Adsorption of Organic Dyes on Magnetic Iron Oxide Nanoparticles. Part II: Field-Induced Nanoparticle Agglomeration and Magnetic Separation

This paper (part II) is devoted to the effect of molecular adsorption on the surface of magnetic iron oxide nanoparticles (IONP) on the enhancement of their (secondary) field-induced agglomeration and magnetic separation. Experimentally, we use Methylene Blue (MB) cationic dye adsorption on citrate-coated maghemite nanoparticles to provoke primary agglomeration of IONP in the absence of the field. The secondary agglomeration is manifested through the appearance of needlelike micron-sized agglomerates in the presence of an applied magnetic field. With the increasing amount of adsorbed MB molecules, the size of the field-induced agglomerates increases and the magnetic separation on a magnetized micropillar becomes more efficient. These effects are mainly governed by the ratio of magnetic-to-thermal energy α, suspension supersaturation Δ₀, and Brownian diffusivity D_eff of primary agglomerates. The three parameters (α, Δ₀, and D_eff) are implicitly related to the surface coverage θ of IONP by MB molecules through the hydrodynamic size of primary agglomerates exponentially increasing with θ. Experiments and developed theoretical models allow quantitative evaluation of the θ effect on the efficiency of the secondary agglomeration and magnetic separation.

Predictors of malignant middle cerebral artery infarction after mechanical thrombectomy

INTRODUCTION

Several predictors have been described to early diagnose malignant middle cerebral artery infarction (MMI) and select patient for hemicraniectomy. Nevertheless, few studies have assessed them among patients with acute ischemic stroke undergoing mechanical endovascular thrombectomy (MET). The overall objective in this study was to evaluate these predictors in patients undergoing MET in the purpose to guide the medical care in the acute phase.

METHODS

We selected patients from a prospective local database which reference all patients eligible for treatment with Alteplase thrombolysis and/or mechanical endovascular thrombectomy in acute stroke. We investigated demographic, clinical, and radiological data. Multivariate regression analysis was used to identify clinical and imaging predictors of MMI.

RESULTS

In 32 months, 66 patients were included. Eighteen (27.3%) developed MMI. Malignant evolution was associated with: severity of neurological deficit and level of consciousness at admission, infarct size in DWI sequence and involvement of other vascular territories. Study groups didn't differ in terms of successful reperfusion. Two variables were identified as independent predictors of MMI: DWI infarct volume (p<0.001) and time to thrombectomy (p=0.018). A decision tree based on these two factors was able to predict malignant evolution with high specificity (100%) and sensibility (73%).

CONCLUSION

Our study proposes a practical decision tree including DWI lesion volume and delay before thrombectomy to early and accurately predict MMI in a subgroup of patients with MCA infarction undergoing MET regardless to the status of reperfusion.

Bilateral calcaneal insufficiency fractures due to chronic carbamazepine use for trigeminal neuralgia: A case report

Stress fractures of calcaneus are uncommon cause of heel pain. Stress fractures could be seen in risc groups such as metabolic diseases/medications causing poor bone quality and exposing repetitive microtrauma. Anti-epileptic drug (AED) use is related with poor bone quality and increased fracture risc. Although carbamazepine-induced stress fracture is a well-known entity and there are case reports in other bones such as the femoral neck, bilateral calcaneal insufficiency fractures is an extraordinary location. To the best of our knowledge, this is the first case reporting an insufficiency fracture involving calcaneus in the relevant literature. Due to the rarity of both conditions, we decided to present and discuss this patient. When patients receiving AED treatment present with heel pain without previous plantar fasciitis history or traumatic event, insufficiency fractures should be kept in mind. This case highlights the importance of screening adverse effect of CBZ on bone metabolism in patients with long CBZ use. We report here a 41-year-old lady suffering from bilateral heel pain without trauma history. Her complaining did not respond to analgesics and stretching exercises of plantar fascia. In her past medical history she reported ongoing carbamazepine (CBZ) use over 8 years for trigeminal neuralgia. She had had low bone mineral density; defined as osteopenia. Both calcaneus MRI revealed bilateral stress fractures of calcaneum. She had been advised immobilization for 6 weeks, vitamin D and calcium supplements. CBZ has been stopped by neurology specialist and she had undergone microvascular decompression surgery for intractable pain of trigeminal neuralgia. She is doing well with full recovery from heel pain and trigeminal neuralgia at the end of one year. CBZ use causes poor bone quality through vitamin D metabolism. Heel pain without traumatic event, objective findings of plantar fasciitis and calcaneal spur syndrome in an CBZ using patient insufficiency fracture of calcaneus should be remembered and evaluated rigorously.

