ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Mammalian cardiac myocytes express multiple gap junction channel proteins or connexins. Expression patterns of the avian homologues of the mammalian cardiac connexins change during cardiac morphogenesis in association with changes in the electrophysiologic properties of intercellular junctions in chick cardiac myocytes. To determine whether expression of cardiac connexins is developmentally regulated in humans, we characterized connexin mRNA and protein content and distribution in hearts of 11 human fetuses (74 to 122 d gestational age), seven children (0.5 mo to 3 y of age), and two adults. Northern blot analysis identified transcripts of connexin40 (Cx40), connexin43 (Cx43), and connexin45 (Cx45) genes in all hearts analyzed. Cx40 mRNA was approximately 5-fold more abundant in samples from fetal hearts than in hearts of children or adults. However, fetal samples used for RNA extraction included atrial as well as ventricular myocardium, whereas samples from children and adults were exclusively ventricular. Northern analysis of adult human right atrial appendages revealed abundant Cx40 mRNA, thus suggesting that the greater amount of Cx40 signal seen on Northern blots from fetal hearts could have been attributable to atrial contributions. Neither Cx43 nor Cx45 mRNA varied significantly in amount in samples from the different developmental stages analyzed. Immunofluorescence identified abundant Cx43 in the known distribution of gap junctions in myocytes in sections of all hearts. Cx45 staining was inconspicuous in fetal hearts but was readily apparent in cardiac myocytes in hearts of older subjects. In contrast, Cx40 staining in the ventricle was confined to mural coronary arteries, apparently in endothelial cells, whereas in the atrium Cx40 staining at myocyte junctions was abundant. Junctions in hypertrophied myocardium of children with congenital or acquired heart disease appeared more prominent and complex than in normal tissues. Thus, the human heart contains multiple connexins, but their distribution and developmental patterns differ from each other and from those in other species. Cx45 expression is not restricted to the fetal human heart. Cx40 expression in ventricles occurs selectively in coronary arteries.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The use of conventional methods to detect a possible infectious cause of Kawasaki disease (KD) has been unsuccessful. Using the polymerase chain reaction and DNA hybridization techniques, we have sought evidence that a known or new herpesvirus, parvovirus, or bacterial pathogen is related etiologically to KD. Peripheral blood DNA from acute KD patients was subjected to amplification and dot-blot hybridization to detect the presence of herpesvirus DNA, and acute KD peripheral blood and serum DNA were subjected to dot-blot hybridization for the presence of parvoviral DNA. All samples were negative for both herpesvirus and parvovirus DNA. In addition, we analyzed buffy-coat white blood cell DNA, synovial fluid DNA, and frozen autopsy and formalin-fixed, paraffin-embedded myocardial tissue DNA from KD, patients for the presence of highly conserved bacterial 16S ribosomal RNA gene sequences with the polymerase chain reaction, and all were negative. These results argue against a direct pathogenic role for herpesviruses, parvoviruses, and bacteria in KD. This approach to the detection of highly conserved genomic sequences among broad groups of microorganisms can be adapted for the detection of other groups of microorganisms and may yet prove useful in the search for an etiologic agent of KD.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The plasma creatinine concentration is elevated at birth and decreases concomitantly with the rapid increase in glomerular filtration rate that occurs in the first postnatal weeks. The velocity of these changes was assessed during the first 3 wk of life of 66 term and preterm infants. The plasma creatinine concentration, creatinine clearance, and sodium fractional excretion were measured serially at weekly intervals, starting 1–4 d after birth [mean = 1.5 ± 0.8 (SD) d]. Premature infants were separated into three groups according to their birth weight: group 1, 1001 to 1500 g; group 2, 1501 to 2000 g; and group 3, 2001 to 2500 g. Group 4 included 28 term infants (mean birth weight = 3165 ± 78 g). Mean gestational ages in the preterm groups were 31.3, 32.8, and 34.4 wk in groups 1, 2, and 3, respectively. The plasma creatinine concentration on d 1.5 was significantly higher in preterm (91 ± 4 μmol/L) compared with term infants (66 ± 3 μmol/L). The differences in plasma creatinine were still present during the second week of life, with values of 64 ± 5, 58 ± 7, 47 ± 8, and 40 ± 4 μmol/L in groups 1, 2, 3, and 4, respectively. The difference vanished by d 22–23. On d 1.5, creatinine clearance correlated positively with gestational age, amounting to 0.65 ± 0.14, 0.92 ± 0.19, 1.42 ± 0.31, and 3.36 ± 0.32 mL/min in groups 1, 2, 3, and 4, respectively. Creatinine clearance increased rapidly with postnatal age, the velocity of the maturation being less marked in the most premature infants. The fractional excretion of sodium was significantly higher in the most premature infants, with values of 2.0 ± 0.3, 2.2 ± 0.5, 1.1 ± 0.2, and 0.3 ± 0.1% in groups 1, 2, 3, and 4, respectively. The differences vanished by the third week of life. The negative correlation between plasma creatinine on d 1.5 and gestational age suggests that the neonate's creatinine plasma concentration does not simply reflect the mother's plasma concentration.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The effects of gestational age (GA), body weight, and prenatal exposure to betamethasone and indomethacin on the glomerular filtration rate (GFR) on d 3 of life in preterm infants were studied. GFR measurements were performed in 147 preterm infants with a GA between 23.4 and 37.0 wk by means of the continuous inulin infusion technique. Mean GFR values increased significantly with GA (r= 0.60,p< 0.001) and with body weight (r= 0.44,p< 0.001). Multivariate analysis indicated that GA was the most important determinant for this increase. Prenatal exposure to indomethacin resulted in significantly lower GFR values (-0.15 ± 0.03 mL/min,p< 0.001) at d 3 after birth. Prenatal administration of betamethasone and indomethacin significantly (p< 0.001) increased the GFR in comparison with exposure to indomethacin alone to levels not different than those seen in patients who were not prenatally exposed to betamethasone or indomethacin. GFR measurements were repeated in 40 preterm infants on d 10 after birth. During this 7-d period, a significant increase in GFR values (0.17 ± 0.03 mL/min,p< 0.001) was detected. This postnatal increase in GFR values was independent of GA and was not influenced by prenatal exposure to betamethasone or indomethacin. We conclude that prenatal exposure to betamethasone or indomethacin exerts significant effects on the renal function of preterm infants in the first days of life. (Pediatr Res36: 578–581, 1994)

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

An infant girl presented with recurrent episodes of Reye-like syndrome associated with hypoketosis and plasma carnitine levels in the high-normal range. A liver biopsy revealed massive macrovesicular steatosis. Ketogenesis was absent after a long-chain triglyceride loading test; in contrast, the medium-chain triglyceride loading test resulted in a brisk rise in plasma ketone concentration. Carnitine palmitoyltransferase I deficiency was demonstrated in cultured skin fibroblasts. Hypoglycemia was only found once in the neonatal period. Renal carnitine handling was normal except for a higher renal threshold for free carnitine. Mild, persistent metabolic acidosis was a constant feature, even during periods between metabolic decompensation. Evaluation of the renal acidification capacity showed a failure to acidify the urine during spontaneous acidosis but increased acid excretion and a normal decrease of urinary pH after acid loading. Also, a small difference between urine and blood PCO2was found after bicarbonate administration. This acidification defect can best be explained as an abnormality in distal tubular H+secretion: a rate-dependent distal tubular acidosis. It is speculated that long-chain acylcarnitines, substances that cannot be formed by carnitine palmitoyltransferase I-deficient patients, play an essential role in renal acid-base homeostasis.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The effects of perivascular blood on pial arteriolar vasoreactivity to selected vasodilators and vasoconstrictors were examinedin vivoin a newborn pig model. α-Chloralose-anesthetized newborn pigs were fitted with closed cranial windows 4 d after cortical subarachnoid injections of autologous blood. The responsiveness of pial arterioles; to topical application of dilator agents [iloprost, prostaglandin E2(PGE2), histamine, and sodium nitroprusside (SNP)] and vasoconstrictor agents [leukotriene C4and endothelin-1 (ET-1) in artificial cerebrospinal fluid was studied in control and blood-injected piglets. Pial arterioles dilated dose dependently in response to topical application of iloprost, PGE2, histamine, and SNP in the control group, with increases in diameter of 54, 44, 67, and 50% at 10-8M, 10-5M, 10-5M, and 10-5M, respectively. These dilations in response to iloprost, PGE2, and histamine in the blood-injected piglets were significantly attenuated to 23, 18, and 34%, respectively, whereas the dilation in response to SNP was not changed (64%). Constrictions in response to 10-8M leukotriene C4and ET-1 were 16 and 26% and were potentiated by hematoma to 36 and 43%, respectively. The lowest dose of ET-1 (10-12M) significantly dilated pial arterioles in the control but not in the blood-treated group. We conclude that prolonged exposure of pial arterioles to perivascular blood attenuates cerebrovascular dilation in response to selected vasoactive agents (iloprost, PGE2, and histamine) but not to SNP, suggesting that blood-induced attenuation of vasodilation and the generalized vasoconstriction may involve inhibiting the prostanoid/cAMP signaling pathway. Potentiation of vasoconstriction induced by ET-1 and leukotriene C4in the hematoma group could be due to loss of this dilator influence.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

During severe oxygen shortage, the fetal brain resorts to anaerobic metabolism and AT? becomes catabolized. High levels of nucleosides, hypoxanthine, and xanthine (ATP catabolites) in cerebrospinal fluid (CSF) may therefore be associated with increased neonatal neurologic morbidity. In 22 fetal lambs (3 to 5 d after surgery, gestational age 123.5 ± 3.5 d), arterial oxygen content was progressively reduced to 35% of the baseline value with a balloon occluder around the maternal common internal iliac artery. This resulted in a 1-h period of asphyxia, leading to a pH of 7.02 ± 0.03 and a base excess of −17.0 ± 1.0 mM. Mortality was 50%. CSF was sampled from the spinal cistern and analyzed using HPLC. During reoxygenation, hypoxanthine and xanthine may serve as substrate for xanthine oxidase with concomitant production of oxygen-derived free radicals, which may aggravate cerebral damage. The main difference between surviving and nonsurviving animals was the speed of increment of ATP catabolites in CSF: in the surviving group levels increased steadily, recovery values being significantly elevated compared with asphyxia values, whereas in the nonsurviving group the rise was rapid and levels during asphyxia did not differ significantly from levels during recovery. We conclude that1) catheterization of the spinal cistern leads to increased levels of CSF hypoxanthine, xanthine, and inosine, and2) during fetal asphyxia, levels of these ATP catabolites and lactate in CSF increase.3) Maximum levels are reached during the recovery period and are similar for surviving and nonsurviving animals, but during asphyxia CSF levels of hypoxanthine and lactate were higher in the nonsurviving fetuses.4) The rate of increase of ATP catabolites in CSF is higher in the nonsurviving animals and may therefore be predictive for fetal death.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID