Biomedical subjects

R Bergmann

Publications and source records attributed to R Bergmann.

At least 19 recordsLinked to original sources

PubMed2005

Small animal positron emission tomography in food sciences.

Positron emission tomography (PET) is a 3-dimensional imaging technique that has undergone tremendous developments during the last decade. Non-invasive tracing of molecular pathways in vivo is the key capability of PET. It has become an important tool in the diagnosis of human diseases as well as in biomedical and pharmaceutical research. In contrast to other imaging modalities, radiotracer concentrations can be determined quantitatively. By application of appropriate tracer kinetic models, the rate constants of numerous different biological processes can be determined. Rapid progress in PET radiochemistry has significantly increased the number of biologically important molecules labelled with PET nuclides to target a broader range of physiologic, metabolic, and molecular pathways. Progress in PET physics and technology strongly contributed to better scanners and image processing. In this context, dedicated high resolution scanners for dynamic PET studies in small laboratory animals are now available. These developments represent the driving force for the expansion of PET methodology into new areas of life sciences including food sciences. Small animal PET has a high potential to depict physiologic processes like absorption, distribution, metabolism, elimination and interactions of biologically significant substances, including nutrients, 'nutriceuticals', functional food ingredients, and foodborne toxicants. Based on present data, potential applications of small animal PET in food sciences are discussed.

Animal Nutritional Physiological Phenomena↗

PubMed2005

Catabolism of native and oxidized low density lipoproteins: in vivo insights from small animal positron emission tomography studies.

The human organism is exposed to numerous processes that generate reactive oxygen species (ROS). ROS may directly or indirectly cause oxidative modification and damage of proteins. Protein oxidation is regarded as a crucial event in the pathogenesis of various diseases ranging from rheumatoid arthritis to Alzheimer's disease and atherosclerosis. As a representative example, oxidation of low density lipoprotein (LDL) is regarded as a crucial event in atherogenesis. Data concerning the role of circulating oxidized LDL (oxLDL) in the development and outcome of diseases are scarce. One reason for this is the shortage of methods for direct assessment of the metabolic fate of circulating oxLDL in vivo. We present an improved methodology based on the radiolabelling of apoB-100 of native LDL (nLDL) and oxLDL, respectively, with the positron emitter fluorine-18 ((18)F) by conjugation with N-succinimidyl-4-[(18)F]fluorobenzoate ([(18)F]SFB). Radiolabelling of both nLDL and oxLDL using [(18)F]SFB causes neither additional oxidative structural modifications of LDL lipids and proteins nor alteration of their biological activity and functionality, respectively, in vitro. The method was further evaluated with respect to the radiopharmacological properties of both [(18)F]fluorobenzoylated nLDL and oxLDL by biodistribution studies in male Wistar rats. The metabolic fate of [(18)F]fluorobenzoylated nLDL and oxLDL in rats in vivo was further delineated by dynamic positron emission tomography (PET) using a dedicated small animal tomograph (spatial resolution of 2 mm). From this study we conclude that the use of [(18)F]FB-labelled LDL particles is an attractive alternative to, e.g., LDL iodination methods, and is of value to characterize and to discriminate the kinetics and the metabolic fate of nLDL and oxLDL in small animals in vivo.

Animals↗

PubMed2005

Synthesis and biodistribution of an 18F-labelled resveratrol derivative for small animal positron emission tomography.

