Contaminant transport in soil: A comparison of the Theory of Porous Media approach with the microfluidic visualisation

Visualisation of the groundwater flow and contaminant transport can play a significant role for a better understanding of contaminant fate, which helps decision-makers and contaminated site planners to choose and implement the best remediation strategies. In this paper, a microfluidic chip coated with nanoclay was developed to mimic soil behaviour. Scanning electron microscopy (SEM) images and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed that all the features and surfaces are coated with nanoclay. The change of contact angle for the native polydimethylsiloxane (PDMS) from 151^° ± 4^° to 73^° ± 6^° for modified ones is indicative of a considerable shift to hydrophilic behaviour. Moreover, the transport process in the developed chip was simulated utilising the Theory of Porous Media (TPM) and computational fluid dynamic (CFD) approaches. Although the results of both numerical approaches are in good agreement with experiments, the Root Mean Square Error (RMSE) of the predicted contaminant concentration by TPM at two observation points is less than that of CFD.

Reliability of the qualitative behavior assessment as included in the Welfare Quality Assessment protocol for growing pigs

Positive emotions constitute a very important part of animal welfare. They are, however, also the most challenging elements to be objectively measured. Due to its feasibility, the qualitative behavior assessment (QBA) is included in the Welfare Quality Assessment protocol for growing pigs as the animal-based measurement tool for positive emotions. Reliability testing on the QBA in the form as included in the protocols is, however, rare. Therefore, the present study aimed at the evaluation of the inter- and intraobserver as well as test-retest reliability of the QBA in growing pigs. This was done by trained observers based on 19 joint on-farm assessments, the repeated assessments of 24 farms during 2 growing periods, and 107 video sequences. The results were compared between the observers and the repeated farm visits. Therefore, millimeter values were directly compared by calculation of Spearman's rank correlation coefficients (RS), and furthermore, the results were subjected to a principal component analysis (PCA). The results identified 2 main principal components (PC; PC1 and PC2) together explaining from 42 to 75% of the variation in the recorded variables of the different PCA. The factor loadings that the adjectives reached on PC1 and PC2 were compared by calculation of RS between observers and farm visits, respectively. Reliability was interpreted as acceptable if at least a moderate correlation was detected; that is, RS was greater than or equal to 0.4. Regarding the on-farm assessments, and, therefore, under practical conditions, no sufficient interobserver reliability (RS = -0.16 for PC1 and RS = 0.13 for PC2) was found. In terms of the test-retest reliability, only 1 comparison of 2 farm visits showed a positive correlation for PC1 (RS = 0.79) as well as for PC2 (RS = 0.64). The other 5 comparisons presented negative to weak positive correlations. However, based on video sequences, good interobserver (RS = 0.67 for PC1 and RS = 0.60 for PC2) and intraobserver (RS = 0.94 for PC1 and RS = 0.44 for PC2) reliability was achieved. Therefore, the present study revealed good reliability for the QBA in the form as it is currently included in the Welfare Quality Assessment protocol for growing pigs based on video sequences but insufficient reliability for the application on the farm.

Existence and vanishing of the breathing mode in strongly correlated finite systems

One of the fundamental eigenmodes of finite interacting systems is the mode of uniform radial expansion and contraction-the breathing mode (BM). Here we show in a general way that this mode exists only under special conditions: (i) for harmonically trapped systems with interaction potentials of the form 1/rgamma (gamma in R not equal 0) or log(r), or (ii) for some systems with special symmetry such as single-shell systems forming platonic bodies. Deviations from the BM are demonstrated for two examples: clusters interacting with a Lennard-Jones potential and parabolically trapped systems with Yukawa repulsion. We also show that vanishing of the BM leads to the occurrence of multiple monopole oscillations which is of importance for experiments.

Ground state of a confined Yukawa plasma including correlation effects

The ground state of an externally confined one-component Yukawa plasma is derived analytically using the local density approximation (LDA). In particular, the radial density profile is computed. The results are compared with the recently obtained mean-field (MF) density profile [Henning et al., Phys. Rev. E 74, 056403 (2006)]. While the MF results are more accurate for weak screening, the LDA with correlations included yields the proper description for large screening. By comparison with first-principles simulations for three-dimensional spherical Yukawa crystals, we demonstrate that the two approximations complement each other. Together they accurately describe the density profile in the full range of screening parameters.

