摘要:

Protein phosphatase 2A (PP2A) is a second messenger involved in cell cycle regulation, cell transformation, and cell fate determination. We previously identified a gene encoding the α catalytic subunit of PP2A in the embryonic rat heart, but its role in cardiac morphogenesis was unknown. In this study, we examined the developmental expression of PP2AαmRNA and protein in the heart using Northern and Western analysis,in situhybridization, and immumohistochemical staining. We found two major PP2Aαtranscripts in the rat heart (1.8 and 2.4 kb), at all stages examined. By Western blotting, PP2Aαprotein levels were twice as high in the embryonic rat heart compared with the adult.In situhybridization on embryonic d 12 showed that PP2AαmRNA was expressed in the heart, brain, tail, and limb buds. Cardiac PP2Aαexpression was regionally restricted to the atrium, ventricle, and truncus arteriosus. PP2Aαexpression did not extend into the more distal aortic sac or aortic arches. Cross-sectional hybridization revealed PP2AαmRNA in the epicardium, pericardium, and endothelium. Later in development, mRNA expression was also detected at high levels in mesenchymal cells populating the endocardial cushions and in myocardium. At term, PP2Aαwas highly expressed in endothelial cells, but not in the underlying myocardium. PP2Aαprotein had a similar distribution at all embryonic stages examined. These results show that there is transcriptional, translational, and cell-specific regulation of PP2Aαduring heart development. We speculate on the role of PP2Aα-mediated dephosphorylation in cardiac morphogenesis and suggest a number of possible molecular targets.Abbreviations: PP2A,protein phosphatase 2A;PP2Aα,α catalytic subunit of protein phosphatase 2A;PBT,PBS + 0.3% Triton X-100;HB,hybridization buffer;GAPDH,glyceraldehyde-3-phosphate dehydrogenase

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Viral infections may induce an acquired form of immunodeficiency, generally lasting a few weeks. In the more severe form, such as HIV infection, the immunodeficiency is permanent. Programmed death of T cells represents one of the mechanisms by which HIV determines the T cell functional impairment, finally resulting in the destruction of T cells. In this study, we evaluated whether an altered regulation of apoptosis was also implicated in the anergy associated with the common measles or varicella-zoster virus (VZV) infections in infancy. A spontaneous apoptosis of peripheral blood mononuclear cells was observed in children who had suffered from these infections as long as 6 mo after the acute disease. Apoptosis was demonstrated through analysis of cellular DNA content, morphologic evidence of cell nuclei shrinkage, and by analysis of DNA degradation. Stimulation of T cells through anti-CD4 MAb increased the number of apoptotic cells with a maximal effect 72 h after the stimulation. Our results suggest that apoptosis may account for the anergy that follows acute viral infections in infancy.Abbreviations: TCR,T cell receptor;VZV,varicella-zoster virus;PBMC,peripheral blood mononuclear cells;PHA,phytohemagglutinin;PMA,phorbol myristate acetate;PI,propidium iodide

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Intestinal epithelial (Caco-2) cells secrete the chemokine, IL-8, after stimulation with IL-1β, but not after lipopolysaccharide. Butyrate is a short chain fatty acid derived from the metabolism of intestinal contents by gut bacteria. Butyrate concentrations reflect, therefore, the bacterial microenvironment established within the intestine. We hypothesized that butyrate may alter the secretion of IL-8 by intestinal epithelial cells in response to stimulation by IL-1β or lipopolysaccharide. Caco-2 cells were incubated in varying concentrations of sodium butyrate (0-20 mM) for 24 h before stimulation with lipopolysaccharide or IL-1β. IL-8 secretion was measured over 24 h by ELISA. IL-8 mRNA accumulation was detected by Northern blots. Lipopolysaccharide induced the secretion of IL-8 only after Caco-2 cells cells had been cultured with sodium butyrate. Furthermore, butyrate significantly enhanced IL-8 secretion by cells stimulated with IL-1β. Butyrate also increased IL-8 mRNA accumulation in stimulated Caco-2 cells. Intestinal epithelial cells can, therefore, be primed by butyrate to become activated by lipopolysaccharide and proinflammatory cytokines. This may represent a mechanism by which intestinal epithelial cells can regulate intestinal inflammation in response to changes in the intestinal milieu.Abbreviations: DMEM,Dulbecco's modified Eagle's medium;DTS,DMEM supplemented with human transferrin and selenous acid;GRO,growth related

