Investigation of Coxiella burnetii contamination in commercial milk and PCR method for the detection of C. burnetii in egg

A total of 244 milk samples collected from supermarkets in Tokyo were examined for contamination with Coxiella burnetii. C. burnetii DNA was detected in 131 (53.7%) of the samples by nested PCR. PCR-positive samples were injected into immunosuppressed A/J strain mice. Of the 22 PCR-positive milk samples tested, none resulted in isolation of C. burnetii from the mice. Heat-treatment was sufficient to inactivate C. burnetii in commercial milk. In addition, a PCR detection method for C. burnetii in chicken egg was developed. Egg yolk was added to an equal volume of 1 mol/L of NaCl phosphate buffer and homogenized for removal of protein and lipid. After centrifugal separation, the supernatant was removed, and template DNA in the precipitate was extracted using SDS, proteinase K and NaI. Using such prepared samples, 3.2 x 10(1) C. burnetii particles in 1 g of egg yolk could be detected by nested PCR. All of 200 chicken egg samples collected from supermarkets in Tokyo were negative for C. burnetii by the nested PCR method.     

New estimation methods of bacterial concentration by measuring ATP changes during incubation

New estimation methods of bacterial cell concentration in samples by measurement of the increase in bacterial adenosine-triphosphate (ATP) content during incubation using a conventional firefly luminometer were established. When an Escherichia coli cell suspension was incubated in nutrient broth, the increase in the ATP content of the suspension during the incubation period followed a sigmoidal curve. The increase ratio of the ATP content of the suspension at a given period of incubation (5 hours in this study) to the initial ATP content was greater at higher initial cell concentrations. With this relationship, the initial cell concentration of a test suspension could be predicted from the measured ratio; this was called the end point method. On the other hand, the lag period in the ATP increase curve was longer at lower initial cell concentrations. A highly linear relationship was observed between the lag period and the logarithm of the initial cell concentrations. Based on this relationship, a delay method was developed for prediction. The two relationships were also observed for bacterial suspensions of Klebsiella sp., Staphylococcus aureus, Bacillus subtilis, and Pseudomonas sp. These results suggested that the two methods have the potential to estimate the bacterial cell concentration of a sample suspension.     

A new logistic model for bacterial growth

A new logistic model for bacterial growth was developed in this study. The model is based on a logistic model, which is often applied for biological and ecological population kinetics. The new model is described by a differential equation and contains an additional term for suppression of the growth rate during the lag phase, compared with the original logistic equation. The new model successfully described sigmoidal growth curves of Escherichia coli and Salmonella under various initial conditions. Data for E. coli were obtained from our experiments and data for Salmonella from the literature. When the new model was compared with a modified Gompertz model, which is widely used by many predictive microbiology researchers, it proved to be superior to the Gompertz model. Further, Salmonella growth at varying temperature could be well simulated by the new model. These results indicate that the new model will be a useful tool to predict bacterial growth under various temperature profiles.     

Bonding mechanism between alumina and niobium

Diffusion couples of Al₂O₃ single-crystal, sapphire, and Nb polycrystal were heat-treated in the temperature range 1873 to 2073 K under pressure in the range 3 to 15.2 MN m^–2 for various times up to 3.6×10³ sec. Tensile testing at various temperatures up to 1873 K in a vacuum of about 10^–3 Pa, Knoop hardness testing at room temperature, optical microscopy, scanning electron microscopy, transmission electron microscopy, and electron-probe X-ray microanalysis studies were carried out on the specimens. From the results, it was concluded that the fairly high bond strength of a Al₂O₃-Nb interface might be attributed to the formation of a thin NbO _x layer, which had grown epitaxially on the Al₂O₃ surface. Lattice matching between Al₂O₃ and NbO _x phases was also considered.     

Structural observations of the interface of explosion-bonded Mo/Cu system

The structure of the interface of explosion-bonded Mo/Cu system has been examined by optical and electron (TEM, AEM) microscopy. Molybdenum and copper can be directly bonded along the flat interface without a diffusion zone, but only on the copper side of the interface is a thin (about 10 m thick) bond layer, which consists of very fine subgrains with an ill-defined boundary. The microstructure in the bond layer is generated by severe dynamic deformation due to jetting and subsequent recovery with frictional heating. On the molybdenum side, originally-existing and elongated subgrains are observed just adjacent to the interface, even after bonding. These results indicate that jetting can occur only on the copper side, with a strength much lower than molybdenum because bonding must be carried out at an impact pressure as low as possible to avoid cracking of molybdenum as well as melting of copper during welding.     

