Classroom aerosol dispersion modeling: experimental assessment of a low-cost flow simulation tool.

The purpose of this study was to assess the utility of a low-cost flow simulation tool for an indoor air modeling application by comparing its outputs with the results of a physical experiment, as well as those from a more advanced computational fluid dynamics (CFD) software package. Five aerosol dispersion tests were performed in two different classrooms by releasing a CO2 tracer gas from six student locations. Resultant steady-state concentrations were monitored at 13 locations around the periphery of the room. Subsequently, the experiments were modeled using both a low-cost tool (SolidWorks Flow Simulation) and a more sophisticated tool (STAR-CCM+). Models were evaluated based on their ability to predict the experimentally measured concentrations at the 13 monitoring locations by calculating four performance parameters commonly used in the evaluation of dispersion models: fractional mean bias (FB), normalized mean-square error (NMSE), fraction of predicted value within a factor of two (FAC2), and normalized absolute difference (NAD). The more sophisticated model performed better in 15 of the 20 possible cases (five tests at four parameters each), with parameters meeting acceptance criteria in 19 of 20 cases. However, the lower-cost tool was only slightly worse, with parameters meeting acceptance criteria in 18 of 20 cases, and it performed better than the other tool in 3 of 20 cases. Because it provides useful results at a fraction of the monetary and training cost and is already widely accessible to many institutions, such a tool may be worthwhile for many indoor aerosol dispersion applications, especially for students or researchers just beginning CFD modeling.

Comparison of adsorption of Remazol Black B and Acidol Red on microporous activated carbon felt.

The adsorption of two anionic dyes, Remazol Black B (RB5) and Acidol Red 2BE-NW (AR42), onto a microporous activated carbon felt was investigated. The characterization of carbon surface chemistry by X-ray microanalysis, Boehm titrations, and pH-PZC measurements indicates that the surface oxygenated groups are mainly acidic. The rate of adsorption depends on the pH and the experimental data fit the intraparticle diffusion model. The pore size distribution obtained by DFT analysis shows that the mean pore size is close to 1nm, which indicates that a slow intraparticle diffusion process control the adsorption. The adsorption isotherms were measured for different pH values. The Khan and the Langmuir-Freundlich models lead to the best agreement with experimental data for RB5 and AR42, respectively. These isotherm simulations and the pH dependence of adsorption show that the adsorption capacity is mainly controlled by nondispersive electrostatic interactions for pH values below 4. The adsorption kinetics, the irreversibility of the process, and the influence of the pH indicate that the rate of adsorption in this microporous felt proceeds through two steps. The first one is fast and results from direct interaction of dye molecules with the external surface of the carbon material (which account for 10% of the whole surface area); in the second, slow step, the adsorption rate is controlled by the slow diffusion of dye molecules into the narrow micropores. The influence of temperature on the adsorption isotherms was studied and the thermodynamic parameters were obtained. They show that the process is spontaneous and exothermic.

European quality system for tissue banking.

AIM: The aims of this project were to analyze the factors that influence quality and safety of tissues for transplantation and to develop the method to ensure standards of quality and safety in relation to tissue banking as demanded by European Directive 2004/23/EC and its technical annexes. It is organized in 4 Working Groups, the objectives of each one being focused in a specific area. STANDARDS: The Guide of Recommendations for Tissue Banking is structured into 4 parts: (1) quality systems that apply to tissue banking and general quality system requirements, (2) regulatory framework in Europe, (3) standards available, and (4) recommendations of the fundamental quality and safety keypoints. REGISTRY: This Working Group handled design of a multinational musculoskeletal tissue registry prototype. TRAINING: This Working Group handled design and validation of a specialized training model structured into online and face-to-face courses. The model was improved with suggestions from students, and 100% certification was obtained. AUDIT: The Guide for Auditing Tissue Establishments provides guidance for auditors, a self-assessment questionnaire, and an audit report form. The effectiveness and sustainability of the outputs were assessed. Both guides are useful for experienced tissue establishments and auditors and also for professionals that are starting in the field. The registry prototype proves it is possible to exchange tissues between establishments throughout Europe. The training model has been effective in educating staff and means having professionals with excellent expertise. Member states could adapt/adopt it. The guides should be updated periodically and perhaps a European organization should take responsibility for this and even create a body of auditors.

Cefuroxime, rifampicin and pulse lavage in decontamination of allograft bone.

The risk of bacterial infection through allogenic bone transplantation is one of the major problems facing tissue banks. Different screening methods and decontamination procedures are being used to achieve a safe surgical result. The purpose of this study was to investigate the contamination rate in fresh frozen bone allografts after treating them with different decontamination methods. The allografts were contaminated by rubbing on the operating theatre floor for 60 min, after which they were rinsed either with sterile physiological saline, cefuroxime or rifampicin solution or they were washed with low-pressure pulse lavage of sterile physiological saline. Our findings show that low-pressure pulse lavage with sterile saline solution is very effective in removing bacteria from bone allograft, when compared with the antibiotic solutions tested.