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Employing immunohistochemical and Western blot analyses, we investigated the cellular localization (22-d fetal and 14-d postnatal animals) and concentrations (22-d fetal to 21-d postnatal animals) of rat hepatic glucose transporters (Glut 1 and Glut 2) and glucokinase in response to development and uteroplacental insufficiency with IUGR. Glut 1, the predominant fetal hematopoietic cellular isoform, persisted in postnatal hematopoietic islands and was noted minimally in fetal hepatic cellular membranes. A ≈40% extrauterine decline in Glut 1 levels paralleled the decline in hematopoietic cells. IUGR increased the fetal hepatic Glut 1 levels in parallel with an expanded hematopoietic cell mass (p< 0.05). In contrast, IUGR failed to alter the 2-fold increase in extrauterine Glut 2 concentrations(1-7-d postnatal animals), the isoform found in fetal and postnatal hepatocytic cell membranes. Glucokinase, the nuclear enzyme, increased 25% postnatally. IUGR caused a 16% increase in fetal glucokinase levels and a≈25% decline at postnatal d 1 (p< 0.05) without a comparable change in the hepatocytic cell number (92 ± 6versus86± 4). We conclude that hepatic Glut 1 concentrations reflect the extramedullary hematopoietic cellular mass, whereas extrauterine Glut 2 changes herald the need for enhanced flexibility in hepatocytic glucose transport with the initiation of food ingestion. The age-related alteration along with the IUGR-induced compensatory changes in the nuclear-mitochondrial glucokinase levels attributes a critical role for this enzyme in perinatal hepatocytic glucose homeostasis.Abbreviations: IUGR,intrauterine growth restriction;GST,glutathioneS-transferase

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Preterm and term human milk samples obtained at various times after delivery were analyzed for the presence of molecular forms of the human milk enzyme, bile salt-stimulated lipase (BSSL). Thirty-five percent of both the preterm and term milk samples contained two molecular forms of BSSL, of variable molecular mass. The remainder contained only one molecular species of either 115 kD (50%) or 120 kD (15%). The number of molecular forms present was not related to length of lactation, maternal age, gestation, or maternal blood group. The specific activity of BSSL purified from term milk was similar to that purified from preterm milk, and there was no difference in specific activity whether one or two molecular forms were present. This study demonstrates heterogeneity of both molecular mass and molecular forms. We conclude that preterm babies fed their own mother's milk are unlikely to be disadvantaged with respect to fat digestion as BSSL secreted in preterm milk appears to be very similar to that produced in term milk, although we cannot exclude other functional differences.Abbreviation: BSSL,bile salt-stimulated lipase

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Human GH is encoded by the GH-1 gene which belongs to the GH gene cluster encompassing a distance of about 65 kb on the long arm of chromosome 17. Familial isolated growth hormone deficiency (IGHD) is associated with at least four Mendelian disorders. These include two forms that have autosomal recessive inheritance (IGHD types IA and IB) as well as autosomal dominant(IGHD type II) and X-linked (IGHD III) forms. The aim of our study was to evaluate the prevalence of all GH-1 gene alterations by sequencing the whole GH-1 gene after PCR amplification among 151 affected subjects from 83 families with severe IGHD (height: <-4.5 SD score). A high frequency of GH-1 gene alterations was found in families with IGHD type IA (8/12, 66.7%), whereas only a low frequency of GH-1 gene defects was present in all the other GH-deficient families (7/71, 9.9%). The absolute frequency of GH-1 gene deletions was 8.7% (6/69), 11.8% (4/34), and 18.7% (9/48) in Northern Europeans, Mediterraneans, and Asians, respectively, giving an overall frequency of 12.5% (19/151). The sizes of the deletions were heterogeneous with the most frequent (78%) being 6.7 kb. In addition, 6% (9/151) of the patients presented GH-1 gene mutations such as frameshift, stop codon and splicing error. Furthermore, total GH-1 gene abnormalities varied among different populations from 11.6% in Northern Europe, 14.7% in Mediterranean countries and 31.2% in Asia. Most striking, however, was the low frequency rate of 1.7% (2/119) of GH-1 gene mutations responsible for the most common phenotype of IGHD, namely type IB, among the subjects characterized by the production of deficient but detectable amounts of GH after provocative stimuli. This finding underlines the necessity to focus rather on the promoter region of the GH-1 gene (cis-acting elements andtrans-acting factors), and on other candidate genes specific for the GH axis than the GH-1 gene itself to define genetically the IGHD type IB phenotype in more detail.Abbreviations: CSH,chorionic somatomammotropin gene;CSHP,chorionic somatomammotropin pseudogene;IGHD,isolated growth hormone deficiency

