摘要:

The human neonate is uniquely susceptible to serious and overwhelming bacterial and fungal infections. While deficiencies of antibody, complement, and T lymphocytes certainly contribute to this susceptibility, abnormal polymorphonuclear leukocyte function appears to be a major host defense abnormality in the neonate. Functional defects in neonatal polymorphonuclear leukocyte adherence, aggregation, movement, phagocytosis, and intracellular killing have been described in the term or preterm infant. Only recently, however, have the techniques become available to examine the biochemical and structural mechanisms underlying abnormal polymorphonuclear leukocyte function in the neonate. It now appears that there may be developmental defects in signal transduction, cell surface receptor upregulation and mobility, cytoskeletal rigidity, microfilament contraction, oxygen metabolism, and intracellular antioxidant mechanisms. Defining the biochemical and physiologic abnormalities in these cells may lead to therapeutic regimens for pharmacologically correcting these developmental defects in cell function.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Serum from patients with cystic fibrosis and normal controls was used to opsonize mucoid and nonmucoid Pseudomonas aemginosa particles. Opsonic activity was then determined by measuring the production of superoxide anion (O2-) from normal neutrophils stimulated with the opsonized particles. Without any opsonization, mucoid P. aeruginosa stimulated significantly more O2-than nonmucoid P. aeruginosa. Responses to nonmucoid P. aemginosa observed with heat-inactivated serum from patients with cystic fibrosis were significantly higher (p=0.008) than those observed with heat-inactivated control sera. Comparisons made between patients who were colonized with P. aeruginosa and those who were not showed that heat activated serum from colonized patients had significantly higher levels of opsonic activity than heat inactivated serum from patients who were not colonized. These differences were observed with either mucoid or nonmucoid P. aeruginosa. A negative correlation was also observed between opsonic activity and clinical status measured by Schwachman scores of colonized patients. These data indicate that in patients colonized with P. aemginosa the deterioration of their clinical status correlated with increased opsonic activity reflected in the oxidative burst response of neutrophils.

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:

Redistribution of regional blood flow is an important compensatory response to acute hypoxemia which preserves oxygen delivery to the most vital organs. It is not known if this change in blood flow persists when hypoxemia is prolonged, as occurs in cyanotic congenital heart disease. Chronic hypoxemia was produced in newborn lambs by creating pulmonary stenosis and an atrial septal defect. Oxygen saturation was maintained at 60- 70% of control for 2 wk. Distribution of cardiac output was then measured with radionuclide-labeled microspheres. As compared with control, chronic hypoxemia did not alter total cardiac output. Regional blood flow was redistributed, however, the pattern of this redistribution was different from that seen during acute hypoxemia. Myocardial and cerebral blood flows, which increase during acute hypoxemia, return to control levels during chronic hypoxemia. Renal, splenic, gastrointestinal, carcass, and skin blood flows remain decreased. Hemoglobin gradually increases so that after 2 wk of hypoxemia total systemic oxygen delivery returns toward control. However, oxygen delivery to all organs except the heart and brain is reduced. Thus, although cardiac output and total systemic oxygen delivery return toward normal during chronic hypoxemia, these measurements may not reflect important regional variations in blood flow and oxygen delivery. Decreased oxygen and substrate delivery to the gastrointestinal tract, liver, and carcass may account for the alterations of metabolism and growth seen in the newborn with cyanotic congenital heart disease.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Type I hereditary tyrosinemia is characterized by the almost complete absence of fumarylacetoacetase in tissues and cells from patients. To investigate the -nature of the enzyme deficiency, extracts of tissues (liver and kidney) and cells (lymphocytes and fibroblasts) were immunochemically screened for the presence of fumarylacetoacetase enzyme protein. The antibodies used were raised in rabbits against fumarylacetoacetase purified from beef liver. These antibodies cross-reacted strongly with the human enzyme. No cross-reacting material was found in extracts from liver (n = 4) and kidney (n = 1) from patients. Extracts from lymphocytes and cultured skin fibroblasts from patients were investigated as well. However, no crossreacting material was found in extracts of these cells.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Salivary antibodies were studied in 112 infants between 1 day and 8 yr of life. SIgA anticasein was present from birth in breast-fed and bottle-fed infants. Bottle-feeding resulted in significantly higher concentrations of SIgA anticasein at 3 wk to 3 months of life as compared to breast-feeding. Salivary anticasein declined toward the end of the 1st yr and was present in less than half of the children older than 1 yr. Salivary anti-lactoglobulin was also present at birth in some infants. Levels increased slightly over the following 3 months but remained low. Only a minority of older children had this antibody in their saliva.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The head sizes of 38 patients, growth hormone (GH) deficient following craniospinal (n=26) or cranial irradiation (n= 12), have been assessed before (n=38) and on completion of GH therapy (n=15) or at the end of a similar period of observation without GH (n=7). These results were compared to the change in head size seen in idiopathic GH deficiency following GH therapy («=14). Before GH therapy, the latter had small heads [mean occipitofrontal circumference SD score (SDS) —1], which were relatively large compared to the height deficit [height SDS (CA) -4.7], and they exhibited catch-up growth with GH (Aoccipitofrontal circumference SDS + 0.7, final occipitofrontal circumference SDS -0.2). In contrast, over a similar period all patients, who previously had received cranial irradiation in the dosage range 2700-4750 centi-Geigy, irrespective of the radiation schedule or GH treatment, showed a decrease in occipitofrontal circumference SDS (mean? -0.9), a significant difference to the expected head growth of normal children over a similar period (p<0.01). We have noted that restricted head growth occurs in the years following cranial irradiation and is unaffected by GH therapy. Earlier work has shown that cranial irradiation may impair intelligence. The exact relationship between intellectual impairment and stunted head growth remains to be determined.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

