Alloxan-induced diabetes mellitus in pregnant sheep and chronic fetal catheterization.

25 female sheep of the Texel breed were made hyperglycaemic by administration of alloxan monohydrate (ALX) in early pregnancy and 15 ewes served as controls. Average venous glucose levels (mean +/- standard deviation) increased from 3.5 +/- 0.

Alinidine as a model of the mode of action of specific bradycardic agents on SA node activity.

Three different bradycardic agents, alinidine, AQ-A39 and UL-FS49 increase the intrinsic cycle length of the isolated SA node preparation of the rabbit. This increase is mainly caused by a decrease in rate of diastolic depolarization. One of these agents, alinidine, was used to study the underlying ionic mechanism of the decrease in the diastolic depolarization rate in isolated cells and small cell clusters of the rabbit SA node.

Functional morphology of the pig sinoatrial node.

The porcine sinoatrial node in an isolated right atrium preparation is characterized by unifocal impulse generation. It has a rather elongated shape and the larger part of its volume is taken up by collagen and fibroblasts. The impulse appears to emerge from a site where the percentage of myofilaments is relatively low.

Functional morphology of the mammalian sinuatrial node.

The primary pacemaker area is located at the site with lowest percentage of myofilaments and the highest rate of diastolic depolarization in rabbit, guinea-pig, cat and pig. All investigated sinuatrial nodes contained large amounts, 45% or more, of collagen. There was, however, substantially more collagen in the sinuatrial nodes of the cat and the pig than in the rabbit and the guinea-pig.

Plasma atrial natriuretic peptide (ANP) in late pregnancy and puerperium.

Plasma concentrations of atrial natriuretic peptide (ANP) were determined ante- and post-partum in 7 healthy primiparous women. ANP was measured at weekly intervals from the 35th week of pregnancy onwards and throughout the puerperium up to the sixth week post-partum. In all seven patients the mean of the ANP values during the first four days post-partum was higher than in late pregnancy.

The intrinsic cycle length in small pieces isolated from the rabbit sinoatrial node.

In this study we show that small pieces of tissue cut from the intact sinoatrial node beat faster, but with the same regularity as the intact sinoatrial node. The pieces with highest diastolic depolarization rate are not isolated from the primary pacemaker area, but from sites closer to the crista terminalis. In pieces cut from the primary pacemaker area, changes in the action potential configuration are restricted to the action potential duration, whereas in pieces cut from sites closer to the crista terminalis, not only the action potential duration has decreased, but also the diastolic depolarization rate has increased.

The development of beat-rate synchronization of rat myocyte pairs in cell culture.

When two spontaneously beating neonatal rat heart cells in tissue culture were allowed to grow together they synchronized their originally independent beats to a common rhythm, as measured with an opto-electronic technique. Both single isolated cells and cell pairs exhibited a highly irregular beating pattern. Beating irregularity was strongly and positively correlated with mean interbeat interval.

Lethal lung hypoplasia in infants after prolonged rupture of membranes.

A retrospective study to detect the frequency of lethal lung hypoplasia in 48 cases with prolonged rupture of membranes (greater than 7 days) before 34 weeks' gestation was made. Fourteen infants died (29%), but only four deaths (8.3%) were due to lung hypoplasia.

Effect of reducing uteroplacental blood flow on movements and on electrocortical activity of fetal sheep.

Eight chronically instrumented fetal sheep were asphyxiated for 1 h by partial occlusion of the uterine blood supply. Fetal movements, as reflected by phasic activity in the nuchal electromyogram, decreased during the period of asphyxia. Tonic activity also decreased.

A comparative study of three indices of umbilical blood flow in relation to prediction of growth retardation.

The literature reporting Doppler ultrasound flow velocity waveform analysis of the umbilical artery and its applications for detecting intrauterine growth retardation (IUGR) is growing rapidly. Several indices originally introduced to evaluate different vascular beds in adults, are used to assess the vascular bed resistance downstream the umbilical artery (i.e.

The umbilical artery blood flow velocity waveform in relation to fetal breathing movements, fetal heart rate and fetal behavioural states in normal pregnancy at 37 to 39 weeks.

In 19 normal pregnancies between 37 and 39 weeks of gestation, the blood flow velocity waveform (FVW) of the umbilical artery was studied in relation to fetal breathing movements, fetal heart rate (FHR) and the fetal heart rate patterns (FHRPs) A and B. FHRP A is stable, with a narrow oscillation bandwidth, FHRP B shows a wider oscillation bandwidth. Although for state-assessment it is necessary to record three variables simultaneously, the linkage of these variables in the near-term healthy fetus is such, that FHRP A and B may be used for the assignment of behavioural states 1F and 2F.

