Automatic detection of skate strokes in short-track speed skating using one single IMU: validation of a new method

Greater impulse is a key performance indicator of success in short track speed skating. The main objective of this study was to develop a method to measure skating strokes using a single IMU. Eight elite or world-class speed skaters had one IMU placed against their skin on the lower back, and a camera setup was positioned to capture the test. A maximal speed trial was then executed by each participant, and the data were analysed to estimate agreement between the camera and IMU estimates of skate stroke events. Inter-evaluator reliability was assessed on a dataset of 22 athletes performing speed trials as well. The algorithm detected 100% of the strokes identified on the video capture system with a root mean square error of 0.06s. Bland-Altman analysis showed a bias of 0.03s between the two methods, which corresponds to the frame rate of the camera. The inter-evaluator reliability yielded an intra-class correlation of 1.00 (ICC3,1) from a dataset of 7089 strokes. This study provides an example of on-ice evaluation of speed skating strokes using a single IMU. This equipment is less expensive than that employed by previous authors and can be implemented in training situations with low invasiveness.

[Colchicum poisoning by confusion with wild garlic (Allium ursinum)]

INTRODUCTION

Colchicine poisoning is a life-threatening intoxication.

CASE REPORT

We report a case of food poisosing with Colchicum autumnale by confusion with wild garlic. The clinical presentation is the same as that of colchicine drug intoxication. The evolution can be fatal in case of massive ingestion. The proximity of the place of growth and their similar appearance in spring make Colchicum and wild garlic plants that can easily be confused.

CONCLUSION

Physicians have to be vigilant in case of dysenteric syndrome and biological disturbances in spring and look for the consumption of perennial plant preceding symptoms.

Relationship between electrical and rheological properties of sewage sludge - Impact of temperature

Rheological properties are key criteria for sewage sludge management but are difficult to determine in situ. Because the literature often links rheological characteristics to surface charges of particles that interact, the underlying electrostatic interactions could be key characteristics explaining the rheological behavior of sludge. This paper analyzed the impact of temperature on both rheological and electrical properties. Both liquid and solid properties appear to be related to electrical impedance spectroscopy measurements because they obey the same relationships with the same activation energies. Infinite viscosity follows an Arrhenius law with temperature, whereas the storage modulus shows VTF (Vogel-Tamman-Fulcher) behavior. Sludge electrical behavior can be modeled by an equivalent 2-branch parallel circuit whose respective impedances follow Arrhenius and VTF relationships. More interestingly, resistors are proportional to (dissipative) viscous characteristics, whereas capacitances are proportional to the (storage) elastic modulus. These similarities and relationships underlie the same interactions that seem to be involved in both rheological and electrical properties. These interdependences are quite logical but open new insights into sludge characterization.

Detection of bacteriuria and bacteremia in newborn calves by a catalase-based urine test

BACKGROUND

Bacteremia occurs frequently in newborn calves. The predictive value of clinical signs is low, suggesting the use of calf-side diagnostic tests.

OBJECTIVES

To investigate testing of urine catalase activity (Uriscreen test) for bacteriuria and bacteremia detection.

ANIMALS

Five colostrum-free calves and 3 colostrum-fed control calves.

METHODS

Controlled experimental trial. Colostrum-free calves were inoculated PO with Escherichia coli O78+. A clinical score was established to define the onset of the illness. Blood and urine (cystocentesis) samplings and cultures, and Uriscreen tests, were performed 4-6 times from inoculation to death. Three control calves received the same management as 3 inoculated calves, but with colostrum and without inoculation.

RESULTS

Bacteremia was demonstrated in all of the inoculated colostrum-free calves and in none of the control calves. The E. coli O78+ strain, E. coli, and Klebsiella spp. were recovered from 4/5, 5/5, and 2/5 inoculated colostrum-free calves, respectively. Urine cultures were negative for the 2 groups at the start of the experiment; 5/5 colostrum-deprived inoculated calves were positive for E. coli thereafter whereas 3/3 controls remained negative. Concordance of Uriscreen tests with bacteremia and bacteriuria was 0.86 and 0.88, respectively. Kappa value of agreement between Uriscreen and bacteremia and bacteriuria was 0.73 and 0.76, respectively. Sensitivity of Uriscreen for bacteremia and bacteriuria was 80.0 and 86.6%, respectively, and specificity was 92.8 and 88.8%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

The results suggest that Uriscreen can be used for detection of bacteremia in neonatal calves in connection with a constant bacteriuria.

