Cultivation of rice for animal feed with circulated irrigation of treated municipal wastewater for enhanced nitrogen removal: comparison of cultivation systems feeding irrigation water upward and downward.

To achieve enhanced nitrogen removal, we modified a cultivation system with circulated irrigation of treated municipal wastewater by using rice for animal feed instead of human consumption. The performance of this modified system was evaluated through a bench-scale experiment by comparing the direction of circulated irrigation (i.e. passing through paddy soil upward and downward). The modified system achieved more than three times higher nitrogen removal (3.2 g) than the system in which rice for human consumption was cultivated. The removal efficiency was higher than 99.5%, regardless of the direction of circulated irrigation. Nitrogen in the treated municipal wastewater was adsorbed by the rice plant in this cultivation system as effectively as chemical fertilizer used in normal paddy fields. Circulated irrigation increased the nitrogen released to the atmosphere, probably due to enhanced denitrification. Neither the circulation of irrigation water nor its direction affected the growth of the rice plant and the yield and quality of harvested rice. The yield of rice harvested in this system did not reach the target value in normal paddy fields. To increase this yield, a larger amount of treated wastewater should be applied to the system, considering the significant amount of nitrogen released to the atmosphere.

First isolation of West Nile virus in Zambia from mosquitoes.

Mosquito surveillance studies to identify mosquito-borne flaviviruses have identified West Nile Virus (WNV) for the first time in Zambia. The Zambian WNV isolate from Culex quinquefasciatus mosquitoes collected in the Western Province was closely related genetically to WNV lineage 2 South African strains which have been previously shown to be highly neuroinvasive. These data provide the first evidence of the circulation of WNV in Zambia and suggest there should be an increased awareness of possible associated human and animal diseases in that country.

A patient with untreated tongue carcinoma surviving for 15 years.

A rare case of untreated tongue carcinoma survived for 15 years is presented. A 43-year-old Japanese woman was referred to our department with a 1.8 cm x 1.0 cm white and red non-indurated lesion of the left border of the tongue. The histological examination showed a diagnosis of well-differentiated squamous cell carcinoma. We informed the patient and her family that she had a Stage I tongue carcinoma and needed to receive treatment immediately. However, they refused treatment. Fifteen years later, the patient presented again, complaining of a 55 mm x 40 mm painful gradual-growth swelling of the same site as before, and the clinical stage was T3N2aM0 (Stage IV). The patient agreed to receive radical surgery following preoperative chemoradiotherapy this time. Currently the patient has been free of recurrence for 4 years. Clinical and immunohistochemical features of this rare case are presented and discussed.

Effect of acute exposure to cold on the levels of corticosterone and pituitary hormones in plasma collected from free conscious cannulated rats.

To investigate the initial response of the pituitary and adrenal cortex functionings of rats acutely exposed to cold, we developed a technique for cannulation which allowed sequential blood collection from conscious and freed rats. Two cannulae were inserted, one into the carotid artery used for collection and the other into the femoral vein for blood transfusion to keep the blood volume constant. Significant increases in plasma corticosterone and thyrotropin were evoked within 15 min after exposure. While plasma growth hormone (GH) slightly decreased, and the prolactin level tended to fall by 1 hr after cold exposure but the difference was not significant as compared with control values.

Protein modelling using a chimera reference protein derived from exons.

Bovine pancreatic beta-trypsin (PDB ID-code: 1TPO) which is registered in the Brookhaven Protein Data Bank (PDB) consists of four exons. The results of homology searches for each exon in the PDB showed that homologous proteins were tonin (PDB ID-code: 1TON), rat mast cell protease (PDB ID-code: 3RP2__A), kallikrein A (PDB ID-code: 2PKA__B) and kallikrein A (2PKA__B) respectively. Thus, for the three-dimensional structure prediction of 1TPO, a chimera protein was constructed from the three proteins mentioned above and the 3-D structure prediction was performed using this chimera reference protein. The modelled structure of 1TPO was energetically optimized by molecular mechanics and molecular dynamics simulation and was compared with its X-ray crystal structure registered in the PDB. The root mean square deviations (r.m.s.d.) of main chain atoms and the neighbouring active site (5 A sphere from His57, Asp102 and Ser195) between the modelled structure and the X-ray structure were 1.66 and 0.94 A respectively. Porcine pancreatic elastase (PDB ID-code: 3EST) which is registered in the PDB was used as the reference protein and the modelled structure from 3EST was also compared with the X-ray data. The r.m.s.d. of main chain atoms and that of the active site were 2.14 and 1.18 A respectively. These results clearly support the propriety of this method using the chimera reference protein.

Three-dimensional model of the human PAF receptor.

The amino acid sequence analysis of the human platelet-activating factor (PAF) receptor showed that residues thought to be important structurally and functionally were well conserved. This suggested similarities of the three-dimensional structure (3D structure) between the human PAF receptor and other receptors that couple to guanine nucleotide binding (G) proteins. Thus, a three-dimensional model of this receptor was constructed using the 3D structure of bacteriorhodopsin as the reference protein, by means of the BIOCES[E] computer-modeling system. This model has seven alpha-helical transmembrane segments which form a central core and an S-S bond between the second and third extracellular loops. The distance of the S-S bond is about 2 A, which is thought to be reasonable. In the transmembrane domain, the side chains of Asp-63, Asn-285 and Asp-289 became oriented toward the central core and form a negatively charged site. This receptor model suggests that the positively charged choline moiety of PAF is attracted to this negatively charged site by electrostatic forces and that PAF may induce conformational changes in the receptor, leading to G-protein activation.