Numerical investigation of spray combustion in jet mixing type combustor for low NOx emission

The present paper describes a numerical investigation of spray combustion in a jet mixing type combustor. In this combustor, kerosene spray was injected with a pressure atomizer, and high speed combustion air was introduced towards the spray flow through some inlet air nozzles to improve mixing of the spray and the air. In the numerical simulation, the conservative equations of mass, momentum and energy in the turbulent flow field were solved in conjunction with the k–ε two equation turbulence model. The effects of the diameter and the number of air inlet nozzles on the combustion behavior and NO emission were numerically investigated. When the diameter of the inlet air nozzle decreased from 8 to 4 mm, the calculated NO mole fraction in the exhaust gas was drastically decreased by about 80%. An increase in the inlet velocity resulted in improvement of the mixing of the spray and the air, and hence, the high temperature region where thermal NO was formed became narrow. As a result, the exhaust NO mole fraction decreased. Furthermore, a decrease in exhaust NO mole fraction was explained by a decrease in the residence time in the high temperature region above 1800 K.     

Poly(ADP-ribose) Polymerase 1 Mediates Rab5 Inactivation after DNA Damage

Parthanatos is programmed cell death mediated by poly(ADP-ribose) polymerase 1 (PARP1) after DNA damage. PARP1 acts by catalyzing the transfer of poly(ADP-ribose) (PAR) polymers to various nuclear proteins. PAR is subsequently cleaved, generating protein-free PAR polymers, which are translocated to the cytoplasm where they associate with cytoplasmic and mitochondrial proteins, altering their functions and leading to cell death. Proteomic studies revealed that several proteins involved in endocytosis bind PAR after PARP1 activation, suggesting endocytosis may be affected by the parthanatos process. Endocytosis is a mechanism for cellular uptake of membrane-impermeant nutrients. Rab5, a small G-protein, is associated with the plasma membrane and early endosomes. Once activated by binding GTP, Rab5 recruits its effectors to early endosomes and regulates their fusion. Here, we report that after DNA damage, PARP1-generated PAR binds to Rab5, suppressing its activity. As a result, Rab5 is dissociated from endosomal vesicles, inhibiting the uptake of membrane-impermeant nutrients. This PARP1-dependent inhibition of nutrient uptake leads to cell starvation and death. It thus appears that this mechanism may represent a novel parthanatos pathway.     

A case of multiple early gastric cancer showing complete response to UFT-E after endoscopic mucosal resection

The aim of this study was to investigate whether MR imaging of trabecular bone structure using magnetic inhomogeneity measurements is related to the amount of bone mineral in human vertebrae. Weight, bone mineral content (BMCDXA), bone mineral per area (BMADXA) and bone mineral density (BMDCT) were determined in 12 defatted human lumbar vertebrae (L2-L4) by weighing, dual X-ray absorptiometry (DXA) and CT. Inhomogeneity caused by susceptibility differences between trabecular bone and surrounding water was studied with MR imaging at 1.5 T using the GESFIDE sequence. The pulse sequence determines the transverse relaxation rate R2(*) and its two components, the non-reversible transverse relaxation rate (R2) and the reversible transverse relaxation rate (R2'; i. e. relaxation rate due to magnetic susceptibility) in a single scan. Voxel size was 0.9 x 1.9 x 5.0 mm. Positive significant correlations between R2' and weight, BMCDXA, BMADXA and BMDCT were observed (r > 0.61 and p < 0.05 for all). Unexpectedly, R2 was also positively correlated with weight, BMCDXA and BMDCT (r > 0.66 and p < 0.05 for all), but not with BMADXA. Thus, R2' measurements are related to the amount of bone mineral, but they also provide information which is not obtainable from bone mineral measurements.     

Flavor production from a non-stick oil by moulds

Natural flavor was accidentally produced from rice cake products in Japan. A non-stick oil had been sprayed on the products during the production process. It was found that a Penicillium corylophilum strain, a contaminant of the oil, produced the flavor from the oil. The ingredients of the flavor were four volatile substances, 2-heptanone, 2-nonanone, 2-heptanol, and 2-nonanol. Challenge tests with the mould strain in a rice cake system were performed under various conditions. The volatile substances were produced in the largest amounts at 25 degrees C, followed by 20 or 30 degrees C then 10 degrees C. 2-Heptanone was produced most remarkably at 25 degrees C, followed by 2-nonanone, 2-heptanol, and 2-nonanol. The growth patterns of the mould were similar between 20-30 degrees C, and the growth at 10 degrees C was delayed. The non-stick oil itself had neither flavor nor volatile substance. The flavor was also produced from coconut oil, which was one of the materials of the non-stick oil. No bacteria or yeasts tested produced any flavor from the non-stick oil, whereas most of the moulds tested produced flavor components.