Pressurised electro-osmotic dewatering of activated and anaerobically digested sludges: electrical variables analysis.

Pressurised electro-osmotic dewatering (PEOD) of two sewage sludges (activated and anaerobically digested) was studied under constant electric current (C.C.) and constant voltage (C.V.) with a laboratory chamber simulating closely an industrial filter. The influence of sludge characteristics, process parameters, and electrode/filter cloth position was investigated. The next parameters were tested: 40 and 80 A/m², 20, 30, and 50 V-for digested sludge dewatering; and 20, 40 and 80 A/m², 20, 30, and 50 V-for activated sludge dewatering. Effects of filter cloth electric resistance and initial cake thickness were also investigated. The application of PEOD provides a gain of 12 points of dry solids content for the digested sludge (47.0% w/w) and for the activated sludge (31.7% w/w). In PEOD processed at C.C. or at C.V., the dewatering flow rate was similar for the same electric field intensity. In C.C. mode, both the electric resistance of cake and voltage increase, causing a temperature rise by ohmic effect. In C.V. mode, a current intensity peak was observed in the earlier dewatering period. Applying at first a constant current and later on a constant voltage, permitted to have better control of ohmic heating effect. The dewatering rate was not significantly affected by the presence of filter cloth on electrodes, but the use of a thin filter cloth reduced remarkably the energy consumption compared to a thicker one: 69% of reduction energy input at 45% w/w of dry solids content. The reduction of the initial cake thickness is advantageous to increase the final dry solids content.

Mathematical modelling of slow pyrolysis of a particle of treated wood waste.

Low-temperature pyrolysis is a possible method for the disposal of wood waste treated with chromated copper arsenic (CCA). A mathematical model (heat and mass transfer) including chemical reactions of the thermal degradation of a particle of wood is presented. A spherical particle is heated by a convective nitrogen flow. The progress of the pyrolysis process is characterized by three main steps: (1) drying of the wet sample; (2) heating of the sample until ignition of pyrolysis reactions; (3) pyrolysis and subsequent production of char and volatiles. The mathematical model is based on the volume averaging concept and it uses Shafizadeh and Chin [F. Shafizadeh, P.S. Chin, Thermal deterioration of wood, wood technology: chemical aspects, ACS Symposium Series 43 (1977) 57-81] pyrolysis model to describe the reaction pathway. It is solved by the line method, taking time as the preferred variable. Our model predicts intra-particle profiles for several variables (temperature, moisture content, concentration of wood). Simulations are presented with a spherical particle of 1cm radius.

Systemic inflammation alters the inflammatory response in experimental lipopolysaccharide-induced meningitis.

Experiments to evaluate the effect of the level and duration of endotoxaemia on the meningeal inflammatory response were performed in order to determine if systemic inflammation alters meningitis. Rabbits received either saline or Escherichia coli O111:B4 lipopolysacharide (LPS) intravenously at various doses (1, 3 or 10 microg) and times (-8, -2 or 0 h) before an intracisternal injection of 20 ng LPS. An intracisternal LPS injection together with saline intravenously produced a peak cerebrospinal fluid (CSF) tumour necrosis factor (TNF) level (95 +/- 26 ng/ml) at 2 h and peak leucocyte level (5413 +/- 764 cells/microl) at 4 h post-injection. Blood leucocytes were slightly elevated (12 000 +/- 500/microl at 0 h; 16 900 +/- 280/microl at 8 h) but plasma TNF was always undetectable (< 0.05 ng/ml). Conversely, intravenous injection of 3 or 10 microg LPS 2 h prior to intracisternal LPS injection impaired pleocytosis (peak < 220 cells/microl) and delayed ( approximately 4 h) and reduced peak CSF TNF levels (3 microg LPS 5.0 +/- 1.2 ng/ml; 10 microg LPS 6.9 +/- 1.9; P < 0.05). Intravenous administration of 1 microg LPS was less inhibitory to CSF inflammation, but delayed onset (peak 1100 +/- 60 leucocytes/microl CSF at 8 h; 6.3 +/- 0.3 ng TNF/ml CSF at 4 h; both P < 0.05). Neutropenia nadirs were dependent on LPS dose (1 microg, 4500 +/- 1700; 3 microg, 1900 +/- 60; 10 microg, 1100 +/- 100 all at 4 h post-intravenous dose). Peak plasma TNF levels were not dose-dependent (> 8 ng/ml), but plasma TNF was always detectable (> 0.2 ng/ml at 10 h post-intravenous dose). Intravenous LPS administration at 0 h also blocked pleocytosis, but the inhibitory effect was lost when administration at -8 h. In conclusion, the degree and duration of endotoxaemia affect the meningeal inflammatory response to LPS in experimental meningitis.