Cationic phosphonolipids as nonviral vectors: in vitro and in vivo applications

Since the development of the concept of gene therapy using cationic lipids as nonviral vectors by Felgner's group in 1987, numerous molecules have been synthesized. Such vectors were first proposed to avoid viral vector-induced drawbacks. But, it quickly became clear that a thorough knowledge of their physical and chemical characteristics was fundamental to use them under optima conditions. Over the last years our laboratory has developed a family of cationic lipids called phosphonolipids whose structure is based on that of natural phosphonolipids; compared with other vectors, these compounds had to be well-tolerated by biologic membranes. Some of our synthesized molecules exhibited an interesting potential for gene transfer, both in vitro and in vivo. Structural changes in the different parts (hydrophobic, hydrophilic, and intermediary domains) of these vectors were evaluated in vitro on different cell-lines; these studies led us to select some of these molecules to carry out in vivo tests. So, the plasmid/phosphonolipid complexes were first administered to mice by intratracheal and aerosol routes with a beta-galactosidase plasmid as reporter gene. In a second set of experiments, we explored the possibilities offered by intravenous injection; in these studies, we used a luciferase plasmid as reporter gene because of its high sensibility. These experiments revealed a transgene expression essentially localized in the lungs. In a further study, we compared systemic administration with local ones; we, then, observed that the optimum formulation of a given molecule depended on its route of administration.

Increased N-linked glycosylation leading to oversialylation of monomeric immunoglobulin A1 from patients with Sjögren's syndrome

Increased serum immunoglobulin A (IgA) level is a common finding in primary Sjögren's syndrome (pSS). IgA might not be properly eliminated because of an abnormal glycosylation. We reported previously that IgA1 from patients with pSS was oversialylated. We extend this finding by showing that monomeric IgA1 contains more sialic acid (SA) in patients than in controls, as determined by enzyme-linked immunosorbent assay (ELISA) and Western blot with Sambucus nigra agglutinin (SNA), a lectin specific for SA. To localize this excess of SA on the N- and/or O-linked oligosaccharides, we analysed them separately, using N- and O-linked oligosaccharide profiling kits based on fluorophore-assisted carbohydrate electrophoresis. N-linked, but not O-linked, oligosaccharides of patients' IgA1 were oversialylated, and this seemed to be linked to an excess of SA on the same number of polysaccharides as normal IgA1. To localize the abnormality to the Fab and/or Fc fragments, monomeric IgA1 was digested with protease, separated and transferred to nitrocellulose, where SA was identified by SNA. Both Fab and Fc fragments appeared to be oversialylated. Oversialylation of N-linked oligosaccharides of IgA1 from patients with pSS might prevent the recognition of IgA by receptors that are responsible for their clearance, resulting in an excess of serum IgA and related immune complexes.

Pulmonary haemorrhage as a predominant cause of death in leptospirosis in Seychelles

We examined the cause of death during a 12-month period (1995/96) in all consecutive patients admitted to hospital with leptospiral infection in Seychelles (Indian Ocean), where the disease is endemic. Leptospirosis was diagnosed by use of the microscopic agglutination test and a specific polymerase chain reaction assay on serum samples. Seventy-five cases were diagnosed and 6 patients died, a case fatality of 8%. All 6 patients died within 9 days of onset of symptoms and within 2 days of admission for 5 of them (5 days for the 6th). On autopsy, diffuse bilateral pulmonary haemorrhage (PH) was found in all fatalities. Renal, cardiac, digestive and cerebral haemorrhages were also found in 5, 3, 3 and 1 case(s), respectively. Incidentally, haemoptysis and lung infiltrate on chest radiographs, which suggest PH, were found in 8 of the 69 non-fatal cases. Dengue and hantavirus infections were ruled out. In conclusion, PH appeared to be a main cause of death in leptospirosis in this population, although haemorrhage in other organs may also have contributed to fatal outcomes. This cause of death contrasts with the findings generally reported in endemic settings.

Analysis of the structural changes of a phosphate glass during its dissolution in simulated body fluid

The structural changes of two calcium-sodium metaphosphate glasses during its dissolution in simulated body fluid (SBF) have been analyzed by Fourier transform Raman spectroscopy (FT-Raman), scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM). The results showed that no structural changes could be detected during the first week of dissolution. However, after approximately 4 weeks of dissolution the analysis of the glass surface revealed the presence of a thin orthophosphate layer. The elemental analysis of this layer by X-ray dispersive energy showed the presence of calcium phosphate ions, while almost no sodium was detected. The observation of the glasses by ESEM showed the formation of small crystals when the water vapor pressure of the chamber was decreased. This indicates that the layer analyzed by SEM and FT-Raman was related to a hydrated calcium phosphate layer.

Evaluation by Vickers indentation of fracture toughness of a phosphate biodegradable glass

Indentation tests are commonly used for the evaluation of fracture toughness of brittle materials, particularly glasses and ceramics, because this technique requires only a small polished area on the specimen surface from which a large number of data points can be generated rapidly. However, a wide variety of equations for the calculation of fracture toughness of ceramic materials by means of Vickers indentation are available. Such equations are obtained phenomenologically and their parameters adjusted in such a way that the KIC values obtained are in good agreement with those obtained by conventional methods. This is the reason why it is necessary to check which type of equation reproduces more accurately the results obtained by means of conventional methods for the material which is going to be investigated. In the present work seven different fracture toughness equations widely used in glass and ceramic studies are considered and the results are compared with those obtained by conventional methods, such as single-edge notch beam (SENB) specimens tested in three-point bending. The role played by the applied indentation load is considered.

The structure and development of French prosodic representations

Prosody is assumed to play a crucial role during the preverbal stage of infancy, as well as to be essential for the pragmatics of speech. Our experiments are aimed at analyzing the production and perception of illocutionary forms. Using a semantic neutralization procedure, the performance of children (5, 7, and 9 years old) and adults was compared in two experiments focusing on prosodic representations in production and perception tasks. The first experiment investigated subjects' control of prosody in the unfolding of utterances by studying the acoustic configurations of four illocutionary forms, two corresponding to the linguistic mode (assertion, interrogation) and two corresponding to the emotional mode (happiness, sadness). The second experiment examined subjects' identification of the same illocutionary forms as above, plus an additional form, irony, all produced by an expert speaker, using a word-by-word gating procedure. During speech production, control of the fundamental frequency of the voice emerged earlier in childhood (5-year-olds) than control of rhythmic parameters (7-year-olds) for the linguistic mode, whereas control of all parameters was achieved by the age of five for the emotional mode. Children were similar to adults with respect to the planning of intonation and they used it right from the beginning of the sentence, which was not the case for the planning of duration. During speech perception, only adults were able to anticipate illocutionary forms. Taken together, the results strengthen the idea that prosodic representations are acquired gradually during development, and they show that pitch contour is acquired before duration parameters.

Short-term ventilatory effects in workers exposed to fumes containing zinc oxide: comparison of forced oscillation technique with spirometry

Following the occurrence of metal fume fever in some subjects after the installation of an electric furnace in a steel plant, a survey was undertaken to examine whether subjects exposed to fumes containing zinc oxide would exhibit a detectable impairment in ventilatory function, and whether a forced oscillation technique (FOT) was more suited for this detection than conventional spirometry. Pulmonary function measurements were made in 57 exposed workers (production or maintenance) and 55 nonexposed workers (maintenance or strandcasting department) at the beginning and near the end of a work shift (day or night). Maximal expiratory volumes and flows were measured by means of a pneumotachograph, and respiratory resistance (Rrs) and reactance at various frequencies by means of a FOT. These measurements were repeated 1 day later. During the day shift, there were no significant differences in pulmonary function between exposed and control workers. However, during the night shift, an influence of exposure on pulmonary function was revealed both by spirometry and by FOT: workers exposed at night showed a slight decrease in vital capacity (VC) and in forced expiratory volume in one second (FEV1), and a decline in respiratory resistance (Rrs) with oscillation frequency, that were more marked than in unexposed subjects. In contrast to the frequency dependence of Rrs, the changes of lung volumes and expiratory flows were related to differences in initial values between exposed and nonexposed workers. The decrease in FEV1 was maintained the day after exposure. The forced oscillation technique proved at least as sensitive as spirometry to detect small across-shift changes in ventilatory function. Although the effects on pulmonary function were small, it is likely that they represent a subclinical response to the inhalation of small quantities of zinc oxide.

Unsteadiness of breathing in patients with hyperventilation syndrome and anxiety disorders

