Changes in maternal cardiovascular parameter during tocolysis and in the dorsal position shock syndrome (author's transl)

Maternal circulatory parameters and fetal heart rate were measured in 25 healthy pregnant women in the last trimenon during treatment with Fenoterol, Fenoterol in combination with Verapamil and Verapamil alone. Dosages were used in accordance with the tocolytic guidelines from Weidinger and Wiest. We were able to demonstrate that the betamimetic Fenoterol alone and in combination with the Ca++-antagonist Verapamil strongly increases the maternal heart rate an the maternal cardiac output whereas the peripheral resistance decreases accordingly. The average blood pressure stayed leveled, so that a decreased uterine blood flow cannot be assumed under betamimetics from the maternal cardiovascular point of view. However, there are indications for an increased placental blood flow during tocolysis. The betamimetic drug show no significant effect on the fetal heart rate. Additional application of the Ca++-antagonist Verapamil during tocolysis with Fenoterol (in dosages usually used for tocolysis) doesn't change cardiovascular reactions caused by Fenoterol. Change in position from supine to left lateral position caused a short term increase in the maternal cardiac output even noted in pregnant women without a clinically observed cavasyndrom. These changes of maternal cardiac output are comparable with those in orthostatic stress situations.     

Dual microelectrodes for distance control and detection of nitric oxide from endothelial cells by means of scanning electrochemical microscope

Dual Pt disk microelectrodes consisting of a 10-microm distance sensor and a 50-microm nitric oxide sensor were prepared. The 50-microm electrode was modified with Ni(4-N-tetramethyl)pyridyl porphyrin enclosed in the polymer network of a negatively charged electrodeposition paint. This paint prevented the dissolution of the otherwise soluble porphyrin in the aqueous test medium due to charge interactions. It also denied negatively charged ions in the analyte solution access to the electrode surface by electrostatic repulsion, thereby preventing interference from anions such as nitrite, nitrate, and ascorbate. With the aid of a scanning electrochemical microscope, it was possible to use the distance sensor by recording the negative feedback effect on the reduction of molecular oxygen to "guide" the nitric oxide sensor to various known distances from a layer of adherently growing human umbilical vein endothelial cells for the detection of nitric oxide released from the cells upon stimulation with bradykinin. The use of the distance sensor made it possible to preserve the integrity of the adherently growing cells concomitantly with the modified electrode by preventing the deterioration of the modifying layer during the distance adjustment step.     

Residual stresses in thin polymer films cause rupture and dominate early stages of dewetting

In attempting to reduce the size of functional devices, the thickness of polymer films has reached values even smaller than the diameter of the unperturbed molecule. However, despite enormous efforts for more than a decade, our understanding of the origin of some puzzling properties of such thin films is still not satisfactory and several peculiar observations remain mysterious. For example, under certain conditions, such films show negative expansion coefficients or show undesirable rupture although energetically they are expected to be stable. Here, we demonstrate that many of these extraordinary effects can be related to residual stresses within the film, resulting from the preparation of these films from solution by fast evaporation of the solvent. Consequently, depending on thermal history and ageing time, such films show significant changes even in the glassy state, which we quantify by dewetting experiments and corresponding theoretical studies. Identifying the relevance of frozen-in polymer conformations gives us a handle for manipulating and controlling properties of nanometric thin polymer films.     

Cataloging altered gene expression in young and senescent cells using enhanced differential display

Recently, a novel PCR-based technique, differential display (DD), has facilitated the study of differentially expressed genes at the mRNA level. We report here an improved version of DD, which we call Enhanced Differential Display (EDD). We have modified the technique to enhance reproducibility and to facilitate sequencing and cloning. Using EDD, we have generated and verified a catalog of genes that are differentially expressed between young and senescent human diploid fibroblasts (HDF). From 168 genetags that were identified initially, 84 could be sequenced directly from PCR amplified bands. These sequences represent 27 known genes and 37 novel genes. By Northern blot analysis we have confirmed the differential expression of a total of 23 genes (12 known, 11 novel), while 19 (seven known, 12 novel) did not show differential expression. Several of the known genes were previously observed by others to be differentially expressed between young and senescent fibroblasts, thereby validating the technique.     

Combining 2 x 2 tables that contain structural zeros

When one cell or more of a contingency table is necessarily zero, the table is said to contain structural zeros. These structural voids may be inherent to the problem at hand, or, in some applications, they may be introduced intentionally through the experimental design. With data classified by a third stratification variable, one needs a method for analysing a set of independent 2 x 2 tables. We propose Cochran-Mantel-Haenszel type analyses that combine observations across strata. We also propose tests of hypotheses pertaining to the marginal and conditional probabilities.     