Survival of 25 osteoarticular allografts followed more than 10 years.

An evaluation of the long-term survival rate of 25 osteoarticular allografts was made. Clinical analysis was based on the Mankin scale and the Musculoskeletal Tumor Society (MSTS) Grading system. After a mean follow-up time of 15 years 76% of the osteoarticular allografts had good or excellent rating. The MSTS scale revealed a mean score of 89% for those 20 grafts still functioning according to their primary purpose. Allograft related complications occurred in 32% of the cases being most common among malignant cases. Due to the rather good long-term results, osteoarticular allografts can still be recommended for hemicondylar allograft reconstruction in benign lesions.

Pulse lavage washing in decontamination of allografts improves safety.

We analyzed the bacterial contamination rate of 140 femoral head allografts after rinsing the allografts in different decontamination solutions. Bacterial screening methods and cleansing effect of antibiotics (cefuroxime and rifampicin) and pulse lavage were compared. Swabbing and taking small pieces of bone for culture were the screening methods used. Both methods proved to be quite unreliable. Approximately one-fourth of the results were false negative. Culturing small pieces of bone gave the most accurate and reliable results and, therefore, can be recommended as a bacterial screening method. The use of antibiotics in allograft decontamination is controversial. In prophylactic use antibiotics include risks of allergic reactions and resistant development and our results in the present study show that antibiotics do not improve the decontamination any better than low-pressure pulse lavage with sterile saline solution. Therefore, pulse lavage with sterile saline solution can be recommended for allograft decontamination. Our results demonstrate that it decreases bacterial bioburden as effectively as the antibiotics without persisting the disadvantages.

Distribution of water-soluble and surface-active low-molecular-weight species in acrylic latex films.

Monodisperse core-shell latices were synthesized, differing in the acrylic acid (AA) content in the particle shell (1 or 4 wt%) and the Tg of the acrylic core (around -40 or 10 degrees C). In a first step, the drying mechanisms of the dialyzed latices were studied by confocal Raman spectroscopy. It was shown that, besides some unexpected features (briefly described in the article), drying occurred in a rather classical way, i.e., simultaneously from top to bottom and from edge to center. Then, the distributions of sulfate ion (SO4) (from sodium sulfate) and sodium dodecyl sulfate (SDS) in the dry latex films were established by confocal Raman spectroscopy and attenuated total reflectance (ATR). The two techniques were complementary. SO4 and SDS distributions were quite different, although presenting some common characteristics. In both cases, repartition of the low-molecular-weight species in the film was even less homogeneous when the AA content was lower and the particle core softer. However, SO4 showed enrichment at the film-substrate interface and depletion at the air side, whereas SDS showed concentration maxima at both interfaces. Interpretations stress the importance of desorption from the particle-water interface, transport by water, size effects, and diffusion.

High-pressure saline washing of allografts reduces bacterial contamination.

60 fresh-frozen bone allografts were contaminated on the operating room floor. No bacterial growth was detected in 5 of them after contamination. The remaining 55 grafts had positive bacterial cultures and were processed with three methods: soaking in saline, soaking in antibiotic solution or washing by high-pressure saline. After high-pressure lavage, the cultures were negative in three fourths of the contaminated allografts. The corresponding figures after soaking grafts in saline and antibiotic solution were one tenth and two tenths, respectively. High-pressure saline cleansing of allografts can be recommended because it improves safety by reducing the superficial bacterial bioburden.

Management of clostridial gas gangrene and the role of hyperbaric oxygen.

BACKGROUND AND AIMS: Clostridial gas gangrene is one of the most dreaded infections in surgery. The aim of this study was to investigate the efficacy of surgery, antibiotic treatment, surgical intensive care and especially the role of hyperbaric oxygen in the management of clostridial gas gangrene. MATERIAL AND METHODS: 53 patients, 42 of them submitted from other hospitals in Finland. After the diagnosis had been made the patients underwent surgical debridement, broad spectrum antibiotic therapy and a series of hyperbaric oxygen (HBO) treatments at 2.5 ATA pressure. The necrotic tissue was excised and incisions were made in the affected areas. Amputations were performed when necessary. RESULTS: Twelve patients died (22.6%). Hyperbaric oxygen therapy decreased the systemic toxicity and prevented further extension of the infection thereby improving the overall outcome of the patients. CONCLUSION: Hyperbaric oxygen therapy of gas gangrene seems to be life-, limb- and tissue saving. Early diagnosis remains essential. Patient survival can be improved if the disease is recognized early and appropriate therapy applied promptly. Surgical and antibiotic therapy as well as HBO treatment combined with surgical intensive care must be started as soon as possible.