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Long-acting gonadotropin-releasing hormone (GnRH) analogs (GnRH-a) suppress gonadal steroid production and are used in precocious puberty, resulting in an arrest of pubertal development, a slower epiphyseal maturation, and a deceleration of growth, but an increased final height. However, the way that GnRH-a affect growth is not clear. GnRH-a treatment might not only affect gonadal steroid production but might also modulate the GH axis and thereby affect growth. We used a rat model to investigate the long-term effects of prepubertally started GnRH-a treatment (triptorelin) on growth, spontaneous GH secretion, hepatic GH receptors (GHR), and GH-binding protein (GHBP) and compared it with surgical gonadectomy. Triptorelin affected most parameters in the same direction as surgical gonadectomy but to a lesser extent. In females, growth was enhanced by triptorelin, baseline GH secretion was decreased, and hepatic GHR and GHBP were decreased. Apart from these effects on the GH axis, reduction of the direct inhibiting effect of estrogen on growth could be responsible for the triptorelin-induced growth. In males, triptorelin treatment enhanced body weight gain and slightly enhanced gain in length. GH peak amplitude was the only parameter of GH secretion affected and decreased, whereas GHR or GHBP were not affected. This stimulation of weight gain by long-term triptorelin treatment in male rats, which is opposite the effect of surgical gonadectomy, could indicate an interference of GnRH-a in the hormonal regulation of food intake and body weight control. We conclude that triptorelin treatment affected growth and the GH-GHR-GHBP axis in rats, more markedly in females than in males. However, triptorelin was not as effective as surgical gonadectomy.Abbreviations: GnRH,gonadotropin-releasing hormone;GHR,GH receptor;GHBP,GH binding protein;GnRH-a,GnRH analog;BMI,body mass index;TIMP-1,tissue inhibitor of metalloproteinase-1

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Studies in both the human and ovine near-term fetus have identified the clustering of physiologic and behavioral parameters into states. In a recent study in the human fetus a considerable decrease was found in fetal urine production during nonrapid eye movement (non-REM) compared with REM sleep. Whether this decrease was caused by decreased renal blood flow or changes in urine concentration is not known. This prompted us to investigate the relation between fetal urine production rate and electrocortical activity in the near-term ovine fetus. We hypothesized that in the ovine fetus urine production and renal blood flow during REM [comparable to low voltage electrocortical activity (LV ECoG)] would be lower than during non-REM [(high voltage (HV) ECoG)]. In eight fetal sheep between 123 and 127 d of gestation(term 147 d), ECoG, renal blood flow, urine flow, and urine osmolality were measured continuously for 6 h on 2 consecutive days. Data were analyzed into HV ECoG and LV ECoG whereafter urine flow, urine osmolality, and renal blood flow data were averaged per state. We found no significant differences in urine flow, urine osmolality, or renal blood flow between the two behavioral states in the ovine fetus. Because these data are in sharp contrast to those found in the human fetus, we conclude that the observed dissimilarities in renal responses between the human and sheep fetus add to the already known differences in behavioral states between the two species.Abbreviations: HV,high voltage;LV,low voltage;ECoG,electrocortical activity;Pao2,partial pressure of arterial blood O2;Paco2,partial pressure of arterial blood CO2;PRA,plasma renin activity;REM,rapid eye movement;Sao2,arterial oxygen saturation

