Converging hydrostatic and hydromechanic concepts of preferential flow definitions.

The boundary between preferential flow and Richards-type flow is a priori set at a volumetric soil water content theta* at which soil water diffusivity D (theta*) = eta (= 10(-6) m(2) s(-1)), where eta is the kinematic viscosity. First we estimated with a hydrostatic approach from soil water retention curves the boundary, theta(K), between the structural pore domain, in which preferential flow occurs, and the matrix pore domain, in which Richards-type flow occurs. We then compared theta(K) with theta* that was derived from the respective soil hydrological property functions of same soil sample. Second, from in situ investigations we determined 96 values of theta(G) as the terminal soil water contents that established themselves when the corresponding water-content waves of preferential flow have practically ceased. We compared the frequency distribution of theta(G) with the one of theta* that was calculated from the respective soil hydrological property functions of 32 soil samples that were determined with pressure plate apparatuses in the laboratory. There is support of the notion that theta(K) approximately = theta(G) approximately = theta*, thus indicating the potential of theta* to explain more generally what constitutes preferential flow. However, the support is assessed as working hypothesis on which to base further research rather than a procedure to a clear-cut identification of preferential flow and associated flow paths.

Limited remyelination in Theiler's murine encephalomyelitis due to insufficient oligodendroglial differentiation of nerve/glial antigen 2 (NG2)-positive putative oligodendroglial progenitor cells.

AIMS: Limited remyelination is a key feature of demyelinating Theiler's murine encephalomyelitis (TME). It is hypothesized that a dysregulation of differentiation of oligodendroglial progenitor cells (OPCs) represents the main cause of insufficient regeneration in this model of multiple sclerosis. METHODS: TME virus (TMEV)-infected SJL/J mice were evaluated by footprint analysis, light and electron microscopy, immunohistology, confocal immunofluorescence and RT-qPCR at multiple time points ranging from 1 h to 196 days post infection (dpi). RESULTS: Footprint analysis revealed a significantly decreased stride length at 147 and 196 dpi. Demyelination progressively increased from 14 towards 196 dpi. A mild amount of remyelination was detected at 147 and 196 dpi. Early onset axonal injury was detected from 14 dpi on. TMEV RNA was detectable throughout the observation period and markedly increased between 7 and 28 dpi. Intralesional nerve/glial antigen 2 (NG2)-positive OPCs were temporarily increased between 28 and 98 dpi. Similarly, a transient upregulation of NG2 and platelet-derived growth factor alpha-receptor mRNA was noticed. In contrast, intralesional 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)-positive oligodendrocytes were decreased between 56 and 196 dpi. Although CNPase mRNA remained unchanged, myelin basic protein mRNA and especially its exon 2 containing splice variants were decreased. Glial fibrillary acidic protein (GFAP)-positive astrocytes and GFAP mRNA were increased in the late phase of TME. A mildly increased colocalization of both NG2/CNPase and NG2/GFAP was revealed at 196 dpi. CONCLUSIONS: Summarized, the present results indicated a dysregulation of OPC maturation as the main cause for the delayed and limited remyelination in TME. A shift of OPC differentiation from oligodendroglial towards astrocytic differentiation is postulated.

Confocal laser scanning analysis of an equine oral mast cell tumor with atypical expression of tyrosine kinase receptor C-KIT.

A 20-year-old female horse showed a nodular, firm, focal ulcerated mast cell tumor at the right dorsobuccal face of the tongue. Histologically, the nonencapsulated tumor consisted of dense, infiltrating aggregates of well-differentiated, Cresyl violet-positive mast cells accompanied by numerous eosinophils. Furthermore, they exhibited a strong, diffuse, intracytoplasmatic immunohistochemical signal for tryptase and a faint membrane-associated and perinuclear signal for tyrosine kinase receptor KIT. Confocal laser scanning microscopy confirmed an aberrant spatial colocalization of KIT in the Golgi apparatus, which may be the result of a defective protein processing within the tumor cells. The tumor was not associated with a poor prognosis.