Obstetrical policy during labor and perinatal results: a comparison between two university clinics.

The obstetrical policy during labor at two University clinics in Nottingham (United Kingdom) and Nijmegen (The Netherlands) was investigated prospectively and simultaneously during a period of three months (1984). At the University of Nijmegen the obstetrical population tended to be more 'pathologic', and less intervention during labor was observed for early amniotomy, pain relief, induction and augmentation of labor. The pH in umbilical arterial blood was as a mean 0.

Electrophysiological effects of alinidine (ST 567) on sinoatrial node fibres in the rabbit heart.

In a study of the electrophysiological effects of alinidine a concentration of 0.7-14.3 mumol X litre-1 decreased the rate of diastolic depolarisation and prolonged especially the terminal part of the action potential in the rabbit sinoatrial node.

Functional and morphological organization of the cat sinoatrial node.

The feline sinoatrial node has a unifocal impulse generation as previously described for rodents. Its main component is collagen. The primary pacemaker consists of at most 2000 cells, but appears to function normally with less than 500 cells.

Classification of fetal and neonatal heart rate patterns in relation to behavioural states.

For the assessment of behavioural states in the human fetus, the fetal heart rate (FHR) pattern is one of the state variables. A statistical method is described to classify FHR patterns. FHR recordings were made between 38 and 40 wk gestation.

Effects of maternal glucose ingestion on human fetal breathing movements at weeks 24 and 28 of gestation.

The incidence of human fetal breathing movements was studied in normal pregnancies before and after administration of 50 g glucose or a placebo (water) at 24 and 28 weeks. Glucose or water was given to the same women on two separate days in a randomised order. No significant differences were present among the results on the placebo-day and the control period of the glucose-day at either gestational age.

The potential distribution generated by the fetal heart at the maternal abdomen.

The pathways along which the electrical currents generated by the fetal heart are conducted to the surface of the maternal abdomen are not known. As a consequence, in recording the fetal electrocardiogram (FECG) it is hard to predict where electrodes should be placed in order to obtain an optimal signal. The amplitude of the FECG varies with gestation, and there is a large interindividual variability in the amplitude of the FECG and in the optimal recording site among subjects within the same gestational age.

Cardiovascular changes due to premature closure of the ductus arteriosus: a mathematical model.

Changes in the fetal cardiovascular system due to premature closure of the ductus arteriosus are described using a previously validated mathematical model. Results of the simulated closure of the ductus arteriosus are compared with reported results from animal experiments in which the ductus arteriosus was closed pharmacologically with prostaglandin synthetase inhibitors. The computed cardiovascular changes after ductus closure in the model resemble the changes obtained by administration of indomethacin.

Functional and morphological organization of the guinea-pig sinoatrial node compared with the rabbit sinoatrial node.

The primary pacemaker, i.e. the group of pacemaker cells discharging the sinoatrial node comprises less than 1000 cells in the guinea-pig and about 5000 cells in the rabbit.

The second twin.

Perinatal data on 76 twin pregnancies demonstrated a significantly (P less than 0.01) lower Apgar score and acidemia in the umbilical artery for the second twin. Factors such as female sex, prematurity, low birth-weight and instrumental delivery accounted for this difference (P less than 0.

Cycle length dependence of the chronotropic effects of adrenaline, acetylcholine, Ca2+ and Mg2+ in the Guinea-pig sinoatrial node.

Ca (1.1-5.5 mM) has a positive chronotropic action on isolated right atria of the guinea-pig.

The passive electrical properties of spheroidal aggregates cultured from neonatal rat heart cells.

Membrane specific resistance and capacitance of non-spontaneously active spheroidal aggregates, cultured from collagenase-dissociated neonatal rat heart cells, were calculated from changes in membrane potential due to intracellularly injected rectangular hyper- and depolarizing current pulses during diastole. The relation between steady-state membrane voltage displacement and injected current is linear for current pulses between +10 and -10 nA. No significant fall-off of electrotonic potential is measured in an aggregate at increasing distances from the site of current injection.

Phase resetting properties of cardiac pacemaker cells.

Aggregates of heart cells from chicken embryos beat spontaneously. We used intracellular microelectrodes to record the periodic behavior of the membrane potential that triggers the contractions. Every 5-12 beats, a short current pulse was applied at various points in the cycle to study the phase-dependent resetting of the rhythm.