Effects of mineral amendments on trace elements leaching from pre-treated marine sediment after simulated rainfall events

Bauxite extraction by-products (red mud) were used to evaluate their potential ability to stabilize trace elements from dredged and aerated/humidified marine sediment. The investigated by-products were: bauxaline^®(BX) that is a press-filtered red mud; bauxsol™(BS) that is a press-filtered red mud previously washed with excess of seawater, and gypsum neutralized bauxaline^® (GBX). These materials were separately mixed to dredged composted sediment sample considering 5% and 20% sediment: stabilizer ratios. For pilot experiments, rainfall events were regularly simulated for 3 months. Concentrations of As, Mo, Cd, Cr, Zn, Cu, and Ni were analyzed in collected leachates as well as toxicity. Results showed that Cd, Mo, Zn, and Cu were efficiently stabilized in the solid matrix when 20% of BX, BS, and GBX was applied. Consequently, toxicity of leachates was lower than for the untreated sediment, meaning that contaminants mobility was reduced. A 5% GBX was also efficient for Mo, Zn and Cu stabilization. In all scenarios, As stabilization was not improved. Compared to all other monitored elements, Mo mobility seemed to depend upon temperature-humidity conditions during pilot experiments suggesting the need of further investigations.

Minerals as additives for decreasing the toxicity of Mediterranean contaminated dredged sediments

The management of dredged sediments is a priority issue in the Mediterranean sea where sediments are historically polluted. The aims of this study were to evaluate the toxicity of port sediment samples and the effect of three mineral additives (hematite, zerovalent iron (ZVI) and natural zeolite (NZ)) on sediment elutriate toxicity. Four sediments (A, B, C and D) were provided by port authorities after composting procedure; particle size, particulate organic carbon, metals and organic pollutants (TBT, PAHs, PCBs) were determined in whole sediments. Elutriates from these composted sediments were analyzed by determining toxicity level using oyster (Crassostrea gigas) larvae bioassay, metal and dissolved organic carbon concentrations. Toxicity, measured on undiluted elutriates (250 g/L), decreased as follows: A≥B>C∼D. The treatment of sediments with mineral additives (5%) revealed that hematite tends to decrease the elutriate toxicity in all samples, particularly in samples B and C. This effect may be related to metal concentration decrease in elutriates, in particular Cu and Zn, that have a significant toxic effect on oyster larvae. ZVI and NZ have a variable influence on elutriate toxicity. Results suggest that hematite may be a possible candidate for decreasing chemical concentration and improving the quality of elutriates. Hematite could be used for sediment stabilization prior to the deposit in a specific site or landfill.

Sorption behaviour of caesium on a bentonite sample

Sorption of elements like Cs on clay is one of the principal processes delaying their release from deep repositories of nuclear wastes into the environment. The sorption processes taking place between non-purified natural clay material (bentonite) and synthetic groundwater (containing Ca, Mg, Na, K and carbonates) were therefore studied experimentally and modelled for Cs to determine whether thermodynamic computer codes capable of predicting the behaviour of this element in natural systems might be developed. The model used, based on the properties of a pure montmorillonite phase, incorporates the surface reactions for natural major ions and sorbing cations but does not have any adjustable parameters. The weight of each parameters used in the model is assessed. Surface reactions are classified as either major or minor, and a simplified model of Cs sorption that considers only the major processes is proposed. This simplified model might correspond to the less sophisticated thermodynamic model included in coupled geochemistry-transport models.