Use of a transient model to simulate fluidized bed incineration of sewage sludge.

This paper presents a mathematical model dedicated to fluidized bed incineration of sludge. The main assumptions as well as the principal equations of the model are presented. Basically, this model relies on instantaneous pyrolysis of sludge and on a five zones description of the hydrodynamics into the incinerator. Its originality is essentially due to the introduction of a two-dimensional buffer zone between the bubble and the emulsion phase. The chemistry of the gaseous system is described by chemical equilibrium. Results of a start up procedure have been presented in order to illustrate the ability of the model to describe transient behavior. To validate the model from an energetic point of view, different types of sludge (primary, activated and digested) have been computed and compared to industrial data and to results obtained from a simple calculation. The lower dryness limit corresponds to self incineration of the sludge. The higher one corresponds to maximal thermal level that should not be exceeded within the furnace.

Patupilone (epothilone B, EPO906) and imatinib (STI571, Glivec) in combination display enhanced antitumour activity in vivo against experimental rat C6 glioma.

PURPOSE: The microtubule-stabilizing agent patupilone (epothilone B, EPO906) and the tyrosine kinase inhibitor imatinib (STI571, Glivec) which primarily inhibits Bcr-Abl, PDGF and c-Kit tyrosine kinase receptors, were combined in vivo to determine if any interaction would occur with respect to antitumour effect and tolerability using rat C6 glioma xenografted into nude mice. METHODS: Patupilone and imatinib were administered alone or in combination at suboptimal doses. Imatinib treatment (orally once daily) was initiated 4 days after s.c. injection of rat C6 glioma cells into athymic nude mice and patupilone administration (i.v. once per week) was started 3 or 4 days after imatinib treatment. RESULTS: As a single agent, imatinib was inactive in the regimens selected (100 mg/kg: T/C 86% and 116%; 200 mg/kg: T/C 68% and 84%; two independent experiments), but well tolerated (gain in body weight and no mortalities). Patupilone weekly monotherapy demonstrated dose-dependent antitumour effects (1 mg/kg: T/C 67% and 70%; 2 mg/kg: T/C 32% and 63%; 4 mg/kg: T/C 3% and 46%). As expected, dose-dependent body weight losses occurred (final body weight changes at 1 mg/kg were -7% and -3%; at 2 mg/kg were -23% and -13%; and at 4 mg/kg were -33% and -15%). Combining 2 mg/kg patupilone and 200 mg/kg per day imatinib in one experiment produced a non-statistically significant trend for an improved antitumour effect over patupilone alone (combination, T/C 9%), while in the second experiment, enhancement was seen with the combination and reached statistical significance versus patupilone alone (combination, T/C 22%; P=0.008). Reduction of the imatinib dose to 100 mg/kg per day resulted in no enhancement of antitumour activity in combination with 2 mg/kg patupilone. Reduction of the patupilone dose to 1 mg/kg resulted in a reduced antitumour effect, and only a trend for synergy with either imatinib dose (combination, T/C 46% and 40%). Pooling the data from the two experiments confirmed a significant synergy for the combination of 2 mg/kg patupilone and 200 mg/kg per day imatinib (P=0.032), and a trend for synergy at the 1 mg/kg patupilone dose. Reduction in the imatinib dose to 100 mg/kg per day resulted only in additivity with either dose of patupilone. Body weight losses were dominated by the effect of patupilone, since no greater body weight loss was observed in the combination groups. CONCLUSION: Combining patupilone with high-dose imatinib produced an increased antitumour effect without affecting the tolerability of treatment in a relatively chemoresistant rat C6 glioma model. Such results indicate that further evaluation is warranted, in particular to elucidate possible mechanisms of combined action.