An anti-CD4 (CDR3-loop) monoclonal antibody inhibits human immunodeficiency virus type 1 envelope glycoprotein-induced apoptosis.

Inhibition of human immunodeficiency virus type 1 (HIV-1)-inducing programmed cell death (PCD) by anti-CD4 monoclonal antibodies (mAbs) was investigated using DNA intercalant YOPRO-1 assay. We found that 13B8.2, an mAb that binds the CDR3-like loop in domain 1 (D1) of CD4, protected infected CEM cell cultures against HIV-1-induced PCD. Protection was not observed using another anti-CD4 mAb (BL4) that binds D1-D2, suggesting that the mechanism involved in cell protection against HIV-1-induced PCD requires engagement of precise CD4 epitopes. Because 13B8.2 is known to inhibit syncytia formation and virus transcription, this mAb could inhibit HIV-1-induced PCD by (1) inhibiting virus gene expression, (2) preventing viral envelope-CD4 interaction, and/or (3) interfering with apoptotic signals. Our data indicated that the absence of enhanced PCD in infected cell cultures treated with 13B8.2 mAb probably was the result of inhibition of HIV-1 replication and virus spread. Moreover, 13B8.2 mAb was found to inhibit PCD mediated by membrane-expressed HIV-1 envelope glycoproteins. Finally, we found that 13B8.2 mAb displayed no protective interference with apoptotic signal induced by Fas, dexamethasone, and serum withdrawal.

Anti-GM-CSF monoclonal antibody therapy for refractory acute leukemia.

Several phase I trials and pilot studies using Monoclonal Antibody (MoAb) have been performed in B-cell neoplasms, but this approach has not until now been extensively tested in myeloid leukemias. Recently, we evaluated the use of anti-Granulocyte-Macrophage Colony-Stimulating Factor MoAb (Anti-GM-CSF MoAb) in acute myeloid leukemia (AML). Eight patients fulfilled inclusion criteria and received a single course of Anti-GM-CSF MoAb infusion during 5 to 15 days. Anti-GM-CSF MoAb was well tolerated and was detectable in pharmacokinetics studies. Using Human Anti-Rat Antibodies (HARA), we also observed an immunological response to the MoAb. Despite sufficient levels detected in the serum and biological activity of Anti-GM-CSF MoAb in vivo, no anti-leukemic effect was noted, except for one patient who had a decrease of 50% in the marrow blast cell mass. These observations indicate that leukemic proliferation in vivo involves a complex network spanning many mechanisms, and inhibition of leukemia is not effective if only one of these key targets is attacked. The development of these new approaches may be more effective in the future.

Hyperbaric oxygen in the treatment of Fournier's gangrene.

OBJECTIVE: To investigate the efficacy of operation, antibiotic treatment, hyperbaric oxygen, and surgical intensive care in the management of Fournier's gangrene. DESIGN: Retrospective study. SETTING: University hospital, Finland. SUBJECTS: 33 patients, most of them referred from other hospitals. INTERVENTION: Debridement, broad spectrum antibiotics, and hyperbaric oxygen (HBO) treatment at 2.5 atmospheres absolute pressure. Excision of necrotic tissue and incisions in the affected areas. Urinary and faecal diversions when necessary. MAIN OUTCOME MEASURES: Morbidity and mortality. RESULTS: Only three patients died (9%). Hyperbaric oxygen reduced systemic toxicity, prevented extension of the necrotising infection, and increased demarcation, thereby improving the overall outcome. CONCLUSION: To reduce mortality and morbidity, effective treatment of Fournier's gangrene should be started promptly. Debridement and antibiotics combined with surgical intensive care must be started as soon as possible. Hyperbaric oxygen is both life and tissue saving. It is an important adjunct that prevents extension of necrosis and reduces systemic toxicity.

In vitro selection of HIV-1 resistant to an anti-CD4 monoclonal antibody that inhibits virus transcription.

Phase I studies using monoclonal antibodies (mAbs) that bind to the Ig-CDR3-like loop in domain 1 of CD4 (e.g., 13B8-2 mAb) have already been documented for HIV-1-infected patients. In vitro, such mAbs do not inhibit virus to cell fusion but are able to inhibit virus envelope-mediated syncytia formation. Moreover, these mAbs inhibit Tat-induced activation of HIV-1 promoter and HIV-1 transcription in infected CD4+ cells. Here, we report the selection of escaped mutant virus or viruses derived from HIV-1Lai capable of replicating in vitro in the presence of concentrations of 13B8-2 mAb, that usually inhibit HIV-1Lai particle production. The escaped mutant virus or viruses, termed HIV-1Lai13EM, kept the major enzymatic restriction sites found in HIV-1Lai and remained sensitive to anti-CD4 mAb-, soluble CD4-, and recombinant gp120-mediated inhibition of syncytia formation. Possible genetic changes affecting the tat gene or the 5' long terminal repeat (LTR) were investigated. Partial sequence analysis of HIV-1Lai13EM and a control HIV-1Lai grown for 85 days in CEM cells, demonstrated that the first tat exon of these two viruses encoded identical proteins. Although a point mutation G>A was frequently encountered (6 of 13 sequences) in the LTRs of HIV-1Lai13EM at position -188 within the negative regulatory element (NRE), this mutation did not confer the escape mutant phenotype. Our study indicates that the mutant phenotype probably requires genetic changes in a region or regions outside the LTRs.