The breathing pattern of 399 patients with hyperventilation syndrome (HVS) and/or with anxiety disorders and that of 347 normal controls was investigated during a 5 min period of quiet breathing and after a 3 min period of voluntary hyperventilation. The diagnosis of HVS was based on the presence of several suggestive complaints occurring in the context of stress, and reproduced by voluntary hyperventilation. Organic diseases as a cause of the symptoms were excluded. The anxiety disorders were diagnosed by means of an abbreviated version of the Anxiety Disorders Interview Schedule (ADIS). There was a large overlap between the two diagnoses. Simply breathing via a mouthpiece and pneumotachograph made end-tidal CO2 fractional concentration (FET,CO2) decrease progressively both in hyperventilators and in patients with anxiety disorders, but not in normals. At the start of the measurement the FET,CO2 was not different between patients and healthy subjects. In patients < or = 28 yrs, the decrease of FET,CO2 resulted from a higher tidal volume, and in patients > or = 29 years from an increase in frequency. After voluntary hyperventilation, the recovery of FET,CO2, was delayed in patients, due to a slower normalization of respiratory frequency in females and in older males, and of tidal volume in younger males, and also due to less frequent end-expiratory pauses. When breathing was recorded first by means of inductive plethysmography (Respitrace), the progressive decline of FET,CO2 seen in patients was not observed: from the onset of the recording, FET,CO2 was reduced in patients. It did not change further when, immediately afterwards, the subject switched to mouthpiece breathing. The finding that breathing through a mouthpiece induces hyperventilation in patients and that recovery of FET,CO2 is delayed after voluntary hyperventilation, suggests that the respiratory control system is less resistant to challenges (mouthpiece or voluntary hyperventilation) in those patients. On the other hand, the lower values of FET,CO2 measured during recording by means of a Respitrace probably result from a challenge, prior to the recordings, induced by the fitting of the measuring device to the patient. This unsteadiness of breathing characterizes patients with hyperventilation syndrome and those with anxiety disorders, but is not sufficiently sensitive to be used for individual diagnosis.

Influence of breathing therapy on complaints, anxiety and breathing pattern in patients with hyperventilation syndrome and anxiety disorders

The effect of breathing therapy was evaluated in patients with hyperventilation syndrome (HVS). The diagnosis of HVS was based on the presence of several suggestive complaints occurring in the context of stress, and reproduced by voluntary hyperventilation. Organic diseases as a cause of the symptoms were excluded. Most of these patients met the criteria for an anxiety disorder. The therapy was conducted in the following sequence: (1) brief, voluntary hyperventilation to reproduce the complaints in daily life: (2) reattribution of the cause of the symptoms to hyperventilation: (3) explaining the rationale of therapy-reduction of hyperventilation by acquiring an abdominal breathing pattern, with slowing down of expiration: and (4) breathing retraining for 2 to 3 months by a physiotherapist. After breathing therapy, the sum scores of the Nijmegen Questionnaire were markedly reduced. Improvements were registered in 10 of the 16 complaints of the questionnaire. The level of anxiety evaluated by means of the State-Trait Anxiety Inventory (STAI) decreased slightly. The breathing pattern was modified significantly after breathing retraining. Mean values of inspiration and expiration time and tidal volume increased, but end-tidal CO2 concentration (FETCO2) was not significantly modified except in the group of younger women (< or = 28 years). A canonical correlation analysis relating the changes of the various complaints to the modifications of breathing variables showed that the improvement of the complaints was correlated mainly with the slowing down of breathing frequency. The favorable influence of breathing retraining on complaints thus appeared to be a consequence of its influence primarily on breathing frequency, rather than on FETCO2.

Ultrastructural study of the Pacinian corpuscles in the newborn and adult dog forefoot

Pacinian corpuscles (PC) of the newborn and adult dog forefoot were studied by electron microscopy. The PC of newborn dog forefoot show a rare development: they exhibit a lamellar arrangement, although the lamellar compartments do not surround completely the fiber. The outer core cells show a well-developed perinuclear endoplasmic reticulum. They are surrounded by a discontinuous basal lamina. Mast cells between the lamellae of the outer core are observed. Desmosome-like and zonula adherens junctions, as well as pinocytotic vesicles, are shown in the inner core cells. Intermediate filaments are also observed in the glial cells of the inner core. In PC of adult dog forefoot a general organization of a concentrically arranged capsule, outer core, intermediate layer and inner core around a nerve ending is always present. In the intermediate layer, lamellar cells (specialized fibroblast) do not surround completely the inner core. The inner core lamellae possess numerous pinocytotic vesicles, an extensive network of filaments, special cell junctions (gap, desmosome) and a discontinuous basal lamina. The present results show a conservative structural organization in PC, although differences among species are discussed.

Serological survey for orthopoxvirus infection of wild mammals in areas where a recombinant rabies virus is used to vaccinate foxes

Several fox vaccination campaigns against rabies have been undertaken in Belgium by using a vaccinia-rabies recombinant virus distributed in baits in the field. However, foxes and other wild animals that may ingest the baits could be infected at the same time by another orthopoxvirus, such as cowpox virus, which circulates in wildlife. Recombination between the two viruses could therefore occur. A serological survey for antibodies to orthopoxvirus, and particularly to cowpox virus, was undertaken in foxes and in several other wild species. Antibodies were detected only in two rodent species, in 16 of 25 bank voles (64 per cent) and in two of 29 woodmice (7 per cent). The risk of virus recombination in wildlife can therefore be considered to be extremely low.

[Hantavirus infection: a "new" exotic zoonosis among us]

Hantavirus disease is a recently recognized zoonosis. The main vectors are infected but healthy wild rodents or laboratory rats. Transmission to man occurs via inhalation of aerosolised excretions. Kidneys or lungs are the target organs during the disease, but a systemic affection with multi-organ involvement is possible, and can be fatal. To date, at least 16 different serotypes of hantavirus have been characterized, 8 of them being of clinical importance. Each serotype has its own rodent vector and its own geographical spread. In Europe, the red bank vole (Clethrionomys glareolus) is the main rodent vector carrying the Puumala serotype which is the etiologic agent of a viral affection known as nephropathia epidemica (NE). Belgium witnessed in 1993 its most important NE outbreak with more than 60 cases in the southern part of the region between Sambre and Meuse, Chimay being the main focus.

Total respiratory impedance measured by means of the forced oscillation technique in subjects with and without respiratory complaints

The purpose of this study was to determine whether the forced oscillation technique is more sensitive than spirometry to detect lung function alterations in subjects with respiratory complaints. The input impedance of the respiratory system (between 2 and 24 Hz) and maximal expiratory flows and volumes were measured in 1,255 subjects referred for routine spirometry. A questionnaire concerning respiratory complaints was administered. A discriminant analysis was performed between subgroups of subjects without (137 males and 140 females), with moderate (115 males and 109 females) and with marked respiratory complaints (149 males and 132 females). A clear-cut separation was achieved by this analysis only between those subjects without and with marked complaints. Both lung volumes and flows as well as impedance parameters (mean value and frequency dependence of resistance in females, mean resistance in males) contributed to the discrimination of subjects without and with marked respiratory complaints, although there was only a moderate decrease of discriminative power when the impedance parameters were excluded. The contribution of the forced oscillation parameters to discriminative power was larger in females than in males (40 vs 19%), which may be related to the higher prevalence of asthma in our population of females. Excluding the subjects with marked functional impairment improved the share of forced oscillation parameters only slightly with respect to lung volumes and flows (females 54 vs males 23%). Considered separately, however, the sensitivity of spirometry and forced oscillation technique to detect symptomatic people appeared to be similar. We conclude that impedance measurements by forced oscillation technique and routine spirometry are both associated with respiratory complaints. Our results indicate that the information provided by impedance measurements can be complimentary to that obtained by spirometric indices.

Assessment of reversibility of airflow obstruction

The application of the forced oscillation technique to assess reversibility of airflow obstruction was compared with that of indices of forced expiration and plethysmographic airway resistance (Raw). In 125 patients with airflow obstruction, we measured total respiratory resistance (Rrs) and reactance (Xrs), Raw and specific airway conductance (sGaw), maximal flow-volume curves and forced expiratory volume in 1 s (FEV1), before and 30 min after 2 x 20 micrograms salbutamol by MDI. Salbutamol induced significant change in mean value of all measured indices. The changes in impedance data consisted of decrease in mean value and of negative frequency dependence of Rrs, an increase in Xrs with slight decrease of its positive frequency dependence. Multivariate analysis of differences between pre- and postbronchodilator values showed that the single indices with the greatest sensitivity to detect the effect of salbutamol were, in decreasing order, (1) in relative change (% baseline value): Raw, Rrs at 6 Hz (Rrs6), forced vital capacity (FVC), FEV1, and (2) in absolute change: FVC, sGaw or Raw, Rrs6, FEV1, maximal expiratory flow (MEF50). The effect of salbutamol was described best in (1) by a combination of Raw and FVC and in (2) by sGaw and FVC. For individual detection of bronchodilator effect, threshold values were calculated from mean reproducibility of the three baseline values of the various indices, attempting to estimate whether response to a bronchodilator is statistically significant. The greatest number of significant responses were observed for Raw, sGaw, FEV1, and FVC in that succession, Rrs6 being markedly less sensitive. This discrepancy is due to the lack of Rrs6 response to bronchodilators in patients with severe airway obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

A new series of imidazolones: highly specific and potent nonpeptide AT1 angiotensin II receptor antagonists