Moisture distribution in activated sludges: a review.

The dewatering of residual sludges is a current problem due to the huge production of this waste. Activated sludges are generally hard to dewater, and the design and the control of the separation operations are often quite difficult. In order to better understand this problem, pertinent indices are needed. The knowledge of how water is distributed within activated sludge is an interesting approach. Current literature dealing with this topic is, however, relatively difficult to apply. This work presents a review of the problem of moisture distribution classification and measurement within activated sludge. The main techniques used for this analysis are compared and discussed in detail. The estimation of the water binding energy is also extremely commented upon. Finally, the paper discusses the utility of this type of analysis to examine the conditioning and dewatering of activated sludge.

The prediction of filter belt press dewatering efficiency for activated sludge by experimentation on filtration compression cells.

The filter belt press is commonly used to dewater activated sludge. However, little research has been done on this process and the prediction of its efficiency. Experimentation has been carried out in a filtration compression cell (FCC) and in a pilot scale filter belt press. It offers a way of determining filter belt press efficiency thanks to simple laboratory research. The pressure distribution around the pressing roller was measured inside the pilot scale filter belt press. It showed progressive increase (up to a certain maximum value: plateau), which was followed by a rapid decrease. The impact of the progressive increase of applied pressure onto the dry solid sludge content was observed in FCC. Similar dry solid contents were obtained from both the above laboratory devices when the application of the pressure is comparable (in time and increasing rate).

Un modelo de dolor asociado a cáncer de huesos en la rata / A rat model of bone cancer pain

En este artículo se describe el primer modelo conocido de dolor por cáncer de huesos en la rata. Ratas SpragueDawley recibieron inyecciones intratibiales de células M R M T-1 singénicas de carcinoma de glándula mamaria de rata y exhibieron conductas indicativas de dolor, como: alodinia mecánica, diferencia en el peso apoyado en las patas traseras e hiperalgesia mecánica. La aparición del tumor óseo y el daño estructural del hueso se vigilaron mediante análisis radiológico, medidas cuantitativas del contenido mineral e histología. Las inyecciones intratibiales de 3 x 103 ó 3 x 104 células M R M T-1 singénicas produjeron un tumor que se propagó rápidamente dentro de la tibia, causando una intensa remodelación del hueso. Las radiografías mostraron importantes daños en el hueso cortical y las trabéculas entre 10 y 14 días después de la inoculación de 3 x 103 células MRMT-1 y, al cabo de 20 días, los daños amenazaban la integridad de la tibia. Mientras que el contenido mineral y la densidad mineral disminuyeron significativamente en hueso afectado por el cáncer, el número de osteoclastos en el hueso compacto peritumoral no experimentó cambios. Sin embargo, la tinción con fosfatasa ácida resistente al tartarato puso de manifiesto la existencia de un gran número de células policariotas parecidas a los osteoclastos presentes dentro del tumor. No se observó crecimiento tumoral después de la inyección de células MRMT-1 destruidas con calor. Las inyecciones intratibiales de 3 x 103 ó 3 x 104 de células MRMT-1, células destruidas con calor o excipiente no p ro d u j e ron cambios en el peso corporal ni en la temperatura interna en los 19-20 días siguientes. La actividad general en los animales que recibieron una inyección de células MRMT-1 vivas o destruidas con calor fue mayor que en los animales de control, pero la actividad del grupo tratado con células MRMT-1 disminuyó al avanzar la enfermedad. En las ratas que recibieron inyecciones intratibiales de células MRMT-1 se produjo la aparición gradual de alodinia mécanica e hiperalgesia mecánica/disminución del peso apoyado en el miembro afectado, a partir de 12-14 ó 1012 días después de la inyección de 3 x 103 ó 3 x 104 células, respectivamente. Estos síntomas no se observaron en las ratas que recibieron células destruidas con calor o excipiente. Los datos sobre la conducta de los animales sugieren un intervalo razonable para la evaluación de los agentes antinociceptivos entre el día 14 y el día 20 después de la inoculación de las células cancerosas en este modelo. El tratamiento agudo con morfina (1-3 mg.kg- 1, por vía subcutánea (s.c.)) consiguió una disminución proporcional a la dosis de la frecuencia de respuesta de retirada de la pata trasera frente a estimulación con filamentos de von Fre y 17 ó 19 días después de la inyección de 3 x 103 células M R M T-1. Se observó también una reducción significativa de la diferencia en el peso apoyado en las patas traseras. El tratamiento agudo con celebrex (10-30 mg.kg- 1 s.c.) no influyó en la alodinia mecánica ni en el diferente peso apoyado en las patas traseras de las ratas 20 días después del tratamiento con 3 x 103 células MRMT- 1 .Aunque la fisiopatología del dolor oncológico no se conoce bien, el aumento significativo de la tinción con proteína acídica fibrilar glial (GFAP) en los correspondientes segmentos de la médula espinal ipsilateral sugiere una posible participación de los astrocitos. En resumen, la inducción de cáncer de huesos en la rata con la línea de células MRMT-1 singénicas de cáncer mamario constituye un modelo preclínico válido del dolor asociado a metástasis óseas. Al progresar el tumor en la cavidad de la médula ósea parece una marcada hiperalgesia mecánica y alodinia, aunque el estado general del animal sigue siendo satisfactorio. El tratamiento agudo con morfina tiene cierto efecto analgésico en el peso apoyado en las patas traseras, pero celebrex, un inhibidor selectivo de COX-2, no influye en los cambios de conducta relacionados con el dolor en este modelo. (AU)