Retesting of bone donors 2 months after donation guarantees sufficient safety of bone allografts.

Both allogeneic bone grafting and blood transfusion may transmit infections from the donor to the recipient. The most effective means to reduce the risk of infection is careful donor selection and screening of donors for markers of infection. The risk of blood transfusion-transmitted HIV infection in Finland, calculated with the incidence/window period model, is approximately 1:3,300,000. The calculated risk for hepatitis B (HBV) and C (HCV) is 1:217,000 and 1:147,000 donations, respectively. In bone banking we can further reduce the risks by retesting the living donors. Retesting 2 months after donation seems to be sufficient, at least in countries with a low incidence of transplantation-transmitted infections.

Bone bank service in Finland. Experience of bacteriologic, serologic and clinical results of the Turku Bone Bank 1972-1995.

560 bones were harvested by The Turku Bone Bank between 1972-1995. It was started with massive allografts for bone tumor surgery, but today most are femoral heads for hip revision surgery. The increase in harvested bones nearly trebled from 1984-1989 to 1990-1995. Only 1 positive hepatitis C test was found. There were no hepatitis B or HIV positive donors. The incidence of discarding after screening was 24%, with positive bacterial growth (8%, usually Staphylococcus epidermidis) as the commonest reason. 2 massive grafts with negative cultures when harvesting were positive after thawing and resulted in deep infection. 369 allografts were transplanted. The infection rate of massive allografts for bone tumor surgery was 5/63 in 1973-1995, and 2/52 in 1985-1995. The infection rate for hip revision surgery was 3.4%. The clinical functional results correspond to those reported in larger international series.

MDR-related properties of K 562 cells grown in two different culture media.

Using a synthetic substitute, Ultroser HY, for fetal bovine serum to supplement a classical RPMI 1640 culture medium produced changes in the properties of sensitive and of multidrug-resistant K 562 cells. Though no morphological changes were found, a statistically significant decrease in doubling-time was noted. Plasma membranes were more rigid, as reflected by an increase in the order parameter values. Adriamycin cytotoxicity was decreased, as shown by an increase in IC 50 values. The THP-adriamycin uptake, monitored by fluorimetry, was diminished even when the revertant agent verapamil was added. Moreover, the apparent number of Pgp 170 molecules per cell was lower for resistant cells grown with Ultroser HY. Thus Pgp 170 was not involved in the MDR increase induced by Ultroser HY. In conclusion, it must be kept in mind that environmental factors such as media chemical composition influence the MDR phenomenon and that environmental factors may also influence the MDR phenomenon in clinical situations.

Inhibition of human immunodeficiency virus type 1 production in infected peripheral blood mononuclear cells by human leukocyte antigen class I-specific antibodies: evidence for a novel antiviral mechanism.

A well-characterized mechanism by which anti-HLA class I monoclonal antibodies (MAb) inhibit human immunodeficiency virus type 1 (HIV-1) propagation in in vitro cell cultures is the neutralization of the virus through interactions with HLA molecules associated with the virion envelope. Yet, the possibility that another mechanism of inhibition might affect a postbinding stage of the virus life cycle has been strongly suggested by our previous investigations. To demonstrate that the interaction of MAb B1-1G6 with the light chain of cell surface-expressed HLA class I molecules inhibits a postbinding step of the HIV-1 life cycle, peripheral blood mononuclear cells (PBMCs) were exposed to viruses grown in HLA class I-negative, CD4-positive cells (these viruses, which did not carry HLA class I molecules, cannot be neutralized by anti-HLA MAb during the first round of infection), and PCR was used at various times postexposure to search for the different forms of HIV-1 DNA and RNA in virus-exposed PBMCs cultured in either the presence or [correction of] absence of MAb B1-1G6. Although viral DNA was found in MAb B1-1G6-treated cells, spliced HIV-1 mRNA could not be detected in those cells. In contrast, HIV-1 gene expression was found in HIV-1-infected PBMCs treated with B9-12-1, another HLA class I-specific MAb which prevents infection of cells by cell-free viruses but which fails to inhibit cell-to-cell transmission of HIV-1. These results highlight a second antiviral mechanism by which anti-HLA MAb inhibit in vitro HIV-1 propagation.