Resveratrol (3,4',5-trihydroxy-trans-stilbene) is a naturally occurring phytoalexin and polyphenol existing in grapes and various other plants, and one of the best known 'nutriceuticals'. It shows a multiplicity of beneficial biological effects, particularly, by attenuating atherogenic, inflammatory, and carcinogenic processes. However, despite convincing evidence from experimental and clinical studies, data concerning the role of resveratrol and other members of the large polyphenols family for human health is still a matter of debate. One reason for this is the lack of suitable sensitive and specific methods, which would allow direct assessment of biodistribution, biokinetics, and the metabolic fate of these compounds in vivo. The unique features of positron emission tomography (PET) as a non-invasive in vivo imaging methodology in combination with suitable PET radiotracers have great promise to assess quantitative information on physiological effects of polyphenols in vivo. Herein we describe the radiosynthesis of an (18)F-labelled resveratrol derivative, 3,5-dihydroxy-4'-[(18)F]fluoro-trans-stilbene ([(18)F]-1), using the Horner-Wadsworth-Emmons reaction as a novel radiolabelling technique in PET radiochemistry for subsequent functional imaging of polyphenol metabolism in vivo. In a typical "three-step/one-pot" reaction, (18)F-labelled resveratrol derivative [(18)F]-1 could be synthesized within 120-130 min including HPLC separation at a specific radioactivity of about 90 GBq/mumol. The radiochemical yield was about 9% (decay-corrected) related to [(18)F]fluoride and the radiochemical purity exceeded 97%. First radiopharmacological evaluation included measurement of biodistribution ex vivo and positron emission tomography (PET) studies in vivo after intravenous application of [(18)F]-1 in male Wistar rats using a dedicated small animal PET camera with very high spatial resolution. Concordantly with data on bioavailability and metabolism of native resveratrol from the literature, these investigations revealed an extensive uptake and metabolism in the liver and kidney, respectively, of [(18)F]-1. This study represents the first investigation of polyphenols in vivo by means of PET.

Animals↗

PubMed2005

Biodistribution and catabolism of 18F-labelled isopeptide N(epsilon)-(gamma-glutamyl)-L-lysine.

Isopeptide bonds between the epsilon-amino group of lysine and the gamma-carboxamide group of glutamine are formed during strong heating of pure proteins or, more important, by enzymatic reaction mediated by transglutaminases. Despite the wide use of a microbial transglutaminase in food biotechnology, up to now little is known about the metabolic fate of the isopeptide N(epsilon)-(gamma-glutamyl)-L-lysine. In the present study, N-succinimidyl-4-[(18)F]fluorobenzoate was used to modify N(epsilon)-(gamma-glutamyl)-L-lysine at each of its two alpha-amino groups, resulting in the 4-[(18)F]fluorobenzoylated derivatives, for which biodistribution, catabolism, and elimination were investigated in male Wistar rats. A significant different biochemical behavior of the two labelled isopeptides was observed in terms of in vitro stability, in vivo metabolism as well as biodistribution. The results suggest that the metabolic fate of isopeptides is likely to be dependent on how they are reabsorbed - free or peptide bound.

Animals↗

PubMed2005

Variability of total serum immunoglobulin E levels from birth to the age of 10 years. A prospective evaluation in a large birth cohort (German Multicenter Allergy Study).

BACKGROUND: Many environmental factors influence the concentration of total serum IgE (tIgE); however, tIgE synthesis is believed to be under strong genetic influence. Multiple genetic studies on tIgE regulation have been performed. For these population-based studies tIgE was commonly determined at one time-point, assuming that tIgE phenotypes (adjusted for age and gender) are stable over time. OBJECTIVE: We assessed correlations of tIgE levels from birth to the age of 10 years in the birth cohort MAS (Multicenter Allergy Study; n=1314). MATERIALS AND METHODS: We determined cord-blood IgE levels, total and specific IgE at the age of 1, 2, 3, 5, 6, 7, and 10 years. Spearman correlation coefficients were calculated for tIgE at different time-points. All analyses were performed in the entire cohort, adjusted for gender, as well as in non-atopic children only. RESULTS: tIgE percentiles increased steadily from birth to the age of 10 years with higher values for boys than for girls at each time-point. tIgE values from birth to 3 years of age correlated poorly with tIgE levels at 10 years (r<0.5). However, good correlations (r>0.8) were observed for tIgE concentrations at 6, 7 and 10 years. The same results were observed when the analyses were limited to non-atopic children. CONCLUSION: In childhood, tIgE levels underlie remarkable variation over time even in the absence of atopy. For cross-sectional population-based genetic and epidemiologic studies, tIgE values of children <5 years should be interpreted with caution since these values correlate poorly with tIgE levels later in life.

Age Factors↗

PubMed2003

PrP Sc-like prion protein conformer in sudden infant death syndrome brain.

Nothing is known about the pathophysiology of sudden infant death syndrome (SIDS). Here we show the presence of misfolded prion protein (PrP(Sc)-like) in extracts of various sections of the brains of two SIDS victims. DNA sequence information for one of these (death at 12 days) revealed two nucleotide variants in the protein coding region of the PrP gene. This may be a key finding in the understanding of SIDS pathology, and may suggest ways for identifying risk factors for SIDS in newborn infants.

