Silica nanoparticles separation from water: aggregation by cetyltrimethylammonium bromide (CTAB).

Nanoparticles will inevitably be found in industrial and domestic wastes in the near future and as a consequence soon in water resources. Due to their ultra-small size, nanoparticles may not only have new hazards for environment and human health, but also cause low separation efficiency by classical water treatments processes. Thus, it would be an important challenge to develop a specific treatment with suitable additives for recovery of nanoparticles from waters. For this propose, this paper presents aggregation of silica nanoparticles (Klebosol 30R50 (75nm) and 30R25 (30nm)) by cationic surfactant cetyltrimethylammonium bromide (CTAB). Different mechanisms such as charge neutralization, "depletion flocculation" or "volume-restriction", and "hydrophobic effect" between hydrocarbon tails of CTAB have been proposed to explicate aggregation results. One important finding is that for different volume concentrations between 0.05% and 0.51% of 30R50 suspensions, the same critical coagulation concentration was observed at CTAB=0.1mM, suggesting the optimized quantity of CTAB during the separation process for nanoparticles of about 75nm. Furthermore, very small quantities of CTAB (0.01mM) can make 30R25 nanosilica aggregated due to the "hydrophobic effect". It is then possible to minimize the sludge and allow the separation process as "greener" as possible by studying this case. It has also shown that aggregation mechanisms can be different for very small particles so that a special attention has to be paid to the treatment of nanoparticles contained in water and wastewaters.

Involvement of Tetrahymena pyriformis and selected fungi in the elimination of anthracene, and toxicity assessment of the biotransformation products.

Anthracene (AC) is a non-mutagenic and non-carcinogenic, low-molecular-weight polycyclic aromatic hydrocarbon present in the environment. Its toxicity can be dramatically increased after solar-light exposure. Biotransformation capacities of AC by Tetrahymena pyriformis and a selection of eight micromycetes were studied, and the ability of these microorganisms to detoxify the polluted ecosystems was assessed. We showed that T. pyriformis was able to accumulate high amounts of AC without any transformation. In contrast, the fungi Cunninghamella elegans, Absidia fusca, Absidia cylindrospora, Rhodotorula glutinis, and Aspergillus terreus were able to transform AC with a high efficiency. Cytotoxicity assays conducted on HeLa cells and T. pyriformis showed that crude extract from A. fusca culture medium obtained after AC biotransformation was not toxic. For A. fusca and A. cylindrospora, 1-4 dihydroxyanthraquinone was shown to be the major product during the biotransformation process. This compound seemed to be a dead-end metabolite at least for the Absidia strains. The cytotoxicity of 1-4 dihydroxyanthraquinone was higher than that of AC to T. pyriformis but lower to HeLa cells. On the whole our results showed that the microorganisms studied were all able to decontaminate an AC-polluted ecosystem, either by accumulating or transforming the compound. A possible detoxification process resulting from AC biotransformation can be considered only using the human cell model.

[Neonatal onset of Menkes disease: diagnosis interest of cupremia and microscopic examination of the hairs]. / Maladie de Menkes néonatale: intérêts diagnostiques de la cuprémie et de l'examen microscopique des cheveux.

BACKGROUND: Menkes disease is a rare X-linked disorder due to a defect in intracellular copper transport. Clinical symptoms appear during the first months of life, with a progressive developmental delay leading to death within a few years. Diagnosis is confirmed by the demonstration of copper retention in fibroblasts and/or DNA testing. However, these investigations are complexes and time consuming. CASE REPORT: We report 1 case of Menkes disease with neonatal onset, diagnosed on multiple organ failure, hypothermia, and major central nervous system damage, leading to death in a few weeks. The diagnosis, suggested by the clinical features, was rapidly supported by the microscopic examination of the hairs, showing pili torti, and the demonstration of severely decreased levels of plasma copper and ceruloplasmin. Diagnosis was further confirmed by the demonstration of an increased copper uptake and retention in fibroblasts. CONCLUSION: This report highlights the clinical variability of Menkes disease with the possibility of a neonatal onset. Microscopic examination of the hairs and the determination of copper and ceruloplasmin plasma levels are simple and inexpensive investigations, which can provide rapidly valuable information to support this diagnosis.

Assessment of anthracene toxicity toward environmental eukaryotic microorganisms: Tetrahymena pyriformis and selected micromycetes.

The toxicity of anthracene, a nonmutagenic, noncarcinogenic, low-molecular-weight polycyclic aromatic hydrocarbon present in the environment, was assessed using a ciliated protozoan, Tetrahymena pyriformis, and a selection of 10 micromycetes from different taxonomic groups living in two environmental compartments, namely aquatic and soil ecosystems. With T. pyriformis, a concentration-dependent inhibitory effect was shown on the cell proliferation rate, IC(50) = 33.40+/-4.84 mg/L (kinetic method). Phagocytosis of nonsoluble anthracene was confirmed by the presence of digestive vacuoles with photon microscopy. In fungi, anthracene did not exhibit a fungicide effect but showed a fungistatic action. Except for Absidia fusca and Cladosporium herbarum, the micromycetes showed a concentration-dependent decrease in growth. From IC(50) values determined by endpoint or kinetic methods, Rhodotorula glutinis and all of the Ascomycotina (except for Penicillium chrysogenum) were the most sensitive species, while Phanerochaete chrysosporium, P. chrysogenum, and the two Deuteromycotina were more resistant to anthracene. Our discussion focuses on the evaluation of toxicity by the two methods used for the calculation of the IC(50) values (endpoint and kinetic), the advantages of studying growth by a kinetic method (the dynamic aspect), and a comparison of toxicity to T. pyriformis and the different micromycetes.

Biodegradation capability of Absidia fusca Linnemann towards environmental pollutants.

The purpose of this work was to study the bioremediation capability of Absidia fusca Linnemann (Zygomycete) towards different classes of xenobiotics (lignin-derived compounds, chloroaromatic compounds, polycyclic aromatic hydrocarbons) the presence of which in contaminated soils, water and sediments poses a significant risk to the environment and human health. Two strains from different origins were compared. One was from an official collection and grown in non-inducing conditions, while the other was isolated during the course of the survey of fungal flora in a polluted soil from Annaba (Algeria). All data were analyzed and results validated via a statistical treatment. We showed the effect of the factors studied (origin of the strain, xenobiotic) but also the interactions between these factors. The strain of A. fusca isolated from a polluted soil was able to efficiently degrade most of the xenobiotics tested, particularly: pentachlorophenol, phenol, catechol, guaiacol and ferulic acid. This property also existed in the other strain but at a very low level.

Management of major blunt renal lacerations: is a nonoperative approach indicated?

OBJECTIVES: The aim of the study was to determine whether a nonoperative approach is able to reduce renal parenchymal loss after renal trauma. METHODS: Sixty-four consecutive patients with major blunt renal lacerations were treated from 1988 to 1999. Initial management was conservative. In group 1 (35 patients) delayed hemorrhage, persistent urinoma or hemodynamic instability were dealt with by open surgery. In group 2 (29 patients), most complications were dealt with using endoscopic procedures; open surgery was reserved exclusively for major complications. RESULTS: In group 1, 7 patients were not operated and 28 patients were managed surgically. Twenty (57%) patients underwent total (8) or partial (12) nephrectomy. In 8 patients the surgical intervention was open drainage of perinephric collection (6) and/or renorrhaphies (2). Four patients in this group developed urinary fistulae treated successfully with ureteral stents. Length of hospital stay was 9.6 days (3-25 days). In group 2, persistent hemodynamic instability led to nephrectomy in 1 case. The remaining 28 patients were managed conservatively, with endoscopic ureteric stenting in 5 cases. A persistent urinary extravasation with hyperthermia led to open drainage of perinephric urinoma (5) and renorrhaphy (2). No delayed nephrectomy was necessary. Average hospital stay was 12 days (5-21 days). Only 1 patient in this group developed hypertension. CONCLUSION: For most patients and with close follow-up available, conservative treatment represents a real alternative to open surgery in major blunt renal lacerations. In our experience, open surgery usually results in loss of renal parenchyma.

Recurrent pyelonephritis without vesicoureteral reflux: is there a role for an antireflux procedure?

PURPOSE: To evaluate the results of an endoscopic antireflux procedure in women with recurrent acute pyelonephritis and no evidence of vesicoureteral reflux (VUR) on voiding cystograms. PATIENTS AND METHODS: From 1989 to 1999, 603 female patients were hospitalized for acute pyelonephritis with unilateral loin pain, chills, fever, and a positive urine culture. Of these patients, 48 (8%) had recurrent episodes of acute pyelonephritis and underwent a thorough diagnostic work-up including intravenous urography or renal CT scan, cystoscopy, and voiding cystourethrography (VCUG). Vesicoureteral reflux was demonstrated in 21 patients, who were then offered an antireflux procedure, either surgical or endoscopic. Another 27 patients had no reflux on VCUG; in 15 cases, the upper urinary tract was normal, and the ureteral orifices did not show any abnormality on cystoscopy. The other 12 patients in this group with a normal VCUG had one or more abnormal findings normally associated with VUR: renal scarring in five and ureteral duplication in two. Golf-hole ureteral orifices were noted in two patients. The intravesical ureter was short (< 5 mm) in five patients. In spite of the normal VCU, we offered these patients endoscopic treatment of VUR by submeatal injection of Teflon or microparticulate silicone (Macroplastic). The median follow-up before treatment was 4 years (range 1-15.3 years); 0.3 episodes of acute pyelonephritis per patient-month of follow-up were noted. The frequence of preoperative and postoperative episodes of acute pyelonephritis was compared with Wilcoxon's paired analysis. The median postoperative follow-up was 3.9 years (range 1.1 months-10.2 years). RESULTS: There were no significant postoperative complications. One patient had two episodes of acute pyelonephritis during pregnancy. On the whole, 11 patients (91%) were free of recurrent pyelonephritis after treatment. Overall, 0.003 episodes of acute pyelonephritis per patient-month of postoperative follow-up were observed. The result was statistically significant (P < 0.01). CONCLUSION: Recurrent acute pyelonephritis is frequently related to VUR. Intermittent reflux can be difficult to demonstrate on voiding conventional or nuclear cystograms but can be suspected in the presence of ureteral duplication, renal scarring, or abnormal ureteral orifices. Adult patients with recurrent episodes of upper urinary tract infection and normal cystograms should be considered for an endoscopic antireflux procedure in the presence of anatomic abnormalities commonly associated with reflux.

Human immunodeficiency virus type 1 Tat protein impairs selenoglutathione peroxidase expression and activity by a mechanism independent of cellular selenium uptake: consequences on cellular resistance to UV-A radiation.

The expression of the HIV-1 Tat protein in HeLa cells resulted in a 2.5-fold decrease in the activity of the antioxidant enzyme glutathione peroxidase (GPX). This decrease seemed not to be due to a disturbance in selenium (Se) uptake. Indeed, the intracellular level of Se was similar in parental and tat-transfected cells. A Se enrichment of the medium did not lead to an identical GPX activity in both cell lines, suggesting a disturbance in Se utilization. Total intracellular 75Se selenoproteins were analyzed. Several quantitative differences were observed between parental and tat-transfected cells. Mainly, cytoplasmic glutathione peroxidase and a 15-kDa selenoprotein were decreased in HeLa-tat cells, while phospholipid hydroperoxide glutathione peroxidase and low-molecular-mass selenocompounds were increased. Thioredoxin reductase activity and total levels of 75Se-labeled proteins were not different between the two cell types. The effect of Tat on GPX mRNA levels was also analyzed. Northern blots revealed a threefold decrease in the GPX/glyceraldehyde phosphate dehydrogenase mRNA ratio in HeLa-tat versus wild type cells. By deregulating the intracellular oxidant/antioxidant balance, the Tat protein amplified UV sensitivity. The LD50 for ultraviolet radiation A was 90 J/cm2 for HeLa cells and only 65 J/cm2 for HeLa-tat cells. The oxidative stress occurring in the Tat-expressing cells and demonstrated by the diminished ratio of reduced glutathione/oxidized glutathione was not correlated with the intracellular metal content. Cellular iron and copper levels were significantly decreased in HeLa-tat cells. All these disturbances, as well as the previously described decrease in Mn superoxide dismutase activity, are part of the viral strategy to modify the redox potential of cells and may have important consequences for patients.

Removal of herbicides from liquid media by fungi isolated from a contaminated soil.

Fungi were isolated from soil samples corresponding to pesticide-contaminated soil (CS) and noncontaminated soil (NCS) in the Annaba vicinity (Algeria) and identified. The number of isolates obtained from CS and NCS were 263 and 288, respectively. The most frequent species (Aspergillus fumigatus, A. niger, A. terreus, Absidia corymbifera, and Rhizopus microsporus var microsporus) were not sensitive to the pesticides. The growth of the genus Trichoderma was inhibited by the pesticides, while genera Absidia and Fusarium were stimulated. The 53 species isolated were assayed for their ability to remove metribuzin from liquid medium. Only Botrytis cinerea from NCS and Sordaria superba and Absidia fusca from CS removed more than 50% of the compound after 5 d. Metamitron was very resistant. Among the 21 species tested, only Alternaria solani (from NCS), Drechslera australiensis (from CS and NCS), and Absidia fusca (from CS) reduced the concentration in the medium more than 10% (10-16%). Twelve species were grown with linuron, seven of them were inefficient in removing this compound. The two strains of Sordaria macrospora yielded 22 to 25% depletion, while Botrytis cinerea depleted linuron almost completely. Among the 31 species assayed for their ability to eliminate metobromuron, Botrytis cinerea (from CS and NCS) depleted almost completely the chemical from the medium. Rhizopus oryzae and Absidia fusca from CS removed 40 and 47% of the compound, respectively. No systematic relationships were observed between the soil contamination and herbicide elimination capacities of soil fungi. Absidia fusca and Botrytis cinerea were particularly interesting for bioremediation purposes because they were able to transform efficiently three of the four compounds assayed.

Early endoscopic realignment of post-traumatic posterior urethral disruption.

OBJECTIVES: The management of complete or partial urethral disruption is controversial, and much debate continues regarding immediate versus delayed definitive therapy. We further analyze our experience and long-term results using early endoscopic realignment. METHODS: Between April 1987 and January 1999, 29 men with posterior urethral disruption (23 complete and 6 partial) underwent primary urethral realignment 0 to 8 days after injury. Pelvic fractures were present in 23 patients. In all patients, the actual operating time for realignment was 75 minutes or less. All patients were evaluated postoperatively for incontinence, impotence, and strictures. RESULTS: After a mean follow-up of 68 months (range 18 to 155), all patients were continent. Four patients (13.7%) required conversion to an open perineal urethroplasty. At the last follow-up visit, 25 (86%) of the 29 patients were potent and 4 achieved adequate erections for intercourse using intracorporeal injections (prostaglandin E(1)). Twelve patients (41%) developed short secondary strictures and were successfully treated with internal urethrotomy. The mean follow-up of these 12 patients was 83 months (range 34 to 120). Urinary flow rate measurement at the last follow-up visit revealed satisfactory voiding parameters in all patients. CONCLUSIONS: Primary endoscopic realignment offers an effective method for treating traumatic urethral injuries. Our long-term follow-up provides additional support for the use of this technique by demonstrating that urethral continuity can be established without an increased incidence of impotence, stricture formation, or incontinence. In case of failure, endoscopic realignment does not compromise the result of secondary urethroplasty.

A conservative approach to major blunt renal lacerations with urinary extravasation and devitalized renal segments.

OBJECTIVES: To determine the feasibility of a conservative (expectant) approach to major blunt renal laceration with urinary extravasation and devitalized renal segments. PATIENTS AND METHODS: All patients treated conservatively who presented between 1990 and 1999 with major renal laceration (grade 4 and 5) were retrospectively reviewed to determine whether urinary extravasation and devitalized segments adversely affected the outcome. For each patient the data collected included the initial emergency department evaluation, findings on computed tomography, associated injuries, duration of hospital stay, transfusion requirements, complications and follow-up imaging. RESULTS: Of 20 patients who sustained blunt trauma resulting in a major renal laceration (five grade 5 and 15 grade 4) with urinary extravasation, 11 had coexisting devitalized segments. There was a statistically significant difference in the length of hospital stay (16.3 vs 7.3 days), blood transfusions (six vs two patients, P < 0.08) and the need for delayed surgical intervention (nine vs two, P < 0.01) between patients with and with no devitalized segments, respectively. Urinary extravasation spontaneously resolved in two of 11 patients with and in seven of nine with no devitalized segment, respectively (P < 0.05) CONCLUSIONS: Urinary extravasation will resolve spontaneously in most patients with blunt renal trauma, and expectant treatment does not adversely affect the outcome or prolong hospitalization. In patients who present with a major renal laceration associated with devascularized segments, conservative management is feasible in those who are clinically stable with blunt trauma. However, the physician must be especially aware of the probable complications within this subset of patients.

Biodegradation of anthracene and fluoranthene by fungi isolated from an experimental constructed wetland for wastewater treatment.

Pilot-scale constructed wetlands were used to treat water contaminated by polycyclic aromatic hydrocarbons (PAHs), particularly fluoranthene, and the possible role of fungi present in these ecosystems was investigated. A total of 40 fungal species (24 genera) were isolated and identified from samples (gravel and sediments) from a contaminated wetland and a control wetland. All of them were assayed for their ability to remove anthracene (AC) and fluoranthene (FA) from liquid medium. FA was degraded efficiently by 33 species while only 2 species were able to remove AC over 70%. A selection of 10 strains of micromycetes belonging to various taxonomic groups was further investigated for FA and AC degradation, toxicity assays and phenoloxidases (POx) detection. Interesting and not previously reported species were revealed (Absidia cylindrospora, Cladosporium sphaerospermum, and Ulocladium chartarum). They were all able to highly degrade the PAH-model compounds chosen. An interesting inducibility was noted for Ulocladium chartarum. Degradative ability of fungi was not related to their extracellular POx activity. This study may contribute to the improvement of constructed wetlands for water treatment, which may be enriched in efficient fungi.

[Symptom scores: what do they describe exactly?]. / Les scores symptômes: que décrivent-ils exactement?

OBJECTIVE: Standardized symptom scores have been developed to evaluate voiding disorders. The most widely used in France are the IPSS and Madsen-Iversen. These self-assessment questionnaires are by definition subjective. The objective of this study was to compare the capacities of the IPSS and Madsen-Iversen score to describe the patient's voiding status and to define the patient's level of understanding of these questionnaires. PATIENTS AND METHODS: One hundred male patients were included in this prospective study. All completed an IPSS and Madsen-Iversen questionnaire. Physical examination, uroflowmetry and post-voiding bladder ultrasonography were also performed. RESULTS: The description of the voiding status was considered to be satisfactory or fairly satisfactory, with a total of 85% for IPSS and 87% for Madsen-Iversen. Understanding of the questionnaire was high with a value of 84% for IPSS and 83% for Madsen-Iversen. Neither the order of completion of the IPSS or Madsen-Iversen questionnaires nor the patient's age influenced these results. CONCLUSIONS: No difference was demonstrated between the IPSS score and the MADSEN-IVERSEN questionnaire in terms of description and comprehension. However, one out of five patients experienced difficulties completing these questionnaires.

[An uncommon tumor of the urinary bladder: the small cell carcinoma]. / Une tumeur vésicale rare: le carcinome à petites cellules.

Primary small cell carcinoma of the urinary bladder is an uncommon tumor, compared to the frequency of urothelial tumors. Fifty percent of cases are combined with a non endocrine carcinomatous component. We report six new cases of this tumor, three of pure, and three associated with an urothelial carcinoma. Diagnosis is easy established by the immunohistochemical study which show the neuro-endocrine differentiation of these aggressive tumors. Pathologist needs to look for a neuro-endocrine part in all bladder cancer, as its presence modify the treatment. Chemotherapy is used in these cancers, due to their high metastatic power. Places of radical surgery and radiotherapy need to be specified.

Oxidative stress involvement in chemically induced differentiation of K562 cells.

The erythroid differentiation of K562 cells could be achieved by exposure to several pharmacologic agents, including hemin, butyric acid (BA), and anthracycline antitumor drugs such as aclarubicin (ACLA) and doxorubicin (DOX). When used at subtoxic concentrations, these drugs induce the overexpression of erythroid genes, leading to hemoglobinization of cells. Because anthracyclines are known to generate oxidative damage, we intended to demonstrate the involvement of an oxidative stress in the chemically induced differentiation process. The addition of antioxidants to anthracycline- and BA-induced cells decreased their growth and dramatically reduced the percentage of differentiated cells at day 3. Northern blot analysis showed that antioxidants also decrease the expression of erythroid genes and related transcription factors in induced cells. Moreover, analyses of oxidative stress markers showed that treatment with BA, ACLA, and DOX lead to a decrease in reduced glutathione and antioxidant enzymes (glutathione peroxidase [GPx], glutathione reductase [GRase], CuZn superoxide dismutase [SOD], and catalase [CAT]). In addition, DOX increased thiobarbituric acid reactants (TBARs), and MnSOD activity was decreased by BA and DOX. Finally, the production of reactive oxygen species (ROS) by differentiating agents was demonstrated using the dihydroethidium probe in a microspectrofluorometric assay. Altogether, these results strongly suggest the involvement of an oxidative stress generated by BA or anthracyclines as the first step in the irreversible differentiation process. Additionally, these results underline the differences between BA, ACLA, and DOX molecular mechanisms.

Exserohilum israeli, a new species isolated from soil from Timna Park (Israel), and its physiological properties.

Fungi isolated from soil in Timna Park (Israel) were found to belong to a new species of Exserohilum for which the name Erserohilum israeli sp. nov. is proposed. The main physiological properties of members of this species are discussed and the influence of temperature and copper concentrations on the growth and morphology of the fungus were investigated.

Antimicrobial and antitumor activities of mycosporulone.

The conditions for optimal production of mycosporulone (1) are given. Its cytotoxic, antimicrobial, and antitumor activities are described. The biological activities of 1 were compared with those of known antibacterial, antifungal, and antitumor agents. The compound was particularly active against Pseudomonas aeruginosa and Staphylococcus aureus (resistant to penicillin). Compound 1 was not toxic to normal human cells (MRC(5)), although it exhibited cytotoxic activity against the human tumor cell lines MDA-MB 231 and PC(3) and the murine L-1210 leukemia cell line.

Menkes disease: study of the mitochondrial respiratory chain in three cases.

Mitochondrial oxidative metabolism in three patients with typical Menkes disease was studied. In two cases, a general decrease in all of the respiratory chain complex activities (I, II, III and IV) was observed. However, in the most severe case, these activities were entirely normal. Our results emphasize the diversity of the cellular expression of Menkes disease which can, in some cases, be associated with a mitochondrial encephalomyopathy.

Degradation of phenolic and chloroaromatic compounds by Coprinus spp.

Three species of Coprinus: C. sp, C. cinereus and C. micaceus were compared on solid media for some aspects of their physiological behaviour and cultural requirements (temperature, pH, substrate). Constitutive extracellular enzymatic activities were also determined. The Coprinus spp. exhibited different physiological and cultural features. Cultures of the 3 Coprinus species in synthetic liquid medium showed an efficient degradation of phenolic lignin model compounds (catechol, ferulic acid, guaiacol, phenol, protocatechuic acid syringic acid and vanillic acid) and pentachloronitrobenzene, while pentachlorophenol was not metabolized after 5 days perhaps because of a strong adsorption on mycelial biomass. It was suggested that phenoloxidases were not necessarily required for the metabolization of these compounds. Coprinus species may share a common degrading system for monomeric phenolic and chloroaromatic compounds.

Characterisation of the acoustic cavitation cloud by two laser techniques.

An experimental investigation of the size and volumetric concentration of acoustic cavitation bubbles is presented. The cavitation bubble cloud is generated at 20 kHz by an immersed horn in a rectangular glass vessel containing bi-distilled water. Two laser techniques, laser diffraction and phase Doppler interferometry, are implemented and compared. These two techniques are based on different measuring principles. The laser diffraction technique analyses the light pattern scattered by the bubbles along a line-of-sight of the experimental vessel (spatial average). The phase Doppler technique is based on the analysis of the light scattered from single bubbles passing through a set of interference fringes formed by the intersection of two laser beams: bubble size and velocity distributions are extracted from a great number of single-bubble events (local and temporal average) but only size distributions are discussed here. Difficulties arising in the application of the laser diffraction technique are discussed: in particular, the fact that the acoustic wave disturbs the light scattering patterns even when there are no cavitation bubbles along the measurement volume. As a consequence, a procedure has been developed to correct the raw data in order to get a significant bubble size distribution. After this data treatment has been applied the results from the two measurement techniques show good agreement. Under the emitter surface, the Sauter mean diameter D(3, 2) is approximately 10 microm by phase Doppler measurement and 7.5 microm by laser diffraction measurement at 179 W. Note that the mean measured diameter is much smaller than the resonance diameter predicted by the linear theory (about 280 microm). The influence of the acoustic power is investigated. Axial and radial profiles of mean bubble diameters and void fraction are also presented.