Environmental exposure assessment of fluoroquinolone antibacterial agents from sewage to soil

The behavior of fluoroquinolone antibacterial agents (FQs) during mechanical-biological wastewater treatment was studied by mass flow analysis. In addition, the fate of FQs in agricultural soils after sludge application was investigated. Concentrations of FQs in filtered wastewater (raw sewage, primary, secondary, and tertiary effluents) were determined using solid-phase extraction with mixed phase cation exchange disk cartridges and reversed-phase liquid chromatography with fluorescence detection. FQs in suspended solids, sewage sludge (raw, excess, and anaerobically digested sludge), and sludge-treated soils were determined as described for the aqueous samples but preceded by accelerated solvent extraction. Wastewater treatment resulted in a reduction of the FQ mass flow of 88-92%, mainly due to sorption on sewage sludge. A sludge-wastewater partition coefficient (log Kd approximately 4) was calculated in the activated sludge reactors with a hydraulic residence time of about 8 h. No significant removal of FQs occurred under methanogenic conditions of the sludge digesters. These results suggest sewage sludge as the main reservoir of FQ residues and outline the importance of sludge management strategies to determine whether most of the human-excreted FQs enter the environment. Field experiments of sludge-application to agricultural land confirmed the long-term persistence of trace amounts of FQs in sludge-treated soils and indicated a limited mobility of FQs into the subsoil.     

Particle Size of Whole Meal Rye Bread does not Affect the Digestibility of Macro-Nutrients and Non-Starch Polysaccharides and the Energy Value of Dietary Fibre in Humans

The effect of particle size of whole meal rye bread on the apparent digestibility of macro-nutrients, non-starch polysaccharides (NSP) and energy, the energy value of rye NSP and on faecal weight was studied in balance experiments in seven young women. The whole meal breads were prepared from one single batch of rye milled to two different particle sizes (coarse bread: 50% of particles >2 mm, 90% >1 mm; fine bread: 86% of particles <0·5 mm, 58% <0·2 mm). Two diets containing either coarse (350 g day⁻¹) or fine (377 g day⁻¹) whole meal bread and a low fibre control diet were consumed for 3 weeks each in a 3×3 cross-over design. Relative to the low fibre control diet, digestibility of protein, NSP and energy was significantly lower for the diets containing the whole meal breads. Digestibility of fat was the same for all diets. Partial digestible energy value for each g of NSP from coarse and fine whole meal rye bread was calculated to be −3±7 and 1±5 kJ, respectively. There were no differences between coarse and fine whole meal rye bread in the effects on the parameters measured with the exception on faecal wet weight, which was higher for the coarse bread diet.     

The cost of auditing outpatient records

When patient records are to be auditied in a program designed to assess the quality of medical care rendered, careful consideration must be given to the cost of the system implemented. Structured data collection and a defined treatment plan are advantageous in facilitating the use of nonphysicians for the majority of the audit. A system using checklists to ensure adequate recording of subjective and objective data and a defined treatment plan for a common symptom complex were implemented by physicians and physician's assistants with a patient load averaging more than 1,000 patient contacts per week in a general medical clinic at Duke University Medical Center. Audit was subsequently accomplished at a cost of 96 cents per record. To reduce this cost, more efficient methods of selecting records for audit should be developed.     

Oxytocin analogues with combined high smooth muscle and negligible antidiuretic activities. Investigation of position 7 in neurohypophyseal hormones

The proline residue in position 7 of oxytocin occupies one of the four corner positions in the two beta turns proposed for the preferred conformation of the pituitary hormone. It has been suggested that synthetic modifications of the residues in these corner positions will yield analogues in which one or more of the biological activities of the parent hormone is highly accentuated in terms of potency relative to other activities. In a continued effort to test this hypothesis the following analogues of oxytocin were prepared: [7-glycine]oxytocin, [1-beta-mercaptopropionic acid,7-glycine]oxytocin, [7-alanine]oxytocin, and [1-beta-mercaptopropionic acid,7-alanine]oxytocin. These peptides were found to possess the following specific activities, respectively: rat uterotonic, 65 +/- 2, 355 +/- 3, 22 +/- 1, 123 +/- 4; avian vasodepressor, 5.3 +/- 0.8, 17 +/- 0.4, 4.8 +/- 0.1, 9.8 +/- 0.5; rat antidiuretic, less than0.01, 0.062, 0.081 +/- 0.01, 0.17 +/- 0.01; rat pressor, 0.3, 0.5, 0.4, 0.5 unit/mg. Thus the analogues retain high uterotonic activity but exhibit strongly diminished renal and vascular activities relative to oxytocin. Especially noteworthy is [1-beta-mercaptopropionic acid,7-glycine]oxytocin with its high uterotonic activity but very low antidiuretic and pressor activities. The activity profile of this analogue combined with the fact that it is only slowly enzymatically degraded warrants further investigations of this peptide for clinical applications.     

Fatigue perturbed creep of pure aluminum at ambient temperatures

The creep of 99.999 pct pure aluminum subject to tension-tension cyclic stressing (dynamic creep) has been studied and compared to creep for the peak cyclic stress applied statically (static creep). The creep rate for a cyclic stress of 29.8 to 3.7 MPa was always found to be greater than the creep rate for static application of a stress of 29.8 MPa over the temperature range of 302 K to 348 K. The ratio of the dynamic creep rate to the static creep rate was found to increase with increasing strain and decreasing temperature. The apparent activation energy measured for dynamic creep was less than that measured for static creep. The substructure for dynamic creep is softer than for static creep and probably accounts for the accelerated creep rate and the lower observed activation energy.     

A generalization of a matrix occupancy problem

An extension of the so-called committee problem is discussed in terms of the occupancy of a certain matrix whose row totals are taken as fixed, and whose cell entries are constrained to lie between zero and defined maxima. A statistic is constructed as a function of the column totals and used to test the significance of a column effect, irrespective of row differences. Two special cases when the cell maxima are constant, first within rows and second within columns, yield a covariance matrix for the column totals whose inverse may be found explicitly, and this in turn leads to a relatively simple expression for the test statistic. Applications of this generalized problem to certain health research situations are discussed, and the adequacy of a X2 approximation to the statistic's null distribution is mentioned.     

The microstrain behavior of a bcc Fe-Si-Ti alloy

An investigation of the microstrain behavior of an age-hardenable, ferritic Fe-Si-Ti alloy has been made with the aim of characterizing the deformation processes in the early stages of yielding. In the solution-treated condition the value of the elastic limit obtained of 268 MN/m² after 1 pct prestrain is comparable with published values for Fe-Si alloys. In the aged conditions mechanical hysteresis was detected with zero prestrain and this is attributed to the restoring force on glide dislocations produced by antiphase boundaries in sheared particles. Both the elastic and anelastic limits are strongly dependent on the state of precipitation. In the prepeak and peak aged conditions the anelastic limit exhibits an extremely high dependence on strain. This is attributed to glide dislocations encountering areas of the particle array which are more difficult to penetrate and to the rapidly growing back stress due to dislocation accumulation in the well defined slip bands which are characteristic of deformation of this type of alloy.