Hemispheric specialization in infant chimpanzees (Pan troglodytes): evidence for a relation with gender and arousal

The current study extends previous documentation of behavioral asymmetries in hand-to-mouth, self-consoling behaviors of infant chimpanzees. The underlying source of lateralized hand-to-mouth, self-calming behavior was investigated by comparing individual differences in neonatal arousal levels, regulatory ability, and motor performance with individual differences in the degree of laterality at 3 months. Asymmetrical hand-to-mouth, self-calming behaviors at 3 months of age were significantly related to general arousal at 2 days of age (i.e., the Range of State cluster scores measured by the Brazelton Neonatal Behavioral Assessment Scale). Simply stated, chimpanzees with a right-hand bias in hand-to-mouth behavior exhibited lower arousal at 2 days of age compared with nonright-handed individuals. The only item of the Range of State cluster to distinguish subjects was irritability: Right-handed subjects were less irritable. Previously, a trend was reported with respect to sex differences in the laterality of hand-to-mouth behavior. With the greater number of subjects in the present study, we found that females exhibited a significantly greater right-hand bias for hand-to-mouth behaviors (12 of 13) than did males (9 of 15). We conclude that neonatal arousability, and not regulatory capacity or motor performance, predicts the degree of laterality found in hand-to-mouth, self-calming behaviors in 3-month-old chimpanzees. These data are discussed from the standpoint of early pari-parturitional or intrauterine factors affecting lateralized development.     

Real-time ultrasonic scan conversion via linear interpolation of oversampled vectors

Scan conversion is required in order to display conventional B-mode ultrasonic signals, which are acquired along radii at varying angles, on standard Cartesian-coordinate video monitors. For real-time implementations, either nearest-neighbor or bilinear interpolation is usually used in scan conversion. If the sampling rate along each radius is high enough, however, the gray-scale value of a given pixel can be interpolated accurately using the nearest samples on two adjacent vectors. The required interpolation then reduces to linear interpolation. Oversampling by a factor of 2 along with linear interpolation was superior to bilinear interpolation of vectors sampled to match pixel-to-pixel spacing in 6 representative B-mode images. A novel 8-bit linear interpolation algorithm was implemented as a CMOS VLSI circuit using a readily available, high-level synthesis tool. The circuit performed 30 million interpolations per second. Arithmetic results produced by the 8-bit interpolator on 7-bit samples were virtually identical to IEEE-format, single-precision, floating-point results.     

Retention of insoluble particles after local intrabronchial deposition in dogs

Recent studies have challenged the generally accepted hypothesis that bronchial particle clearance is complete within 24-48 h postdeposition. We studied bronchial retention of inert particles using a bronchoscope and microspray nozzle to localize deposition in a bronchus while avoiding alveolar deposition. Six-microliter aliquots (444 kBq) of submicrometer (number mean diameter = 0.22 microns, geometric standard deviation = 1.75) technetium-99m-labeled (99mTc) sulfur colloid (SC) particles (n = 6) or the unbound radiolabel 99mTc-pertechnetate (99mTcO4-; n = 3) were sprayed onto a 5-mm-diam bronchus in halothane-anesthetized dogs. Radioactivity at the deposition site and clearance pathway was monitored externally with a gamma camera beginning immediately postspray. Bronchial retention of SC was 8.5 +/- 2.4 and 1.5 +/- 0.7% at 3 and 24 h postspray, respectively. Tracheal mucus velocity was measured at 10.4 +/- 2.2 mm/min. For comparison, clearance of inhaled submicrometer SC particles was also measured in the same dogs. Retention of inhaled aerosolized SC (peripheral lung deposition) was 98.1 +/- 1.1 and 76.3 +/- 1.8% at 3 and 24 h, respectively. 99mTcO4- cleared from the bronchi slightly more rapidly than did SC. Radioactivity was readily detected in the blood after deposition of 99mTcO4- but not of SC. Thus SC cleared by mucociliary transport, whereas 99mTcO4- cleared predominantly by transepithelial absorption. We conclude that clearance of submicrometer particles from a 5-mm conducting airway is very nearly complete by 24 h, with approximately 92% of the clearance occurring within the first 3 h postdeposition.     

Electrophysiological evidence for oxytocin receptors on sympathetic preganglionic neurones--an in vitro study on the neonatal rat

The action of oxytocin (0.01-1 microM) on sympathetic preganglionic neurones was studied by intracellular recording in slices of neonatal rat thoracic spinal cord. In 85% of the cells superfusion induced a slow tetrodotoxin-insensitive depolarization accompanied by the appearance or increase in frequency of repetitive discharges. Oxytocin also caused some cells to switch from silent neurones to spontaneously active ones. These effects were reversibly blocked by a specific oxytocin antagonist.