Effects of anti-glaucoma drugs timolol and GLC756, a novel mixed dopamine D2 receptor agonist and D1 receptor antagonist, on endotoxin-induced-uveitis and -arthritis in rats.

Anti-glaucoma drugs exhibiting anti-inflammatory properties are desirable for the long-term treatment of glaucoma since they may reduce the risk for treatment-related inflammatory processes in outer compartments of the eye. The purpose of this study was to evaluate potential anti-inflammatory effects of two topically and systemically applied anti-glaucoma drugs i.e. GLC 756, a novel mixed dopamine D2 receptor agonist and D1 receptor antagonist, and timolol a beta-adrenoceptor antagonist using endotoxin-induced uveitis (EIU) and arthritis in rats as an in vivo model. For EIU, 8-week-old Lewis rats were intravenously injected at 160 microg lipopolysaccharide (LPS) from Salmonella typhimurium. GLC756, timolol, or betamethasone, as a positive control, were either topically (0.4%, 0.5%, and 0.1%, respectively, 16-times 20 microL eye drops during 48 h) or systemically (1mg/kg subcutaneous for 5 days) administered. Cell infiltration in tissue of the eye and knee joint were assessed histopathologically and in special compartments of the eye by confocal microscopy 48 h after LPS-induction. Numerous infiltrating cells were detected in the eyes after LPS-induction and half of the animals showed arthritis. Topical and systemic pre-treatment with GLC756 and timolol resulted in reduced cell infiltration in the eye. In addition, GLC756 reduced, whereas timolol increased the incidence of arthritis. Betamethasone suppressed almost completely the cell infiltration in the eye and the incidence of arthritis. In conclusion, the observations that GLC756 reduced cell infiltration in the eye and the incidence of arthritis after LPS-induction is compatible with anti-inflammatory properties of this drug. By contrast, timolol produced no consistent anti-inflammatory effect since both inhibitory as well as stimulatory effects on inflammatory processes were seen.

Immunohistochemical study about the Flt-1/VEGFR1 expression in the gastrointestinal tract of mouse, rat, dog, swine and monkey.

Fms-like tyrosine kinase 1 (Flt-1) performs a subordinate effector role in mesenchymal angiogenesis and potentially serves an equally important functional role as a self-contained receptor in epithelial cells. In both endothelial cells and epithelial cells, Flt-1/vascular endothelial growth factor receptor 1 (VEGFR1) downstream signalling is involved in regulating cellular processes such as cytoskeletal changes and cellular survival protection. Cellular renewal of the gastrointestinal mucosa is based on these processes and might involve Flt-1/VEGFR1 pathway activities; the molecular mechanisms regulating these cellular dynamics remain unclear. This study was performed to investigate the presence and distribution of Flt-1/VEGFR1 in epithelial cells of the gastrointestinal tract by immunohistochemistry (IHC). Gastrointestinal tissues were taken from eight anatomical sites from mouse, rat, dog, swine and monkey. Present results revealed a cytosolic Flt-1/VEGFR1 staining pattern in mucosal epithelial cells for all investigated species. Non-epithelial structures also displayed a distinct Flt-1/VEGFR1 positivity and included vascular smooth muscle walls, enteric smooth muscle layers, the enteric nervous system and capillary endothelial cells. Diverse intensities of the Flt-1/VEGFR1 binding reaction within each species were observed in the intestinal mucosa with a strong immunoreaction in enterocytes and with a low protein expression in the ileum in most species. Crypt cells in the large intestine were mostly negative for Flt-1/VEGFR1. A peculiar and mainly intranuclear antibody binding reaction was found in Brunner's gland epithelial cells of mouse and rat whereas Brunner's glands of dog, swine and monkey remained completely negative. These results indicate a potential involvement of Flt-1/VEGFR1 in normal restitution of gastrointestinal structures in the species studied. Additionally, intranuclear Flt-1/VEGFR1 antibody binding in Brunner's glands of rodents may suggest a nuclear translocation of the transmembrane VEGFR1 which has not previously been described.

Controlled prospective randomised trial on the effects on pulmonary haemodynamics of the ambulatory long term use of nitric oxide and oxygen in patients with severe COPD.

