[The kangaroo method is a good complement to traditional incubator care].
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Humans↗
Biomedical subjects
M Lindroth
Publications and source records attributed to M Lindroth.
Spontaneous pneumopericardium in an otherwise healthy full-term newborn.
Neonatal pneumopericardium is usually a complication of mechanical ventilation in premature infants with respiratory distress syndrome. We report a full-term neonate who developed pneumopericardium after forceps delivery and mild asphyxia. The child was never ventilated and had no signs of parenchymal lung disease. The pneumopericardium resolved spontaneously. Although drainage of pneumopericardium is usually recommended, this may not always be necessary when there are no signs of cardiac tamponade.
Humans↗
Potential of early chest roentgen examination in ventilator treated newborn infants to predict future lung function and disease.
The potentially of early chest X-ray to predict the risk of lung function abnormalities was studied prospectively in 40 preterm ventilator treated infants in a 8-10-year follow-up investigation. According to the findings at chest X-ray 3 to 10 days after completed ventilator treatment the infants were divided into 3 groups considered to represent increasing risk and severity of lung damage: 1) normal findings, 2) interstitial parenchymal abnormalities exclusively or 3) in combination with local or general hyperinflation. Lung function tests and chest x-ray were performed at the age of 8 to 10 years. A correlation was found between the findings at the early chest roentgen examination and the risk of abnormal lung function at the follow-up. Occurrence of focal or general hyperinflation or both were associated with a greater risk of airway obstruction. Infants with only interstitial abnormalities were, however, at a higher risk than those with normal chest examination to develop general hyperinflation and increased air way obstruction.
Bronchopulmonary Dysplasia↗
Association of ligand-receptor complexes with actin filaments in human neutrophils: a possible regulatory role for a G-protein.
Most ligand-receptor interactions result in an immediate generation of various second messengers and a subsequent association of the ligand-receptor complex to the cytoskeleton. Depending on the receptor involved, this linkage to the cytoskeleton has been suggested to play a role in the termination of second messenger generation and/or the endocytic process whereby the ligand-receptor complex is internalized. We have studied how the binding of chemotactic peptide-receptor complexes to the cytoskeleton of human neutrophils is accomplished. As much as 76% of the tritiated formylmethionyl-leucyl-phenylalanine (fMet-Leu-[3H]Phe) specifically bound to intact cells, obtained by a 30-s stimulation with 20 nM fMet-Leu-[3H]Phe, still remained after Triton X-100 extraction. Preincubating intact cells with dihydrocytochalasin B (dhCB) or washing the cytoskeletal preparation with a high concentration of potassium, reduced the binding of ligand-receptor complexes to the cytoskeleton by 46% or more. Inhibition of fMet-Leu-Phe-induced generation of second messengers by ADP-ribosylating the alpha-subunit of the receptor-coupled G-protein with pertussis toxin, did not reduce the binding of ligand-receptor complexes to the cytoskeleton. However, using guanosine-5'-O-(2-thiodiphosphate) (GDP beta S) to prevent the dissociation of the fMet-Leu-Phe-associated G-protein within electrically permeabilized cells, led to a pronounced reduction (62%) of the binding between ligand-receptor complexes and the cytoskeleton. In summary, in human neutrophils the rapid association between chemotactic peptide-receptor complexes and the cytoskeleton is dependent on filamentous actin. This association is most likely regulated by the activation and dissociation of the fMet-Leu-Phe-associated G-protein.
Actins↗
Measurement of ventilation and respiratory mechanics during continuous positive airway pressure (CPAP) treatment in infants.
A new method has been evaluated for measuring ventilation and lung mechanics in spontaneously breathing infants by means of a face chamber. Airway flow is measured with a pneumotachograph inserted between the face chamber and a stable pressure source. Oesophageal pressure is measured via a water-filled oesophageal catheter. The method is suitable for use in conjunction with continuous positive airway pressure (CPAP) treatment in neonatal intensive care. A flat frequency response curve up to 15 Hz for the two measuring systems (i.e., airway flow and oesophageal pressure), and a time shift between the two respective signals of less than 2 msec are prerequisites for correct evaluation of respiratory mechanics. In preterm infants with chest distortion, the inhomogeneity of pleural pressure affects the significance of resistance and compliance values, as calculated from oesophageal pressure. Supra-diaphragmatic pressure variations reflect the resistive and elastic load on the diaphragm exerted by the lungs and thorax. Thus, oesophageal pressure is still useful in studies of respiratory mechanics in preterm infants.
Apnea↗
Lung function eight years after neonatal ventilation.
