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Biomedical subjects

P Zanen

Publications and source records attributed to P Zanen.

At least 19 recordsLinked to original sources
PubMed2005

Alveolar volume determined by single-breath helium dilution correlates with the high-resolution computed tomography-derived nonemphysematous lung volume.

BACKGROUND: The alveolar volume (V(A)), determined by single-breath helium dilution, is a measure for the total lung capacity (TLC) that is very sensitive to ventilatory disturbances. In chronic obstructive pulmonary disease (COPD), the emphysematous lung parts are less accessible to test gas; therefore, the V(A) is smaller than TLC measured by multiple-breath helium dilution (TLC(He)). OBJECTIVES: The aim of this study was to investigate whether the V(A) represents the nonemphysematous lung parts. METHODS: We measured V(A) as part of the diffusing capacity for carbon monoxide (DL(CO)), TLC(He) and spirometry in 50 patients with COPD. High-resolution computed tomography (HRCT) scans of all subjects were analyzed with the density mask method, where parts with an attenuation of less than -950 Hounsfield units were considered as emphysematous. RESULTS: A strong correlation was observed between the V(A) (mean 5.2 liters) and nonemphysematous HRCT lung volume (mean 5.2 liters, r(2) = 0.9) and between the TLC(He) (mean 6.6 liters) and total HRCT lung volume (mean 6.4 liters, r(2) = 0.9). Bland-Altman plots showed considerable disagreement between the V(A) and the nonemphysematous HRCT lung volume. A weak correlation between the forced expiratory volume in 1 s (mean 46% predicted) and DL(CO) (mean 46% predicted) versus the HRCT emphysema ratio (nonemphysematous/total HRCT lung volume) was observed (r(2) = 0.3 and 0.3, respectively). CONCLUSION: We concluded that the V(A) correlates with the nonemphysematous HRCT lung volume, although the two measurements are not equivalent, possibly due to technical factors.

Administration, Inhalation↗
PubMed2005

Pattern of diffusion disturbance related to clinical diagnosis: The K(CO) has no diagnostic value next to the DL(CO).

AIM OF THE STUDY: The diffusion capacity of the lung for carbon monoxide (DL(CO)) is an important tool in the diagnosis and follow-up of patients with pulmonary diseases. In case of a decreased DL(CO) the K(CO), defined as DL(CO)/V(A) (V(A) is alveolar volume), can differentiate between normal alveolocapillary membrane (normal K(CO)) and abnormal alveolocapillary membrane (low K(CO)). The latter category consists of decreased surface of the membrane, increased thickness or decreased perfusion of ventilated alveoli. The V(A)/TLC (TLC is total lung capacity determined by whole body plethysmography) can partially differentiate between these categories. The aim of this study was to investigate the diagnostic value of the specific diffusion disturbances, which can be constructed by combining the DL(CO), K(CO) and V(A)/TLC. METHODS: In 460 patients the diagnosis made by clinicians were fitted into five diagnostic categories: asthma, chronic obstructive pulmonary disease (COPD), treatment effects of haematologic malignancies, heart failure and diffuse parenchymal lung diseases (DPLD). These categories were linked to the pattern of diffusion disturbance. RESULTS: Almost all patients with asthma have a normal DL(CO), most patients in the other groups do not have the expected pattern of diffusion disturbance, especially in the group with DPLD a bad match is observed. CONCLUSION: In this study the pattern of diffusion disturbance is of limited use in establishing a diagnosis. The use of the K(CO) next to the DL(CO) has no additional diagnostic value. Regional ventilation-perfusion inequality probably forms an important underlying mechanism of decreased DL(CO).

Adolescent↗
PubMed2005

Could interchangeable use of dry powder inhalers affect patients?

The aim of asthma treatment is optimal disease control. Poor asthma control results in considerable patient morbidity, as well as contributing to the considerable burden placed by the disease on healthcare budgets. There is a need for costs to be carefully scrutinised, with the switching of patients to inhaler devices with lower acquisition costs likely to be increasingly considered. However, before such practice becomes widespread, it is important to establish whether or not this could adversely impact on patients and the level of disease control. For approval to have been given, all marketed inhalers must have satisfied current regulatory requirements for devices. Full preclinical and clinical development programmes are not required when application is made for authorisation to market a new inhaler containing an existing chemical entity, although clinical equivalence testing must be used. Both beneficial and adverse effects should be tested, and the limits of equivalence must be clearly defined, based on therapeutic relevance. It should be noted that equivalence studies are invalid when the end point is not responding (i.e. at the top of the dose-response curve) and when equivalence limits approach or are equal to the magnitude of the drug effect. Approval on the basis of regulations designed to safeguard quality of dry powder inhalers does not mean that devices are interchangeable. When using an inhaler, there are many stages between the patient and the therapeutic effect, involving device design, pharmaceutical performance and patient behaviour. Regulations governing new devices cover only a few of the many factors affecting disease control. Furthermore, clinical trials to assess equivalence may not take into account factors in patient behaviour or variations in patient inhaler technique that may affect use of devices in real-life situations. When assessing the consequences of interchangeable use of dry powder inhalers on healthcare costs, it is important to ensure that the acquisition cost of the devices is not the only cost considered. Other costs that should be considered include the cost of time spent demonstrating to the patient how to use the new device, the cost of additional physician visits to address patient concerns and the management costs if disease control is adversely affected.

Administration, Inhalation↗
PubMed2005

Can patients use all dry powder inhalers equally well?

If patients are unable to use their inhaler, drug delivery may be unsatisfactory and the patients may fail to benefit from the prescribed medication. It is important to consider whether patients can use all dry powder inhalers equally well. Changing a patient from a dry powder inhaler used well to one that the patient is unable to operate effectively could compromise asthma control. The many marketed dry powder inhalers reflect differences in design decisions that could affect lung deposition. Studies using different dry powder inhalers have confirmed that different lung deposition patterns are observed. Furthermore, there may be considerable individual variability in lung deposition. Differences in lung deposition patterns could have clinical effects. Studies may show similar clinical effectiveness with two inhalers, because most products are used at the plateau phase of the dose-response curve, although there may be differences in the adverse event profile. The ideal inhaler does not yet exist. Different dry powder inhalers show some but not all features of the ideal inhaler; hence, patients may prefer some aspects of one inhaler while favouring a different inhaler for other features. The individual balance of features will govern the overall preference for one inhaler over others. The method for operation of dry powder inhalers varies. Ease of use is seen as an important consideration when selecting an inhaler device, which should be evaluated in real-life studies using unselected patient populations. In conclusion, the evidence suggests that patients cannot use all dry powder inhalers equally well.

Administration, Inhalation↗
PubMed2005

Pneumoproteins as a lung-specific biomarker of alveolar permeability in conventional on-pump coronary artery bypass graft surgery vs mini-extracorporeal circuit: a pilot study.

BACKGROUND: Despite improvements of the heart-lung machine (HLM), oxidative stress and subsequent damage to the alveolar capillary membrane still occur after conventional on-pump coronary artery bypass graft (CCABG) surgery. In an attempt to further improve the conventional HLM, a mini-extracorporeal circuit (MECC) was introduced. This new concept is based on minimal volume shifts. The extent of alveolar injury that is associated with this new technique is unknown. The lung-specific biomarkers Clara-cell 16 (CC16) and KL-6 are applied in this study to quantify alveolar dysfunction in both techniques. METHODS: In a prospective observational setting, the concentrations of CC16 and KL-6 were measured during and after 10 consecutive CCABG operations and 10 consecutive coronary artery bypass graft (CABG) operations using MECC (MCABGs). These pneumoproteins were measured after the induction of anesthesia, before clamping of the ascending aorta, after unclamping of the aorta, on arrival to the ICU, and on the following days until discharge. Quantification of the differences of KL-6 and CC16 leakage through the alveolar membranes between the two techniques was realized by calculation of the Student t test. Perioperative and postoperative shunt fractions and clinical observations were monitored simultaneously. The potential value of pneumoproteins as biomarkers for quantification of alveolar permeability during CABG surgery was tested. RESULTS: Significantly reduced concentrations of CC16 were found early after MCABG as compared to CCABG surgery (p = 0.033). KL-6 showed no consistent pattern during both treatment modalities. Early after CCABG surgery, shunt fractions tended to show reduced oxygen transport over the alveolar membrane as compared to MCABG surgery. CONCLUSION: CC16 appears to be a useful biomarker for alveolar permeability during CABG surgery. Injury of the alveolar capillary membrane appears significantly reduced during MCABG surgery. Consistently early postoperative alveolar shunt fractions showed an increased value in CCABG compared to MCABG surgery in the early postoperative phase. Further randomized studies need to confirm the value of CC16 as marker in monitoring alveolar capillary damage during coronary bypass grafting.