BACKGROUND: Pulmonary hypertension is a frequent complication of severe chronic obstructive pulmonary disease (COPD) and a major cause of morbidity and mortality in this condition. Based on the improved survival of these patients due to long term oxygen therapy and the potent and selective pulmonary vasodilation by inhaled nitric oxide, the safety and effectiveness of the combined inhalation of these two gases over a 3 month period was assessed. METHODS: Forty patients with secondary pulmonary hypertension due to COPD were randomly assigned to receive either oxygen alone or "pulsed" inhalation of nitric oxide with oxygen over a period of 3 months. "Pulsed" inhalation of nitric oxide was used to reduce pulmonary ventilation-perfusion mismatch and formation of toxic reaction products of nitric oxide and oxygen. RESULTS: Compared with oxygen alone, the combined inhalation of nitric oxide and oxygen caused a significant decrease in mean (SE) pulmonary artery pressure (from 27.6 (4.4) mm Hg to 20.6 (4.9) mm Hg, p<0.001) and pulmonary vascular resistance index (from 569.7 (208.1) to 351.3 (159.9) dyne x s(-1) x cm(-5) x m(-2), p<0.001) without decreasing arterial oxygenation. Cardiac output increased by 0.5 litres (from 5.6 (1.3) l/min to 6.1 (1.0) l/min, p=0.025). Systemic haemodynamics and left heart function remained unchanged during this period and no increase in toxic reaction products of nitric oxide was observed. CONCLUSIONS: This is the first controlled trial indicating that the "pulsed" inhalation of nitric oxide together with oxygen may be safely and effectively used for the long term treatment of severe COPD.

Analisis de la calidad de la codificación no centralizada / Analysis of the quality of non-centralized coding

Introducción: La cumplimentación del CMBDAH constituye la base del sistema de medida y gestión del producto hospitalario del SNS, mediante la clasificación GRD. Un elemento clave es la integración de la información clínica mediante la codificación. Objetivo: Analizar la calidad de la codificación realizada por personal médico no formado específicamente y valorar la cualificación necesaria para esta tarea. Material y métodos: Unidades de estudio: Informes de alta muestreados por conglomerados. Análisis: Comparativo de variables indicadoras de calidad de la codificación realizada por los clínicos mencionados respecto a un codificador experto. Resultados: Se estudiaron 178 informes. Análisis técnico de la codificación: Diagnóstico Principal: Un 30,9 per cent no tenían bien seleccionado el diagnóstico principal. De los que lo tenían el 44,4 per cent estaban mal codificados. Diagnósticos Secundarios: El codificador experto asignó 3,1 códigos por informe por 1,2 de los clínicos. Fueron correctos un 23,3 per cent. Análisis comparativo de la asignación en GRD: En un 32,0 per cent hubo concordancia. De los que no hubo acuerdo, en un 29,8 per cent hubo mala selección del diagnóstico principal. En un 43,8 per cent el GRD resultante de la codificación de los clínicos del servicio fue el 470.Conclusiones: El nivel de calidad de la codificación realizada por los clínicos fue bajo. La imagen de la casuística que se obtendría sería diferente de la realmente tratada por el servicio. Es conveniente y necesario contar con personal especializado en Sistemas de Información Sanitarios que desarrollen la tarea de codificación de los episodios generados en el hospital, para garantizar la máxima calidad en estos procesos (AU)

Effects of C1 inhibitor and r-SP-C surfactant on oxygenation and histology in rats with lavage-induced acute lung injury.