Adult↗

PubMed2003

Analysis of 6-hydroxy-2-aminocaproic acid (HACA) as a specific marker of protein oxidation: the use of N(O,S)-ethoxycarbonyl trifluoroethyl ester derivatives and gas chromatography/mass spectrometry.

An alteration of low density lipoprotein (LDL) apolipoprotein (apo) B-100 structure by direct oxidative modification is an important mechanism involved in atherogenesis. There is difficulty in quantifying this type of modification because a lack of specific assays. The use of N(O,S)-ethoxycarbonyl trifluoroethyl amino acid esters for a rapid and sensitive determination of 6-hydroxy-2-aminocaproic acid (HACA), a highly specific marker of metal catalyzed protein oxidation, by using standard gas chromatography/electron impact mass spectrometry, is discussed. The derivatives are formed by the unlabored reaction of amino acids with ethylchloroformate plus trifluoroethanol plus pyridine. Femtomole levels of HACA can be reproducible measured in different LDL preparations subjected to oxidative damage in the presence of iron or copper. HACA determination compares well with the measurement of carbonyl groups that are generally accepted as a nonspecific index of protein oxidation. Thus, the method could prove to be a sensitive assay for studying specific apoB-100 modification.

Aminocaproates↗

PubMed2003

3-O-methyl-6-[18F]fluoro-L-DOPA and its evaluation in brain tumour imaging.

3-O-Methyl-6-[(18)F]fluoro-L-DOPA (OMFD) is a major metabolite of 6-[(18)F]fluoro-L-DOPA. Although synthesis of OFMD was primarily established to study the dopaminergic system, as it is an amino acid analogue, uptake in experimental tumours has been found. The aim of this study was to evaluate the applicability of OMFD for brain tumour imaging and to obtain initial estimates of whole-body biodistribution and radiation dosimetry in humans. Nineteen patients with suspected or confirmed brain tumours were investigated with OMFD and dynamic brain PET, complemented by whole-body PET in seven patients. Tracer kinetics were compared for normal brain and intracerebral lesions. Tissue accumulation was quantified with standardised uptake values (SUVs). Whole-body distribution in combination with tracer kinetics from animal experiments was used for the calculation of radiation dosimetry data. On the basis of OMFD PET, viable brain tumour was suspected in 16 patients with SUVs of 3.0+/-0.8 and a tumour to non-tumour ratio of 1.9+/-0.5. Highest tumour and normal brain uptake occurred between 15 and 30 min, with a subsequent slow decrease. Late whole-body tracer distribution was uniform without specific organ accumulation. Elimination occurred via urine. The mean radiation dose to the whole body was estimated at 0.016 mSv/MBq, with the kidneys as dose-critical organ (0.033 mGy/MBq). In conclusion, OMFD enables the visualisation of brain tumours with SUVs similar to other fluorinated amino acids. The whole-body radiation exposure from OMFD is comparable to that from FDG imaging.

Adult↗

PubMed2003

Radiolabelling of isopeptide N epsilon-(gamma-glutamyl)-L-lysine by conjugation with N-succinimidyl-4-[18F]fluorobenzoate.

The isopeptide N(epsilon)-(gamma-glutamyl)-L-lysine 4 was labelled with 18F via N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB). A modified approach for the convenient synthesis of [18F]SFB was used, and [18F]SFB could be obtained in decay-corrected radiochemical yields of 44-53% (n = 20) and radiochemical purity >95% within 40 min after EOB. For labelling N(epsilon)-(gamma-glutamyl)-L-lysine with [18F]SFB the effects of isopeptide concentration, temperature, and pH were studied to determine the optimum reaction conditions. The coupling reaction was shown to be temperature and pH independent while being strongly affected by the isopeptide concentration. Using the optimized labelling conditions, in a typical experiment 1.3GBq of [18F]SFB could be converted into 447MBq (46%, decay-corrected) of [18F]fluorobenzoylated isopeptide within 45 min, including HPLC purification.

Benzoates↗

PubMed2003

In vivo measurement of the serotonin transporter with (S)-([18F]fluoromethyl)-(+)-McN5652.