Aged↗
PubMed2004

An investigation into the predictive value of cascade impactor results for side effects of inhaled salbutamol.

The aim of this study was to compare the Multistage Liquid Impinger (MSLI) and the Andersen Cascade Impactor (ACI) with respect to their power to predict differences in side effects of salbutamol delivered by a dry powder inhaler. Three preparations with the same nominal dose and the same inhaler device but generating aerosols with different aerodynamic particle size distributions were administered to six healthy volunteers in a randomized, placebo-controlled, four-way crossover study. Cumulative doses from 400 up to 1600 microg were given. The serum potassium level (K+-serum) and the heart rate (HR) were measured at baseline and 15 min after each dose. Both the MSLI and ACI showed large differences between the aerodynamic particle size distributions of the three preparations. The decrease in K+-serum revealed significant differences between the three active preparations and was significant for doses of 800 microg and higher. The HR results showed differences between the active preparations only at a nominal dose of 1600 microg and only for the preparation with the highest fine particle dose (FPD) compared to the other two preparations. The K+-serum appears to be a more sensitive measure for side effects than the HR. In vivo-in vitro correlations (IVIVCs) were established between the amounts of salbutamol deposited on the various cumulative impactor stages and the K+-serum. The best IVIVCs were obtained in the FPD range, resulting in correlation coefficients of at least 0.78. It is concluded that cascade impactor results in the FPD range of the MSLI as well as the ACI correlate well with the K+-serum. Cascade impactor analysis thus provides a clinically meaningful tool in the development and the quality control of salbutamol inhalation powders.

Administration, Inhalation↗
PubMed2004

No association between interleukin-18 gene polymorphisms and haplotypes in Dutch sarcoidosis patients.

Previously, an association between susceptibility to sarcoidosis and a polymorphism in the interleukin (IL-18) gene (IL-18 -607A/C) has been reported in Japanese. The aim of the present study was to validate this association in a clinically well-characterized population of Dutch Caucasians. Three other polymorphisms at positions -656, -137, and 1248 were included in order to extend the mapping of the IL-18 gene and to enable the construction of haplotypes. Polymorphisms were determined using sequence-specific primers (SSPs) and polymerase chain reaction (PCR). A total of 236 individuals was studied (133 patients and 103 controls). No significant differences were observed in the distribution of the -607 and the other polymorphisms between Dutch sarcoidosis patients and controls. However, significant differences in IL-18 -607 genotype and allele frequency distributions were found between the Dutch and the Japanese. From the investigated IL-18-promoter polymorphisms, we were able to deduce four haplotypes. No differences were observed in haplotype frequencies between Dutch sarcoidosis patients and controls. In conclusion, IL-18 polymorphisms do not appear to influence the susceptibility to sarcoidosis in Dutch Caucasians. Important differences in allele frequencies were observed between Japanese and Dutch sarcoidosis patients and controls.

DNA Primers↗
PubMed2004

Duration of effect of single-dose inhaled fluticasone propionate on AMP-induced bronchoconstriction.