OBJECTIVE: To assess the effects of C1 inhibitor (INH) administration and r-SP-C surfactant application on oxygenation and lung histology in an acute respiratory distress syndrome model. DESIGN AND SETTING: Randomized, controlled experimental study in an animal research laboratory. MATERIAL: 36 adult male Sprague-Dawley rats. INTERVENTIONS: Animals were subjected to repetitive lung lavage. Four experimental groups and two control groups were studied: groups 1 and 2 served as controls. Animals of groups 3-6 received 200 U/kg body weight C1-INH (group 3), 25 mg/kg r-SP-C surfactant (group 4) or both (group 5) at 60 min postlavage (pl). Animals of group 6 were treated with 200 U/kg C1-INH1 at 10 min pl. Animals of group 1 were killed 60 min (min) pl, animals of groups 2-6 were killed at 210 min pl. Thereafter the lungs were excised for histological examination. MEASUREMENTS AND RESULTS: Hyaline membrane formation, intra-alveolar neutrophil (PMN) accumulation and intra-alveolar/perivascular haemorrhage were graded semiquantitatively (0-4). Blood gases were determined 120, 150, 180 and 210 min pl. At 210 min pl pO(2) in group 4 (456+/-74 mmHg) and group 5 (387+/-155 mmHg) was significantly higher than in controls (72+/-29 mmHg) or after C1-INH monotherapy (group 3: 120+/-103, group 6: 63+/-12 mmHg). PMN infiltration after C1-INH monotherapy was significantly less severe than in controls. The combination of r-SP-C surfactant and C1-INH led to significantly lower PMN infiltration than surfactant monotherapy. CONCLUSION: In this lavage-induced acute respiratory distress syndrome model the administration of C1-INH might be followed by a higher clinical efficacy of exogenously supplied recombinant SP-C surfactant.

Continuous venovenous hemofiltration improves arterial oxygenation in endotoxin-induced lung injury in pigs.

BACKGROUND: Hypoxemia is common in septic acute lung failure. Therapy is mainly supportive, and most trials using specific inhibitors of key inflammatory mediators (ie., tumor necrosis factor alpha, interleukin 1) have failed to prove beneficial. The authors investigated if a nonspecific blood purification technique, using zero-balanced high-volume continuous venovenous hemofiltration (CWH), might improve arterial oxygenation in a fluid-resuscitated porcine model of endotoxin-induced acute lung injury. METHODS: Piglets of both sexes weighing 25-30 kg were anesthetized and mechanically ventilated. After baseline measurements, animals received an intravenous infusion of 0.5 mg/kg endotoxin (Escherichia coli lipopolysaccharide). One hour after endotoxin, animals were randomly assigned to either treatment with CWH (endotoxin + hemofiltration, n = 6) or spontaneous course (endotoxin, n = 6). At 4 h after randomization, animals were killed. Hemofiltration was performed from femoral vein to femoral vein using a standard circuit with an EF60 polysulphone hemofilter. RESULTS: Endotoxin challenge induced arterial hypoxemia, an increase in peak inspiratory pressure, pulmonary hypertension, and systemic hypotension. Treatment with CWH did not improve systemic or pulmonary hemodynamics. However, arterial oxygenation was increased in endotoxin-challenged animals at 5 h after completion of endotoxin infusion, as compared with animals not receiving CVVH (arterialoxygen tension, 268+/-33 vs. 176+/-67 mm/Hg, respectively, P < 0.01). In addition, treatment with CWH attenuated the endotoxin-induced increase in peak inspiratory pressure and increased lung compliance. CONCLUSION: These results suggest that nonspecific blood purification with high-volume CWH improves arterial oxygenation and lung function in endotoxin-induced acute lung injury in pigs, independent of improved hemodynamics, fluid removal, or body temperature.

Tromethamine buffer modifies the depressant effect of permissive hypercapnia on myocardial contractility in patients with acute respiratory distress syndrome.

In patients with acute respiratory distress syndrome (ARDS), permissive hypercapnia is a strategy to decrease airway pressures to prevent ventilator-induced lung damage by lowering tidal volumes and tolerating higher arterial carbon dioxide tension. However, in experimental studies hypercapnia impairs myocardial contractility and hemodynamic function. We investigated the effect of short-term permissive hypercapnia on myocardial contractility and hemodynamics in patients with ARDS. We hypothesized that the administration of tromethamine (THAM), a buffer which does not increase carbon dioxide production, would modify these changes. In 12 patients with ARDS, permissive hypercapnia was implemented for 2 h with a target Pa(CO(2))of 80 mm Hg. Patients were randomized to have respiratory acidosis corrected by THAM (pH-corrected group), or not corrected (pH-uncorrected group). Hemodynamic responses were measured, and transesophageal echocardiography (TEE) was used to determine myocardial contractility. Permissive hypercapnia resulted in significant decreases in systemic vascular resistance (SVR) and increases in cardiac output (Q). Myocardial contractility decreased in both groups but significantly less in the pH-corrected group (approximately 10%) than in the pH-uncorrected group (approximately 18%, p < 0.05). Mean arterial pressure decreased and mean pulmonary arterial pressure increased significantly only in the pH-uncorrected group. All values returned to baseline conditions 1 h after permissive hypercapnia was terminated. Our study demonstrates a reversible depression of myocardial contractility and hemodynamic alterations during rapid permissive hypercapnia which were attenuated by buffering with THAM. This may have applicability to the clinical strategy of permissive hypercapnia and allow the benefit of decreased airway pressures to be realized while minimizing the adverse hemodynamic effects of hypercapnic acidosis.

[Thoracic CT scan in intensive care unit patients: information supplementary to thoracic radiography]. / Thorakale Computertomographie am Intensivpatienten--Zusatzinformation zum Thorax-Röntgen.

PURPOSE: To assess the diagnostic value of thoracic CT-scans in comparison with conventional chest radiographs in ICU-patients. METHODS: Chest radiographs and corresponding thoracic CT-scans of 25 consecutive surgical ICU-patients were reviewed and interpreted independently by two radiologists. We analyzed the additional information provided by CT-scans and the diagnostic and therapeutic relevance of these findings. RESULTS: In 22 patients (88%), thoracic CT revealed 35 single additional findings, in comparison with the corresponding bedside radiographs. In 7 cases (28%), these findings (tube-malpositioning, mediastinitis, mediastinal abscess and pneumothorax) required modification of patient management. Of 7 patients with tube thoracostomy, 3 tubes were malpositioned, which was only depicted on CT-scans. In 10 of 21 cases (48%), pleural effusions could only be visualized by CT. 3 of 5 (60%) pneumothoraces were detected by CT-scans only. There were no significant complications during transport or CT-examination. CONCLUSION: Thoracic CT may provide significant information in addition to plain chest radiographs, particularly when specific problems or questions, referring to the management of ICU-patients, arise.

Additive effects of phosphodiesterase-4 inhibition on effects of rSP-C surfactant.

We have tested the effects of combined treatment with a recombinant surfactant protein C based surfactant (rSP-C surfactant) containing a phosphodiesterase-4 (PDE-4) inhibitor, roflumilast, in a lung lavage model of acute lung injury. The following groups were tested: (1) controls receiving sham exposure; (2) PDE-4 inhibitor (6.0 mg/kg body weight, intratracheally) alone; (3, 4) rSP-C surfactant (25 and 100 mg phospholipids [PL] per kg body weight) alone; and (5, 6 ) treatment with rSP-C surfactant (25 and 100 mg PL per kg body weight) combined with the PDE-4 inhibitor at a dose of 6.0 mg/kg body weight. The different groups were compared with respect to improving oxygenation and histopathologic changes, e.g., hyaline membrane (HM) formation. Both doses of rSP-C surfactant improved oxygenation while even this high dose of the PDE-4 inhibitor alone did not influence oxygenation compared with untreated control animals. Addition of the PDE-4 inhibitor led to improved oxygenation based on both doses of rSP-C surfactant. The PDE-4 inhibitor alone prevented further HM formation and infiltration of neutrophil leukocytes. The rSP-C surfactant was able to prevent further HM formation. Based on both doses of rSP-C surfactant, addition of the PDE-4 inhibitor showed additional effects on oxygenation and inhibition of HM formation. The effects of combined treatment were superior to each treatment alone, leading to the conclusion that a rSP-C surfactant containing a PDE-4 inhibitor may act synergistically in this animal model of acute lung injury. We conclude that combined treatment with rSP-C surfactant and a PDE-4 inhibitor may be an effective treatment for patients with acute lung injury.