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

In uterohypoxia may affect the development of the brain and result in altered respiratory responses postnatally. Using a barometric plethysmograph, we examined the effects of exposing pregnant guinea pigs to 200 ppm carbon monoxide (CO) for 10 h/d from d 23-25 of gestation until term(≈68 d) on the ventilatory responses of their 4-5-d-old neonates at rest, and during progressive asphyxia and steady state hypercapnia. Exposure to this concentration of CO produced significantly higher levels of carboxyhemoglobin(COHb) in maternal (8.53 ± 0.6%versus0.25 ± 0.1%) and fetal blood (13.0 ± 0.4%versus1.6 ± 0.1%) from CO-treated animals when compared with controls. Hematocrit was significantly higher in the CO-treated neonates (46.3 ± 1.0%versus41.3± 0.9%) at 5-6 d of age, although no difference existed between the groups for COHb at this time. There was no difference between the groups for length of gestation, litter size, or birth weight, but CO-treated neonates were significantly smaller at 4 d of age (102.4 ± 3.7 g) compared with controls (132.0 ± 5.0 g). At 4-5 d of age there was no difference between the groups for either tidal volume (VT), respiratory frequency (f), or minute ventilation (VE) at rest, but during steady state hypercapnia (4 and 6% CO2) the CO-treated neonates had a significantly greaterVTandVE(but notf) than did controls. During progressive asphyxia, CO-treated animals had a significantly greaterVTthan did controls from 1-8% CO2. There was a significant fall infat 1 and 3% CO2in CO-treated animals; however, this effect did not persist, resulting in a significantly increasedVEfrom 3 to 8% CO2. The inspiratory flow rate(VT/expiratory time) was significantly increased in the CO-treated neonates during progressive asphyxia; this occurred in the absence of a difference in inspiratory time between the groups. These results indicate that prenatal exposure to CO increases CO2sensitivity in 4-5-d-old guinea pigs. This may be due to developmental alterations in the areas of the brainstem responsible for respiratory control.Abbreviations: COHb,carboxyhemoglobin;f,respiratory frequency;Hct,hematocrit;ppm,parts per million;TE,expiratory time;TI,inspiratory time;TTOTAL,total cycle time between breaths;TI/TTOTAL,inspiratory duty cycle;VE,minute ventilation;VT,tidal volume;VT/TI,inspiratory flow rate

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Tidal liquid ventilation (TLV) with perfluorochemical fluid (PFC) has been successfully used experimentally for up to 4 h. However, no studies of prolonged TLV have been reported. We hypothesized that full-term newborn lambs can safely and effectively be liquid-ventilated for up to 24 h. To test this hypothesis, 17 lambs were liquid-ventilated; 7 for 4 h, 5 for 12 h, and 5 for 24 h. Arterial blood samples were obtained for PFC uptake, lipid analysis, and blood gas measurements. Tissues were obtained for histologic and biochemical analysis. Arterial blood gas and mean arterial blood pressure were as follows(mean ± SEM): pH 7.48 ± 0.04; PaCO230.6 ± 2.8; PaO2424 ± 17; mean arterial pressure 76 ± 16 mm Hg. PFC blood levels increased rapidly to a mean of 5.2 ± 3.9 μg/mL. PFC tissue levels increased significantly (p< 0.01) from 260± 45 μg/g at 4 h to 400 ± 140 μg/g at 12 h. There was no further increase in PFC tissue levels by 24 h (456 ± 181 μg/g). There was a significant difference in PFC concentration as a function of tissue (p< 0.01). Furthermore, there was a significant correlation (r= 0.88;p< 0.01) between the amount of PFC and lipid in blood and tissue. Microscopic examination of the lungs demonstrated no evidence of barotrauma. These data demonstrate that prolonged TLV can be safe and efficacious for up to 24 h in full-term newborn lambs.Abbreviations: GC,gas chromatograph;PAI,end inspiratory alveolar pressure;PAE,end expiratory alveolar pressure;PFC,perfluorochemical fluid;TLV,tidal liquid ventilation;VT,tidal volume;PaO2,partial pressure of arterial O2;PaCO2,partial pressure of arterial CO2;FIO2,fractional concentration of inspired CO2;PIO2,partial pressure of inspired O2;PICO2,partial pressure of inspired CO2

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID