Power spectral analysis of heart rate in relation to sleep position

We used spectral analysis of heart rate variability, as a measure of autonomic tone, to determine spectral power differences in infants sleeping supine and prone. We studied 29 infants with a birth weight of 1,915 +/- 939 g, at the postconceptional age of 36 +/- 2 weeks. We then calculated total power (TP), low-frequency power (LF, 0.03-0.15 Hz), and high-frequency power (HF, 0.5-1.0 Hz). TP corresponds to overall heart rate variability, LF to both sympathetic and parasympathetic activity, and HF to parasympathetic activity only. Median (25th, 75th percentile) TP (beats/min2) in the supine position was 32.60 (23.12, 59.90), which was significantly higher than the prone position of 25.87 (14.94, 35.57). Similarly, LF (beats/min2) in the supine position of 13.82 (8.63, 23.31) was significantly higher than the prone position of 9.79 (5.46, 14.33). No significant difference was seen in the HF. We conclude that the prone position is associated with decreased heart rate variability and probably decreased sympathetic tone, which imply decreased autonomic stability in this position.     

Short term arterial remodelling in the aortae of cholesterol fed New Zealand white rabbits shown in vivo by high-resolution magnetic resonance imaging — implications for human pathology

High-resolution, non-invasive imaging methods are required to monitor progression and regression of atherosclerotic plaques. We investigated the use of MRI to measure changes in plaque volume and vessel remodelling during progression and regression of atherosclerosis in New Zealand White rabbits. Atherosclerotic lesions were induced in the abdominal aorta by balloon injury and cholesterol feeding. MR images (2D) of the abdominal aorta were acquired with cardiac and respiratory gating using a fast spin echo sequence with and without fat-suppression. In an initial study on rabbits treated for 30 weeks we imaged the aortae with a spatial resolution of 250x250 micrometers with a slice thickness of 2 mm and achieved a close correlation between MRI-derived measurements and those made on perfusion pressure-fixed histological sections (r(1) = 0.83, slope p(1) < 0.01). We subsequently imaged 18 rabbits before and periodically during 12 weeks of cholesterol feeding (progression) followed by 12 weeks on normal diet (regression). Aortic wall (atherosclerotic lesion) volume increased significantly during progression and decreased during regression. In contrast, lumen volume increased during progression and did not change during regression. In conclusion, this study confirms that non-invasive, high-resolution MRI can be used to monitor progression and regression of atherosclerosis, each within 3 months and shows, for the first time in a short-term model, that positive remodelling occurs early during progression and persists through regression of atherosclerotic lesions.     

Macrophage death and the role of apoptosis in human atherosclerosis

The arterial disease atherosclerosis is responsible for severe morbidity and is the most common cause of death in the Western population. The complete pathogenesis of the disease is unknown, but multiple risk factors have been identified that correlate with the development of its complications such as heart attack and stroke. Evidence suggests that atherosclerosis is an inflammatory disease and the major cell types involved are smooth muscle cells, macrophages, and T lymphocytes. In this paper, we review the function of macrophages in the context of atherosclerosis and we also discuss the role and significance of macrophage death, including apoptosis. There is much evidence, certainly in vitro, suggesting that low-density lipoprotein becomes atherogenic when it undergoes cell-mediated oxidation within the artery wall. Besides inducing apoptosis in vitro, oxidized low-density lipoprotein may also cause extensive DNA damage in intimal cells, which might presage apoptosis. We review the results of experimental and clinical studies, which may indicate how the complications of atherosclerosis could be prevented by using different therapeutical strategies including bone marrow transplantation and gene therapy.     

Parental compliance with home cardiorespiratory monitoring

AIMS—To evaluate parental compliance with home cardiorespiratory monitoring of premature infants with apnoea, siblings of infants who died of sudden infant death syndrome (SIDS), and infants with an apparent life threatening event (ALTE), during the first month of use.METHODS—A retrospective review of the first month''s recordings was conducted on 39 premature infants with apnoea, 13 siblings of SIDS, and 16 infants with ALTE. All infants were singletons. Recommendations during the study period (1992-1994) were for daily use for 23hours per day. Measurements were average daily hours of use and consistency of use (daily or variable). Gestational age, maternal age, and socioeconomic status as measured by receipt of public assistance were also recorded.RESULTS—Siblings of SIDS were monitored for fewer hours than were premature or ALTE infants. Only 54% of sibings of SIDS were monitored daily, compared to 87% of premature infants and 93% of ALTEs. Within each diagnostic category socioeconomic status did not affect average hours of monitoring. Consistency of use was more evident in those with private insurance, although the trend did not reach significance.CONCLUSIONS—Parents of infants with apnoea of prematurity or ALTE are highly compliant with cardiorespiratory monitoring recommendations in the first month of monitor usage. Siblings of SIDS are monitored for fewer hours and are less likely to be monitored on a daily basis.     

