Addition of Novobiocin in pre-enrichment step can improve Salmonella culture protocol of modified semisolid Rappaport–Vassiliadis

The aim was to investigate the effect of addition of Novobiocin to the non-selective buffered peptone water (BPW) for pre-enrichment of Salmonella in connection with plating on modified semisolid Rappaport-Vassiliadis (MSRV). In a semi-quantitative study, the level of Salmonella following pre-enrichment of 32 presumably naturally contaminated swine fecal samples were assessed for BPW with and without addition of Novobiocin (22 microg/ml). In another experiment, a total of 400 swine fecal samples were screened for the presence of Salmonella spp., in order to compare the performance of the non-selective pre-enrichment broth with BPW made semi-selective by addition of Novobiocin. The semi-quantitative assessment of the Salmonella level showed that addition of Novobiocin in the pre-enrichment step on average increased the level of Salmonella 1.2 log dilution steps. When growth was scored at five levels, 90 samples opposed to 50 yielded a strong positive reading (+++) when Novobiocin was applied. Growth was on average 0.3 scores higher when pre-enriched with Novobiocin. The difference in growth score medians of the two methods was highly significant (Sign test; p<0.001). Despite the increased sensitivity, 13 culture-positive samples were missed when using the Novobiocin-containing BPW. In conclusion, a simple addition of Novobiocin in the BPW pre-enrichment step of fecal samples may facilitate reading and thereby detection of Salmonella on MSRV. The increase of Salmonella in the semi-quantitative study may be caused by a reduction in the number of competitive microorganisms.

Molecular cloning of a functional allatostatin gut/brain receptor and an allatostatin preprohormone from the silkworm Bombyx mori

The cockroach-type or A-type allatostatins are inhibitory insect neuropeptides with the C-terminal sequence Tyr/Phe-X-Phe-Gly-Leu-NH(2). Here, we have cloned an A-type allatostatin receptor from the silkworm Bombyx mori (BAR). BAR is 361 amino acid residues long, has seven transmembrane domains, shows 60% amino acid residue identity with the first Drosophila allatostatin receptor (DAR-1), and 48% identity with the second Drosophila allatostatin receptor (DAR-2). The BAR gene has two introns and three exons. These two introns coincide with and have the same intron phasing as two introns in the DAR-1 and DAR-2 genes, showing that the three receptors are not only structurally but also evolutionarily related. Furthermore, we have cloned a Bombyx allatostatin preprohormone that contains eight different A-type allatostatins. Chinese hamster ovary cells permanently transfected with BAR DNA react on the addition of 4 x 10(-9)M Bombyx A-type allatostatins with a second messenger cascade (measured as bioluminescence), showing that BAR is a functional A-type allatostatin receptor. Southern blots suggest that Bombyx has at least one other BAR-related gene in addition to the BAR gene described in this paper. Northern blots and quantitative reverse transcriptase-polymerase chain reaction of different larval tissues show that BAR mRNA is mainly expressed in the gut and to a much lesser extent in the brain. To our knowledge, this is the first report on the molecular cloning and functional expression of an insect gut/brain peptide hormone receptor.

Evaluation of quality changes in walnut kernels (Juglans regia L.) by Vis/NIR spectroscopy

Storage of walnut kernels in light and at room temperature, as is common practice, is detrimental to their sensory quality and shelf life. This study demonstrates that Vis/NIR spectroscopy, in combination with multivariate data analysis (chemometrics), is a most capable rapid method for monitoring the overall quality deterioration of walnut kernels. Spectral predictions of the sensory attributes nutty and rancid tastes by partial least-squares regression (PLSR) resulted in correlations (r(2)) of 0.77 and 0.86, respectively, whereas with PLSR prediction of the chemical parameter hexanal content a correlation (r(2)) of 0.72 was obtained. The study further establishes that storage in light results in pronounced oxidative changes, especially in walnuts stored at 21 degrees C, whereas dark storage at 5 degrees C results in walnuts without any trace of rancid taste during 25 weeks of storage at accelerated storage conditions (50% oxygen).

[The self-regulation process, adjustment and defense. Interdisciplinary study]

The study of the processes of self-regulation and defense may serve as an example illustrating the interdisciplinary research in psychiatry. Belying on the topography of mental disturbance as described by the systemal method, this study can profit from the findings of animal ethology and oceanographyt++ and thus conceive of the diversity and integration of the defense mechanisms of living systems beloging to different levels in the hierarchy of species. These insights may contribute to a refinement of the analysis of the human defense mechanisms met in psychiatry. As an example of this an analysis of phobic avoidance is related.

