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G Putz

Publications and source records attributed to G Putz.

At least 19 recordsLinked to original sources
PubMed2000

High-frequency oscillatory ventilation does not decrease endothelin release in lung-lavaged rabbits.

UNLABELLED: High-frequency oscillatory ventilation (HFO) has been shown to reduce lung injury and pulmonary arterial pressure (PAP). We hypothesized that HFO leads to decreased endothelin 1 (ET-1) and endothelin 3 (ET-3) release when compared to conventional mechanical ventilation (CMV) in lung-lavaged rabbits. DESIGN: Prospective, randomized, controlled animal study. In 26 adult New Zealand White Rabbits ventilated by CMV or HFO under hypoxemic and normoxemic conditions after lung lavage (CMV-hypo: n = 5; CMV-normo: n = 8; HFO-hypo: n = 7; HFO-normo: n = 6) we recorded systemic and PAP, measured blood gases, ET-1 and ET-3 and calculated intrapulmonary venous admixture during a 4-h experiment. ET-1 was significantly increased after lavage (p < 0.05) with no further increase until the end of the experiment. Neither pulmonary arterial nor systemic arterial ET-1 differed between CMV and HFO or between hypoxemia and normoxemia. Systemic arterial ET-3, however, was significantly higher in HFO-hypo than in the other two groups ventilated under normoxemic conditions at the end of the experiment (HFO-hypo vs. CMV-normo, p < 0.05; HFO-hypo vs. HFO-normo, p < 0.05). PAP showed a continuous increase in all groups (p < 0.05). We did not find any correlation between PAP and ET-1 or ET-3. Intrapulmonary venous admixture increased in animals ventilated under hypoxemic conditions, whereas it decreased after lung lavage in those ventilated under normoxemic conditions until the end of the experiment (HFO-normo, p < 0.05). CONCLUSIONS: This study suggests that HFO does not decrease ET-1 and ET-3 release compared to CMV in lung-lavaged rabbits. Hypoxemia, however, may increase ET-3 release from the lungs, leading to an increased intrapulmonary shunt.

Animals↗
PubMed1999

Production of surfactant protein C in the baculovirus expression system: the information required for correct folding and palmitoylation of SP-C is contained within the mature sequence.

Surfactant protein C (SP-C) is synthesized in the alveolar type II cells of the lung as a 21 kDa propeptide which is proteolytically processed to a 4.2 kDa mature active form. The main function of this extremely hydrophobic protein is to enhance lipid insertion into the air/liquid interface in the lung upon inhalation. This is necessary to maintain a relatively low surface tension at this interface during breathing. In this report we describe the production of mature human SP-C in the baculovirus expression system. The recombinant protein contains a secondary structure with a high alpha-helical content (73%), comparable to native SP-C, as determined by circular dichroism and attenuated total reflection Fourier transform infrared analysis. The expressed protein is a mixture of dipalmitoylated (15%) and non-palmitoylated SP-C. This suggests that the information required for palmitoylation is contained within the sequence of the mature protein. The activity of the protein to insert phospholipids into a preformed monolayer of lipids at an air/liquid interface was determined with a captive bubble surfactometer. Recombinant SP-C significantly reduced the surface tension at the air/liquid interface during dynamic expansion and compression. We conclude that correctly folded, dipalmitoylated and active SP-C can be expressed in the baculovirus expression system. Our results may facilitate investigations into the relation between structure and function of SP-C and into protein palmitoylation in general.

Animals↗
PubMed1999

Hydrophobic lung surfactant proteins B and C remain associated with surface film during dynamic cyclic area changes.

The biophysical activity of lung surfactant depends, to a large extent, on the presence of the hydrophobic surfactant proteins B (SP-B) and C (SP-C). The role of these proteins in lipid adsorption and lipid squeeze-out under dynamic conditions simulating breathing is not yet clear. Therefore, the aim of this study was to investigate the interaction of spread hydrophobic surfactant proteins with phospholipids in a captive-bubble surfactometer during rapid cyclic area changes (6 cycles/min). We found that SP-B and SP-C facilitated the rapid transport of lipids into the air-water interface in a concentration-dependent manner (threshold concentration > or = 0.05:0.5 mol% SP-B/SP-C). Successive rapid cyclic area changes did not affect the concentration-dependent lipid adsorption process, suggesting that SP-B and SP-C remained associated with the surface film.

Phospholipids↗
PubMed1999

Persistence of phase coexistence in disaturated phosphatidylcholine monolayers at high surface pressures.