A rat model of bone cancer pain.

This study describes the first known model of bone cancer pain in the rat. Sprague-Dawley rats receiving intra-tibial injections of syngeneic MRMT-1 rat mammary gland carcinoma cells developed behavioural signs indicative of pain, including: mechanical allodynia, difference of weight bearing between hind paws and mechanical hyperalgesia. The development of the bone tumour and structural damage to the bone was monitored by radiological analysis, quantitative measurement of mineral content and histology. Intra-tibial injections of 3 x 10(3) or 3 x 10(4) syngeneic MRMT-1 cells produced a rapidly expanding tumour within the boundaries of the tibia, causing severe remodelling of the bone. Radiographs showed extensive damage to the cortical bone and the trabeculae by day 10-14 after inoculation of 3 x 10(3) MRMT-1 cells, and by day 20, the damage was threatening the integrity of the tibial bone. While both mineral content and mineral density decreased significantly in the cancerous bone, osteoclast numbers in the peritumoural compact bone remained unchanged. However, tartarate-resistant acid phosphatase staining revealed a large number of polykariotic cells, resembling those of osteoclasts within the tumour. No tumour growth was observed after the injection of heat-killed MRMT-1 cells. Intra-tibial injections of 3 x 10(3) or 3 x 10(4) MRMT-1 cells, heat-killed cells or vehicle did not show changes in body weight and core temperature over 19-20 days. The general activity of animals after injection with live or heat-killed MRMT-1 cells was higher than that of the control group, however, the activity of the MRMT-1 treated group declined during the progress of the disease. Rats receiving intra-tibial injections of MRMT-1 cells displayed the gradual development of mechanical allodynia and mechanical hyperalgesia/reduced weight bearing on the affected limb, beginning on day 12-14 or 10-12 following injection of 3 x 10(3) or 3 x 10(4) cells, respectively. These symptoms were not observed in rats receiving heat-killed cells or vehicle. Behavioural data suggest a reasonable time window for evaluation of anti-nociceptive agents between day 14 and 20 after cancer cell inoculation in this model. Acute treatment with morphine (1-3mg/kg, subcutanously (s.c.)) produced a dose-dependent reduction in the response frequency of hind paw withdrawal to von Frey filament stimulation 17 or 19 days following intra-tibial injections of 3 x 10(3) MRMT-1 cells. A significant reduction in the difference in hind limb weight bearing was also observed. Acute treatment with celebrex (10-30 mg/kg, s.c.) did not affect mechanical allodynia or difference in weight bearing in rats 20 days following treatment with 3 x 10(3) MRMT-1 cells. Although the pathophysiology of cancer pain is largely unknown, significant enhancement of glial fibrillary acidic protein (GFAP) staining in the corresponding segments of the ipsilateral spinal cord highlights the possible involvement of astrocytes. In summary, the induction of bone cancer in the rat by the syngeneic MRMT-1 mammary tumour cell line provides a valid pre-clinical model for pain associated with bone metastases. Significant mechanical hyperalgesia and allodynia develops in association with the progression of the tumour in the bone marrow cavity, while the general condition of the animal remains satisfactory. While acute treatment with morphine has some analgesic effect on hind limb sparing the selective COX-2 inhibitor, celebrex, has no influence on the pain-related behavioural changes in this model.

