polymer was superior to 10% glucose as it also produced a lower luminal osmolality (351 mOsm/kg versus 427 mOsm/kg at 30 min). Luminal polyethylene glycol concentrations revealed comparable increases in intraluminal water content after 10% polymer and 5% glucose (22% versus 25% at 30 min). After polymer injections, 4 times as much glucose was present in the mucosa as in the succus, whereas, after 5% glucose injections, a high concentration of glucose remained in the succus.These results indicate that polymer solutions produce lower luminal osmolality than glucose solutions of similar weight. Additionally, enhanced glucose absorption by the mucosal cell is suggested in animals injected with polymer. Polymerized glucose should, therefore, provide twice the calories of glucose without a disparate increase in the intestinal osmolality and intraluminal diffusion of extracellular water.SpeculationA polymerized glucose preparation, when administered orally, produces a lower immediate intraluminal solute content and osmolality than a glucose solution of the same concentration by weight when each has comparable electrolytes. Hydrolysis of the polymer within the intestinal lumen and on contact with the brush border of the intestine provides nutrient without increase in water movement into the proximal small bowel. Because of these properties, such a polymer may be useful in the oral nutritional rehabilitation of neonates and infants with diarrhea. It remains to be seen whether the pathogenesis of the diarrheal state may also prove to be of significance in determining the beneficial effect of this therapy.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

In order to determine whether the mobilization of intracellular triglycerides observed in cultured human adipocytes is associated with changes in the activities of acid and neutral lipases, the activities of both enzymes were measured weekly on cultured adipocytes for several months. The activity of acid lipase was initially very low, but rose to levels 40 times the original activity within 3 months. The activity of neutral lipase decreased rapidly within the first 2–4 weeks and remained at approximately 25% of original levels thereafter.SpeculationThere is increasing evidence that the human adipocyte is highly specialized and that it is derived from a stromal precursor present in the adipose tissue. The cell has the capacity to acquire in culture the properties of the precursor, as evidenced by the appearance of acid lipase and disappearance of neutral lipase. We submit that the low level of acid lipase in the adipocyte is related to its lipid storage function. It remains to be proven that it is not primary to the differentiation of the adipocyte from its precursor. Furthermore, we speculate that a direct biochemical relationship exists between the neutral lipase and intracellular triglyceride stores in the adipocyte.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Eighty-nine metabolic balance studies were performed with 12 normal infants ranging in age from 14–746 days. Intake and fecal and urinary excretions of lead were determined and net absorption and net retention were calculated. Subjects were fed milk or formula and commercially prepared strained foods. Intakes of lead ranged from 0.83–22.61 μg/kg/day with a mean of 9.43 μg/kg/day. Urinary excretion averaged 1.02 (SD 0.68) μg/kg/day and was positively correlated with lead intake (Fig. 1). Fecal excretion was highly correlated with intake of lead (Fig. 2); fecal excretion exceeded intake in 10 studies. In 61 balance studies with lead intakes greater than 5 μg/kg/day, net absorption averaged 41.5% of lead intake and net retention averaged 31.7% of intake.Retention of lead was highly correlated with lead intake (Fig. 3). Urinary plus fecal excretion of lead exceeded intake in 19 of 28 balances in which lead intakes were less than 5 μg/kg/day. Absorption and retention of lead were inversely correlated with intake of calcium (Fig. 4). Absorption and retention of lead accounted for greater percentages of intake of lead in this study of infants and young children than have been reported in studies of older subjects.SpeculationHighly efficient absorption and retention of ingested lead by young children may be partly responsible for the high prevalence of lead intoxication in this age group.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Baseline plasma osmolality (pOsm) and plasma arginine vasopressin (pAVP) were measured in chronically catheterized fetal sheep. Mean baseline pAVP in fetuses from 101–120 days was 1.9 ± 0.46 μU/ml (mean ± SEM) with a pOsm of 293 ± 1.8 mOsm/kg. In fetuses of 121–141 days of gestation, mean pAVP was significantly lower, 0.77 ± 0.19 μU/ml (P< 0.05), with a similar pOsm (293 ± 1.9 mOsm/kg). The logarithmic baseline pAVP values were linearly correlated with pOsm for both groups. Hypertonic saline infusion resulted in a similar increase in the log pAVP corrected for the rise in pOsm in the 101–120-day fetuses and in 121–141-day fetuses. The slope of this response was similar to that of the steady state relationship. The data indicates that the fetal osmoreceptor system for control of arginine vasopressin secretion is fully functional in the last trimester of pregnancy.SpeculationThe fetal hypothalamic posterior pituitary system appears to show a relatively heightened response to increases in plasma osmolality during the last trimester of gestation. This may reflect the heightened hypothalamic activity postulated to explain the high circulating growth hormone levels at this time. The higher baseline plasma vasopressin levels in the younger fetuses would support this view. Alternatively, the augmented responsiveness may represent an adaptive response to the immaturity of the fetal kidney with respect to free water clearance or an adaptive response to some extrarenal function of the hormone on salt and water homeostasisin utero.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID

摘要:

Rabbits delivered at 27.0 days of gestation were studied after administration of cortisol (2 mg/kg/day), aminophylline (6.25 mg/kg/day), or sterile saline to the does on days 24–26 of gestation. Survival at 60 min was 52.9% in the aminophylline-treated group and 22.2% in the control and cortisol-treated groups with all animals being in a warm, oxygen-enriched environment and receiving frequent tactile stimulation. Lung volume at 30 cm H2O was lower in the cortisol-treated group than in the controls or aminophylline-treated group in animals surviving for 60 min (Table 2). The aminophylline-treated group retained significantly more gas at low pressures on the deflation curve (Table 2) and had significantly more phosphati-dylcholine recovered in lung lavage fluid (Table 3) than the other groups. Aminophylline appears to have enhanced lung maturation better than cortisol in this experimental model.SpeculationImproved survival of prematurely delivered rabbits after aminophylline administration (as compared with cortisol) may be due to a combination of factors including enhanced maturation of the lungs as well as stimulation of the respiratory center.

ISSN:0031-3998    

出版商:OVID    

年代:1978

数据来源: OVID