DNA vaccination with both the haemagglutinin and fusion proteins but not the nucleocapsid protein protects against experimental measles virus infection.

Plasmids that expressed the nucleocapsid, haemagglutinin and fusion proteins of measles virus (MV) were used to immunize cotton rats (Sigmodon hispidus) against intranasal MV infection. After immunization with all three plasmids, T cell responses and MV-specific antibodies were induced. A reduction in virus titre was observed in lung tissue from animals immunized with plasmids expressing the viral glycoproteins. Histologically, however, a moderate peribronchitis was observed after immunization with the plasmid expressing the fusion protein whereas, after immunization with plasmids expressing haemagglutinin or both glycoproteins, only mild or focal peribronchitis was seen. Immunization with the nucleocapsid did not reduce virus titres, probably because of the failure to induce neutralizing antibodies. A disadvantage of plasmid immunization was its inefficacy in the presence of MV-specific 'maternal' antibodies. This indicates that genetic immunization has to be improved to be a useful alternative vaccine against measles.

Treatment with epoprostenol reverts nitric oxide non-responsiveness in patients with primary pulmonary hypertension.

OBJECTIVE: To assess whether long term treatment with epoprostenol might restore primary non-responsiveness to nitric oxide (NO) in patients with primary pulmonary hypertension. METHODS: Seven patients with primary pulmonary hypertension receiving intravenous epoprostenol continuously because of failure of NO to influence pulmonary haemodynamics during initial testing were followed over a period of 13-29 months. Afterwards, acute vascular reactivity towards NO was tested again during right heart catheterisation. RESULTS: Administration of NO after continuous epoprostenol treatment for a mean period of 18 months improved arterial oxygen saturation (p < 0.01) and cardiac index (p < 0.05), and decreased mean pulmonary artery pressure (p < 0.01) and total pulmonary vascular resistance (p < 0.01) in patients previously unresponsive to NO. CONCLUSIONS: Long term treatment with epoprostenol reverts initial refractoriness to NO in patients with primary pulmonary hypertension. Thus the addition of NO to epoprostenol treatment might cause further improvement in the course of the disease.

Effect of recombinant SP-C surfactant in a porcine lavage model of acute lung injury.

Synthetic surfactants allow examination of the effects of specific components of natural surfactant. To determine whether surfactant containing apoprotein C, dipalmitoyl-phosphatidylcholine, phosphatidylglycerol, and palmitic acid restores gas-exchanging function in acute lung injury (ALI), we administered such surfactant (in doses of 50 or 100 mg/kg and in volumes from 1 to 6 ml/kg) or phospholipid (PL) alone, by intratracheal instillation, to pigs with ALI induced by massive saline lavage. Animals ventilated with 100% O(2) and receiving 1, 2, 4, or 6 ml/kg of 50 mg/kg recombinant surfactant apoprotein C (rSP-C) surfactant or 2 ml/kg of 50 mg/kg PL (control) had mean arterial PO(2) values, 4 h after treatment, of 230, 332, 130, 142, or 86 Torr, respectively. Animals receiving 1, 2, or 4 ml/kg of 100 mg/kg rSP-C surfactant or 2 ml/kg of 100 mg/kg PL (control) had mean arterial PO(2) values of 197, 214, 148, or 88 Torr, respectively. Surfactant PL distribution was homogeneous. Hyaline membrane formation was reduced in treated animals. Thus, in this model of ALI, rSP-C with PL has the capacity to improve gas exchange and possibly modify lung injury.

Controlled airway pressure therapy, nitric oxide inhalation, prone position, and extracorporeal membrane oxygenation (ECMO) as components of an integrated approach to ARDS.