Ground state of a confined Yukawa plasma

The ground state of an externally confined one-component Yukawa plasma is derived analytically. In particular, the radial density profile is computed. The results agree very well with computer simulations of three-dimensional spherical Coulomb crystals. We conclude in presenting an exact equation for the density distribution for a confinement potential of arbitrary geometry.

Antibiotic resistance in Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes in respiratory tract infections in outpatients

Sensitivity patterns of Streptococcus pneumoniae, Haemophilus influenzae and Streptococcus pyogenes were studied prospectively in an outpatient population seeking medical advice for respiratory tract infections (RTI) in the Southern parts of Stockholm. In total, 3,214 nasopharyngeal and 1,907 throat swabs were cultured during January-February 1996. 32% of the patients had received antibiotics during the previous year. Reduced penicillin sensitivity in S. pneumoniae was rare (1.3%) and only seen in patients treated with antibiotics during the previous 4 months. Beta-lactamase production in H. influenzae was found in 13.4% of patients who had been treated with antibiotics during the last 4 months and in 7.9% of the others. No resistance (< 1%) to erythromycin was seen in S. pyogenes. In this population-based surveillance, the levels of resistance in common respiratory tract pathogens were thus low and correlated to previous antibiotic treatment. Strict indications for antibiotic treatment in uncomplicated RTI are advocated to maintain a low resistance rate. Penicillin is still the drug of choice in patients without frequent recurrences of RTI in a setting similar to the one studied.

Is penicillin the appropriate treatment for recurrent tonsillopharyngitis? Results from a comparative randomized blind study of cefuroxime axetil and phenoxymethylpenicillin in children. The Swedish Study Group

The efficacy of cefuroxime axetil compared with phenoxymethylpenicillin (PcV) was studied in group A beta-haemolytic streptococci (GAS) culture-proven tonsillitis in children aged 3-12 years with a history of at least 1 episode of tonsillopharyngitis requiring antibiotic therapy during the previous 3 months. This was a comparative, randomized, investigator-blind, multicentre study. A total of 236 children received either cefuroxime axetil suspension or PcV syrup. Inclusion criteria were a positive, rapid, group A strep test verified by bacteriological culture and clinical signs and symptoms of tonsillopharyngitis. Cefuroxime axetil treatment gave a significantly higher bacteriological eradication rate and clinical cure rate than PcV. At day 2-5 post treatment the eradication rates were 99/114 (87%) for cefuroxime axetil vs 61/109 (56%) for PcV (p < 0.001). The clinical cure rates were 98/114 (86%) and 73/109 (67%) respectively (p < 0.01). Up to 21-28 days post-treatment, 9/114 (8%) cefuroxime axetil patients and 37/109 (34%) PcV patients were treatment failures or had recurrence/reinfection of GAS tonsillopharyngitis (p < 0.001). More than 90% of the patients who experienced bacteriological treatment failure at either the first or second follow-up had the same serotype isolated pre- and post-treatment. During the study period, 21/114 (18%) patients in the cefuroxime axetil group and 50/109 (46%) patients in the PcV group received additional antibiotics (p < 0.001). No serious adverse events were noted and the mild adverse events were equally distributed among the patients in the 2 study groups: 15% for cefuroxime axetil and 14% for PcV.

Theoretical aspects of detection of bacteraemia as a function of the volume of blood cultured

Clinically significant bacteraemia in adults is characterized by low numbers of circulating bacteria. Assuming a Poisson or a binomial distribution we have calculated the probability of detecting bacteria as a function of the concentration in blood, estimated the concentration of bacteria in blood from a given test result, and calculated the blood volume required to detect bacterial growth with a probability of 95% at a given mean number of colony-forming units (cfu) per sample unit. These theoretical assumptions have been used on an empirical population of patients with proven bacteraemia.

RESULTS

18% of Staphylococcus aureus bacteraemias and 29% of Escherichia coli bacteraemias have circulating bacteria with an estimated spread of less than 0.04 cfu/ml. With a 95% probability of detection of a bacteraemia, a concentration in blood corresponding to 3 cfu/sampling unit is necessary. In our empirical material, where 30 ml was cultured, the probability of detection of E. coli bacteraemias would have decreased by 11% if 20 ml had been cultured, and 27% if only 10 ml had been cultured. The corresponding figures for S. aureus were 6% and 15%, respectively. For low grade E. coli bacteraemias (< 0.04 cfu/ml) the decrease would have been 33% and 67%, respectively.