Prior reports that the coexistence of the liquid-expanded (LE) and liquid-condensed (LC) phases in phospholipid monolayers terminates in a critical point have been compromised by experimental difficulties with Langmuir troughs at high surface pressures and temperatures. The studies reported here used the continuous interface of a captive bubble to minimize these problems during measurements of the phase behavior for monolayers containing the phosphatidylcholines with the four different possible combinations of palmitoyl and/or myristoyl acyl residues. Isothermal compression produced surface pressure-area curves for dipalmitoyl phosphatidylcholine (DPPC) that were indistinguishable from previously published data obtained with Langmuir troughs. During isobaric heating, a steep increase in molecular area corresponding to the main LC-LE phase transition persisted for all four compounds to 45 mN/m, at which collapse of the LE phase first occurred. No other discontinuities to suggest other phase transitions were apparent. Isobars for DPPC at higher pressures were complicated by collapse of the monolayer, but continued to show evidence up to 65 mN/m for at least the onset of the LC-LE transition. The persistence of the main phase transition to high surface pressures suggests that a critical point for these monolayers of disaturated phospholipids is either nonexistent or inaccessible at an air-water interface.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1999

Localization of a candidate surfactant convertase to type II cells, macrophages, and surfactant subfractions.

Pulmonary surfactant exists in the alveolus in several distinct subtypes that differ in their morphology, composition, and surface activity. Experiments by others have implicated a serine hydrolase in the production of the inactive small vesicular subtype of surfactant (N. J. Gross and R. M. Schultz. Biochim. Biophys. Acta 1044: 222-230, 1990). Our laboratory recently identified this enzyme in the rat as the serine carboxylesterase ES-2 [F. Barr, H. Clark, and S. Hawgood. Am. J. Physiol. 274 (Lung Cell. Mol. Physiol. 18): L404-L410, 1998]. In the present study, we determined the cellular sites of expression of ES-2 in rat lung using a digoxygenin-labeled ES-2 riboprobe. ES-2 mRNA was localized to type II cells and alveolar macrophages but not to Clara cells. Using a specific ES-2 antibody, we determined the protein distribution of ES-2 in the lung by immunohistochemistry, and it was found to be consistent with the sites of mRNA expression. Most of the ES-2 in rat bronchoalveolar lavage is in the surfactant-depleted supernatant, but ES-2 was also consistently localized to the small vesicular surfactant subfraction presumed to form as a consequence of conversion activity. These results are consistent with a role for endogenous lung ES-2 in surfactant metabolism.

Animals↗
PubMed1998

A spreading technique for forming film in a captive bubble.

Mechanisms underlying the surface properties of lung surfactant are extensively studied in in vitro systems such as the captive-bubble surfactometer (CBS), the pulsating-bubble surfactometer, and the Wilhelmy balance. Among these systems, the CBS is advantageous when a leakproof system and high cycling rates are required. However, widespread application of the CBS to mechanistic studies of dynamic surfactant protein-phospholipid interactions of spread film and to comparative studies between spread and adsorbed film is hampered because spreading of film is difficult. In addition, when film is formed by adsorption, the amount of material required is fairly large. We have developed an easy spreading technique that allows routine formation of film by spreading of small amounts of surfactant components at the air-water interface of an air bubble in a CBS. The technique is reliable, precise, and accurate, and the biophysical activity of film formed by spreading is similar to that of film formed by adsorption. This method will be useful for mechanistic studies of surfactant components under dynamic conditions and for comparative studies of spread films and adsorbed films.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1998

Plasmalogens effectively reduce the surface tension of surfactant-like phospholipid mixtures.