Starting from the structure of the novel nonpeptide AT1 receptor antagonist DuP 753 (losartan), a new series of potent antagonists was designed. In these compounds the central imidazole nucleus was replaced by the dihydroimidazol-4-one structure. The most active compounds had a spirocyclopentane or a spirocyclohexane ring in position 5. Like the imidazole series, the best substituents were the linear butyl chain in position 1 and the [2'-(tetrazol-5-yl)biphenylyl]methyl group in position 3. Antagonistic activity was assessed by the ability of the compounds to competitively inhibit [125I]AII binding to the AT1 subtype receptor and to antagonize AII-induced contractions in rabbit aorta rings. The most active compounds had IC50 values in the nanomolar range. In conscious rats, compounds 4 and 21 antagonized the AII pressor response when administered orally. Compound 21 (SR 47436) was the most active; it was recently shown to also be active in cynomolgus monkeys both intravenously and orally. This molecule is now undergoing clinical trials for the treatment of hypertension.

Total respiratory resistance and reactance in patients with asthma, chronic bronchitis, and emphysema

A comparison was made of total respiratory resistance (Rrs) and reactance (Xrs) determined between 6 and 26 Hz by means of a forced oscillation technique in 27 patients with asthma (group A), 28 patients with chronic bronchitis (group B), and 20 patients with emphysema (group E) to examine whether the method can provide data capable of distinguishing among these diseases. The three groups demonstrated a similar reduction in the FEV1. In addition, static and dynamic lung volumes, maximal expiratory flows, diffusing capacity for CO, airway resistance (Raw), and elastic lung recoil were measured. The observed alterations of Rrs and Xrs consisted of an increase in Rrs, a decrease in Rrs with frequency, and a decrease in Xrs. However, significant differences were found between the three groups: Rrs at 6 Hz and average Rrs were most increased in group A, whereas the negative frequency dependence of Rrs and the decrease in Xrs were least pronounced in group E. In all groups Rrs at 6 Hz, the average slope of Rrs, and the average level of Xrs were tightly interrelated and showed in addition a high correlation with airway resistance; the correlations with FEV1 were less satisfactory. Discriminant analysis performed on the complete set of data, excluding diffusing capacity and elastic lung recoil, which were used as selection criteria, demonstrated that forced oscillation parameters were the most important factors discriminating among the groups.

Total respiratory resistance and reactance in patients with diffuse interstitial lung disease

In 54 patients with interstitial lung diseases and no signs of airway obstruction we measured lung volumes, maximal expiratory flows, diffusing capacity (DLCO), total respiratory resistance (Rrs) and reactance (Xrs) between 4 and 26 Hz by means of the forced oscillation technique. In all patients DLCO was less than 75% of the expected value. Patients were classified into two groups depending on total lung capacity (TLC): group A with TLC less than 80% of expected, and group B with TLC of 80% or more. Group A demonstrated a decrease of Xrs especially at low frequencies, with small, not significant changes in Rrs. In the patients in this group with the lowest values of TLC (less than 50%), we observed an increase of Rrs at low frequencies causing a negative frequency dependence of Rrs. In group B no distinct changes of Rrs and Xrs occurred. Canonical correlation analysis between routine lung function data and forced oscillation parameters, showed tight correlations between TLC in absolute value or VC in percent of the predicted value on the one hand and average level of Xrs and average slope of Xrs (and Rrs) vs frequency curves on the other hand. Measurements of lung mechanics in five additional patients and comparison with a model of the respiratory system suggest that the changes of Rrs and Xrs are not explained totally by the observed increase in lung tissue resistance and decrease in lung compliance. The observed changes in Rrs and Xrs are not specific for restrictive lung disorders; similar changes are met also in moderately advanced obstructive diseases.

Reference values of total respiratory resistance and reactance between 4 and 26 Hz in children and adolescents aged 4-20 years

In 403 healthy subjects, 4 to 20 years of age, we measured total respiratory resistance (Rrs) and reactance (Xrs) between 4 and 26 Hz. When possible, vital capacity and forced expiratory volume in one second were also determined. The Rrs and Xrs vs frequency data depend on age or height, on sex, and slightly on weight. During growth, Rrs and the frequency dependence of Rrs decrease while Xrs increases. Only part of these changes may be explained entirely by a size effect. The variations with growth of ventilation unevenness, of airway wall compliance and of the topographic distribution of airway resistances probably also play a role. The influence of the interactions between height and age, and height and weight on Rrs and Xrs differ between sexes. Adult values for Rrs and Xrs are attained at the age of 15 years in girls and 18 years in boys.