Isolation and in-vitro and in-vivo characterisation of a mutant of Pseudomonas aeruginosa PAO1 that exhibited a reduced postantibiotic effect in response to imipenem.

The postantibiotic effect (PAE) is the persistent inhibition of bacterial growth after a brief exposure to an antibiotic. Most beta-lactams do not induce a PAE for Gram-negative bacteria, but PAEs have been reported for carbapenems and penems. This study investigated the effect of sequential doses of imipenem on the PAE for Pseudomonas aeruginosa and Escherichia coli cultures in a chemostat. The PAE for the bacterial population did not change even after six successive exposures to imipenem. Nevertheless, screening of colonies isolated after repeated drug exposure identified a single P. aeruginosa mutant whose imipenem PAE was shortened, although the MIC was unchanged. The PAEs for the parent and mutant were studied in vitro in batch culture by monitoring: (i) viable counts; (ii) electrical impedance of the culture medium; (iii) incorporation of radiolabelled N-acetyl-D-glucosamine and (iv) cell volume changes. PAEs for the parent and mutant were found to be significantly different by all in-vitro methods used. Moreover, the median cell volume in antibiotic-exposed cultures remained much smaller and less heterogeneous than in the control cultures, even though both cultures were growing at the same rate. The mutant was found to have a reduced expression of a 52 kDa outer membrane protein. These observations suggest that factors in addition to suppression of bacterial growth should be considered when studying the PAE. The PAEs of imipenem for the parent and mutant were studied in a thigh infection model in leucopenic mice. Similar PAEs were observed in vivo for both parent and mutant in one experiment and no PAEs for either organism were found in a second experiment. This study showed that although the PAE is a stable in-vitro phenomenon, the lack of correlation between the in-vitro and in-vivo results warrants caution in attributing clinical significance to the PAE of imipenem.

Extracorporeal carbon dioxide removal and low-frequency positive-pressure ventilation. Improvement in arterial oxygenation with reduction of risk of pulmonary barotrauma in patients with adult respiratory distress syndrome.

Mortality of the adult respiratory distress syndrome (ARDS) remains high and could be increased by pulmonary barotrauma induced by positive-pressure mechanical ventilation. Extracorporeal CO2 removal combined with low-frequency positive-pressure ventilation (ECCO2R-LFPPV) has been proposed to reduce lung injury while supporting respiratory failure. Use of this technique in 23 patients resulted in the following: a dramatic and highly significant increase of PaO2 obtained rapidly with ECCO2R-LFPPV, allowing subsequent reduction in inspired oxygen fraction; a reduction of the risk of barotrauma evidenced by a significant decrease in pressures and insufflated volumes; a survival rate of 50 percent. Bleeding was the only complication related to the technique and was the cause of death in four patients. This method allowed improvement in gas exchange along with reduction of the risk of barotrauma caused by the ventilator.

Iatrogenic complications in adult intensive care units: a prospective two-center study.