The radiolabeled serotonin transporter (SERT) ligand [(11)C](+)-McN5652 has recently been used in clinical positron emission tomography (PET) studies for SERT imaging. However, this radioligand offers disadvantages in routine clinical settings because of its short radioisotope half-life (eg PET facilities within hospitals without a cyclotron need to acquire such radioligands from distant cyclotron units for clinical use). S-([(18)F]fluoromethyl)-(+)-McN5652 ([(18)F](+)-FMe-McN5652) is an analogue which has been synthesized newly, and has a significantly longer radioisotope half-life. In the porcine brain, it demonstrates the same characteristic distribution pattern of serotonin-uptake sites like the (11)C-labeled congener with the highest binding in the midbrain and thalamus and the lowest in the cerebellum and occipital cortex. It shows a 30% higher blood-brain transfer and a slower peripheral metabolism than [(11)C](+)-McN5652. Rather uniform brain binding was observed after injection of the pharmacologically inactive radiolabeled enantiomer, or after pretreatment with the highly selective SERT inhibitor citalopram. The norepinephrine uptake inhibitor maprotiline did not show any inhibitory effect. Using a one-tissue compartment model (K(1), k"(2)) or a two-tissue compartment model (K(1) to k(4)) with or without constraints for calculation, the regional binding parameters of [(11)C](+)-McN5652 and [(18)F](+)-FMe-McN5652 are highly correlated among each other and with the SERT density, as determined by in vitro binding of [(3)H]citalopram. Using constraints to correct for the free fraction and nonspecific binding of the radiotracers, a considerable increase of the midbrain-occipital cortex ratios with higher values for [(18)F](+)-FMe-McN5652 compared to [(11)C](+)McN5652 was revealed. It is concluded that [(18)F](+)-FMe-McN5652 has better features than [(11)C](+)McN5652 for SERT imaging with PET.

Animals↗

PubMed2003

Measurement of 5-hydroxy-2-aminovaleric acid as a specific marker of metal catalysed oxidation of proline and arginine residues of low density lipoprotein apolipoprotein B-100 in human atherosclerotic lesions.

gamma-Glutamyl-semialdehyde (gammaGSA) is a major product of the metal catalysed oxidation of apolipoprotein B-100 (apoB-100) proline and arginine residues. On reduction, gammaGSA forms 5-hydroxy-2-aminovaleric acid (HAVA). This report describes the application of HAVA measurement to characterise the formation of gammaGSA in low density lipoprotein (LDL) recovered from human atherosclerotic lesions. HAVA concentrations were greatly increased in LDL from early (mean, 10.25; SD, 3.49 mol/mol apoB-100; p < 0.01), intermediate (mean, 11.18; SD, 2.37 mol/mol apoB-100; p < 0.01), and advanced (mean, 9.91; SD, 2.15 mol/mol apoB-100; p < 0.01) lesions, when compared with LDL from normal aortic tissue (mean, 0.05; SD, 0.01 mol/mol apoB-100). These findings support the hypothesis that pathways involving metal catalysed oxidation of LDL apoB-100 are of pathological importance in atherogenesis.

Adult↗

PubMed2002

Ergonomic aspects of four different types of laparoscopic instrument handles with respect to elbow angle. An electromyogram-based study.

BACKGROUND: Only few studies have tested different ergonomic aspects of the working posture assumed by laparoscopic surgeons. Although no experimental data are available for a laparoscopic setting, a working posture with a horizontal forearm or an elbow angle 90 degrees to 120 degrees has been recommended for performing minimally invasive surgery (MIS). The comparison of electromyogram (EMG) activities in different muscles provides information about the force developed by each muscle and allows assessment of its contribution to a functional movement. The current study aimed to investigate whether certain handles do not support this posture. METHODS: For this study, 12 volunteers were postured in two different standardized arm positions, defined by elbow angles of 90 degrees and 120 degrees. They were manipulating a 0.1-N and a 2.5-N microswitch with four different types of instrument handle design: axial handle, ring handle, shank handle, Hirschberg handle. During the test, the EMG activities of five forearm muscles were recorded and normalized with respect to the maximum voluntary activity of the respective muscle. RESULTS: Virtually no significant difference in EMG activity was found between the two elbow angles in any of five forearm muscles for a simple grasping maneuver. Thus, the muscle activity required to manipulate different types of MIS handles is similar for the elbow angles of 120 degrees and 90 degrees. CONCLUSIONS: The current study did not show relevant differences between the two elbow angles for any of the four handles during a simple grasping maneuver with respect to the force required in the main forearm muscles.