Effect of rib cage and abdominal restriction on total respiratory resistance and reactance

In 14 healthy male subjects we studied the effects of rib cage and abdominal strapping on lung volumes, airway resistance (Raw), and total respiratory resistance (Rrs) and reactance (Xrs). Rib cage, as well as abdominal, strapping caused a significant decrease in vital capacity (respectively, -36 and -34%), total lung capacity (TLC) (-31 and -27%), functional residual capacity (FRC) (-28 and -28%), and expiratory reserve volume (-40 and -48%) and an increase in specific airway conductance (+24 and +30%) and in maximal expiratory flow at 50% of control TLC (+47 and +42%). The decrease of residual volume (RV) was significant (-12%) with rib cage strapping only. Abdominal strapping resulted in a minor overall increase in Rrs, whereas rib cage strapping produced a more marked increase at low frequencies; thus a frequency dependence of Rrs was induced. A similar pattern, but with lower absolute values, of Rrs was obtained by thoracic strapping when the subject was breathing at control FRC. Xrs was decreased, especially at low frequencies, with abdominal strapping and even more with thoracic strapping; thus the resonant frequency of the respiratory system was shifted toward higher frequencies. Partitioning Rrs and Xrs into resistance and reactance of lungs and chest wall demonstrated that the different effects of chest wall and abdominal strapping on Rrs and Xrs reflect changes mainly of chest wall mechanics.

Pepstatin analogues as novel renin inhibitors

Pepstatin analogues corresponding to the general formula A-X-Y-Sta-Ala-Sta-R were synthesized in solution phase. Various changes in the nature of the A, X, and Y groups were made to improve the inhibitory potency against human plasma renin activity. The results were interpreted by use of the active-site model based on the sequence of human angiotensinogen. The tert-butyloxycarbonyl group and the isovaleryl group were found to be the most effective acyl groups (A). The analogues having a Phe residue in place of Val1 (X) and His or amino acid with an aliphatic side chain such as norleucine or norvaline in the Y position showed the highest inhibition of human plasma renin activity with IC50 values of about 10(-8)M. Esterification or amidification of the carboxyl group of the C-terminal statine did not change the inhibitory potency. The selectivity for rat, dog, pig, and monkey plasma renin of the most interesting compounds was studied.

Forced oscillation technique: comparison of two devices

The respiratory impedances in healthy subjects and patients with advanced obstructive lung disease were measured between 2 and 32 Hz, using two forced oscillation techniques: the setup used previously by Grimby et al. (J. Clin. Invest. 47: 1455-1465, 1968) and a modified device in which the pneumotachograph is replaced by a 2-m-long tube and the ratio of pressures at both ends of the tube is determined. The advantages of the latter device are that 1) its impedance and frequency characteristics can be predicted by classical physics, 2) the only requirement for correct measurements are a match of the pressure transducers, and 3) high-pass filters are not needed to suppress the influence of breathing. On the other hand, the device is more sensitive to the turbulences induced by the subject's own breathing. This drawback can be avoided by interposing a piece of tubing between the mouth and proximal pressure recording site.

Pulmonary resistance and compliance by auto- and cross-correlation functions of transpulmonary pressure and flow

A technique is described on how to calculate the pulmonary resistance and compliance from the higher order harmonics present in mouth flow and transpulmonary pressure signals during spontaneous breathing. The estimates of resistance and compliance (or rather reactance) obtained from these harmonics following a conventional Fourier transform are not reliable because of a lack of reproducibility. This is obviated by a preliminary smoothing of the signals by means of auto- and cross-correlation functions. Both the conventional and the modified technique yield identical results for the fundamental component of breathing.

Frequency dependence of pulmonary compliance and resistance in patients with obstructive lung disease

The frequency dependence of pulmonary compliance and resistance was investigated in 27 patients with obstructive lung disease. Compliance and resistance were determined either by the conventional zero crossing (Cdyn) and isovolume (RL) technique or by a modified Fourier analysis following a smoothing procedure (auto- and cross-correlation function) yielding an effective compliance and resistance, CL and RL. The latter technique was used to calculate CL and RL from the fundamental and third and fourth harmonics present in the flow and transpulmonary pressure signals. Three breathing frequencies were investigated: 0.5, 1, and 2 Hz. Both Cdyn and CL, calculated from the fundamental component, decreased progressively with frequency. However, Cdyn showed less frequency dependence than CL. CL calculated from the harmonics was significantly smaller than CL from the fundamental at the same breathing frequency. RL, as well as RL calculated from the fundamental, tended to increase with frequency. A decline of resistance with frequency became apparent, however, when RL from the fundamental was compared with RL obtained from the corresponding higher order harmonics. These results suggest that the frequency dependence of resistance can be masked by the usual procedure of breathing at several frequencies. Instead the measurements should be performed at a single frequency, for instance spontaneous breathing, by computing resistance from the higher order harmonics present in the breathing signals.