Forty children who had had artificial ventilation during the neonatal period were studied at the age of 8-10 years with spirometry, the nitrogen washout test, bicycle exercise test, pulse oximetry, electrocardiogram, vectorcardiogram, and chest radiography. The median gestational age at birth was 29 weeks, and the median birth weight was 1310 g. Hyaline membrane disease was the indication for neonatal ventilation in 25 children. Bronchopulmonary dysplasia was diagnosed from radiographs in 11 infants (27%). Airway obstruction was observed in 10 of 11 children who had had bronchopulmonary dysplasia and in nine of 29 children who had not. After inhalation of terbutaline, the forced expiratory volume in one second (FEV1) was significantly increased. General hyperinflation was found in 16 of 17 children with abnormal chest radiographs (eight who had had bronchopulmonary dysplasia and nine who had not). Functional residual capacity was significantly higher in children with abnormal radiographs. Each child had a normal maximum working capacity and a normal electrocardiogram, and all but two had normal vectorcardiograms. Oxygen saturation at maximum work load decreased significantly in both groups of children. The risk of future respiratory problems calls for further follow up of lung function and chest radiography.
Electrocardiography↗
Problems associated with the preparation of whole mounts of cytoskeletons for high resolution electron microscopy.
The resolution currently available in both transmission and scanning electron microscopes is theoretically adequate to visualize the organization of the cytoskeleton at the supramolecular and macromolecular levels. However, achieving this resolution in practice requires that the methods used to prepare the specimens both preserve the structures of interest and render them visible for observation in the microscope without obscuring or altering them. In this paper we discuss our own and others efforts to develop methods to overcome several problems associated with preparing whole mounts of cytoskeletons for observation by electron microscopy. These problems include: controlling the degree to which cellular components are extracted; the effects of osmium tetroxide on the cytoskeleton; controlling and recognizing shrinkage and drying artifacts; the choice of a method of visualization; deposition of grain-free ultrathin films of metal; and interpreting the results. The standard procedure which we currently use consists of the following steps: growing cells on carbon-stabilized Formvar-coated gold electron microscope grids; extracting in 0.5% Triton X-100 detergent in a microtubule stabilizing buffer; postfixing in 2.5% glutaraldehyde in stabilizing buffer; freeze-drying; magnetron sputter-coating with 1.5 nm of tungsten; and observation by TEM, SEM, or STEM. Cytoskeletons prepared in this manner contain over 100 polypeptides and are composed of a complex three dimensional meshwork of clean, uniform filaments, the smallest of which are 7 nm in diameter. A structure resembling the microtrabecular lattice is present only if the cells are prefixed with a relatively long bifunctional protein crosslinking reagent prior to extraction with detergent.
Animals↗
Effects on respiration of CPAP immediately after extubation in the very preterm infant.
The effects of continuous positive airway pressure (CPAP) on pulmonary function during weaning from ventilator treatment were examined immediately after extubation in 17 very preterm infants, who had been ventilator-treated because of hyaline membrane disease (15 infants) and chronic pulmonary insufficiency of prematurity (two infants). Seven infants had bronchopulmonary dysplasia. Median birthweight was 920 g and median gestational age 26 completed weeks. The median duration of ventilator treatment was 10 days. Application of CPAP by means of a face chamber device after endotracheal extubation significantly lowered the frequency of apnea (P = 0.02) and enhanced oxygenation (P = 0.001). The respiratory mechanical indices derived from flow rate and juxta-diaphragmatic esophageal pressure measurements showed a reduced elastic (P = 0.03) and resistive (P = 0.02) load on the diaphragm. Even if the measured values do not accurately represent absolute resistances and compliances, the relative values of end-inspiratory and end-expiratory pressures differed significantly with and without CPAP (P = 0.001 and 0.002, respectively). We found CPAP applied via the face chamber technique immediately after extubation to be beneficial and to facilitate weaning from ventilator treatment in very preterm infants.
Female↗
Transforming growth factor (TGF beta) decreases the proliferation of human bone marrow fibroblasts by inhibiting the platelet-derived growth factor (PDGF) binding.
Human bone marrow fibroblasts were cultivated and characterized by immunofluorescent staining and electron microscopy. Their interactions with PDGF and TGF beta were studied. While a positive intracellular antifibronectin staining was observed, the cultured cells were not labeled with specific antibodies toward factor VIII von Willebrand factor (F VIII/vWF), desmin, and macrophage antigen. Moreover, electron microscopy excluded the presence of endothelial cells by the absence of Weibel-Palade bodies. The binding of pure human PDGF to the cultured bone marrow fibroblasts was investigated. Addition of an excess of unlabeled PDGF decreased the binding to 75 and 80%, which means that the nonspecific binding represented 20-25% of total binding, whereas epidermal growth factor (EGF) had no effect. Two classes of sites were detected by Scatchard analysis with respectively 21,000 and 37,000 sites per cell, with a KD of 0.3 x 10(-10) M and KD of 0.5 x 10(-9) M. The stimulation of DNA synthesis by PDGF was quantified by [3H]thymidine incorporation. When PDGF was added alone at a concentration of 15 ng/ml, it induced a maximal DNA synthesis of 400%, which increased up to 900%, in the presence of platelet-poor plasma (PPP). On the other hand, PDGF-induced fibroblast proliferation was inhibited in a dose-dependent manner by TGF beta. This inhibition was related to a significantly decreased binding of 125I-labeled PDGF observed in the presence of TGF beta. Our results suggested that PDGF and TGF beta could modulate the growth of bone marrow fibroblasts.