Early expression of the BM88 antigen during neuronal differentiation of P19 embryonal carcinoma cells

Previous studies have shown that the BM88 antigen, a neuron-specific molecule, promotes the differentiation of mouse neuroblastoma cells [23] (Mamalaki A., Boutou E., Hurel C., Patsavoudi E., Tzartos S. and Matsas R. (1995) The BM88 antigen, a novel neuron-specific molecule, enhances the differentiation of mouse neuroblastoma cells. J. Biol. Chem. 270, 14201-14208). In particular, stably transfected with the BM88 cDNA, Neuro 2a cells over-expressing the BM88 antigen are morphologically distinct from their non-transfected counterparts; they exhibit enhanced process outgrowth and a slower rate of division. Moreover, they respond differentially to growth factors [10] (Gomez J., Boutou E., Hurel C., Mamalaki A., Kentroti S. , Vernadakis A. and Matsas R. (1998) Overexpression of the neuron-specific molecule BM88 in mouse neuroblastoma cells: Altered responsiveness to growth factors. J. Neurosci. Res. 51, 119-128). In order to further elucidate the role of the BM88 antigen in the differentiation of developing neurons we used the in vitro system of differentiating P19 cells which closely resembles early murine development in vivo. In this study, P19 cells were driven to the neuronal pathway with retinoic acid. We examined by immunofluorescence studies the expression of the BM88 antigen in these cells and we found that it correlates well with the expression of the polysialylated form of the neural cell adhesion molecule (PSA-NCAM) which characterizes early differentiating post-mitotic neurons. In contrast, very few of the BM88 antigen-positive/PSA-NCAM-positive cells expressed neurofilament protein, a marker of more mature neurons. Our findings, in accordance with previously reported data, strongly suggest that the BM88 antigen is involved in the early stages of differentiation of neuronal cells.

Overexpression of the neuron-specific molecule BM88 in mouse neuroblastoma cells: altered responsiveness to growth factors

Previous studies have shown that the BM88 antigen, a novel neuron-specific molecule, promotes the differentiation of mouse neuroblastoma (Neuro 2a) cells. In particular, stably transfected, with the BM88 cDNA, Neuro 2a cells overexpressing the BM88 antigen (Neuro2a-BM88 cells) are morphologically distinct from the nontransfected Neuro 2a cells; they exhibit enhanced process outgrowth and a slower rate of division. In this study we used Neuro2a and the morphologically differentiated Neuro 2a-BM88 cells to compare their responsiveness to growth factors. The growth factors we used were nerve growth factor (NGF), basic-fibroblast growth factor (b-FGF), and glial cell-line derived neurotrophic factor (GDNF). In addition, we used glial conditioned medium derived from either newborn mouse cerebral cortex (NBCC) or aged mouse cerebral hemispheres (MACH), as a source of normal glial factors. Because these cells express the cholinergic phenotype, we used choline acetyltransferase (ChAT) activity as a biochemical marker for comparison. A differential responsiveness to these factors was observed between Neuro 2a and Neuro 2a-BM88. The presence of NGF, 25 ng/ml, in the culture medium did not affect ChAT activity in either cell type. In contrast to NGF, in the presence of b-FGF, 5 ng/ml, the transfected cells, Neuro 2a-BM88, responded with a marked increase in ChAT activity. On the other hand, with GDNF, 1 ng/ml, only Neuro 2a cells showed an increase in ChAT activity. Finally, we found no response to the glial conditioned media, although these media contain several growth factors, including b-FGF. In conclusion, our findings show that overexpression of the neuron-specific antigen BM88 in neuroblastoma cells modifies their properties with respect to growth factor sensitivity, and, hence, the Neuro 2a and Neuro 2a-BM88 are suitable cell models to examine the role of growth factors in neuronal differentiation.

The BM88 antigen, a novel neuron-specific molecule, enhances the differentiation of mouse neuroblastoma cells

The BM88 antigen is a neuron-specific molecule widely distributed in the mammalian nervous system. It is a 22-kDa, apparently not glycosylated, integral membrane protein, which appears early during brain development and remains at high levels in the mature animal. Here, we describe the cDNA cloning of the porcine BM88 antigen and present evidence that this protein is involved in neuroblastoma cell differentiation. The deduced protein is a novel molecule consisting of 140 amino acids and bears a putative transmembrane domain at the COOH-terminal region. The mRNA of this protein is expressed only in neural tissues, where it is restricted to neurons. Stably transfected Neuro-2a cells overexpressing the BM88 antigen exhibited a significant change in morphology, reflected by enhanced process outgrowth, and a slower rate of division. Moreover, in the presence of differentiation agents, such as sucrose and retinoic acid, an accelerated differentiation of the transfected Neuro-2a cells was observed. Especially in the presence of sucrose, the consequent overexpression of the BM88 antigen in the transfected cells resulted in their enhanced morphological differentiation accompanied by the induction of neurofilament protein expression. Our results suggest that the BM88 antigen plays a role in the differentiation of neuroblastoma cells.

Purification and characterization of neuron-specific surface antigen defined by monoclonal antibody BM88

Monoclonal antibody BM88 recognizes a neurospecific surface antigen in the CNS and the PNS. In the present study, the antigen recognized by BM88 was immunopurified from pig brain and shown to be a 22-kDa polypeptide by reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Under nonreducing conditions a protein of 40 kDa was obtained, a result indicating that the antigen is composed of two polypeptide chains of equal molecular weight linked by disulfide bridges. Gel filtration of the purified antigen in the presence of Emulphogene suggested that it may be either a monomeric or a dimeric protein. However, in the presence of Triton X-100 a monomeric structure was implied. N-Glycanase digestion indicated that the protein is probably not glycosylated. The purified antigen was characterized as an integral membrane protein by hydrophobic chromatography and phase-separation experiments with Triton X-114. The antigen, or at least the antibody binding region of the molecule, is very susceptible to protease attack, as judged by protease digestion experiments on brain membranes. By using very low concentrations of papain combined with short incubation times, the antigen was converted to a 16.3-kDa membrane-associated polypeptide as assessed by immunoblotting. This polypeptide contained the BM88 binding epitope. Soluble BM88 immunoreactive polypeptides were not obtained. Bacillus cereus phospholipase C was also unable to solubilize the antigen from the membrane. Our results suggest that the molecule, possessing at least one small extramembranous domain, is attached to the membrane via a polypeptide chain.

[The first permanent molars and palatal or mandibular variations]

101 children, each of them with two teleradiographies, were selected. The first X-ray was taken at the time of the mixed dentition, the second one, when the permanent dentition was established. The purpose of the research is to show the oscillations of the palatine and mandibular planes, and their link to the movements of the first permanent molars. The palatine plane is found to swing between -7 degrees and +5 degrees with an average of -0.97 degree. The posterior part of that plane rocks downwards in 51% of the children. The limits are -7 degrees and -1 degree, with an average of -3.2 degrees. In 22%, the plane rocks upwards between +1 degree and +5 degrees with an average of +3.1 degrees. In 27% it moves parallel to itself. The posterior part of the mandibular plane varies between -6 degrees and +5 degrees, with an average of -1.1 degrees. It rocks downwards in 48% of the cases, between -6 degrees and -1 degree with an average of -3.9 degrees. In 22% of the children, this plane rocks upwards between +1 degree and +5 degrees with an average of +2.5 degrees. In 30%, it moves parallel to itself. The overall result is that the more the posterior part of the palate, or of the mandible moves downwards, the more the first permanent molars get straight or move forwards.

[Performance of Pall filters (RC 100 and PL 100) for the removal of leukocytes from red-cell concentrates and platelets]