Airway hyperresponsiveness induced by adenosine-5'-monophosphate (AMP) is regarded as a reliable model for allergic asthma and for the evaluation of anti-asthmatic drugs. Single-dose inhaled corticosteroids (ICS) are known to be protective in this model, but the duration of action of these drugs in this model has never been studied. The duration of ICS protection was determined by administration of single-dose fluticasone propionate (FP; 1,000 micrograms) up to 26 h before AMP challenge. A randomised, double-blind, placebo-controlled, four-way crossover study was performed in 13 mild asthmatics (mean +/- SD predicted forced expiratory volume in one second (FEV1) 98 +/- 7%). Each subject received placebo and FP (at 26, 14 or 2 h prior to the AMP challenge). Furthermore, the marker exhaled nitric oxide (eNO) was studied after administration at these time points to investigate whether eNO also demonstrates the duration of action of ICS. The doubling concentrations difference (DCD) of AMP causing a 20% fall in FEV1, when FP was administered 26, 14 or 2 h prior to challenge, was significantly increased as compared with placebo: DCD (95% confidence interval) at 26 h, 0.73 (0.20-1.26), p = 0.008; 14 h, 1.50 (0.99-2.01), p < 0.001; and 2 h, 2.89 (2.37-3.40), p < 0.001. However, eNO was not significantly affected at these time points. In conclusion, a single dose of 1,000 micrograms inhaled fluticasone propionate protects against adenosine-5'-monophosphate airway hyperresponsiveness up to 26 h after dosing. This study suggests that adenosine-5'-monophosphate challenge can be used as a sensitive marker to study the duration of action of inhaled corticosteroids.

Adenosine Monophosphate↗
PubMed2003

Lung function changes and pulmonary complications in patients with stage III non-small cell lung cancer treated with gemcitabine/cisplatin as part of combined modality treatment.

INTRODUCTION: Lung cancer is the leading cause of cancer mortality. Chemotherapy, ideally a platinum-based regimen as part of combined modality treatment, is appropriate for selected patients with locally advanced stage III non-small cell lung cancer (NSCLC) who have a good performance status. However, chemotherapy can induce side effects including lung function changes. AIM OF THE STUDY: Retrospective analysis of lung function changes in 44 patients with stage III NSCLC treated with neoadjuvant chemotherapy (NCT) followed by surgery and/or radiotherapy. PATIENTS AND METHODS: NCT consisted of three cycles of gemcitabine/cisplatin. The following data were analysed: age, sex, the presence of chronic obstructive pulmonary disease (COPD), smoking behaviour, response, complications after surgery and/or radiotherapy, and VC, FEV(1), DL(co) and K(co) before and after chemotherapy. DL(co) values were corrected for haemoglobin concentrations. RESULTS: We found a significant decline of K(co) (-13.5% of pred; 95% CI: -16.6 to -10.4; P<0.0001), independent of tumor response or presence and severity of COPD. FEV(1) and FEV(1)/VC showed significant increases irrespective of tumor response. Significantly more pulmonary complications were recorded in the radiotherapy group after NCT (P=0.009) compared to patients who underwent surgical therapy after NCT. CONCLUSIONS: Patients diagnosed with NSCLC stadium III who were treated with NCT consisting of cisplatin and gemcitabine showed a significant decline of DL(co) and K(co), irrespective of tumor response, presence and severity of COPD, sex and number of cycles of chemotherapy. Significantly more pulmonary complications were seen in patients treated with NCT and radiotherapy compared with patients treated with NCT and surgery. Questions concering the pathophysiological mechanisms of lung function changes and long term follow-up of pulmonary toxicity due to NCT remain still unanswered and have to be subject of future studies.

Adult↗
PubMed2003

Flow dependency and off-line measurement of exhaled NO in children.

Levels of exhaled nitric oxide (eNO) are flow-dependent, and the choice of an optimal flow rate for off-line and on-line eNO measurement has raised much debate. Recently, a flow rate of 50 ml/s was recommended, but children younger than 5-6 years are not capable of stabilizing their expiratory flow at low flow rates. The power of off-line eNO values to discriminate between normal and atopic children was therefore evaluated at different exhalation flow rates. At flow rates of both 8.3 ml/s and of 350 ml/s, children (8-12 years) sensitive to house dust mite have two-fold higher eNO values (p < 0.001) as compared with children lacking such a sensitivity. The power of eNO to discriminate between normal and atopic subjects was similar at the two flow rates (no difference in AUC of receiver operation curves, p = 0.89). All children from 4.5 to 5 years of age (n = 29) could perform a single off-line exhalation manoeuvre at high (>350 ml/s) but not at low (8.3 ml/s) flow rates. At high exhalation flow rate, eNO was 7.1 +/- 2.4 (mean +/- SD) median, 6.5 p.p.b. with a mean variation coefficient of 5.5%. Depending on their developmental level, about half of the younger children (35-46 months of age) could perform an off-line exhalation manoeuvre at high flow rate with good reproducibility (mean variation coefficient of 6.6%). It is concluded that an exhalation flow rate of 350 ml/s is feasible to determine off-line eNO-values in children from 3.5 years of age, and that this high flow rate does not compromise the power of eNO to detect allergic disease.

