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T Nicolai

Publications and source records attributed to T Nicolai.

At least 19 recordsLinked to original sources
PubMed2001

Structure of aggregating kappa-carrageenan fractions studied by light scattering.

We have studied kappa-carrageenan fractions with varying molar mass, obtained by sonication, using static and dynamic light scattering and polarimetry. The samples were characterised in 0.1 M NaCl and 0.1 M NaI, i.e. in the coil and helix conformation, respectively. We find that the molar mass and size of the untreated sample are the same in the coil and helix conformation. For the sonicated samples, we find larger average molar masses and sizes in the helix conformation. The critical temperature, T(c), below which the coil-helix transition sets in, decreases with decreasing molar mass. Aggregation is induced by lowering the temperature in the presence of 0.01 M KCl, which leads to the formation of locally rigid bundles of kappa-carrageenan chains. The thickness of the bundles increases slowly with time and we have not observed stabilisation, even after 24 h at 10 degrees C below T(c). The local structure of the aggregates is the same for all fractions, but at a given temperature, the rate of aggregation decreases with decreasing molar mass.

Carrageenan↗
PubMed2001

Pediatric bronchoscopy.

Diagnostic flexible endoscopy for pediatric respiratory diseases is performed in many centers. Technical advances have resulted in performance of interventional bronchoscopies, and new diagnostic indications are being explored. Indications with documented clinical benefit include congenital or acquired progressive or unexplained airway obstruction. Pulmonary infections in immunodeficient children who do not respond to empirical antibiotic treatment may be diagnosed by bronchoscopy and bronchoalveolar lavage (BAL). The potential usefulness of bronchoscopy and BAL for managing chronic cough, wheeze, or selected cases with asthma or cystic fibrosis requires further study. The use of transbronchial biopsies (TBB) is established in pediatric lung transplantation. The role of TBB in the diagnosis of chronic interstitial lung disease in children remains to be determined. For a number of interventional applications, rigid endoscopy is required, and pediatric bronchoscopists should be trained in its use. Complications in pediatric bronchoscopy are rare, but severe nosocomial infection or overdosing with local anesthetics has occurred. The issues of quality control, video documentation, interobserver variability of findings, and educational standards will have to be addressed in the future as bronchoscopy use becomes less restricted to only large pediatric pulmonary units.

Airway Obstruction↗
PubMed2001

Metal airway stent implantation in children: follow-up of seven children.

Long segment malacia of the trachea or main stem bronchi in children is not always suitable for surgical correction; patients may therefore remain ventilator-dependent and/or experience severe obstructive crises. We treated 7 children (ages, 4 months to 9 years) with extreme structural central airway obstruction with stent implantations. Six were mechanically ventilated; 5 had frequent life-threatening obstructive spells requiring deep sedation or paralysis. Diagnoses were: syndrome-associated tracheobronchomalacia (n = 4), malignancy infiltrating the carina (n = 1), congenital tracheal stenosis (n = 1), and tracheobronchial compression by a malpositioned aorta (n = 1). Six tracheal and 13 bronchial stents were endoscopically placed. The prostheses included mesh titan (n = 5), the newer shape memory material nitinol (n = 13), and 1 Y-shaped carina stent. Follow-up was reported for 7 weeks to 72 months. All patients showed marked improvement of their respiratory obstruction. Six children were weaned at least temporarily from ventilation. No significant bleeding, stenosis, or perforation was observed. Seven stents were changed after up to 14 months. Three children are well and at home. In 2 children airway stabilization was successful, but they later died from causes unrelated to stent placement, and 2 children died due to generalized airway disease. Soft metal mesh airway stents can offer a therapeutic option in life-threatening inoperable obstruction of the trachea and main stem bronchi in children.

Airway Obstruction↗
PubMed2000

[Asthma therapy in children. Value of long acting beta-mimetic drugs and anti-leukotrienes].

In recent years, new therapeutic options have become available for the treatment of bronchial asthma in childhood. In children older than five years, long-acting beta mimetics are now an accepted medication, especially for severe forms of asthma or significant nocturnal symptoms. These new drugs should be prescribed only in combination with inhaled steroids. An effect of these beta mimetics on the inflammatory reactions underlying asthma is not to be expected. The second new therapeutic approach is the use of antileukotrienes, which are of particular help in children with a compliance problem vis-a-vis inhaled steroids, although their antiobstructive effect is weaker than that of beta mimetics or medium- or high-dose inhaled steroids. Whether the combination of these drugs with inhaled steroids can improve asthma control or reduce the use of steroids in children remains to be elucidated.

Adrenergic beta-Agonists↗
PubMed2000

Effect of lung water content, manipulated by intratracheal furosemide, surfactant, or a mixture of both, on compliance and viscoelastic tissue forces in lung-lavaged newborn piglets.

OBJECTIVE: To study the impact of lung water content and its reduction by a topically applied diuretic on respiratory and lung tissue mechanics in comparison with surfactant administration in surfactant-deficient newborn piglets with lavage-induced lung injury. DESIGN: Controlled, randomized study. SETTING: Animal research facility. SUBJECTS: Newborn piglets. TREATMENT Piglets were surfactant depleted by lung lavage and, after a pretreatment period, randomly treated with intratracheal furosemide, furosemide and surfactant, or with surfactant alone. MEASUREMENTS AND MAIN RESULTS: Dynamic compliance (C(DYN)), static compliance (C(ST)), stress-adaptation pressures (P(DIFF)) and post mortem lung water content were determined. Static compliance in the furosemide-surfactant group was not significantly higher than in the surfactant group. At the end of the study, C(ST) did not differ between the three groups because C(ST) in the furosemide group had increased to values similar to those of the surfactant-containing treatment groups: C(ST) F+S: 0.73 +/- 0.2 mL/cm H2O/kg body weight (BW); C(ST) S: 0.61 +/- 0.11 mL/cm H2O/kg BW; and C(ST) F: 0.60 +/- 0.19 mL/cm H2O/kg BW). Compliance was inversely and P(DIFF) was directly correlated to lung water (LW) content (C(ST) vs. LW: r2 = .59, p = .001; C(DYN) vs. LW: r2 = .49, p = .006; P(DIFF) vs. LW: r2 = .37, p = .059), independent of the type of treatment. Changes in C(ST) and C(DYN) were inversely related to changes in P(DIFF). Intrapulmonary furosemide was more rapidly absorbed when administered to the surfactant-depleted lung alone compared with the mixture with surfactant, and intrapulmonary furosemide had a rapid systemic effect. CONCLUSION: Although the combination of surfactant with a diuretic failed to increase respiratory compliance to a significantly larger extent than surfactant alone, furosemide at the end of the study increased respiratory compliance to a level similar to surfactant-containing treatments. Lung water content and, to a lesser extent, the absence or presence of surfactant appeared to determine lung mechanics, and its impact on lung mechanics was similar to surfactant administration.

Animals↗
PubMed1999

Lower prevalence of asthma and atopy in Turkish children living in Germany.

Ethnic origin has been reported to affect the prevalence of atopic diseases in several studies in different parts of the world. However, little is known about the prevalence of asthma and atopy in immigrants living in Europe. The objective of this study was to evaluate the prevalence of asthma and atopy in Turkish children living in Germany and to investigate the role of ethnic origin on the development of asthma and atopy in this population. In a cross-sectional survey the prevalence of physician-diagnosed asthma, atopy, skin-prick tests and bronchial hyperresponsiveness (BHR) to cold dry air challenge was assessed in 7,445 school children aged 9-11 yrs, living in Munich, south Germany. Questionnaires were distributed to the parents for self-completion and children underwent skin prick tests and cold air hyperventilation challenge. The Turkish children showed a significantly lower prevalence of asthma (5.3 versus 9.4%, p<0.05) than their German peers. Furthermore, atopy, as assessed by skin prick tests (24.7 versus 36.7%, p<0.001) and BHR (3.9 versus 7.7%, p<0.001), was less common in Turkish children. In multivariate regression models controlling for potential explanatory factors, Turkish origin still showed a significantly lower risk of developing asthma, atopic sensitization and BHR. The prevalence of childhood asthma was therefore shown to be lower in Turkish children living in Germany than in Turkey. These findings suggest that the lower prevalence of asthma and allergy in Turkish children living in Germany might be attributable to a selection bias affecting the parents of these children, as healthy individuals may have decided to come to Germany for work.

Age Distribution↗
PubMed1999

Air pollution and respiratory disease in children: what is the clinically relevant impact?

Acute exposure to air pollution is associated with increased respiratory symptoms and decreases in lung function in children. Most of the respiratory symptoms are nonspecific and not severe. However, lower respiratory symptoms and extra use of bronchodilators may be increased by about one third with exposure to peak levels of ozone in children with asthma. Sensitivity to air pollution does not seem to be determined by the severity of preexisting asthma and there is no indication that new cases of asthma are induced by ozone exposure. However, hospital and outpatient admissions for children with preexisting asthma may be increased in the range of 20% with acute exposure to ambient ozone peaks and possibly with increased sulfur dioxide. This indicates a significant impact of acute effects of air pollution on respiratory health in children, and an increase in the use of medical resources which will vary with the local exposure level and duration. Chronic exposure to increased levels of respirable particles, SO2 and NO2 are associated with up to threefold increases in nonspecific respiratory symptoms such as chronic cough, but not with asthma. Exposure to high traffic flow has been found to lead to significant increases in respiratory symptoms, while no clear effect on the inception of asthma has been documented. Although these symptoms are usually not severe, they will contribute to an increased use of pediatric health care facilities. It appears unlikely that long-term exposure to pollutants or irritants is responsible for the secular increase in asthma and allergy observed in Western countries. Whether exposure to car traffic is a significant risk factor for acute asthma or its inception remains to be clarified.

Air Pollution↗
PubMed1999

Environmental air pollution and lung disease in children.

Acute exposure to air pollution is associated with increased respiratory symptoms and decreases in lung function in children. Respiratory symptoms in healthy children are usually nonspecific and not severe. Lower respiratory symptoms and extra use of bronchodilators will increase by about one-third with exposure to peak levels of ozone in children with asthma. Similarly, sulphates will increase the use of medication and decrease lung function in asthmatic children. Hospital and outpatient admissions for children with pre-existing asthma may be increased in the range of 20% with acute exposure to ambient ozone peaks and possibly with increased sulphur dioxide (SO2). Short-term nitrogen dioxide (NO2) exposure from indoor and outdoor sources has been associated with nonspecific respiratory symptoms and decreased lung function, again particularly in children with pre-existing asthma. No effect on hospital admissions has been documented. Chronic exposure to respirable particles, SO2 and NO2 is associated with up to three-fold increases in nonspecific chronic respiratory symptoms. Exposure to high traffic flow and, in particular, truck traffic and diesel exhaust leads to significant increases in respiratory symptoms and decreases in lung function, while no clear effect on the inception of asthma has been documented. It appears unlikely that long-term exposure to pollutants or irritants is responsible for the increase in asthma and allergy observed in many countries. However, although the effect of air pollution is small in most children, it has a significant influence on the health of children with pre-existing lung disease. Owing to the large number of individuals exposed this results in a considerable burden for the health system.

Air Pollutants↗
PubMed1998

Effect of dampness at home in childhood on bronchial hyperreactivity in adolescence.

BACKGROUND: Relatively little is known about risk factors for the persistence of asthma and respiratory symptoms from childhood into adolescence, and few studies have included objective measurements to assess outcomes and exposure. METHODS: From a large cross sectional study of all 4th grade school children in Munich (mean age 10.2 years), 234 children (5%) with active asthma were identified. Of these, 155 (66%) were reinvestigated with lung function measurements and bronchial provocation three years later (mean age 13.5 years). RESULTS: At follow up 35.5% still had active asthma. Risk factors for persisting asthma symptoms in adolescence were more severe asthma (OR 4.94; CI 1.65 to 14.76; p = 0.004) or allergic triggers (OR 3.54; CI 1.41 to 8.92; p = 0.007) in childhood. Dampness was associated with increased night time wheeze and shortness of breath but not with persisting asthma. Risk factors for bronchial hyperreactivity in adolescence were bronchial hyperreactivity in childhood (p = 0.004), symptoms triggered by allergen exposure (OR 5.47; CI 1.91 to 25.20; p = 0.029), and damp housing conditions (OR 16.14; CI 3.53 to 73.73; p < 0.001). In a subgroup in whom house dust mite antigen levels in the bed were measured (70% of the sample), higher mite antigen levels were associated with bronchial hyperreactivity (OR per quartile of mite antigen 2.30; CI 1.03 to 5.12; p = 0.042). Mite antigen levels were also significantly correlated with dampness (p = 0.05). However, the effect of dampness on bronchial hyperreactivity remained significant when adjusting for mite allergen levels (OR 5.77; CI 1.17 to 28.44; p = 0.031). CONCLUSION: Dampness at home is a significant risk factor for the persistence of bronchial hyperreactivity and respiratory symptoms in children with asthma. This risk is only partly explained by exposure to house dust mite antigen.

Adolescent↗
PubMed1997

Pollution and the development of allergy: the East and West Germany story.

Allergic diseases are partly genetically determined, but environmental factors have a strong influence on the expression of allergic symptoms in genetically predisposed subjects. In particular, outdoor air pollution has received widespread attention as a potential manifestation factor. The unification of Germany provided a unique opportunity to study the impact of radically different environmental and social conditions on the development of allergies in two genetically homogeneous populations. A high car density and NO2 exposure were typical for many West German cities. Severe pollution due to heavy industrialization and private coal burning for heating purposes were the main sources of air pollution in East German cities. We assessed the prevalence of asthma and allergic disorders in 9-11 year old children in in East Germany (Leipzig and Halle) and in West Germany (Munich). All fourth grade pupils in Munich (n = 7,445) were compared with those in Leipzig and Halle 1991 (n = 3,105). Hay fever, skin test reactivity to common aeroallergens and asthma were considerably more prevalent in West Germany as compared to East Germany. When atopy was taken into account, there was no longer a significant difference in the prevalence of asthma between the two parts of the country.

Air Pollution↗
PubMed1997

Epidemiology of pollution-induced airway disease: urban/rural differences in East and West Germany.

The prevalence of asthma and allergic disorders was assessed in 9-11 year-old children in Leipzig and Halle in East Germany, as well as in Munich, West Germany. Both East German cities are heavily polluted due to private burning of coal and industrial emissions, while Munich has low smoke emissions but heavy road traffic. All fourth grade pupils in Munich were compared with those in Leipzig and Halle. Non-specific airway disease (bronchitis), cough, and autumn/winter nasal symptoms were most prevalent in Leipzig and Halle. Hay fever and skin test reactivity to aeroallergens were higher in West Germany compared with East Germany. Furthermore, the prevalence of asthma was also higher in the West German study area. Increased skin prick test reactivity in the West explained the increased prevalence of asthma. Longitudinal analysis showed increased respiratory symptoms on days with high mean levels of sulphur dioxide and oxides of nitrogen, as well as on days with a high peak level of 10 mu respirable particles (PM10) in East Germany. The effects of these pollutants were additive. Exposure to heavy road traffic in Munich was related to decreased pulmonary function and non-specific airway symptoms, but not to allergic sensitization and asthma.

Air Pollutants↗
PubMed1997

Increased prevalence of sensitization against aeroallergens in adults in West compared with East Germany.

BACKGROUND: An increased prevalence of allergic diseases and atopic sensitization as assessed by skin-prick testing in children in West compared with East Germany has been reported. OBJECTIVES: This study was designed to evaluate whether such a difference is also present in adults, and if this can be shown when using a serological test for allergic sensitization. METHODS: Two large samples representative for all adults between 25 and 69 years of age were drawn in West (1991, n = 5313) and East Germany (1992, n = 2617). A serological test screening for IgE-antibodies to common aeroallergens (SX1) was performed. A questionnaire was used to assess the presence of clinical respiratory allergy, known possible risk factors for allergies and confounding variables. RESULTS: Allergic sensitization decreased with age. Significantly more subjects < 45 years of age had a positive allergy test in West as compared to East Germany. The prevalence of clinical allergy was also higher in West Germany. This difference was significant in younger adults and was independent of other risk factors identified. These additional risk factors encompassed younger age, higher educational level, male sex, and living in a community with more than 100,000 inhabitants. CONCLUSION: Sensitization to common aeroallergens as determined by a multiple allergen RAST test in adults below 45 years of age living in West Germany is increased compared to East Germany. This increase cannot be explained by genetic differences and is similar to the West to East decreasing gradient in allergies reported from studies in children employing skin-prick tests.

Adult↗
PubMed1996

[Endoscopy of the respiratory tract in childhood].

Technical developments in the field of pediatric bronchoscopy have expanded the diagnostic possibilities of this procedure while, at the same time making it less invasive: Today, almost all such examinations can be carried out on an outpatient basis and flexible fiberoptic instruments can be used in children who have reached school age with only analgesia and sedation. Technical innovations include endoscopic laser surgery, for example, to treat subglotic hemangiomas even in very young infants and endoluminal balloon dilatation for airway stenoses. These developments have improved and rendered less stressful the diagnosis and treatment of airway stenoses in children.

Airway Obstruction↗
PubMed1996

Relation of indoor heating with asthma, allergic sensitisation, and bronchial responsiveness: survey of children in south Bavaria.

OBJECTIVE: To investigate the relation between different types of heating and the prevalence of atopic diseases, skin test reactivity, and bronchial hyperresponsiveness. DESIGN: Cross sectional survey among school-children aged 9-11 years. Skin prick tests, pulmonary function tests, and bronchial challenge in the children and self completion of a written questionnaire by the children's parents. SUBJECTS: 1958 children in a rural area in southern Bavaria, Germany. MAIN OUTCOME MEASURES: Prevalence of asthma, hay fever, and atopic dermatitis as determined by parents' answers to a questionnaire; the atopic status of the child assessed by skin prick tests; and bronchial responsiveness to cold air challenge in the children. RESULTS: After possible confounders were controlled for, the risk of developing hay fever (odds ratio = 0.57; 95% confidence interval 0.34 to 0.98), atopy defined as at least one positive reaction to a panel of common aeroallergens (0.67; 0.49 to 0.93), sensitisation to pollen (0.60; 0.41 to 0.87), and of bronchial hyperresponsiveness (0.55; 0.34-0.90) was significantly lower in children living in homes where coal or wood was used for heating than in children living in homes with other heating systems. CONCLUSIONS: Factors directly or indirectly related to the heating system used in rural Bavarian homes decrease the susceptibility of children to becoming atopic and to developing bronchial hyperresponsiveness.

Asthma↗
PubMed1996

Bilateral bronchial balloon dilatation and Strecker stent implantation in a ventilated child with malignant carinal stenosis.

Tracheobronchial endoluminal reconstruction and stenting has become a valuable palliative tool in adults with intrathoracic tumors compromising the airways. Tracheobronchial balloon dilatation has been recently used in children and even neonates. We report a case of severe airway obstruction requiring emergency intubation and artificial ventilation in a 5-year-old child with intrathoracic recurrence of a rhabdomyosarcoma. Endoscopic balloon dilatation through the endotracheal tube with subsequent implantation of a non self-expanding metal mesh stent was used successfully, allowing extubation and discharge of the child from ICU.

Airway Obstruction↗
PubMed1996

The effect of temperature and ionic strength on the dimerisation of beta-lactoglobulin.

Bovine beta-lactoglobulin is a globular whey protein that associates partly and reversibly in dimers in the native state. Static and dynamic light scattering techniques have been used to determine the relative amount of monomers and dimers, and to estimate their size and shape in different conditions. The effect of the ionic strength on the dimerisation has been studied at pH 2, where the protein is highly charged. A simple model, taking into account the monomer-dimer equilibrium and virial interactions has been used. The strength of the interactions depends on the amount of added salt, i.e. ionic strength, and influences the dimer dissociation. When the ionic strength decreases, the equilibrium is shifted towards the monomeric form. The dissociation, however, is only complete at very low concentration. The effect of temperature has been studied at pH 7 and low concentration where virial interactions are negligible. The dissociation increases with increasing temperature (5 degrees C - 76 degrees C). At high temperatures, protein-protein aggregation is fast, even at low concentration. The temperature dependence can be described using a simple Van't Hoff model, even at temperatures where aggregation occurs. The ionic strength and temperature dependence both indicate that beta-lactoglobulin solutions have to be considered as a mixture of monomers and dimers.

Hydrogen-Ion Concentration↗
PubMed1996

Respiratory hypersensitivity and environmental factors: East and West Germany.

We assessed the prevalence of asthma and allergic disorders in 9-11 year old children in Leipzig and Halle in East Germany, and Munich, West Germany. Both East German cities were heavily polluted due to private coal burning and industrial emissions, whereas Munich has moderate industry but heavy car traffic. All fourth grade pupils in Munich (n = 7445) were compared with those in Leipzig, 1990 (n = 1429) and Leipzig and Halle, 1991 (n = 3105). The prevalence of hay fever and skin test reactivity to common aeroallergens was considerably higher in West Germany as compared to East Germany. Furthermore, the prevalence of asthma was also higher in the West German study area. However, when atopy was taken into account, there was no longer a significant difference in the prevalence of asthma between the two parts of the country.

Air Pollutants↗