The levels of the vitamin K-dependent clotting factors are markedly lower in the human fetus and newborn than in older infants and adults. Direct measurement of vitamin Ki in cord plasma records low or undetectable levels. This phenomenon, although the norm, is referred to as vitamin K deficiency and is a significant risk factor for hemorrhage in the fetus and newborn. Sister chromatid exchange (SCE), which may be used as an index of mutagenic activity, was assayed in cultured leukocytes of placental and adult blood following phytohemagglutinin stimulation. The mean number of SCEs per metaphase in human placental blood was 3.32 ± SE 0.219 as compared with levels of 5.13 ± SE 0.273 in young adults (p < 0.01), and in the presence of added vitamin K, at a concentration of 1 × 10”6 M the SCE increased significantly in both adult and placental cells. In vitro SCE dose response curves to Ki in the blood of fetal and maternal sheep were obtained. When five fetal sheep were given 1 mg of Ki by catheter into the femoral vein the SCE increased from 3.94 ± SE 0.15 preinjection to 5.38 ± SE 0.23 at 24 h postinjection (p < 0.01). In the pretreatment fetal sheep, serum vitamin Ki was below detectable levels in all seven animals in which it was assayed and reached levels as high as 0.3 × 10−6M 1 h post-K, injection. The low level of K, in the fetus may in fact confer some biological advantage by reducing the risk of mutagenic events during a period of rapid cell proliferation.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Proteoglycan was isolated from the epiphyseal cartilage of the knee joint from human fetuses, ranging in age from 11 to 19 wk of gestation. The content of proteoglycan, per wet weight of cartilage, increased with gestational age, and structural changes were observed in the proteoglycan subunits, particularly with respect to hydrodynamic size and the position of sulfation of the chondroitin sulfate chains. While 6-sulfation remained fairly constant on about half the disaccharide residues during the age period examined, the proportion of nonsulfated residues decreased with gestational age and there was a corresponding increase in the proportion of 4-sulfated residues. Other structural parameters showed little change, and after 11 wk of gestation the majority of proteoglycan subunits were able to interact with hyaluronic acid to form aggregates. Link proteins were detected in the cartilage at all ages and their abundance increased with age relative to other cartilage proteins. They showed little change in structural heterogeneity, with the two larger molecular forms predominating. In contrast to the proteoglycans, cartilage proteins were in high abundance at 11 wk of gestation, but decreased considerably with time, although there was little change in the relative proportion of the majority of the components.

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

Phototherapy of newborn rats (NBR) resulted in a decrease in serum calcium and melatonin levels. Transcranial light penetrance in NBR increased with wavelength. Below 640 nm (penetrance = 6.9%), no hypocalcemic effect could be demonstrated. Shielding the occiput of NBR prevented a decrease in serum calcium during phototherapy and substantially reduced the decrease in melatonin found in unshielded NBR. Intraperitoneal injection of propranolol, an inhibitor of melatonin synthesis, caused a decrease in serum calcium in shaded NBR. In contrast, when melatonin was injected with propranolol a decrease in serum calcium did not occur. Additionally, intraperitoneal isoproterenol before phototherapy protected against a decrease in serum calcium. These data are consistent with an hypothesis that a decrease in serum calcium during phototherapy results from transcranial photic inhibition of melatonin synthesis

ISSN:0031-3998    

出版商:OVID    

年代:1987

数据来源: OVID