In-vitro activity of the new penems FCE 22101 and FCE 24362 alone or in combination with aminoglycosides against streptococci isolated from patients with endocarditis

Seven strains of viridans streptococci isolated from patients with endocarditis were inhibited in vitro by 0.06-2 mg/l and 0.016-0.5 mg/l of the penems FCE 22101 and FCE 24362 respectively. The MBCs were the same or two-fold higher than the respective MIC with three exceptions. One strain of Streptococcus faecalis was only inhibited (8 mg/ml respectively 0.5 mg/l; MBC greater than 32 mg/l) and one strain of Str. faecium was resistant (MIC greater than or equal to 16 mg/l). When combined with gentamicin or netilmicin a bactericidal and synergistic killing was observed within 1-8 h in all strains except Str. faecium. Synergy could also be confirmed in all cases by following bacterial growth kinetics after elimination of antibiotics, by calculating the difference between the times required for bacteria exposed to antibiotic and unexposed bacteria to increase in numbers (PAE).

Isolation of Francisella tularensis biovar palaearctica from human blood

Francisella tularensis septicemia has previously been reported in the USA, where Francisella tularensis biovar tularensis (type A) occurs endemically. The present report describes two cases of septicemia caused by the Euro-Asian Francisella tularensis biovar palaearctica (type B). The patients lived in an endemic region of Sweden and presented with high fever and pneumonia. Both patients recovered. The ability of Francisella tularensis biovar palaearctica to cause bacteremia has consequences for laboratory safety.

Factors influencing the biological inactivation of high protein bound beta-lactam antibiotics in vitro

Unpredictable inactivation of antimicrobial agents may cause erratic results in pharmacokinetic studies. In this study we followed the inactivation of the high protein bound beta-lactams flucloxacillin, dicloxacillin and ceftriaxone in vitro. The antibiotics were added to pools of human and rabbit sera, ultrafiltrates of these pools, rabbit interstitial fluid, phosphate buffered saline (PBS), rabbit albumin in PBS and sodium dodecyl sulphate (SDS) treated preparations of human sera. Ceftriaxone was relatively stable but different serum pools varied significantly in their flucloxacillin and dicloxacillin inactivating capacity. The dominating inactivation took place within five minutes after the addition of antibiotics to serum. The inactivating factor was heat stable at 56 degrees C, 0.5 h, of relatively high molecular weight, and not related to albumin. The inactivating capacity could be diminished by SDS-treatment of serum suggesting a lipoprotein nature.

Susceptibility to beta-lactam antibiotics and gentamicin of gram-negative bacilli isolated from hospitalized patients: a Swedish multicenter study

A total of 952 blood and 1543 urine isolates of gram-negative bacilli from hospitalized patients in 1986-1987 were consecutively collected by 10 Swedish laboratories and tested for susceptibility to 8 beta-lactam antibiotics and to gentamicin. The isolates were mostly Escherichia coli (58% and 44%, respectively) and Klebsiella sp. (17% and 18%). Resistance to ampicillin in blood and urine isolates was found in 35% and 45%, respectively, to piperacillin in 5% and 6%, to cephalothin in 26% and 34%, to cefuroxime in 12% and 22%, to cefotaxime in 3% and 5%, to ceftazidime in 1% and 1%, to imipenem in 0.5% and 0.1%, to aztreonam in 3% and 2%, and to gentamicin in 0.8% and 0%. Resistance of clinically important gram-negative bacilli to new beta-lactam antibiotics and to gentamicin is infrequent in Sweden.

Density of the microflora in hand eczema before and after topical treatment with a potent corticosteroid

Twenty patients with hand eczema were studied with the use of quantitative bacteriologic cultures before and after successful topical treatment with a potent corticosteroid. One sample was taken from the most pronounced eczematous lesion, a second from skin affected with only erythema, and a third from clinically normal skin. Before quantitative bacteriologic analysis, the different species were combined into three main groups: Staphylococcus aureus, other aerobes, and anaerobes. Before treatment, S. aureus colonized the most pronounced eczematous lesion in eighteen of twenty patients and exceeded 10(5) cfu/cm2 in fifteen of twenty patients. The geometric mean count of S. aureus before treatment was significantly higher in eczema (10(4.8) cfu/cm2) than in erythema (10(3.4) cfu/cm2) and significantly higher in erythema than in normal skin (10(1.7) cfu/cm2). The density of other aerobes and anaerobes was similar in the three sampling sites. After treatment, the mean count of S. aureus was significantly reduced at all three sampling sites, and the densities became equal. Treatment did not affect the mean count of other aerobes or anaerobes.