Antecedents and neonatal consequences of low Apgar scores in preterm newborns: a population study

BACKGROUND: To examine the antenatal and early neonatal correlates of low Apgar scores (<3 and <6 at 1 and 5 minutes) in preterm newborns (23-34 weeks' gestation). OBJECTIVE: The use of Apgar scoring for premature newborns remains widespread, despite controversy regarding its reliability as a measure of morbidity and mortality in the neonatal period. DESIGN: A cohort of 852 preterm newborns born during a 34-month period between 1984 and 1987 was studied. Newborns were stratified into 2 groups by gestational age (23-28 weeks and 29-34 weeks), and data were analyzed, controlling for gestational age in single weeks. SETTING: Two academic and 1 community hospital, which together accounted for 83% of all preterm births in a tri-county area of central New Jersey during the study period. PATIENTS: All premature newborns (birth weight <2000 g and gestational age <35 weeks) born in the participating hospitals during the study period were evaluated. MAIN OUTCOME MEASURES: Antecedents included maternal illness during pregnancy, maternal complications of labor and delivery, and fetal heart rate abnormalities during labor and delivery. Consequences included delivery room resuscitation, abnormal physical findings, diagnoses, and therapeutic interventions in the first 6 to 8 hours of life. RESULTS: Premature newborns with low Apgar scores received more cardiopulmonary resuscitation in the delivery room and in the first 6 to 8 hours of neonatal intensive care. Mortality was significantly increased among newborns with low Apgar scores (54% vs. 26% in the 23- to 28-week stratum, 30% vs 6% in the 29- to 34-week stratum). Newborns with low Apgar scores in the 29- to 34-week stratum more often required intubation, positive pressure ventilation, and umbilical vessel catheterization. Newborns with low Apgar scores had higher rates of bradycardia, pneumothoraces, acidosis, and increased oxygen requirement during the first 6 to 8 hours of life. Maternal illness, complications of labor and delivery;, and fetal heart rate decelerations did not correlate with subsequent Apgar scores of newborns. The presence of severe bradycardia (<90/min) and fetal heart rate accelerations correlated with low Apgar scores in the 29- to 34-week group. CONCLUSION: Low Apgar scores are associated with increased neonatal morbidity and mortality in preterm newborns. Antenatal maternal history, and pregnancy complications are not clearly associated with low Apgar scores. Therefore, the Apgar score is a useful tool in assessing neonatal short-term prognosis and the need for intensive care among preterm newborns.     

Asynchronous activation of calcium and potassium currents by isoproterenol in canine ventricular myocytes

Adrenergic activation of L-type Ca²⁺ and various K⁺ currents is a crucial mechanism of cardiac adaptation; however, it may carry a substantial proarrhythmic risk as well. The aim of the present work was to study the timing of activation of Ca²⁺ and K⁺ currents in isolated canine ventricular cells in response to exposure to isoproterenol (ISO). Whole cell configuration of the patch-clamp technique in either conventional voltage clamp or action potential voltage clamp modes were used to monitor I _Ca, I _Ks, and I _Kr, while action potentials were recorded using sharp microelectrodes. ISO (10 nM) elevated the plateau potential and shortened action potential duration (APD) in subepicardial and mid-myocardial cells, which effects were associated with multifold enhancement of I _Ca and I _Ks and moderate stimulation of I _Kr. The ISO-induced plateau shift and I _Ca increase developed faster than the shortening of APD and stimulation of I _Ks and I _Kr. Blockade of β₁-adrenoceptors (using 300 nM CGP-20712A) converted the ISO-induced shortening of APD to lengthening, decreased its latency, and reduced the plateau shift. In contrast, blockade of β₂-adrenoceptors (by 50 nM ICI 118,551) augmented the APD-shortening effect and increased the latency of plateau shift without altering its magnitude. All effects of ISO were prevented by simultaneous blockade of both receptor types. Inhibition of phosphodiesterases decreased the differences observed in the turn on of the ISO-induced plateau shift and APD shortening. ISO-induced activation of I _Ca is turned on faster than the stimulation of I _Ks and I _Kr in canine ventricular cells due to the involvement of different adrenergic pathways and compartmentalization.     

