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T Nicolai

Publications and source records attributed to T Nicolai.

At least 73 records · Page 4Linked to original sources
PubMed1993

Evaluation of cold air challenge data in a population sample using a model of bronchial hyperreactivity and disposition to bronchial obstruction.

To explore the role of bronchial hyperreactivity and obstruction after cold air challenge, data from a cross-sectional study of more than 7,000 10-year-old children were used. Current knowledge of hyperreactivity is primarily based on pharmacological provocation tests with variable prechallenge flow rates and their decrease relative to baseline. Using forced expiratory volume (FEV) in 1 sec values before and after cold air challenge, however, it is possible to define a subsample of children with predominant hyperreactivity and a subsample with predominant obstruction after challenge. The prevalence of respiratory symptoms and the diagnoses in the two subsamples were compared. The analysis showed that children with bronchial obstruction have nearly the same frequency of respiratory symptoms as those with bronchial hyperreactivity. A combined model of bronchial obstruction and hyperreactivity was, therefore, more predictive of symptoms than a model of hyperreactivity alone.

Air↗
PubMed1993

A static and dynamic light scattering study of sharp pectin fractions in aqueous solution.

A number of sharp fractions from low methoxyl citrus pectin have been studied using dynamic and static light scattering and size exclusion chromatography. The efficiency of the dynamic light scattering technique for the characterization of aqueous pectin solutions is demonstrated even when aggregages are present. The measured molar mass dependence of the Stokes radius confirms the semi-rigid structure of pectin. The effect of a number of sample manipulations on the aggregate content has been investigated and a simple but effective purification method is presented.

Citrus↗
PubMed1993

Prematurity as a risk factor for asthma in preadolescent children.

Information on long-term respiratory symptoms in prematurely born children is scanty. We studied an unselected population of 9- to 11-year-old schoolchildren. A self-administered questionnaire was distributed to the parents. Children underwent lung function testing, cold air challenge, and skin prick tests. A gestational age < 37 weeks in children with a birth weight < or = 2500 gm was reported by 5% of the parents. Premature girls had significantly more current asthma (odds ratio (OR) 2.6; 95% confidence interval (CI) 1.4, 4.7; p < 0.05), recurrent wheezing (OR 1.7; 95% CI 1.1, 2.7; p < 0.001), recurrent shortness of breath (OR 2.4; 95% CI 1.5, 3.9; p < 0.001), and frequent cough with exercise (OR 1.8; 95% CI 1.1, 2.9; p < 0.05) than term girls, especially if they required mechanical ventilation after birth. No such differences could be shown in boys. More prematurely born children who required mechanical ventilation (OR 3.7; 95% CI 2.2, 6.4; p < 0.0001) had a family history of asthma than children born at term. Significant decrements could be demonstrated for different measurements of lung function in premature girls. These results remained significant after control for confounders in a multivariate regression analysis. No difference was found between groups for bronchial hyperresponsiveness to cold, dry air or for atopic sensitization. We conclude that a family history of asthma may predispose premature children to more severe respiratory disease. Respiratory symptoms and decrements in lung function seen in girls may reflect abnormalities of lung function in survivors of severe neonatal respiratory disease.

Asthma↗
PubMed1993

Inherent coupling of elastic and dissipative behavior of the lung through a viscoelastic time constant.

The simple model best able to describe the viscoelastic behavior of lung tissues contains a Kelvin body. Some facets of the viscoelastic behavior of the model can be characterized by a time constant. We have performed a series of experiments to demonstrate this viscoelastic time constant in open-chest mechanically ventilated puppies by recording the stress recovery after midexpiratory flow interruption. In 19 8- to 10-wk-old puppies, the mean time constant was 0.64 +/- 0.01 (SE) s. This time constant remained unchanged after inhalation challenge with histamine, methacholine, or hypertonic saline, despite marked changes in tissue mechanics (resistance and elastance) and in hysteresivity. The constancy of the viscoelastic time constant demonstrates a tight coupling of the parameters of the Kelvin body model, effectively reducing the viscoelastic parameters to a single degree of freedom, and may explain the coupling between the dynamic elastic and resistive properties of the lung tissues previously demonstrated.

Administration, Inhalation↗
PubMed1993

Reactivity to cold-air hyperventilation in normal and in asthmatic children in a survey of 5,697 schoolchildren in southern Bavaria.

The measurement of bronchial hyperreactivity (BHR) may give additional information to questionnaire-based studies of asthma prevalence. It is desirable to have a provocation method with high specificity that avoids the use of pharmacologic provocations in large numbers of healthy children. It was the aim of this study to establish a range of values for responsiveness to cold-air challenge in normal children, to describe its specificity and sensitivity for a diagnosis of asthma in a large unselected sample of schoolchildren in a field study, and to measure factors associated with hyperresponsiveness. All fourth-grade schoolchildren (9 to 11 yr of age) in Munich and several southern Bavarian communities (n = 9,403) were surveyed with a questionnaire (response rate, 87%), baseline lung function, and cold-air hyperventilation challenge (n = 5,697). A diagnosis of asthma was reported in 7.9% of children. In the reference group, the ninety-fifth percentile (%ile) for the change of FEV1 (DFEV1) was -9.0%; the 90%ile was -7.3%. Asymptomatic children fulfilling all criteria for the reference group showed a significantly increased reactivity if they had a family history of asthma (p = 0.038). With a cutoff for DFEV1 of -9.0% or -7.3% the respective sensitivities to "detect" a diagnosis of asthma were 21.6 and 30.7%, and for asthma with symptoms during the previous 12 months it was 26.2 and 35.1%. Reactivity to cold air increased with the number of episodes of asthma in the previous 12 months. In a multiple linear regression model, factors associated with increased reactivity to cold air were diagnosed asthma, hay fever, male sex, younger age, and a positive skin test.(ABSTRACT TRUNCATED AT 250 WORDS)

Asthma↗
PubMed1993

Effect of volume history on measurements of respiratory mechanics using the interrupter technique.

The importance of the viscoelastic properties of the tissues of the respiratory system has recently been recognized, and lung models have been produced to describe the resistive and viscoelastic properties of the lung. The pulmonary mechanics of 10 rabbits were studied using the interrupter technique to assess the effect of volume history on the resistive and viscoelastic elements of the respiratory system. The influence of the tone of the muscles of respiration was also studied. In healthy lungs, the resistive and viscoelastic elements of the lung are dependent on the volume history of the respiratory system and are significantly lower if these elements do not reach a resting position before expiration. The chest wall made a significant contribution to the resistive and viscoelastic elements of the respiratory system, which was also dependent on the lung volume history. The tone of the muscles of respiration had no effect on the resistive or viscoelastic elements of the respiratory system.

Airway Resistance↗
PubMed1993

Frequency dependence of elastance and resistance in ventilated children with and without the chest opened.

Measurements of respiratory mechanics in mechanically-ventilated children are potentially useful for understanding the pathogenesis and progress of diseases resulting in respiratory failure. Measurement techniques that can be simply and noninvasively employed model the respiratory system as a single compartment. The frequency dependence of elastance and resistance, both of the total respiratory system and of the lungs, was investigated in eight children (aged 2-56 months) undergoing open-heart surgery. The children were studied whilst anaesthetized, paralysed and mechanically-ventilated. Dynamic elastance (Ers) and resistance (Rrs) of the respiratory system and of the lung (EL, RL) were calculated using a multilinear regression technique, with the chest wall intact, prior to the commencement of surgery, and with the chest wall opened via a mid-line sternotomy. Measurements were repeated after brief (60 s) changes in ventilation frequency. The total respiratory system and the lungs demonstrated frequency-dependent behaviour, with elastance increasing and resistance decreasing with frequency. The pattern of the frequency-dependent behaviour was essentially the same, whether the chest wall was intact or opened, suggesting that the chest wall was not solely responsible for this behaviour in these children. These data are consistent with a linear viscoelastic model containing a Kelvin body. When using measurements of respiratory mechanics to follow the progress of respiratory disease in mechanically-ventilated children, this frequency-dependent behaviour must be taken into account.

Airway Resistance↗
PubMed1993

[Surgical complications caused by tracheobronchial foreign body in childhood].

Four cases of tracheobronchial foreign body aspirations are described that necessitated surgical interventions. Bronchial rupture occurred in three cases and in one case the foreign body had to be removed via thoracotomy after endoscopic extraction had failed. The possible complications in case of a chronic tracheobronchial foreign body due to delayed diagnosis are pointed out. The purpose of this contribution is to provide the general practitioner with guidelines to suspect the presence of a foreign body well in time and to refer the patient quickly to a competent hospital for immediate treatment.

Bronchi↗
PubMed1993

[Life threatening late dislocation in chronic foreign body aspiration].

We report a case of a boy with a long-standing foreign body aspiration in the left main bronchus causing severe pneumonia of the left lung. During intravenous therapy with antibiotics there was a life-threatening event with acute dislocation of the foreign body into the right main bronchus, leading to acute respiratory insufficiency. We conclude that in chronic foreign body aspiration antibiotic therapy preceding bronchoscopy should only be performed in in-patients and with strict monitoring.

Airway Obstruction↗
PubMed1993

[Cold air hyperventilation provocation].

The prevalence of asthma was determined by a parental questionnaire in 9403 schoolchildren aged 9-11 years. A cold air challenge was done in 7248 of these children to test for bronchial hyperresponsiveness. Regarding the doctor diagnoses of asthma as reported by the parental questionnaire the specificity of the cold air challenge was 92.5%, the sensitivity 28.7%, the positive predictive value 9.1% and the negative predictive value 98%.

Asthma↗
PubMed1992

[Does breast feeding prevent asthma and allergies? Results of the Munich asthma and allergy study].

The relationship of breast feeding to atopic diseases is studied in a population-based cross sectional study in Munich and Bavaria 1989/1990 in 6,535 german ten year old children. According to the questionnaire answers 1914 (29.3%) children were not breast fed, 2,368 (36.2%) shorter than 2 months, 1,744 (26.7%) 2 to 6 months and 509 (7.8%) more than 6 months. Compared to controls without any allergic disease the relative risk of later asthma, hayfever, atopic dermatitis and of allergic skin sensitization was not diminished by breast feeding. The same result pertained to high risk subgroups defined by positive family history of asthma or hayfever. It is concluded that breast feeding alone has no long term protective effect against atopic diseases.

Asthma↗
PubMed1991

Non-invasive determination of alveolar pressure during mechanical ventilation.

The development of inadvertent positive end-expiratory pressure (PEEPi) in ventilated infants is of clinical relevance and difficult to measure non-invasively. A method for estimating end-expiratory alveolar pressure by applying a multiple regression analysis to airway opening pressure, flow and volume recordings during mechanical ventilation was evaluated. In eight open-chested, paralysed and mechanically ventilated mongrel dogs, alveolar pressure was measured directly with "alveolar capsules". Alteration of ventilation patterns and addition of a resistive element were used in three dogs to induce different levels of PEEPi. End-expiratory alveolar pressure measured directly and determined from multilinear regression of airway opening pressure correlated well (mean error 0.06 +/- 0.53 (+/- SD) hPa, limits of agreement -1.16 to +1.04 hPa). The other five dogs received inhalation challenges, two with histamine, two with hypertonic saline and one with methacholine resulting in a mean increase of respiratory system resistance of 230% (range 141-489%) of the baseline values. The mean error in determining PEEPi was 0.54 +/- 0.37 hPa, the limits of agreement were -0.20 to 1.28 hPa. The method was then applied to seven mechanically-ventilated children (aged 2 months to 8 yrs, weight 4.9-23.5 kg) and the results were compared to the pressure at which inspiration began (equalling PEEPi). Seventy eight measurements were performed during open heart surgery, while compliance changed by between 3 and 186% of baseline values due to the surgical procedures. PEEPi estimated by multiple regression agreed well with the pressure at which inspiration began (mean difference 0.25 +/- 0.68 hPa, limits of agreement -1.12 to 1.62 hPa).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Possibilities for optimization of radiotherapy of esophageal carcinoma through measurement of the oncoradiogenic enzyme peak of glucosephosphate isomerase].

In 20 patients with oesophageal carcinoma blood samples were taken after the first irradiation and the activity of the glycolytic enzyme glucose-6-phosphate isomerase was measured. In all patients there occur GPI peaks at reproducible times. The height of the enzyme peak occurring 15.5 to 19.5 hours p.irr. expresses a significant dependence on tumour size and irradiation dose. The frequency of a late occurring enzyme peak depends on the appearance of regional lymph node metastases. Possible sources of the enzyme peaks are discussed from a radiobiological point of view and the meaning of such enzyme peaks for the optimization of radiation therapy is pointed out.

Adult↗
PubMed1991

[Possibilities for optimizing radiotherapy of cancers of the ENT area by measuring oncoradiogenic enzyme peaks of glucose-6-phosphate isomerase].

Blood samples were taken from 39 patients with head and neck carcinomas after the initial irradiation, and the activity of the glycolytic enzyme glucose-6-phosphate isomerase (GPI) was measured. All patients showed GPI peaks at reproducible times. The height of the enzyme peak occurring 15.5-19.5 h after irradiation, was significantly correlated with tumour size and histological tumour differentiation. A late enzyme peak was associated with regional lymph node metastases. Possible sources of the enzyme peaks are discussed from a radiobiological point of view, and the value of such enzyme peaks for the optimization of radiation therapy is pointed out.

Adult↗
PubMed1990

Correlation of IgE antibody titer to Aspergillus fumigatus with decreased lung function in cystic fibrosis.

Obstructive pulmonary disease is a typical feature of cystic fibrosis (CF) and is often associated with bronchial hyperreactivity. Positive skin-test reactions to Aspergillus fumigatus antigens are frequently seen even in nonatopic patients with CF. Full-fledged allergic bronchopulmonary aspergillosis (ABPA) has been estimated to occur in 10% of patients with CF. The relationship between lung function and presence of IgE antibodies to Aspergillus antigens in patients without ABPA is not clear. In 148 outpatients with CF (aged 6-34 years) specific immunoglobulin E (IgE) to Aspergillus fumigatus antigens, basic lung-function parameters, and bronchial response to salbutamol were measured. Multiple regression was performed for age, weight as percentile for actual height (indicating general condition), and Aspergillus RAST. Aspergillus IgE was present in 46% of patients; 19% had RAST class 3 or 4. Independent negative correlations of Aspergillus RAST with FEV1, FEF50%, FEF25%, RV, Chrispin Norman score, and sRaw (P less than 0.05) were found. Bronchodilator sensitivity did not correlate significantly with age and weight percentile. However, Aspergillus RAST did correlate significantly with bronchodilator response measured by sRaw (P less than 0.05). High titers of Aspergillus RAST might serve as a selective criterion for patients to be included in future studies evaluating broncholytic or antiphlogistic therapies.

Adolescent↗
PubMed1990

Acute viral bronchiolitis in infancy: epidemiology and management.

Acute bronchiolitis due to viral agents (RSV, parainfluenza, influenza, adenovirus) is a relatively frequent disease of infancy. Seasonal epidemic pattern have been recognized, and nosocomial infections in pediatric wards occur. Until age 2 years most children have experienced some form of airway disease attributable to RSV. Some patients require hospital treatment; about 15% of our patients had to be transferred to the intensive care unit. Bronchiolitis seems to be frequently the first manifestation of asthma and we found higher IgG antibody titers to viruses causing bronchiolitis in children with asthma than in controls. Retrospective analysis of the charts of 147 cases of bronchiolitis revealed considerable uncertainty regarding therapeutic concepts. Mainstays of conservative therapy include oxygen, adequate hydration (often IV), and sometimes bronchodilators (based on the clinical impression of effectiveness in the individual patient). Mist therapy and secretolytic agents remain popular, although no clinical effect has been demonstrated. Attention should be directed toward the relief of upper airway obstruction caused by swelling, secretions, and nasogastric tubes. Oxygen administration in infants with coexisting chronic airway disease (e.g., BPD) and bronchiolitis may cause CO2 retention. Bronchodilators can cause hypoxia and increase bronchial compressibility by reducing smooth muscle tone. However, in severe cases a trial under pulse oximetry control seems worthwhile. Steroids seem to bring no clinical improvement, except in infants with protracted wheezing after bronchiolitis and patients with preexisting BPD.

Asthma↗