In vitro aminoglycoside resistance of gram-negative bacilli and staphylococci isolated from blood in Sweden 1980-1984

The in vitro susceptibility to gentamicin, tobramycin, amikacin and netilmicin in septicaemia isolates was followed during 1980-1984 in 6-8 Swedish laboratories. The bacterial distribution was similar over the years and was dominated by Escherichia coli and staphylococci. Resistance to gentamicin was found in 2.3-3.6%, to tobramycin in 1.4-3.4%, to amikacin and netilmicin in 0.5-0.9%. Production of aminoglycoside modifying enzymes was observed among resistant strains.

Cefadroxil once daily for three or seven days versus amoxycillin for seven days in uncomplicated urinary tract infections in women

The cure rate of acute uncomplicated urinary tract infection in general practice using 3 different treatment regimens, was studied in a randomized, multicenter trial. Patients were assigned to receive either cefadroxil 1 g once daily for 3 or 7 days or amoxycillin 375 mg t.i.d. for 7 days. 310 patients entered the study, of whom 230 could be evaluated according to the protocol. Two thirds of the cases were due to infections with Escherichia coli and about one fourth to Staphylococcus saprophyticus. No statistically significant differences in cure rates between the 3 regimens could be demonstrated neither at 1 week nor at 5 weeks of follow-up. The frequency of adverse reactions was low and similar in each treatment group.

Static and dynamic properties of tissue cage fluid in rabbits

The properties of tissue cage fluid in a steel net tissue cage model in rabbits were compared to those of serum by determination of the protein profile, the cell contents, and the pharmacokinetics of 125I albumin, 3H sucrose and 3H fusidic acid. The dominating serum proteins demonstrated by crossed immunoelectrophoresis were also detected in tissue cage fluid but at lower levels and at various ratios. The cell pattern gradually changed from an initial dominance of polymorphonuclear cells to lymphocytes during the five weeks following the subcutaneous implantation of the cages. The distribution of the highly protein-bound fusidic acid was markedly slower and the maximal tissue cage fluid level significantly lower than that of sucrose. Equilibrium of 125I albumin between serum and tissue cage fluid was slowly achieved during the following two weeks. The advantages and disadvantages of tissue cage models for studies of drug pharmacokinetics are discussed. The properties of tissue cage fluid and the possibility of repeated sampling make the model suitable for studies of experimental local infections. The influence of therapeutic agents and the host's response to the infectious process may also be elucidated.

Infection risks from cannulae used to maintain intravenous access

In an experimental in vitro study, it was shown that the rate of infection through the injection route was higher with Venflon cannulae than with Intraflux cannulae (P less than 0.01). A restricted use of cannulae with injection side ports is recommended.

Comparative study of netilmicin/tinidazole versus netilmicin/clindamycin in the treatment of severe abdominal infections

The efficacy of netilmicin combined with tinidazole (N + T) or clindamycin (N + C) in the treatment of severe abdominal infections was evaluated in a prospective randomized study with 20 patients in the N + T group and 21 patients in the N + C group. Normally the maintaining dose for netilmicin was 2.25 mg/kg every 12 h, for tinidazole 400 mg every 12 h and for clindamycin 300-600 mg every 6-8 h. The mean duration time of treatment was 8 days in the N + T group and 10 days in the N + C group respectively. In the N + T group 18 patients were cured and in the N + C group 17 patients. Among aerobic bacteria Escherichia coli was most frequently isolated and among anaerobes Bacteroides sp. All aerobic bacteria with 2 exceptions were susceptible to netilmicin and all anaerobic bacteria but 2 to tinidazole or clindamycin. Adequate serum levels were obtained for each antibiotic during therapy. In this study with a small number of patients the combination of netilmicin and tinidazole was as effective as netilmicin and clindamycin.