Adult↗
PubMed2002

Equivalence testing of salbutamol dry powder inhalers: in vitro impaction results versus in vivo efficacy.

The aim of the study was to evaluate several impactors for in vitro equivalence testing of salbutamol with respect to efficacy and to define in vitro equivalence limits validated with in vivo efficacy data. The four impactors described in Supplement 2000 of the European Pharmacopoeia were used: Glass Impinger (GI), Metal Impinger (MI), Multistage Liquid Impinger (MSLI) and Andersen Cascade Impactor (ACI). Three salbutamol dry powder formulations with different fine particle doses (FPDs) were prepared and the aerodynamic particle size distribution was measured. For each impactor also the recovery was determined. The same three preparations were administered to 12 asthmatic patients in a randomized, placebo-controlled, four-way crossover study. Cumulative doses from 50 microg up to 400 microg were given. The FEV(1) was measured at baseline and 15 min after each dose. The in vitro results showed large differences between the FPDs of the three preparations with all impactors, whereas only small differences were observed between the four impactors. Since the recoveries of the MI and GI were low, in vitro equivalence testing should only be performed with the MSLI or ACI. The in vivo measurements did not show significant differences in efficacy between the three active preparations, even at the most discriminatory dose of 50 microg. It is concluded that in case there are no relevant differences between delivered dose, inhalation device and excipients, for salbutamol dry powder inhalers equivalence can be assumed when the 90% confidence interval for the FPD ratio of the test product and reference product is within 0.50-1.20 and each of the two products has a FPD (particles <6 microm) of at least 10 microg.

Adult↗
PubMed2002

Metal versus plastic spacers: an in vitro and in vivo comparison.

This study compared the metal Nebuchamber with the polycarbonate Volumatic spacer in vivo as well as in vitro. Seventeen asthmatic patients were evaluated in a crossover placebo-controlled double-blind study. Bronchodilation, heart rate and serum potassium levels were measured at baseline and 15 min after administration of salbutamol. Cumulative dose-response curves (200, 400, 800 and 1600 microg) were constructed. The Andersen Cascade Impactor was used to compare the aerodynamic particle size distribution. The FEV(1) measurements showed highly significant differences between placebo and the two active preparations (P<0.001), but not between the two active preparations (P=0.433). The serum potassium levels also showed highly significant differences between placebo and the two active preparations (P=0.009), but not between the two active preparations (P=0.532). Only 1600 microg salbutamol dose raised the heart rate significantly, but the difference between the two active preparations was not significant. The in vitro deposition study revealed no significant differences in the delivered dose or in the fine particle dose (P>0.05). In conclusion, there are no significant differences between the Volumatic and Nebuchamber either in vivo or in vitro.

Administration, Inhalation↗
PubMed2002

Reduction of variability of exhaled nitric oxide in healthy volunteers.

Exhaled nitric oxide (eNO) is elevated in patients with asthma in contrast to healthy subjects, although the variability is high. In this study, we tried to reduce the variability of eNO in healthy subjects. We measured eNO using ERS guidelines with a fixed exhalation flow of 250 ml/s in 117 (72 women, 45 men) non-smoking healthy subjects and correlated this to antropometric data and standard lung function measurements. Using a model previously defined by Hyde et al., we selected parameters that were likely to have a high correlation with eNO. ENO was log-normally distributed. The normal values for eNO are significantly (P < 0.001) different for men and women: in women mean ln eNO levels (SD) were 1.49 (0.34), in men 1.74 (0.41) (back-transformed value 4.43 resp. 5.73 ppb). Using multiple regression analysis, only In D(m,CO), InTLC and In sG(aw) showed a significant positive correlation with In eNO in men, although only 20% of the variability of eNO could be explained. In women no correlation was observed and only 5% ofthe variability was explained. The high variability of eNO could only partly be explained in men, which makes the use of reference equations not very helpful.