Elbow↗

PubMed2002

Distribution of estrone sulfatase in rat brain determined by in vitro autoradiography with 16alpha-[18F]fluoroestradiol-3,17beta-disulfamate.

16Alpha-fluoroestradiol-3,17beta-disulfamate (FESDS) strongly inhibits estrone sulfatase (ES), an enzyme which is also present in the brain. The enzyme is probably involved in important regulatory functions of neurosteroids which may be disturbed in certain brain diseases. In the present study, [18F]FESDS was used to measure the amount of ES in various rat brain regions using quantitative in vitro autoradiography. The obtained values vary between 0.29 pmol (mg protein)(-1) (pons) and 11.5 pmol (mg protein)(-1) (striatum). They are positively correlated with the enzyme activity measured in homogenates of the corresponding regions. Because this radiotracer binds also to carbonic anhydrase in the brain it is only of limited use for in vivo imaging studies.

Adenocarcinoma↗

PubMed2002

Distribution of 16alpha-[18F]fluoro-estradiol-3,17beta-disulfamate in rats, tumour-bearing mice and piglets.

Based on a high affinity to the enzyme estrone sulfatase (ES), 16alpha-[18F]fluoroestradiol-3,17beta-disulfamate ([18F]FESDS) has been suggested as a potential PET radiotracer for imaging steroid-dependent breast tumours. The distribution of [18F]FESDS was studied in rats, tumour-bearing nude mice and piglets. In all species evidence for binding to a second target, the enzyme carbonic anhydrase (CA), was obtained. ES and CA inhibitors significantly reduced the radiotracer uptake in various organs but not in tumours. It is concluded that [18F]FESDS binds to ES and CA in vivo but this binding is not strong enough to allow tumour imaging with positron emission tomography (PET).

Animals↗

PubMed2001

Early childhood infectious diseases and the development of asthma up to school age: a birth cohort study.

OBJECTIVE: To investigate the association between early childhood infections and subsequent development of asthma. DESIGN: Longitudinal birth cohort study. SETTING: Five children's hospitals in five German cities. PARTICIPANTS: 1314 children born in 1990 followed from birth to the age of 7 years. MAIN OUTCOME MEASURES: Asthma and asthmatic symptoms assessed longitudinally by parental questionnaires; atopic sensitisation assessed longitudinally by determination of IgE concentrations to various allergens; bronchial hyperreactivity assessed by bronchial histamine challenge at age 7 years. RESULTS: Compared with children with </=1 episode of runny nose before the age of 1 year, those with >/=2 episodes were less likely to have a doctor's diagnosis of asthma at 7 years old (odds ratio 0.52 (95% confidence interval 0.29 to 0.92)) or to have wheeze at 7 years old (0.60 (0.38 to 0.94)), and were less likely to be atopic before the age of 5 years. Similarly, having >/=1 viral infection of the herpes type in the first 3 years of life was inversely associated with asthma at age 7 (odds ratio 0.48 (0.26 to 0.89)). Repeated lower respiratory tract infections in the first 3 years of life showed a positive association with wheeze up to the age of 7 years (odds ratio 3.37 (1.92 to 5.92) for >/=4 infections v </=3 infections). CONCLUSION: Repeated viral infections other than lower respiratory tract infections early in life may reduce the risk of developing asthma up to school age.

Antibodies↗

PubMed2001

Radio fluorination and positron emission tomography (PET) as a new approach to study the in vivo distribution and elimination of the advanced glycation endproducts N epsilon-carboxymethyllysine (CML) and N epsilon-carboxyethyllysine (CEL).

After synthesis of fluorine-18 labelled analogues by [18F]fluorobenzoylation at the alpha-amino group, biodistribution and elimination of individual advanced glycation endproducts, namely N epsilon-carboxymethyllysine and N epsilon-carboxyethyllysine, were studied in comparison to lysine in rats after intravenous injection using positron emission tomography (PET). The [18F]radiofluorinated amino acids were fast distributed via the blood, followed by a rapid excretion through the kidneys. Elimination kinetics were similar for both AGEs and lysine. For CML and CEL, but not for lysine, a temporary liver accumulation could be observed, which was not connected with any metabolisation or enterohepatic circulation. No further accumulation in any tissues was observable, indicating that increased tissue levels of CML or CEL, which have been described for certain disorders, are exclusively derived from endogenous origin and should not depend on a dietary intake. However, under uremic conditions, an impaired kidney function might result in a significant increase of the AGE-load of blood and tissues. PET based on 18F-labelled AGEs proved to be a promising tool to elucidate the physiological fate of post-translationally modified amino acids and to clarify the role of AGEs as possible "glycotoxins".