The alkenyl-acyl subclass of phosphatidylethanolamine (PtdEtn) and phosphatidylcholine (plasmalogens) are minor components of alveolar surfactant. Plasmalogens promote and stabilize hexagonal structures of phospholipids. In another study (W.R. Perkins, R.B. Dause, R.A. Parente, S.R. Michey, K.C. Neuman, S.M. Gruner, T.F. Taraschi, and A.S. Janoff. Science 273: 330-332, 1996), it was shown that polymorphic phase behavior may have an important role in the effective functioning of pulmonary surfactant. Therefore, we hypothesized that surface properties of phospholipid mixtures that contain plasmalogens are superior to plasmalogen-free mixtures. The effect of plasmalogens on surface tension of surfactant-like phospholipid mixtures (70 mol% dipalmitoyl phosphatidylcholine, 10 mol% phosphatidylglycerol, and 20 mol% PtdEtn) was measured. Using the pulsating bubble surfactometer, we show that an increasing amount of ethanolamine plasmalogens [plasmenylethanolamine (PlsEtn) results in reduction of surface tension (0 mol% PlsEtn 44.7 +/- 1.7, 2 mol% 33.5 +/- 1.7, 4 mol% 36 +/- 3.1, 6 mol% 26.2 +/- 2.9, and 8 mol% 22.2 +/- 0.3 mN/m). By means of the captive bubble surfactometer, minimal surface tension reached with 8 mol% PlsEtn was even lower (3.8 +/- 0.7 mN/m). With regard to morphological studies (B. Fringes, K. Gorgas, and A. Reith. Eur. J. Cell Biol. 46: 136-143, 1988), clofibrate treatment of rats might increase the plasmalogen content of alveolar surfactant. However, in the present study, we could not show that synthesis and secretion of plasmalogens are affected by clofibrate treatment.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

Surfactant replacement therapy in acute respiratory distress syndrome from viral pneumonia.

A modified natural surfactant was administered to a patient with life-threatening adult respiratory distress syndrome caused by viral pneumonia. Subsequently, there was a marked improvement in gas exchange. In order to assess the mechanism for improved oxygenation, computed tomography of the lungs was done. Quantitative analysis of the scans taken before and after surfactant administration indicates that improvement in gas exchange was largely due to the expansion of underinflated and collapsed lung areas. Although this is a single case report, it provides insight into the possible beneficial effect of instilled surfactant in severe respiratory distress from viral pneumonia.

Biological Products↗
PubMed1994

[The prone position in ARDS. A successful therapeutic strategy].

As early as 1974, Brian advocated the prone position for ventilated patients. He suggested that this position might enhance ventilation of the dorsal parts of the lungs, thereby improving oxygenation. These considerations have been confirmed by several experimental and clinical studies. Better secretion removal, decreased intrapulmonary shunting, and an increased FRC are thought to be responsible for the observed improvement of oxygenation. However, the prone position never became very popular in the clinical treatment of the adult respiratory distress syndrome (ARDS). Routine performance of thoracic CT scans in ARDS patients demonstrated preferential distribution of pathological densities in the dependent lung areas. The prone position therefore could possibly benefit these patients, as shown by two recent studies. The aim of our study was to evaluate the influence of repeatedly turning the patient to the prone position on gas exchange and thoracic CT findings in multiple-trauma patients. METHODS. Seven ventilated intensive care patients with severe ARDS (Murray Score > 2.5, Quotient > 0.7, mean airway pressure > 18 cm H2O, thoracic CT scan showing dorsal atelectases) were included in the study. Patients were turned from the supine to the prone position at 12-h intervals using an air-cushion bed (Mediscus, Austria). Redistribution of dystelectatic or atelectatic dependent lung areas was verified by means of repeated thoracic CT scans (Figs. 1, 8). RESULTS. The patients were intermittently turned for 6.5 +/- 1.1 days. The course of gas exchange is shown in Figs. 2 and 3. Initially, improvement of the respiratory quotient could only be achieved during prone positioning, from the 2nd day in the supine position as well. Intrapulmonary shunting showed a similar trend (Figs. 4 and 5). No significant changes in cardiovascular parameters could be observed. Control thoracic CT scans showed uniform reduction of atelectases in dependent lung areas (Figs. 1 and 8). The inspiratory fraction of oxygen could be reduced significantly as of the 2nd day (Fig. 7). Constant levels of positive end-expiratory pressure and tidal volume were associated with decreasing mean and plateau airway pressures (Fig. 6). DISCUSSION. Repeatedly turning the patient to the prone position produced long-lasting improvement of arterial oxygenation, which persists up to the end of the weaning process. This is in good accordance with other studies, however, this is the first study to report an observation period of more than 6 days of repeatedly turning the patient. These positive effects on gas exchange can be attributed to sudden improvement of the ventilation-perfusion ratio within the lung areas that become dependent after turning to the prone position. Due to reduced hydrostatic pressure and relative hyperventilation, previously collapsed alveoli are recruited in the lung areas that become non-dependent after turning to the prone position.

Adult↗
PubMed1994

Evaluation of pressure-driven captive bubble surfactometer.