OBJECTIVES: a) To evaluate the frequency, types, severity, and morbidity of iatrogenic complications; b) determine associated factors that favor iatrogenic complications; and c) suggest new or more efficient protective measures that may be taken to improve patient safety. DESIGN: Prospective, observational study. SETTING: Two ICUs in France. PATIENTS AND METHODS: The study included 382 patients (age > or = 15 yrs; 400 consecutive admissions). Patients were monitored by two physicians in each ICU to assess all iatrogenic complications occurring during their ICU stay, with the exception of adverse effects of drugs. An iatrogenic complication was defined as an adverse event that was independent of the patient's underlying disease. RESULTS: We observed 316 iatrogenic complications in 124 (31%) of the 400 admissions. Of these iatrogenic complications, 107 (in 53 [13%] of the 400 admissions) complications were major, three leading to death. Severe hypotension, respiratory distress, pneumothorax, and cardiac arrest represented 78% of the major iatrogenic complications. Fifty-nine percent of the major iatrogenic complications had clearly identified associated factors. Human errors accounted for 67% of these factors. Patients > 65 yrs (adjusted odds ratio = 2.6, 95% confidence interval: 1.4 to 4.9) and those patients admitted with two or more organ failures (adjusted odds ratio = 4.8, 95% confidence interval: 2.5 to 9.2) were more likely to develop major iatrogenic complications. High or excessive nursing workload also led to an increased risk of major iatrogenic complications. Persistent morbidity, secondary to iatrogenic complications at the time of discharge, was present in five survivors. The risk of ICU death was about two-fold higher for the patients with major iatrogenic complications than in the remaining patients after adjusting for the Organ System Failure Score and the prognosis of the disease (relative risk = 1.92, 95% confidence interval: 1.28 to 2.56). CONCLUSIONS: Major iatrogenic complications were frequent, associated with increased morbidity and mortality rates, related to high or excessive nursing workload, and were often secondary to human errors. To improve patient safety in our ICUs, preventive measures should be targeted primarily on the elderly and the most severely ill patients. Special attention should be given to improving the organization of workload and training, and promoting wider use of noninvasive monitoring.

Relationship between changes in serum estrone levels and outcome in human males with septic shock.

The effect of septic shock on the production of estrogens, other steroid hormones, and gonadotropins in men was investigated. Two groups of male patients in the early septic shock were studied over 3 days following their admission to the Intensive Care Unit. Group I (n = 9) patients recovered and group II (n = 6) patients died. The simplified acute physiological score was 13.5 +/- 1.5 for group I and 21.2 +/- 2.3 for group II (P less than .05). In group I patients, estrogen levels (particularly E1) were high on day 1 and decreased progressively (day 1: 3,515 +/- 884 pmol/L, day 2: 2,450 +/- 292 pmol/L, and day 3: 1,043 +/- 255 pmol/L). In group II patients, estrone levels were as high as in group I on day 1, but increased throughout the 3 days (day 1: 3,250 +/- 1,200 pmol/L, day 2: 4,495 +/- 930 pmol/L, and day 3: 6,123 +/- 966 pmol/L). There were few changes in gonadotropins and other steroid hormones, except that the testosterone levels were below normal in both patient groups, while cortisol was elevated in group II. The changes in serum E1 may provide an accurate marker of individual outcome.

Hemodialysis for acute renal failure in patients with hematologic malignancies.

OBJECTIVE: To assess the prognosis of patients with hematologic malignancies in acute renal failure who require hemodialysis. DESIGN: Retrospective study. SETTING: ICU. PATIENTS: Forty-three consecutive patients. METHODS: Prognostic analysis using both univariate and multivariate (stepwise regression) methods. RESULTS: Fifteen (35%) patients recovered from acute renal failure and 12 (28%) were discharged from the ICU. The prognosis of patients with acute renal failure linked to sepsis is poorer than the prognosis of the patients with acute renal failure from other etiologies. Only one patient survived in the former group (n = 26) and 11 in the latter group (n = 17); p less than .0001 in multivariate analysis. When accompanied by associated respiratory failure, mortality rate was higher (93% vs. 33%; p less than .0001). The Simplified Acute Physiology Score (SAPS) calculated within the first 24 hr of admission was significantly (p less than .001) related to mortality when the SAPS was greater than or equal to 13. The presence of neutropenia and the type of hematologic malignancy were not related to a worse prognosis. Tolerance to hemodialysis appeared good, and complications were rare.

Failure of teicoplanin therapy in two neutropenic patients with staphylococcal septicemia who recovered after administration of vancomycin.