Animals↗

PubMed2001

Comparison of clearance of particles inhaled with bolus and extremely slow inhalation techniques.

Ten healthy nonsmokers inhaled 6-microm (aerodynamic diameter) Teflon particles labelled with 111In twice, once with the shallow bolus technique (volumetic lung depth 76+/-20 mL ([+/- SD]) and once with the extremely slow inhalation technique (0.05 L/s). The radioactivity in the lungs was measured at 1 and 24 hours as well as at 1, 2, and 3 weeks after both inhalations. The 24-hour lung retention a percentage of lung deposition was significantly lower for the bolus inhalation, 46%+/-9% (+/- SD) than for the extremely slow inhalation, 56%+/-11%. The retention after 21 days as a percentage of the 24-hour retention was 55%+/-9% for the shallow bolus inhalation and 56%+/-10% for the extremely slow inhalation. Also within the subjects, clearance was similar for the 2 modes of inhalation. Deposition of particles inhaled with the 2 modes of inhalation was calculated with 2 model, one being based on Monte (Carlo particle transport together with an asymmetric lung model. Deposition predicted with this model agreed well with the experimental data under the assumption that there are large retained fractions only in small ciliated airways (bronchioli) and not in large ones. For the bolus inhalation, the model predicted 43% to 50% deposition in the bronchial (BB) region of initial lung deposition, 33% to 38% in the bronchiolar (bb) region, and 16% to 22% in the alveolar region. For the extremely slow inhalation, the model predicted 31% to 34% deposition in the BB region, 45% to 47% in the bb region, and 21% to 22% in the alveolar region. In addition, it predicted about the same ratio between bb and alveolar depositions for the 2 modes of inhalation. Thus, both the experimental and theoretical data indicate that the shallow bolus particles to a considerable extent reach both the bb and the alveolar regions and that they do that at about the same extent as the particles inhaled extremely slow. This conclusion is concerning the experimental data based on the assumption that there are no large retained fractions in the BB region. Another interpretation of the similar clearance for the two modes of inhalation is that there are large retained fractions in both the BB and the bb regions and that individual charactristics of clearance of these fractions are of importance rather than the site of deposition.

Administration, Inhalation↗

PubMed2001

Environmental tobacco smoke deposition in the human respiratory tract: differences between experimental and theoretical approaches.

Total deposition of environmental tobacco smoke (ETS) particles was measured in a group of 15 nonsmokers who inhaled ETS of count median diameter of 0.2 microm and geometric standard deviation of 1.6. A total deposition of 56.0 +/- 15.9% was observed for nasal breathing and 48.7 +/- 11.5% for oral breathing. In contrast, our stochastic deposition model predicted a total deposition of only 17.9% (male) and 15.7% (female) for nose breathing, and 13.4% (male) and 10.7% (female) for mouth breathing, if based on standard breathing conditions. Consideration of individual lung volumes and breathing parameters for each volunteer resulted in total deposition values of 16.9 +/- 2.2% for nose breathing and 12.1 +/- 2.1% for mouth breathing. The apparent discrepancy between experiment and modeling suggests that either single ETS particles increase substantially in size upon inhalation (up to an order of magnitude) and/or additional physical mechanisms must be invoked that are acting specifically upon ETS particles: (1) hygroscopic growth of ETS particles does not exceed 20-30%; (2) number concentrations in the ETS experiments (3.8 x 10(4), to 1.3 x 10(5) cm(-3)) are too low to increase particle size by coagulation; (3) cast experiments indicate that electrical charge (image forces) may play an important role, but theory predicts only an increase of 20-60%; and (4) cloud settling is unlikely to be a significant factor at such low number concentrations. In conclusion, estimates of the magnitudes of these potential effects demonstrate that none of these mechanisms alone can be responsible for the significantly higher total ETS deposition observed in the experiments. This suggests that a combination of all these mechanisms may be necessary to reconcile experimental and theoretical ETS deposition data, the most likely candidates being image forces and hygroscopic growth.

Biophysical Phenomena↗