通莲汤对胃癌MGC803细胞周期及NF-κBs信号通路的影响

目的: 研究通莲汤对胃癌MGC803细胞形态、生长周期的调节作用及细胞核转录因子κB(NF-κB)信号通路的影响,以探讨该方抑制胃癌细胞增殖的机制。 方法: 将MGC803细胞以1×10⁴个细胞/孔的密度接种于96孔细胞培养板,以含5%胎牛血清DMEM培养液培养,37 ℃,5%饱和湿度的CO₂培养箱孵育,细胞贴壁24 h,分别加入浓度为25~800 mg·L^-1倍比梯度的通莲汤提取液,以10~160 mg·L^-1倍比浓度的氟脲嘧啶为阳性对照组,孵育48 h后,倒置显微镜下观察细胞形态,MTT比色法检测细胞增殖变化,曲线拟合法计算通莲汤和氟脲嘧啶50%抑制浓度(IC₅₀);以两者48 h IC₅₀浓度处理细胞48 h,流式细胞技术(FCM)测定细胞周期,Western blot法测定细胞IκB激酶β(IKKβ),NF-κB,phosph-NF-κB蛋白水平。 结果: 通莲汤和氟脲嘧啶48 h IC₅₀值分别为192.74 mg·L^-1,23.61 mg·L^-1;与空白对照组相比,通莲汤显著影响MGC803细胞周期中G₂期,氟脲嘧啶显著影响MGC803细胞周期中G₁期(P<0.05);通莲汤和氟脲嘧啶均能显著抑制IKKβ与NF-κB的蛋白表达。 结论: 通莲汤抑制MGC803细胞生长与抑制细胞于G₂期,下调NF-κB通路中IKKβ,NF-κB蛋白的表达有关。     

Serum levels of unbound free fatty acids. I: Normative data in term newborn infants.

Free fatty acids (FFA) play essential roles in maintaining physiologic homeostasis in the newborn infant. Most of the FFA in serum is carried in complex with albumin, but a small fraction remains unbound in the aqueous phase.

This study's goal is to report the values of serum levels of unbound free fatty acids (FFAu) in pregnant women and their newborn infants at term gestation.

The measurements were made possible by the availability of the fluorescent probe for unbound FFA, acrylodated intestinal fatty acid binding protein (ADIFAB). Twenty-two mother-infant pairs were enrolled in the study. Maternal levels were obtained immediately before delivery, cord levels at the time of delivery, and infant levels after 24 hours of age.

The level of FFAu measured in maternal samples was 11.8 +/? 4 nM, in cord samples 9.2 +/? 4 nM, and in infants 13.9 +/? 3 nM. These population averages are considerably greater than those observed in healthy adults (7.5 +/? 2.5 nM). No correlation was found between cord levels and birthweight, gestational age, labor duration, mode of deliver, and infant or maternal temperature.

This investigation is the first to measure FFAu in a group of mothers and their infants and provides the technique for future investigations of the biologic activity of free fatty acids.     

Pancreatic secretory responses in L-arginine-induced pancreatitis: comparison of diabetic and nondiabetic rats.

The aim of this work was to study cholecystokinin-octapeptide (CCK-8)-stimulated pancreatic secretion after the induction of pancreatitis with L-arginine (ARG) in rats with or without streptozotocin (STZ) diabetes. One, 3, 7, and 14 days after pancreatitis induction, rats were surgically prepared with pancreatic duct and femoral vein cannulae under urethane anesthesia. Graded doses of CCK-8 ranging from 9 to 2,400 ng/kg/30 min were administered intravenously. In the control group, the step-wise increasing doses of CCK-8 resulted in a characteristic dose-response curve for the pancreatic volume, protein and amylase secretion (maximal volume, protein and amylase output at 600 ng/kg/30 min of CCK-8: 157 +/- 20.2 microl/30 min, 28.3 +/- 1.18 mg/30 min, and 3,750 +/- 92 IU/30 min, respectively). In rats with pancreatitis, the pancreatic volume (both basal and maximal) and amylase secretion were significantly elevated on day 1 versus the control group; then on days 3,7, and 14, the pancreatic secretory volume and amylase were progressively and significantly decreased versus the control group. However, the protein output was continuously decreased versus the control group on days 1, 3, 7, and 14. In diabetic rats, the maximal volume and protein and amylase output were all significantly decreased versus the control group throughout the experiment. In the diabetes + pancreatitis group, the maximal volume and protein and amylase output were all significantly increased versus the diabetes group on days 1, 3, 7, and 14. These results indicate that in the early phase of ARG-induced pancreatitis, the pancreatic secretion is characterized by increases in secretory volume and amylase, with a simultaneous decrease in protein output. Simultaneous diabetes seems to moderate the CCK-8-stimulated secretory changes in both the early and late phases after ARG-induced pancreatitis.