Bone Marrow↗
Comparison of the effects of critical point-drying and freeze-drying on cytoskeletons and microtubules.
We have compared the effects of critical point-drying (CPD) and freeze-drying (FD) on the morphology of Triton-resistant cytoskeletons and microtubules by scanning (SEM) and transmission electron microscopy (TEM). In general, cytoskeletons attached to Formvar films suffer less structural damage than cells or cytoskeletons attached to glass, because the Formvar film absorbs some of the stress associated with shrinkage during drying. However, as seen in stereo-pair electron micrographs, the three-dimensional structure of cytoskeletons prepared by FD is better preserved and shows fewer artefacts than those prepared by CPD. CPD specimens are flatter, often have a concave and apparently collapsed nuclear matrix and show large cracks both in the perinuclear zone and through the cytoskeleton. At least some of the damage appears to be due to residual water in the CO2 used as the substitution fluid, because cytoskeletons dried with a water filter attached to the CPD apparatus show substantially less damage than those dried without the filter. Freeze-dried cytoskeletons consist mostly of unbroken, smooth filaments and have no perinuclear open space. Comparison of the effects of drying on the diameters of in vitro polymerized microtubules showed that the diameter of microtubules is reduced after drying, but that FD causes significantly less shrinkage than CPD. Addition of 0.2% tannic acid to the glutaraldehyde fixative significantly reduces the shrinkage of CPD microtubules, but has no effect on FD microtubules. The observations on microtubules support the hypothesis that drying-induced shrinkage is the result of both pressure and solvent evaporation and they indicate that tannic acid stabilizes samples against the former but not the latter.
Cytoskeleton↗
Preparation of cytoskeletons of cells in culture for high resolution scanning and scanning transmission electron microscopy.
In this tutorial we describe our methods for preparing detergent-extracted cytoskeletons for observation by high resolution scanning (SEM) and scanning transmission (STEM) electron microscopy. We both discuss the theoretical background and provide practical procedures for each of the following steps: cell culture on Formvar-coated gold grids; prefixation with aldehydes or protein crosslinking reagents (homobifunctional N-hydroxy-succinimide esters); extraction with Triton X-100 or Brij 58 detergent in microtubule stabilizing buffer; postfixation in formaldehyde and glutaraldehyde; dehydration; critical point and freeze drying; sputter coating with 1-2 nm of platinum or tungsten; and examination by SEM and both normal and inverted contrast STEM. These methods produce cytoskeletal preparations in which filaments as fine as 7 nm are preserved and can be observed by scanning electron microscopy.
Chemical Phenomena↗
Current perspectives in the management of respiratory distress syndrome.
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Humans↗
Use of sputter coating to prepare whole mounts of cytoskeletons for transmission and high-resolution scanning and scanning transmission electron microscopy.
This paper describes the use of sputter coating to prepare detergent-extracted cytoskeletons for observation by scanning (SEM), scanning transmission (STEM), inverted contrast STEM, and transmission (TEM) electron microscopy. Sputtered coats of 1-2 nm of platinum or tungsten provide both an adequate secondary electron signal for SEM and good contrast for STEM and TEM. At the same time, the grain size of the coating is sufficiently fine to be just at (platinum) or below (tungsten) the limit of resolution for SEM and STEM. In TEM, the granular structure of platinum coats is resolved, and platinum decoration artifacts are observed on the surface of structures. The platinum is deposited as small islands with a periodic distribution that may reveal information about the underlying molecular structure. This method produces samples that are similar in appearance to replicas prepared by low-angle rotary shadowing with platinum and carbon. However, the sputter-coating method is easier to use; more widely available to investigators; and compatible with SEM, STEM, and TEM. It may also be combined with immunogold and other labeling methods. While TEM provides the highest resolution images of sputter-coated cytoskeletons, it also damages the specimens owing to heating in the beam. In SEM and STEM cytoskeletons are stable and the resolution is adequate to resolve individual microfilaments. The best single method for visualizing cytoskeletons is inverted contrast STEM, which images both the metal-coated cytoskeletal structures and electron-dense material within the nucleus and cytoplasm as white against a dark background. STEM and TEM were both suitable for visualizing colloidal gold particles in immunolabeled samples.
Cytoskeleton↗
Endotracheal administration of surfactant in very low birth weight infants with respiratory distress syndrome.
