Minimum inhibitory concentrations of chlorhexidine- and lactic acid-based teat disinfectants: An intervention trial assessing bacterial selection and susceptibility.

Teat disinfection is a recommended preventive tool to improve udder health and to prevent new intramammary infections. However, side effects are discussed, such as bacterial selection of less-susceptible bacteria with the application of certain teat disinfectants. The objective of this study was to assess the species composition and bacterial in vitro susceptibility by means of an interventive trial. For this purpose, 3 different postmilking teat treatments (disinfection with 0.215% chlorhexidine or 3.5% lactic acid, or control group with no dipping) were applied to 28 cows in a 6-d intervention approach using a split-udder design. Milk samples were taken before and after intervention. Bacteria were cultured and differentiated to species or genus level by MALDI-TOF mass spectrometry. Minimum inhibitory concentrations (MIC) were determined, and MIC changes over time were recorded. Susceptibilities to chlorhexidine and lactic acid were compared between species of the genera Staphylococcus, Streptococcus, Corynebacterium, and others. Species composition changed during the intervention. Under the treatment of chlorhexidine and lactic acid, the proportion of coagulase-negative staphylococci (CNS) decreased. An increased proportion of species belonging to the genus Corynebacterium was observed especially under the application of lactic acid. Although both teat disinfectants were basically effective, isolates differed in their susceptibility to both teat disinfectants. Populations of CNS, Staphylococcus aureus, and Corynebacterium spp. showed significantly lower absolute MIC values for chlorhexidine. Compared with other species, Corynebacterium spp. showed the lowest susceptibility for chlorhexidine as well as for lactic acid. A significant increase in MIC values after 6 d of intervention was observed with the lactic acid treatment in all isolates, as well as in CNS. This increase can be interpreted as either adaptation of isolates or displacement of more-susceptible species by less-susceptible species. Further studies using long-term intervention might reveal more pronounced effects on MIC values and species composition.

Excessive sugar intake alters binding to dopamine and mu-opioid receptors in the brain.

Palatable food stimulates neural systems implicated in drug dependence; thus sugar might have effects like a drug of abuse. Rats were given 25% glucose solution with chow for 12 h followed by 12 h of food deprivation each day. They doubled their glucose intake in 10 days and developed a pattern of excessive intake in the first hour of daily access. After 30 days, receptor binding was compared to chow-fed controls. Dopamine D-1 receptor binding increased significantly in the accumbens core and shell. In contrast, D-2 binding decreased in the dorsal striatum. Binding to dopamine transporter increased in the midbrain. Opioid mu-1 receptor binding increased significantly in the cingulate cortex, hippocampus, locus coeruleus and accumbens shell. Thus, intermittent, excessive sugar intake sensitized D-1 and mu-1 receptors much like some drugs of abuse.

Astigmatism-corrected gratings for plane grating-spherical mirror spectrographs.

In order to take full advantage of modern, multiple-element detectors, the astigmatism in traditional plane grating instrument designs must be significantly reduced. Slight cylindrical distortions of the plane grating are shown to correct astigmatism near the plane of dispersion without significantly altering spectral resolution. Basic geometrical theory for all in-plane systems is presented. Extensions to other slight distortions such as anticlastic or toroidal surfaces are given. Limitations imposed by image degradation away from the plane of dispersion are discussed. Ray traces of a representative system are explored. Results and images from a test system that incorporates a cylindrical grating made from a plane master grating are presented.

Stigmatic monochromator design using spherical, normally ruled concave diffraction gratings.

A new system of mounting design for concave diffraction gratings is described. The rules of the system, as applied to spherical gratings, are derived from published theory.

Isomorphic patient management problems: a method of creating equivalent problem-solving tests.

Multiple choice format pre- and post-tests have a high likelihood of being equivalent (i.e. parallel) if well-known guidelines are followed. In the absence of such guidelines for pre- and post-tests of problem-solving, the authors devised a simple method of creating problems that are likely to be equivalent. The method was employed with patient management problems (PMPs) and focuses on maintaining the same form or structure of the problems while making the problems appear different to the examinee. Such problems are 'isomorphic'. The equivalence or parallelism of 10 PMPs with their isomorphic counterparts was demonstrated. The method for creating isomorphic PMPs appears to be applicable for creating equivalent pre- and post-tests composed of problems other than PMPs.