Safety assessment of Lactobacillus brevis KB290 as a probiotic strain

Lactobacillus brevis KB290 (KB290), a plant-derived probiotic lactic acid bacterium, reportedly improves gut health and stimulates immune function. Here we extensively investigated the geno-, acute, subacute, and subchronic toxicity of KB290 and its bacterial translocation potential. KB290 was non-mutagenic in the bacterial reverse mutation assay by the preincubation method. In the single oral dose toxicity test, KB290 at 10(9) cfu/ml was nontoxic at maximum capacity (20 ml/kg). When 10(8), 10(9), or 10(10) cfu/kg was administered daily to rats by gavage for 2 weeks (subacute assay), we observed no clear treatment-related effect and no evidence of bacterial translocation from the gastrointestinal tract. When it was administered for 13 weeks (subchronic assay), we again observed no clear treatment-related effect and no significant toxicological effect. Based on those results, we consider 10(10) cfu/kg per day, the highest dose tested, to be the no observed adverse effect level (NOAEL). These results suggest that KB290 is safe for human consumption.

Distribution of kerosene components in rats following dermal exposure

The systemic distribution of kerosene components in blood and tissues was analysed in rats following dermal exposure. Four types of trimethylbenzenes (TMBs) and aliphatic hydrocarbons (AHCs) with carbon numbers 9-16 (C(9)-C(16)) were analysed as major kerosene components by capillary gas chromatography/mass spectrometry (GC/MS). The kerosene components were detected in blood and all tissues after a small piece of cotton soaked with kerosene was applied to the abdominal skin. The amounts of TMBs detected were higher than those of AHCs. Greater increases in TMB levels were found in adipose tissue in an exposure duration-dependent manner. The amounts of TMBs detected were only at trace levels following post-mortem dermal exposure to kerosene. These findings suggest that kerosene components were absorbed percutaneously and distributed to various organs via the blood circulation. Post-mortem or ante-mortem exposure to kerosene could be distinguished when the exposure duration was relatively long. Adipose tissue would seem to be the most useful for estimating the degree of kerosene exposure.

Magnetic-field-induced superconductivity in a two-dimensional organic conductor

The application of a sufficiently strong magnetic field to a superconductor will, in general, destroy the superconducting state. Two mechanisms are responsible for this. The first is the Zeeman effect, which breaks apart the paired electrons if they are in a spin-singlet (but not a spin-triplet) state. The second is the so-called 'orbital' effect, whereby the vortices penetrate into the superconductors and the energy gain due to the formation of the paired electrons is lost. For the case of layered, two-dimensional superconductors, such as the high-Tc copper oxides, the orbital effect is reduced when the applied magnetic field is parallel to the conducting layers. Here we report resistance and magnetic-torque experiments on single crystals of the quasi-two-dimensional organic conductor lambda-(BETS)2FeCl4, where BETS is bis(ethylenedithio)tetraselenafulvalene. We find that for magnetic fields applied exactly parallel to the conducting layers of the crystals, superconductivity is induced for fields above 17 T at a temperature of 0.1 K. The resulting phase diagram indicates that the transition temperature increases with magnetic field, that is, the superconducting state is further stabilized with magnetic field.

Entrainment function in the suprachiasmatic nucleus of streptozotocin-induced diabetic rats

The term for re-entrainment to a new light-dark cycle in streptozotocin (STZ)-induced diabetic rats was significantly longer than that in control rats. In STZ-induced diabetic rats, the same level of phase delay in the suprachiasmatic nucleus neuronal firing rhythm was observed in control rats after glutamate application. Therefore, 5-HT function in the hypothalamus is thought to be decreased in STZ-induced diabetic rats. These results suggest that postsynaptic neuronal function is still maintained in the suprachiasmatic nucleus of STZ-induced diabetic rats. Therefore, 5-HT mechanisms may play an important role in the maintenance of this function.

Epidermal growth factor delays gastric emptying and small intestinal transit in suckling rats

Suckling (12-d-old) rats that were fasted for 15 h received epidermal growth factor (EGF) s.c. (0.5 and 1.0 microgram per rat, i.e. approximately 2 and 4 micrograms/100 g of body weight), together with motility markers 51Cr-EDTA or Poly R-478, and were killed 45 min later. Counts were measured separately in the stomach and the small intestine, which was divided into 12 segments. Administration of EGF delayed gastric emptying. In controls, the stomach contained 26.1 +/- 1.6% (mean +/- SEM); in EGF-treated rats the stomach contained 75.9 +/- 10.2% and 75.7 +/- 2.5% of the total 51Cr-EDTA counts given. EGF had the maximum effect (1.0 microgram) when given simultaneously with 51Cr-EDTA. Significant, but lower, effects of EGF were seen with the administration of EGF preceded by 10 min or followed by 10 and 20 min with the administration of 51Cr-EDTA (65.8 +/- 5.8%, 60.0 +/- 6.4%, and 54.1 +/- 4.2%, respectively). Small intestinal transit was also delayed. Administration of anti-EGF antiserum did not affect gastric emptying, but accelerated small intestinal transit as determined 30 min after administration of 51Cr-EDTA. These studies are the first to demonstrate the effect of EGF on gastrointestinal motility in vivo in suckling mammals.

Formation of oligosaccharides from lactitol by Aspergillus oryzae beta-D-galactosidase

Six oligosaccharides were first formed from lactitol by a transgalactosylation reaction catalyzed by Aspergillus oryzae beta-D-galactosidase. From the results of methylation analysis, MS, and 1H- and 13C-NMR studies, it was concluded that these oligosaccharides are O-beta-D-galactopyranosyl-(1----4)-O-beta-D-galactopyranosyl-(1----4)-D- glucitol, O-beta-D-galactopyranosyl-(1----3)-O-beta-D-galactopyranosyl-(1----4)-D- glucitol, O-beta-D-galactopyranosyl-(1----4)-[O-beta-D-galactopyranosyl-(1----6)]- D- glucitol, O-beta-D-galactopyranosyl-(1----6)-O-beta-D-galactopyranosyl-(1---4)- glucitol, O-beta-D-galactopyranosyl-(1----4)-[O-beta-D-galactopyranosyl- (1----5)]-D-glucitol, and O-beta-D-galactopyranosyl-(1----4)-[O-beta-D-galactopyranosyl-(1----1)]- D-glucitol. The last three are newly observed oligosaccharides.