We modified the captive bubble surfactometer [S. Schürch et al. J. Appl. Physiol. 67: 2389-2396, 1989] to facilitate the measurement of surface adsorption rates and to simplify its construction. We used a range of standards and monolayers of dipalmitoylphosphatidylcholine to check the calibration of the device against measurements made in a Wilhelmy surface balance and in the captive bubble by using a cathetometer, and we found good agreement. As a further test we measured the surface properties of rabbit lavage lung surfactant (60,000 x average g for 60 min) at 1.0 mg phospholipid/ml. This material adsorbed within 1 s to near-equilibrium surface tension, reached surface tensions of < 5 mN/m on the second compression, and formed very stable films. We conclude that a captive bubble surfactometer can provide accurate information about important surface properties of lung surfactant films.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1994

Comparison of captive and pulsating bubble surfactometers with use of lung surfactants.

We compared surface tension measures of surfactants with various surface activities by using a pulsating bubble surfactometer (PBS) and a captive bubble surfactometer (CBS). Rabbit lung lavage surfactant (60,000 x average g for 60 min), bovine surfactant extract (Survanta), and a synthetic lipid surfactant mixture (dipalmitoylphosphatidylcholine-egg phosphatidylglycerol-palmitic acid) were studied at 1.25 mg phospholipid/ml. The PBS was used either unmodified according to manufacturer's instructions or with the sample chamber capillary kept dry and the sample adsorbing at maximum bubble size (5 min). The CBS was used in a manner that imitated the unmodified PBS. We found that all three techniques indicated low surface tension on the first cycle for 60K. For Survanta, the CBS and the modified PBS reported low surface tension on the first cycle, whereas the unmodified PBS did not achieve this within 10 cycles. For the synthetic lipid surfactant mixture, only the CBS measured low surface tension within 10 cycles. Video observations indicate that the modified PBS performs better than the unmodified PBS because keeping the capillary dry prevents surface film from occupying this large surface during cycling, thereby allowing larger area compressions.

Adsorption↗
PubMed1994

Surface activity of rabbit pulmonary surfactant subfractions at different concentrations in a captive bubble.

This study investigates the surface activity of rabbit pulmonary surfactant subfractions at different concentrations in a new pressure-driven captive bubble surfactometer, which provides more rigorous testing conditions than heretofore applied to this material. Subfractions were separated by centrifugation of lavage return into a third (P3; 1,000 x average g, 20 min), a fourth (P4; 60,000 x average g, 60 min), and a fifth (P5; 100,000 x average g, 16 h) pellet. At 2.0 mg phospholipid/ml, P3 and P4 demonstrated more rapid adsorption, lower minimum surface tensions on first and subsequent compressions, and lower monolayer compressibilities than did P5. This surface activity of P3 and P4 increased with concentration between 0.1 and 2.0 mg phospholipid/ml. Adsorption rate constants were approximately 10,000 times faster than desorption constants. We conclude that, in a normal lung, components of P3 and P4 determine alveolar surface tension. We speculate that under special circumstances even the less surface active P5 could have an important influence at the air-water interface.

Adsorption↗
PubMed1992

Tidal volume, breathing frequency, and oxygen consumption at different pressure support levels in the early stage of weaning in patients without chronic obstructive pulmonary disease.

The objective of this study was to evaluate the influence of different PSV levels on VT, F, VO2 in the early weaning phase of patients without chronic obstructive pulmonary disease. These parameters were tested for the predictive power for the success of the weaning. Patients on SIMV were studied during the first weaning attempt with PSV. Depending on their ventilatory support demands after 24 h they were divided into responders (patients breathing on CPAP) and nonresponders (patients being on a more invasive ventilatory mode). 14 ICU patients without pre-existing pulmonary disease being ventilated for at least 3 days entered the study. 2 of them could be studied a second time after failing the first weaning attempt. Beside the level of ventilatory support no other changes (drugs, nutrition) were allowed. VO2, VT, F were measured by a computer controlled, metabolic unit connected to the expiratory port of a Siemens Servo Ventilator. In addition, airway pressures, arterial pressure and heart rate were recorded. The measurements were performed at PSV of 5, 10 and 20 cmH2O. Arterial blood-gases were drawn at the end of each 60 min lasting PS period. Responders and nonresponders could be separated by the response of VO2, VT and F to a change in PS 10 to PS 20 cmH2O. Patients who significantly increased VT and significantly decreased F did not fulfil our weaning criteria. Our responders did not show a significant change in these two parameters, but a significant increase in VO2 at PS 20 cmH2O could be observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

High-frequency pulsation (HFP) in a patient with Guillain-Barré syndrome.