20 red cell concentrates (buffy-coat not removed), 5 pools of 5 and 5 pools of 10 standards plateles concentrates, as well as 5 single donor platelet concentrates obtained through Haemonetics V50-1 cytoplasmapheresis procedure, were filtered, within 48 hours after donation, using RC 100 and PL 100 blood filters developed by Pall Company. Using the RC 100 filter on red cell concentrates, the rate of leukocyte removal exceeded 99% of the initial values. The residual leukocyte count per unit was 5.8 +/- 3.4 10(6). Leukocytes in red cell concentrates filtered after a previous one on the same filter numbered 18.6 +/- 8.9 10(6). The rate of platelet removal exceeded 97% of the initial amount. Red cell loss was 6 +/- 9% or 4 +/- 3% of a single or a subsequent unit were filtered respectively. Using the PL 100 filter on platelet concentrates, the rate of leukocyte removal exceeded 88% of the initial values. Residual leukocyte counts were 1.4 +/- 0.4 10(6), 6.2 +/- 3.8 10(6) and 1.4 +/- 0.8 10(6) respectively in 6-unit pools, 10-unit pools and machine prepared platelet concentrates. The average platelet loss was 15%. There was no evidence of alteration in the qualitative parameters of red cells or platelets. The filters were easy to handle and the time needed for the whole filtration process was remarkably short.

Neuron- and myelin-specific monoclonal antibodies recognizing cell-surface antigens of the central and peripheral nervous system

Immunohistochemical screening of monoclonal antibodies raised against Triton X-114-treated synaptic membranes revealed two monoclonal antibodies, namely BM88 and BM72, with characteristic binding specificities in the central and peripheral nervous systems of the pig. Monoclonal antibody BM88 was exclusively associated with neuronal elements while BM72 was myelin-specific. Thus, in the central nervous system, immunostaining with BM88 was observed throughout the gray matter of all regions of the forebrain and spinal cord tested. In the peripheral nervous system, BM88 strongly labelled the perikarya and processes of dorsal root ganglion neurons as well as the myelinated and unmyelinated neuronal processes of the dorsal roots; BM88 immunoreactivity was also detected in neuronal cell bodies and fibres of the enteric ganglia. In addition, BM88 immunolabelled the cell-surface of cultured neurons derived from brain. In mixed cultures the staining was uniformly distributed on the perikarya and along the neurites of these cells. However, in neuron-enriched cultures where 95% of the cells were immunochemically identified as neurons, the staining of the neuronal surface membrane was patchy. This phenomenon was independent of days in culture and suggested that the distribution of the BM88 antigen on the cell surface of neurons may be regulated by neuron glia interactions. By Western blotting, the antigen recognized by BM88 in brain membrane fractions which had undergone reducing sodium dodecyl sulphate/polyacrylamide gel electrophoresis was shown to be a 22,000 mol. wt polypeptide. When extracted with Triton X-114 this polypeptide partitioned into the detergent-rich phase, a property typical of an amphipathic membrane protein. In non-reducing conditions BM88 bound to a band with a molecular weight of 43,000. These results show that the BM88 antigen is composed of two polypeptide chains of equal molecular weight linked by disulphide bridges. Monoclonal antibody BM72 recognized a myelin-associated antigen in the central and peripheral nervous system. Immunohistochemical evidence suggested a cell-surface location for this antigen. By solid phase radioimmunoassay, monoclonal antibody BM88 was shown to cross-react with brain membrane fractions from pig, rabbit and rat while BM72 recognized only a pig membrane antigen. Both monoclonal antibodies BM88 and BM72 may be used as specific cellular markers in the nervous system.

A manual semi-micro method for quantitation of haemagglutination

A manual semi-micro method for quantitation of haemagglutination is described. It appears to be of wide use for most agglutination reactions usually performed in test tube, including Coombs-test. It is easy to handle and requires the usual equipment of an immunohaematological laboratory. The accuracy obtained for quantitation of antibody concentrations is similar to that of the auto-analyser.

Red blood cell antibody screening with groupamatic system. II. A two-step haemagglutination technique using a trypsin-polybren-citrate method

The trypsin-polybren-citrate (TPC) technique is based on Lalezari's method and has been developed in the Groupamatic equipment to allow the screening of irregular allo-antibodies which are not detectable on this machine by the present routine techniques. TPC screening has two main advantages: it gives more reliable results for Rh, Kell, Lewis and P antibodies than bromelin-methyl-cellulose, and it permits the screening of Duffy and Kidd antibodies, However, although the TPC technique contributes to an improved quality of the automated screening of blood donor samples, it should not be used as the only method when recipient samples are concerned.