Total resistance and reactance in patients with respiratory complaints with and without airways obstruction

A comparison was made of the frequency dependence of total respiratory resistance, (Rrs), and reactance (Xrs), determined by a forced oscillation technique in 442 healthy subjects and in 126 patients with respiratory complaints, with or without slight airways obstruction. The comparison was performed by means of a discriminant analysis. The latter demonstrated that the Rrs and Xrs data, measured between 8 and 24 Hz, of patients differ from those of healthy subjects primarily by a decrease of Rrs with frequency associated with more negative Xrs (and thus with an increase in resonant frequency). This probably also applies to patients with more advanced airways obstruction. The addition of the FEV1 values to the analysis provides only a small amount of independent information. The forced oscillation technique thus appears to be a sensitive tool to separate healthy subjects (smokers and nonsmokers) from patients with respiratory complaints associated or not with a reduced FEV1.

Lymphatic transport of cholesterol from exogenous and biliary origins in nonfasting rats after intraduodenal infusions of triolein

Labelled thoracic-duct lymph was collected from nonfasting rats with a bile fistula after simultaneous intraduodenal infusions of bile labelled with [1-2 3H] cholesterol and a nutritive mixture containing [4-14C] cholesterol. The gastrointestinal tract, feces, chylomicrons and infranatants were analysed. Both biliary and exogenous cholesterol were absorbed by lymphatic way but the recovery of 3H labelling in total lymph was markedly higher than that of 14C activity. This fact might be due to different rates of cholesterol exchanges from the two origins with the nonlabelled cholesterol present in the enterocytes and further exchanges of the enterocytes cholesterol with plasma cholesterol. Most of radioactivity was detected in chylomicrons. The relative [3H] and [14C] cholesterol specific activities were always low; thus when a little exogenous cholesterol is brought the major part of lymph cholesterol had an endogenous--other than biliary--source.

[Bromazepam against anxiety in psychiatric patients (author's transl)]

In this study involving 30 hospital patients (23 inpatients and 7 out-patients) with neurosis or depressive syndrome, bromazepam 12 mg/24 hours in 2 or 3 divided doses proved effective in controlling anxiety symptoms. The results, as measured by the Hamilton scale, were satisfactory in two-thirds of the cases, notably in neurotic anxiety. Free-floating anxiety and somatic symptoms were relieved. Undesirable reactions consisted of daytime somnolence (5 cases), feeling of dizziness (1 case) and fatigue (1 case).

Normal values of total respiratory resistance and reactance determined by forced oscillations: influence of smoking

In 407 healthy male subjects, smokers and nonsmokers, the resistance and reactance of the respiratory system were determined between 4 and 24 Hz, using a forced oscillation technique. The values are significantly correlated with age, weight, height, FEV1, and vital capacity. After standardization of the data for the latter variables, there are no differences between smokers and nonsmokers. The technique thus lacks sensitivity for the detection of the effects of smoking.

Rapidly decreasing forced expiratory volume in one second or vital capacity and development of chronic airflow obstruction

In a prospective study of 2,406 members of the Belgian Air Force, followed for 3 to 15 yr, 325 demonstrated a yearly decline in FEV1 and/or in vital capacity (VC) that was significantly faster than that expected in healthy nonsmokers. Such rapid declines were met more frequently in heavy smokers and in subjects with a reduced FEV1 or VC. There was no clear-cut association between rapid declines and a history of respiratory diseases. It may be predicted, if the rates of declines do not vary with aging, that about 0.5% of nonsmokers and 4% of heavy smokers in the investigated population will reach disabling airway obstruction (FEV1 of 1.2 L or less) at 65 yr of age. At least 6 to 8 yr of follow-up are required to appreciate with precision the rates of declines in FEV1 or in VC.

Model of elasticity of the human lung

A model of the elasticity of the human lung has been developed to evaluate the relative importance of the characteristics of the lung parenchyma, of thorax configuration, and of gravity on the vertical gradients of pleural pressure and regional volumes, and on the linear displacements of lung tissue, of various lung volumes. The predictions of the model are compared with available experimental data. It is suggested that the bulk elasticity modulus of the human lung is high with respect to that of canine lungs, that the shearing forces are low ("effective" Poison's ratio of about 0.4-0.45), and that the variations of regional pleural pressures and volumes during deflation are determined primarily by the interaction between lung weight and changes in thorax configuration.