A patient with Guillain-Barré syndrome (GBS) developed a respiratory crisis despite recurrent treatment with plasma exchange. Thus mechanical ventilatory support became necessary. As an alternative to conventional ventilatory techniques high-frequency pulsation (HFP), a modified high-frequency jet-ventilation technique was used. According to the observations HFP may be a valuable technique for the continuous adaptation to the patient's individual respiratory demands in GBS.

Adult↗
PubMed1990

Gamma scintigraphic imaging of lung microvascular permeability in adult respiratory distress syndrome.

The sequence of lung microvascular permeability (LMVP) changes in early direct posttraumatic and late indirect pancreatitis-induced adult respiratory distress syndrome (ARDS) was studied and compared with that of a control group, as well as non-ARDS ICU patients. A computerized large field of view gamma camera was used to measure LMVP simultaneously over both lungs by In 113m-labeled transferrin and Tc 99m-labeled erythrocytes. The LMVP index (LMVPI) (%/h) was used to quantify LMVP in the dynamic scintigraphic measurement. In the control group the LMVPI was 2.6 +/- 2.8%/h for the right and 2.0 +/- 2.8%/h for the left lung. Similar values were found in mechanically ventilated ICU patients without ARDS (group A) on admission (right LMVPI 3.2 +/- 2.6, left LMVPI 2.6 +/- 2.7%/h) and 4 days later (right LMVPI 3.9 +/- 2.6, left LMVPI 2.3 +/- 1.8%/h). Interestingly, the initial evaluation of patients with direct early posttraumatic ARDS (lung contusion) (group B) showed significantly (p less than .01) elevated LMVP for the contused side (LMVPI 10.8 +/- 5.1%/h), but normal values for the nontraumatized lung (LMVPI 3.9 +/- 3.4%/h), whereas 4 days later the LMVP increased significantly (p less than .05) on the primarily healthy side (LMVPI 8.0 +/- 5.0%/h) while remaining elevated for the traumatized lung (LMVPI 10.9 +/- 6.0%/h).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[The course of extravascular lung water in severely injured patients in intensive care with and without thoracic trauma].

In patients with multiple injuries, the development of permeability edema can be assumed. However, no uniform shape of this fluid accumulation can be found even in the presence of severe injuries. Based on the first clinical observations, our aim was to search for correlations between the development of extravascular lung water (EVLW) and the individual injury pattern in severely traumatized ICU patients. PATIENTS and METHODS. Our investigations were performed in 48 artificially ventilated ICU patients. According to the prevailing injury pattern patients were divided into three groups: group A: 18 patients (mean age: 32 years, mean Injury Severity Score (ISS) = 29) with isolated thoracic trauma; group B: 10 patients (mean age: 27 years, mean ISS = 42) with severe multiple trauma but without any thoracic injury; group C: 20 patients (mean age: 33 years, mean ISS = 43) with severe multiple trauma and concomitant thoracic trauma. In all patients (group A, B, C), EVLW was determined by means of a double indicator method on a daily basis from the patient's admission to the ICU (day of trauma) until day 10. Additionally, the hemodynamic parameters (heart rate, mean arterial pressure, mean pulmonary arterial pressure, pulmonary capillary wedge pressure and cardiac index) were determined at the same time. RESULTS. As shown in Fig 1, EVLW was slightly elevated on day 1. However, on day 2 EVLW decreased within normal values and remained in that range until the end of the observation period. On day 3 a slight and fleeting increase of EVLW, but within normal range, can be seen. In group B (Fig.2), EVLW can be observed within normal range within a period of 4 days. Starting from day 5 until day 7 a marked increase (p greater than 0.01) in EVLW can be seen. From that maximum point EVLW development reverses slightly until day 10--however, without returning to the normal range. In group C, a marked biphasic pattern can be seen due to EVLW maximum values on post-traumatic days 3 and 7. However, in this group the EVLW was in the pathological range during the whole observation period. No statistically significant differences could be seen, when looking at hemodynamic variables. CONCLUSION. Isolated thoracic trauma will not lead to a marked pathological elevation of EVLW within the lungs. Moreover, EVLW decreases rapidly within a short time period. Based on our results, it seems that severe extrathoracic injuries will intensify microvascular injury in the initial period, as shown in our patients in group C. Increase of EVLW at a later time (day 7), as observed in groups B and C, is possibly the expression of a mediator and activator-induced "septiformal" injury of the microvascular endothelium. This may be caused by the underlying massive peripheral soft-tissue trauma. Specific elevations of EVLW subsequent to the individual injury pattern can indicate that that process has begun and is responsible for the origin of the microvascular injuries.

Adolescent↗