Adult↗
PubMed2001

Survival after resection of metachronous non-small cell lung cancer in 127 patients.

BACKGROUND: In a number of patients with treated primary non-small cell lung cancer (NSCLC) a second primary tumor will be diagnosed. Our experience with surgery in these patients was analyzed and possible prognostic parameters were defined. METHODS: Patients with metachronous NSCLC (n = 127) who underwent resection from 1970 through 1997 were analyzed. All tumors were classified postsurgically. Median interval between the tumors was 3.7 years. Actuarial survival time was estimated and risk factors influencing survival were evaluated. RESULTS: Overall 5-year survival after the first resection was 70% and after the second resection was 26%. Patients with stage IA of the second primary tumor did have a significantly better survival (p < 0.005) as compared with patients with higher staged second primaries. Stage of second primary tumor and age were significant predictors of survival, whereas stage of first tumor, interval between resections, histology, and type of resection were not. CONCLUSIONS: Survival of patients with metachronous NSCLC and resection of both tumors is high, but poorer than after resection of the first tumor. Irrespective of the interval, patients with stage IA second primary tumor may benefit more from pulmonary resection.

Aged↗
PubMed2001

Electro-hydrodynamic atomization of drug solutions for inhalation purposes.

Monodisperse aerosols show therapeutic advantages, but they are difficult to generate. A new method (electrohydrodynamic atomization) is described. A high voltage is applied to a nozzle through which a solution, containing dissolved drug, is pumped. At the nozzle tip, a liquid cone is formed and a stream of monodisperse droplets is released. The droplet diameter is governed by the density, conductivity, and the flow rate of the fluid. The droplets are charged and need to be neutralized. Therefore, a corona discharge system is used. Methylparahydroxybenzoate was used as a model drug, and additional data were generated by using beclomethasone dipropionate (BDP). At a flow rate of 1 ml/h and 0.5% methylparahydroxybenzoate, 1.58-microm particles were produced with a geometric SD of 1.18. Increasing the flow rate to 3 ml/h and the concentration to 3% resulted in 4.55-microm particles with a geometric SD of 1.29. The experiments with BDP resulted in similar particle sizes. The mass of BDP was found to range between 1.42 and 6 microg/l air. Aqueous solutions cannot be sprayed by using this setup. This method can be used to deliver antiasthma drugs to patients.

Administration, Inhalation↗
PubMed2001

Reference values for alveolar membrane diffusion capacity and pulmonary capillary blood volume.

The reference values for diffusion capacity of the alveolar capillary membrane (Tm,CO) and pulmonary capillary volume (Qc) are scarce, while the standard deviations of the equations are large. New equations and residual standard deviations (RSDs) were determined in a sample of healthy subjects. Tm,CO and Qc values were measured in 117 (72 females, 45 males) nonsmoking healthy subjects. The carbon monoxide transfer factor (TL,CO) was determined when the volunteer was breathing room air and subsequently, when the volunteer was breathing 100% oxygen. From these data, Tm,CO and Qc values were calculated. The females' TL,CO was 3.15 mmol x min(-1) x kPa(-1) lower than the males', apparently caused by lower female lung volume. Tm,CO and Qc were lower in females, but correction for lung volume eliminated this difference. Qc(-1) reference equations for females and males, respectively, are 4.375 x 10(-2) - 1.085 x l0(-2) x height and 4.455 x 10(-2) -1.085 x 10(-2) x height (RSD for both sexes: 2.544 x 10(-3)). Tm,CO(-1) reference equations for females and males, respectively, are 0.111+3.304 x 10(-4) x age-4.753 x 10(-2) x height and 0.127+3.304 x 10(-4) x age-4.753 x 10(-2) x height (RSD for both sexes: 1.085 x 10(-2)). The general character of these equations complies with earlier publications, the only difference being that the RSDs are 1.18-2.76 times lower. New reference equations for diffusion capacity of the alveolar capillary membrane and pulmonary capillary volume are available with considerably smaller residual standard deviations.

Adult↗