Haematocrit heterogeneity in blood flows past microfluidic models of oxygenating fibre bundles.

Blood oxygenators act as an extracorporeal artificial lung during certain types of cardiac surgery and intensive care therapies. Inside these devices, blood is forced to flow across an oxygenating bundle, encountering interstitial gaps comparable to those typical of the microvasculature. Despite the well-known effects of such length scales on haemorheology and red blood cell (RBC) behavior, these are generally overlooked in oxygenator modeling and design; it is persistently assumed that RBCs are homogeneously distributed throughout the oxygenating bundle, independently of their microstructure arrangement or main flow directions. The goal of this study is to provide preliminary experimental evidence of heterogeneous RBC distributions inside oxygenating fibre bundles. To this end, a number of microchannels were manufactured inspired by actual oxygenating devices, considering simplified versions of their microstructure. These comprise staggered arrays of micro pillars, which were perfused with RBC suspensions, with feed haematocrit (Ht) and velocities relevant for clinical use. The microchannels were imaged using a microscope and high-speed camera to accurately capture cell distribution. The imaged blood flows revealed the non-uniform nature of RBC distributions in the arrays, characterized by local Ht gradients particularly around the O2 sources inside the bundle. These heterogeneous distributions should be accounted for during oxygenator design, as RBC concentration plays a key role in O2 transport and, ultimately, overall device performance.

Distributed and dynamic modelling of hydrology, phosphorus and ecology in the Hampshire Avon and Blashford Lakes: evaluating alternative strategies to meet WFD standards.

The issues of diffuse and point source phosphorus (P) pollution in the Hampshire Avon and Blashford Lakes are explored using a catchment model of the river system. A multibranch, process based, dynamic water quality model (INCA-P) has been applied to the whole river system to simulate water fluxes, total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations and ecology. The model has been used to assess impacts of both agricultural runoff and point sources from waste water treatment plants (WWTPs) on water quality. The results show that agriculture contributes approximately 40% of the phosphorus load and point sources the other 60% of the load in this catchment. A set of scenarios have been investigated to assess the impacts of alternative phosphorus reduction strategies and it is shown that a combined strategy of agricultural phosphorus reduction through either fertiliser reductions or better phosphorus management together with improved treatment at WWTPs would reduce the SRP concentrations in the river to acceptable levels to meet the EU Water Framework Directive (WFD) requirements. A seasonal strategy for WWTP phosphorus reductions would achieve significant benefits at reduced cost.

Evaluation of mebendazole activity on experimental murine toxocariasis by immune complexes determination.

The mebendazole action on experimental murine toxocariasis, using different formulations and vehicles, was studied by means of the detection of antibodies and immune complexes by ELISA. After inoculation with 1000 embryonated Toxocara canis eggs, BALB/c mice were submitted to the anthelmintic treatment as follows: group 1 (control without treatment); group 2 (mebendazole (MBZ), Lomper, Steve Laboratories, Barcelona, Spain, suspended in 1% sodium carboxymethylcellulose (CMC) at a dose of 100 mg/kg/day); group 3 (MBZ, pure compound suspended in 1% CMC at a dose of 100 mg/kg/day); group 4 (MBZ, pure compound suspended in water at a dose of 100 mg/kg/day); group 5 (MBZ, pure compound, formulated to a solid dispersion at 10% in polyethylene glycol 6000 (PEG) then dissolved in water at a dose of 100 mg/kg/day); group 6 (MBZ, pure compound, formulated to a solid dispersion at 10% in PEG then dissolved in water at a dose of 50 mg/kg/day); group 7 (MBZ, pure compound, formulated to a solid dispersion at 10% in PEG then dissolved in water at a dose of 25 mg/kg/day). The treatments were administered on days 5-7 post-inoculation (p.i.) inclusive. The dynamics of the production of the specific antibodies for both excretory-secretory (ES) antigen or crude extract showed a similar profile as compared to the control group. In groups 2 and 6, from the beginning of the treatment, values of immune complexes fell rapidly and were undetectable for the remainder of the experiment. Reductions of immune complex levels by the 4th-6th, 2nd-3rd and 2nd-5th weeks p.i. were observed from groups 3, 5 and 7, respectively. In the other groups, similar profiles as compared to the control group were observed in the dynamics of the specific immune complexes. The evaluation of chemotherapy by immunological methods is a valid technique for the efficiency of the treatment without the disadvantages of larval recovery from several digested tissues. Mebendazole, pure compound, formulated to a solid dispersion in PEG, then dissolved in water reduced immune complexes from the beginning of the treatment. The larval immobilization produced by MBZ should entail a reduction in their metabolic activity with a reduction in the production of excretory-secretory substances which are responsible for the formation of immune complexes. The rapid clearance of specific immune complexes together with a total larvae reduction would explain the decrease in specific immune complexes, which detection is a valid technique for monitoring the efficiency of treatment.

Evaluation by larval recovery of mebendazole activity in experimental murine toxocariasis.

We have studied the action of mebendazole on experimental murine toxocariasis using different formulations and vehicles. The treatment efficacy was evaluated by larval recovery after digesting several tissues. In the first part of the experiment, the drugs were administered on days 1-3 post infection (p.i.) inclusive (hepato-pulmonary phase of the migration), then the animals were sacrificed by the 1st week p.i. In the second part of the experimental protocol, the treatments were administered on days 4-6 p.i. inclusive (myotropic-neurotropic phase of the migration), with sacrifice of the animals by the 7th week p.i. The 2nd pattern of treatment reduced more effectively the total larval recoveries compared with control animals. However, the larval distribution by organs was scarcely affected. The first pattern of treatment reduced less effectively the total number of larvae, but it significantly inhibited migration.

Idiotypic replica of a Toxocara canis excretory/secretory antigen epitope.

This study describes the production, characterization and use of an anti-idiotype serum raised against the monoclonal antibody TC-1 which recognizes a T. canis excretory/secretory antigen (ES Ag) epitope. Anti-idiotypic (anti-Id or Ab2) antibodies were produced in rabbits using TC-1 F(ab')2 fragments; these anti-Id inhibited ES Ag binding to biotinylated TC-1, and also inhibited a larval microprecipitation assay using TC-1. Assays show that the Ab2 beta or "internal image" of a T. canis ES Ag epitope was obtained. The antibodies have been used as an idiotypic copy of ES Ag in a diagnostic ELISA for murine toxocariosis. Affinity-purified anti-Id antibodies were used to raise a homologous anti-anti-Id (Ab3) response in rabbits. Antibody formation was followed in the sera of BALB/c mice inoculated with embryonated eggs of T. canis during a 12-month infestation. A 3-week latency period was observed before specific anti-TC-1 epitope antibodies were detected. High levels were reached at 7 weeks post-inoculation with a maximum at the ninth month, and were then maintained until the end of the experiment. The results show the possible utility of anti-Id antibodies as an ES Ag molecular replica.

Larval distribution of Toxocara canis in BALB/c mice at nine weeks and one year post-inoculation.

The migratory route of Toxocara canis in the mouse includes two phases: a hepato-pulmonary phase and a myotropic-neurotropic phase. A study was made of the migratory behaviour of larvae one year post-inoculation (p.i.) comparing the results to those obtained at the end of an initial experiment (day 63 p.i). The larval distribution per organ was already definitive at 9 weeks p.i. The total parasitic load showed a reduction when the experiment was prolonged for one year.