Stereotyped behaviour in animals induced by stimulant drugs or by a restricted cage environment: relation to disintegrated behaviour, brain dopamine and psychiatric disease

Stereotyped behaviour can be produced in animals both by stimulant drugs (amphetamine, methamphetamine, cocaine, etc.) and by a restricted cage environment. Strong evidence indicates that the effect of stimulant drugs is mediated through a primary effect on brain dopamine, and further knowledge is now being acquired through studies on dopamine receptors, tolerance and reverse tolerance to amphetamines and the neural connections of dopaminergic sub-systems with other sub-systems in the brain. The forms of stereotypy induced by a restricted cage environment have been compared with other effects of this type of environment on behaviour and general health. This has led to a hypothesis that stereotyped behaviour may function as a survival (or defence) strategy in an unfavourable milieu. Some evidence indicates that brain dopamine is also involved in the mediation of stereotyped behaviour induced by the environment. The relevance of these results in clinical psychiatry is discussed. Stereotypy (and related disintegrated behaviour) is a well known feature of several mental diseases.

Stereotyped behaviour, hyperaggressiveness and "tyrannic" hierarchy induced in bank voles (Clethrionomys glareolus) by a restricted cage milieu

This investigation was originally conceived as a further development of studies made with the "amphetamine model" of psychosis. Since amphetamine itself seemed to be the most important flaw in this model, it was judged promising to study abnormal behaviour in animals elicited without the use of drugs. Bank voles were placed in two different cage milieux, a restricted milieu approaching usual laboratory conditions for experimental animals, and an enriched milieu offering opportunities for satisfaction of natural behavioural (ethological) needs. During an experimental period of 6 months normal behaviours (known from the ethogram of the bank vole) and abnormal behaviours were recorded in eight 5-min observation periods of each cage. Social structure (hierarchy) was studied by the intruder method and social function (peaceful or tyrannic hierarchy) by inspection of the subordinate voles for wounds. Stereotypies, hyperaggressive behaviour and tyrannic hierarchy, replacing normal behaviour and social structure, were seen frequently in the restricted milieu, but only occasionally in the enriched milieu (differences highly significant). It is concluded that these findings indicate possibilities for further development of the basic studies of abnormal behaviour made by means of the "amphetamine model" of psychosis. Opportunities exist for investigation of the interaction of milieu factors with genetic, pharmacological and other factors relevant to the development, prevention and treatment of abnormal behaviour and mental disease.

Relationship between penicillinase production and the in-vitro activity of methicillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin, and cephalothin against strains of Staphylococcus aureus of different phage patterns and penicillinase activity

A total of 157 strains of Staphylococcus aureus of different phage patterns and penicillinase production were investigated for their susceptibility to methicillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin and cephalothin by an agar dilution method. Only strains of the 52, 52A, 80, 81 complex had significantly higher IC-50 values than the rest of the strains. No correlation was found between penicillinase production and the IC-50 values. Penicillinase susceptibility divided the antibiotics into two groups: one including methicillin, oxacillin and cephalothin, and the other included dicloxacillin, cloxacillin and flucloxacillin. Nineteen strains of S. aureus which existed in both a penicillinase producing and a penicillinase non-producing form were examined for susceptibility to the six antibiotics. The difference between penicillinase positive and penicillinase negative variants was especially marked for flucloxacillin and cephalothin. Methicillin induction prior to susceptibility testing had only a minor influence on the results. Investigation of the stability of methicillin and the four isoxazolyl penicillins against penicillinase production by 37 strains of S. aureus showed methicillin to be the most stable antibiotic. This was followed by dicloxacillin, cloxacillin, flucloxacillin, and oxacillin in that order. The order of stability was identical and independent of phage pattern and quantitative penicillinase production.

Rare Gas Diffusion in NaCl

The mobility (diffusion and trapping) of the heavy rare gases Kr, Xe, and Rn in pure and doped NaCl single crystals was measured following ion bombardment to various integrated doses (108 to 2X1016 ions/cm2) and at energies between 30 and 500 keV. No obvious effect of doping on release was found. At low gas concentrations, release was compatible with volume diffusion yielding an acti­vation enthalpy, ΔH, of 1.5 ±0.2 eV. This value was obtained for both very low and very high bombardment energies (≈ 1 and 500 keV) thus indicating that the same release mechanism is operative near the surface and in the bulk material. For this release mechanism, a mobility in small vacancy clusters was suggested. At higher gas concentrations, the release was shifted towards higher temperatures. This retarded release was explained by transient trapping, i. e. by gas-gas or gas-damage interactions, and was shown to have a partially single jump character. Again, the result was the same for low and high bombardment energies.