This study was designed to evaluate whether the ventilatory maneuvers associated with surfactant replacement would, per se, influence oxygenation in newborn infants with severe respiratory distress syndrome. Eight patients (700 to 1400 g), all requiring mechanical ventilation with fraction of inspired oxygen greater than 0.6, were included in the trial; four were randomized to receive surfactant, and the others served as controls. Porcine surfactant (2 ml/kg; phospholipid concentration, 100 mg/ml) was instilled via a naso-endotracheal tube at end-expiration and dispersed into the lungs during a period of standardized "sighing" mediated by the ventilator: two prolonged ventilatory cycles (10 sec each) with an inspiration/expiration ratio of 4:1, followed by a 6-min ventilation with a frequency of 60 breath/min and an inspiration/expiration ratio of 4:1. Control babies received no surfactant but were otherwise subjected to the same ventilatory maneuvers. Surfactant-treated infants showed a rapid increase in transcutaneous oxygen associated with improved lung aeration in chest x-rays; the response was transient in three babies and persistent in one. No improvement was observed in control babies. We conclude that the beneficial effect of surfactant replacement cannot be attributed to the ventilatory maneuvers associated with the instillation procedure.
Critical Care↗
Long-term follow-up of ventilator treated low birthweight infants. I. Chest X-ray, pulmonary mechanics, clinical lung disease and growth.
Chest X-ray, pulmonary mechanics, clinical lung disease and growth were studied in 48 low birthweight infants surviving after ventilator treatment in the neonatal period. Bronchopulmonary dysplasia (BPD) was present in 14 infants shortly after weaning off ventilator. At 4 to 6 years of age most patients had normal chest radiographs but 13 still showed signs of pulmonary fibrosis and hyperinflation. Most patients had low dynamic compliance and high pulmonary resistance shortly after ventilator treatment. All but 8, however, had normal findings at 1 to 1 1/2 years of age. Pneumonias and bronchitis were common during the first two years but thereafter declined in frequency. Weight and length development were retarded for BPD patients during the first two years and for non-BPD patients for the first year. Both groups had a complete catch-up.
Body Height↗
Longterm follow-up of ventilator treated low birthweight infants. II. Neurological and psychological outcome at 6-7 years.
Forty-five of 47 low birthweight infants (less than 2.5 kg b.w.) from a 2 1/2-year period surviving after ventilator treatment in the neonatal period were studied. The children were assessed at the age of 6-7 years by neurological examination and Griffith's test. There were 2 children with diplegia, and one with a descrete hemiplegia. Eleven other children had minor motor disturbances. Fifteen children had short attention span. In the Griffith's test 8 had a general quotient below 3; most often because of low scores in the Locomotor scale and the Performance scales. Eight children had minor motor difficulties and short attention span in combination. These eight children together with the three patients with cerebral palsy, another four patients with low Griffith test and one girl with severe retrolental fibroplasia, and one girl with neurogenic hearing reduction could be at risk for later school difficulties (38%). Finally, one boy was successfully shunted for hydrocephalus. The abnormalities found did not correlate with birthweight or duration of ventilator treatment.
Child↗
Rickets in very low birthweight infants. Influence of supplementation with vitamin D, phosphorus and calcium.
The influence of extra phosphorus (P) and calcium (Ca) on the incidence of rickets was studied in 40 infants with a birthweight below 1.5 kg. All were fed breastmilk and all received vitamin D 1200 IU/day. Half of the infants were supplemented with P 20 mg/kg/day and Ca 30 mg/kg/day. Rickets, diagnosed with X-ray at 5 to 7 weeks of age, developed in 12 infants, 11 of whom weighed below 1.0 kg. In infants below 1.0 kg rickets was significantly more common in the group not receiving extra P and Ca. After diagnosis all were substituted and radiographic healing occurred in all. Serum Ca concentrations were normal in both groups whereas serum P was significantly lower in non-supplemented patients. Serum alkaline phosphatases (ALP) were normal in all patients at the time of diagnosis demonstrating the risk of using ALP as a diagnostic test for rickets in very low birthweight.
Alkaline Phosphatase↗
[Peculiarities of respiratory mechanical studies in spontaneously breathing newborn infants. 3: Practical experiences with respiratory mechanical studies in premature and newborn infants].
The experiences with three different measuring devices for the analysis of respiratory physiology in spontaneously breathing newborns are reported, the construction and the properties of the measuring devices are described, the preparations and the performance of the analysis are explained. Finally, the suitability of each of the measuring devices for the routine application is valuated. The equipments are suitable for the bed-side long-term measurement of mechanics of breathing under spontaneous and CPAP-respiration in order to use the advantages of the analysis of the respiratory physiology for the prophylaxis, therapy and metaphylaxis especially in the neonatology.
Airway Resistance↗