A report is given on two neutropenic patients with staphylococcal septicemia caused by Staphylococcus haemolyticus and Staphylococcus aureus (both strains methicillin-resistant) who failed to respond to therapy with teicoplanin. Both strains were resistant to teicoplanin (MIC 16 and 8 mg/l respectively), but remained sensitive to vancomycin (MIC 2 and 4 mg/l respectively). Replacement of teicoplanin with vancomycin led to full recovery of both patients and their discharge from hospital. These two cases emphasize the importance of clinical and microbiological monitoring of patients with staphylococcal septicemia, even when glycopeptides are used for treatment.

Is intensive care justified for patients with haematological malignancies?

The course of 260 adults with haematological malignancies admitted to a medical intensive care unit was studied to evaluate the value of life support techniques and to research predictive factors. The overall in the medical intensive care unit (MICU) and hospital mortality rates were respectively 43% (113 patients) and 57% (148 patients). Among survivors, 64% (49 patients) were still alive after 6 months and 44% (35 patients) after 1 year. Among 34 haemodialysed patients, the MICU mortality was 67% (23 patients) and among 111 mechanically ventilated patients 85% (94 patients). Prolonged mechanical ventilation, more than seven days, was performed in 11 of the 17 survivors and did not influence long term survival. No individual predictor of mortality was found comparing survivors and non-survivors. However, SAPS, intractable sepsis and failure of more than one organ system were significantly different in non-survivors (p less than 0.001). Among the 20 patients requiring both mechanical ventilation and haemodialysis, only two left the MICU and both died soon thereafter. We conclude that life support therapy should be initiated in patients with haematological disorders and that prolonged mechanical ventilation is compatible with long term survival. However, the combination of mechanical ventilation and haemodialysis is always associated with a poor prognosis and therefore the use of both techniques simultaneously for one patient is questionable.

Atrial natriuretic peptide decreases contractility of cultured chick ventricular cells.

To determine whether atrial natriuretic peptide (ANP) has an inotropic effect, the contractility of spontaneously beating cultured chick embryo ventricular cells was studied in response to rat-ANP (1-23) superfused at concentrations ranging from 10(-10) M to 2.5 x 10(-7) M. r-ANP reversibly decreased contractility with a threshold concentration of 10(-8) M; at the highest concentration, r-ANP decreased contractility to a moderate extent (-30 +/- 4%) r-ANP increased dose-dependently intracellular cGMP levels. Stimulation of contractility with [Ca2+], the calcium-channel agonist BAY K 8644 or isoproterenol attenuated to various degrees the inhibitory effect of r-ANP. By contrast, the inhibitory effect of r-ANP on contractility was unchanged or even enhanced after stimulation of contractility by angiotensin II. There was no difference in r-ANP-induced increase in cGMP whether cells were pre-incubated with angiotensin II or not. These results indicate that r-ANP was able to decrease contractility of cultured cardiac myocytes and suggest a preferential antagonism of the inotropic effect of angiotensin II.

Atrial natriuretic peptide decreases contractility of cultured heart cell: preliminary report.

We tested the hypothesis that atrial natriuretic peptide (ANP) has a direct negative inotropic effect on the cultured chick embryo ventricular cell, an experimental system devoid of endogenous neurotransmitters. At 10(-8) and 2.5 x 10(-7) mol/l ANP [rat ANP-(1-23)] significantly and reversibly decreased contractility in spontaneously beating cells. The positive inotropic effect of angiotensin II (2.5 X 10(-7) mol/l) on spontaneously beating cells was fully antagonized by ANP (2.5 X 10(-7) mol/l) and the amplitude of contraction decreased below control levels. In contrast (1) the increase in contractility in response to extracellular calcium was significantly less altered by ANP and (2) the time-course of the positive inotropic effect of the calcium-channel agonist Bay-K-8644 (5 x 10(9) mol/l) or of the beta-adrenergic agonist isoproterenol (10(-6) mol/l) was unchanged by ANP. These results indicate that ANP-(1-23) has a direct negative inotropic effect on cultured chick heart cells and may affect intracellular messengers involved in the cardiac effects of angiotensin II.