BACKGROUND: Recent years have seen the introduction of innovative additive therapies for acute respiratory distress syndrome. However, because there are no reliable predictors of response to a particular therapy, potential responders to a specific therapeutic intervention may be lost. Therefore, the authors evaluated the effect of a combined therapeutic approach on the survival of patients with acute respiratory distress syndrome, when treated according to a strict algorithm. METHODS: During a 2.5-yr period, 84 patients with acute respiratory distress syndrome were assigned to a standardized treatment protocol. Data analysis was performed by retrospective review of patient charts. Patients were treated using a stepwise treatment algorithm of pressure-controlled ventilation (peak airway pressure < 35 cm H2O), positive end-expiratory pressure (PEEP; 12-15 cm H2O), permissive hypercapnia, inhaled nitric oxide (5-20 ppm), and prone positioning. These interventions were termed "conventional therapy." Response to treatment was defined as a more than 20% increase in arterial oxygen tension (PaO2). Nonresponders were triaged to extracorporeal membrane oxygenation. RESULTS: The overall survival rate was 80%. All patients received conventional therapy up to 96 h; 71 responded to conventional therapy and 59 survived (83%). Thirteen patients (15%) did not respond to conventional therapy and underwent extracorporeal membrane oxygenation; 8 of these patients (62%) survived. For the group, the mean admission lung injury score was 3.3+/-0.5, the PaO2/fractional inspired oxygen tension (F(I)O2) ratio was 96+/-45, and the Acute Physiology and Chronic Health Evaluation (APACHE) II score was 18+/-6. CONCLUSIONS: The 80% overall survival rate achieved in this group of patients with severe acute respiratory distress syndrome may in part reflect the additive beneficial effects of combined treatment methods, such as airway pressure control, nitric oxide inhalation, prone position, and early triage of nonresponders to extracorporeal membrane oxygenation.

A rat model of acute respiratory distress syndrome (ARDS) Part 2, influence of lavage volume, lavage repetition, and therapeutic treatment with rSP-C surfactant.

UNLABELLED: The influence of lavage volume, and lavage repetition with physiological saline solution (groups 1-3: 3x4, 4x4, 5x4, groups 7-9: 3x8, 5x8, 7x8, mL per animal) was studied in a rat lung lavage model of the acute respiratory distress syndrome (ARDS). Anesthetized and tracheotomized rats (12 rats/group) were pressure-controlled ventilated with 100% oxygen at a respiratory rate of 30 breaths/min, inspiration: expiration ratio of 1:2, peak inspiratory pressure of 28 cm H2O at positive end-expiratory pressure of 8 cm H2O during the whole experimental period. To investigate the influence of therapeutic treatment, a recombinant surfactant protein C (rSP-C) containing surfactant was used. Therefore, rats which received a lavage of 4x4 mL per animal (groups 4 to 6) or 7x8 mL per animal (groups 10-12) were treated intratracheally with surfactant doses of 12.5, 25, or 100 mg phospholipids (PL) per kg body weight (bw). In all groups, partial arterial oxygen pressures (PaO2, mm Hg) and partial arterial carbon dioxide pressures (PaCO2, mm Hg) were determined 30 min before, directly after, and 5, 30, 60, 90, 120, 150, 180, and 210 min after the last lavage. Additionally, animals were euthanized 210 min after the last lavage for semiquantitative histopathological grading of coded lung slides. Grading was performed with respect to the severity of hyaline membrane formation (HM), margination and infiltration of polymorphonuclear neutrophil leukocytes (PMNL) into the lung alveoli and interstitial and intraalveolar edema (E). The intrapulmonary distribution of intratracheally applied rSP-C was estimated in selected lung slides stained with polyclonal anti-rSP-C antibody and was compared to unlavaged control rats and unlavaged rats which received 100 mg/kg bw rSP-C. The repetitive lavage depleted the lung from its natural surfactant resources leading to a pathophysiological cascade similar to that of the acute respiratory distress syndrome. PaO2 levels and HM formation showed a lavage-induced decrease. Both changes were significantly dependent on the repetition and volume of the lavage; however, the parameters PMNL and E did not show such a dependence. Treatment with rSP-C surfactant significantly improved oxygenation and reduced HM-formation in a dose-dependent manner independent from the lavage volume. All doses of rSP-C surfactant showed no clear influence on the parameters PMNL and E independently from the lavage volume. In lavaged rat lungs (ARDS-model), the exogenously applied rSP-C was distributed homogeneously along the alveolar lining. Unlavaged rats that received a similar dose of rSP-C showed a marked inhomogeneous extracellular distribution, mainly associated with larger bronchi, while the type II pneumocytes were stained positively in unlavaged control and unlavaged rSP-C treated rats. CONCLUSION: This model mimics very closely the wide spectrum of the clinical situation of human acute lung injury (ALI) because the variation of lavage volume and repetition lead to reproducible different severity grades and states of ALI. The significant reduction of pathognomic changes due to treatment with rSP-C surfactant showed that this is a useful model to estimate the influence of therapeutic concepts in ALI and ARDS.