Pivmecillinam in treatment of Staphylococcus saprophyticus urinary tract infections

In a non-randomised trial 15 women with Staphylococcus saprophyticus bacteriuria were treated with pivmecillinam 200 mg t.i.d. for 1 week. At follow-up 2-4 weeks post treatment only 11 patients were cured. As a complement to the study the occurrence of Staph. saprophyticus bacteriuria was analysed according to age, sex and season. Mecillinam MIC's and viability curves of Staph. saprophyticus were investigated. It is concluded that mecillinam should only be used to treat urinary tract infections caused by bacteria sensitive in vitro.

Rapid technique for detection of pneumococcal pneumonia

Tracheal aspirates from patients with diarrhoea and pneumonia were tested for the presence of pneumococci by both quantitative culture and counter immunoelectrophoresis (CIE). Antigen was demonstrated by CIE in 33/48 of these confirmed cases of pneumonia. The technique is easy to use and gives rapid results.

Serum assays of netilmicin by enzyme multiplied immunoassay technique and bioassay: a comparative study

Serum concentration determinations of netilmicin obtained with bioassay and the enzyme multiplied immunoassay technique were compared. There was no statistically significant difference between the precision of the two techniques (P greater than 0.05). When clinical serum was used, a systematic error was demonstrated between the enzyme multiplied immunoassay technique and bioassay.

Penetration of alafosfalin and ampicillin into tissue cage fluid in rabbits

The pharmacokinetics of alafosfalin and ampicillin were studied in rabbits. Serum concentrations were compared to levels in subcutaneous tissue fluid obtained from implanted tissue cages. The concentrations of alafosfalin exceeded those of ampicillin and the drugs were eliminated at similar rates from serum and tissue fluid.

Penetration of 14C-Ro 13-9904 into tissue cage fluid in rabbits

The pharmacokinetics of Ro 13-9904/001 following i.v. injection of 40 mg/kg was studied in a tissue cage model in rabbits. Binding to rabbit serum proteins was determined by ultrafiltration and found to be 98% at a concentration of 100 microgram/ml. In the early post-injection period concentrations of the drug in rabbit serum reached 500-900 microgram/ml, the antibiotic binding capacity of serum proteins was exceeded and the outflow of drug into the tissues was high. Tissue cage fluid (TCF) concentrations increased during 4h, such as to reach a maximum level of about 30 microgram/ml. After 8 h a t1/2 of 15 h was calculated both in serum and TCF. From 36 h onwards the t1/2 was 75 h. After a single injection of 14C-Ro 13-9904/001 radiological activity could be followed in serum and TCF for 7-10 days and in urine for more than 2 weeks. The results are discussed and compared to those from similar experiments with benzylpenicillin and flucloxacillin.

Penetration of ampicillin and dicloxacillin into tissue cage fluid in rabbits: relation to serum and tissue protein binding

The pharmacokinetics of ampicillin and dicloxacillin following intravenous injection was studied in a tissue cage model in rabbits. Serum protein binding was 98.6% for dicloxacillin and 46.7% for ampicillin, and there were no major differences between the degree of binding in tissue case fluid. The highly bound dicloxacillin gave lower but more sustained levels in tissue cage fluid than ampicillin, and showed a very long elimination half-life. The findings suggest that the flow of albumin into the interstitial space could be of importance for the tissue penetration of highly protein bound antibiotics. The results also indicate dose-dependent pharmacokinetics for dicloxacillin.

Comparison of Staphylococcus aureus carriage and skin infection rates in hospital and office employees

The incidence of Staphylococcus aureus in the nose, throat and superficial wound infections of 99 office staff, 129 psychiatry staff and 115 surgical staff was studied over a 4-week period with the purpose of assessing the potential risk to hospital personnel of staphylococcal infection. Incidence rates, both average and cumulative, were essentially similar in the three groups but certain differences in the ecology of the staphylococcal phage groups were observed. Surgical staff appeared to have a more labile pattern of carriage. As in other Scandinavian studies throat carriage rates were high. Staphylococcal carriage seems largely to depend on individual characteristics rather than environmental factors.

Bacterial contamination of urine, collected in fractions from different phases of micturition. A study in healthy women

With a special technique 4-13 consecutive fractions of urine were collected during micturition from 4 female volunteers at together 12 occasions. Quantitative bacterial cultures were performed in 78 urine fractions. Most fractions contained one or several different bacterial strains-generally in small amounts, wheras only 14% were sterile. Fractions from the end of micturition showed on average less bacterial contamination than the earlier portions. No difference was observed between the bacterial counts after cleaning the area around the urethra as compared with the counts without preparation before sampling.