Concanavalin A hepatotoxicity in mice: tumor necrosis factor-mediated organ failure independent of caspase-3-like protease activation.

Several models of tumor necrosis factor (TNF)/TNF-receptor 1 (TNF-R1)-dependent liver injury in mice were investigated with respect to caspase-3-like protease activation representing a pivotal mechanism of apoptotic cell death. Injection of TNF or T-cell-activating agents (i.e., agonistic anti-CD3 antibody or staphylococcal enterotoxin B [SEB]) into galactosamine (GalN)-sensitized mice caused TNF/TNF-R1-dependent liver injury. Intravenous concanavalin A (Con A) alone induced TNF-mediated hepatotoxicity dependent on both TNF-R1 and TNF-R2. Hepatic caspase-3-like proteases were activated in GalN/TNF, GalN/anti-CD3, or GalN/SEB-treated mice, but not in Con A-treated mice. Consistently, the broad-spectrum caspase inhibitor, benzoyloxycarbonyl-val-ala-asp-fluoromethylketone (zVADfmk), prevented TNF-mediated hepatotoxicity in all GalN-dependent models, but failed to protect against Con A. Under transcriptional arrest, however, Con A induced TNF-R1-dependent, but not TNF-R2-dependent, activation of caspase-3-like proteases, and zVADfmk prevented animals from Con A-mediated liver injury under this condition. Histological analysis revealed distinct differences between Con A- and GalN/Con A-induced liver injury regarding apoptotic morphology of hepatocytes. We conclude that impaired transcription induces a switch of Con A hepatotoxicity toward a caspase-3-like protease-dependent pathway. The observation that the functional state of the transcriptional machinery decides whether TNF-driven hepatocyte apoptosis involves activation of caspase-3-like proteases or alternative signaling pathways in vivo might be of relevance for the immunopathology of the liver.

Analgesic and hemodynamic effects of intrathecal clonidine as the sole analgesic agent during first stage of labor: a dose-response study.

BACKGROUND: Intrathecal clonidine produces dose-dependent postoperative analgesia and enhances labor analgesia from intrathecal sufentanil. The authors evaluated the dose-response potency of intrathecally administered clonidine by itself during first stage of labor with respect to analgesia and maternal and fetal side effects. METHODS: Thirty-six parturients requesting labor analgesia were included in this prospective, randomized, double-blind study. Parturients with < 6 cm cervical dilatation received either 50, 100, or 200 microg intrathecal clonidine. The authors recorded visual analog pain score (VAPS), maternal blood pressure and heart rate, ephedrine requirements, and sedation at regular intervals and fetal heart rate tracings continuously. Duration of analgesia was defined as time from intrathecal clonidine administration until request for additional analgesia. RESULTS: Clonidine produced a reduction in VAPS with all three doses. The duration of analgesia was significantly longer in patients receiving 200 microg (median, 143; range, 75-210 min) and 100 microg (median, 118; range, 60-180 min) than 50 microg (median, 45; range, 25-150 min), and VAPS was lower in the 200-microg than in the 50-microg group. In the 200-microg group, hypotension required significantly more often treatment with ephedrine than in the other groups. No adverse events or fetal heart rate abnormalities occurred. CONCLUSIONS: Fifty to 200 microg intrathecal clonidine produces dose-dependent analgesia during first stage of labor. Although duration and quality of analgesia were more pronounced with 100 and 200 microg than with 50 microg, the high incidence of hypotension requires caution with the use of 200 microg for labor analgesia.