Effect of disinfectants on stability and transmissibility of R-plasmid in E. coli isolated from drinking water.

Drug resistant enteropathogenic E. coli (EPEC, 086 serotype) isolated from contaminated piped drinking water supply (Fecal coliform 160/100 ml) was studied for effect of disinfectants (chlorine and UVB) on stability and transmissibility of R-plasmid. The strain was resistant to streptomycin and bacitracin and tolerant to multiple metal ions of Cd, Cr, Co, As, Ni, Zn and Hg. A plasmid of molecular size of 3.7 Kb was detected in the organism. After exposure to sublethal doses of disinfectants, complete elimination of resistances to streptomycin and Cr was observed. Partial loss of resistance to Hg due to chlorine was detected. Although UVB did not effected the pattern of transmissibility effect on frequency of transfer was observed. Surprisingly, in UVB irradiated cells, significantly enhanced rate of transfer was noted.

Effect of ozone on the viability of some protozoa in drinking water

In this study, water samples from household tanks in several districts of Alexandria were examined for protozoa contamination and studying the effect of ozone and chlorine on their viability. The parasitic protozoa encountered were Giardia, Cryptosporidia, Blastocystis, Cyclospora and Microsporidia. Distilled water was treated by ozone or chlorine. Ozonated water samples were prepared at a concentration of 1 ppm after contact times with ozone of three, five, seven and nine minutes. Chlorine concentrations were 4 and 8 ppm. Parasites were incubated overnight at room temperature with the treated distilled water. The viability of the parasites was assessed by examining the intestinal sections of the infected animals

Ultraviolet, chlorine and ozone disinfection of some enteroviruses in drinking water and treated effluents

The inactivation efficiency of chlorine, ultraviolet light and ozone were determined for poliovirus type 3, Coxsackievirus type B4 and Hepatitis A virus in drinking water and treated effluent. Ultraviolet was more efficient than the other two disinfectants at wave length 254 rim where no infective virus was detected after 4 mm of UV irradiation in both drinking water and treated effluent. Inactivation by chlorine dose more than 25 mg/L was sufficient for studied viruses in both drinking water and treated effluent. Also virus- seeded drinking water was exposed to ozone for 18 min at ozone rate of 319 mg/L/h to obtain the maximum inactivation of PV3, CoxB4 and HAV but about 20 min of ozone exposure was needed for treated effluent. Physico-chemical parameters were measured before and after disinfection assay. No significant changes were observed

Açäo de diferentes sais sobre algumas propriedades texturais do gel (kamaboko) de surimi de sardinha / Action of differents salts on some properties of sardine surimi characteristics

O efeito de diferentes concentraçoes de alguns sais de cloro e de pirofosfato de sódio em algumas propriedades do gel de surimi de sardinha foi estudado. O emprego de MgCl2 incrementou a força do gel do surimi comparativamente ao NaCl (na mesma força iônica), enquanto o emprego de KCl resultou em gel de pior qualidade. Este comportamento foi observado para ambos os tratamentos térmicos empregados: cozimento direto (90 graus Celsius/30 min.) ou "incubaçao + cozimento (40 graus Celsius/30 min + 90 graus Celsius/30 min.) A força do gel mostrou ser fortemente influenciada pelo tratamento térmico empregado, enquanto a capacidade de retençao de água do gel mostrou-se dependente do tipo de sal empregado, porém, nao foi afetada pelo tipo de tratamento térmico. A substituiçao parcial do NaCl por MgCl2 resultou em gel de boas características texturais, e a adiçao de polifosfato de sódio, nos níveis empregados neste trabalho, nao resultou em melhora das propriedades estudadas, sendo mesmo prejudicial ao nível de capacidade de retençao de água.

Cuidados e anti-sepsia da cavidade bucal / Methods of asepsis and antisepsis related to oral procedures

Os autores apresentam os principais cuidados relacionados a procedimentos de anti-sepsia na cavidade bucal, abordando esterilizaçäo dos instrumentos e materiais usados, desinfecçäo, anti-sepsia e proteçäo individual. Os principais anti-sépticos utilizados na cavidade bucal säo a cloro-hexidina e os compostos da polivinilpirrolidona associados ao iodo

Effect of Na+ and Cl-on the velocity of propagation of the spreading depression in chick retina

The chick retina in vitro preparation was used to quantify the effect of Na+ and Cl- on the velocity of propagation of spreading depression (SD). The progressive reduction of chloride concentration in the superfusing Ringer solution, solution, either by partial removal of NaCl or by its partial substitution with isethionate, caused a logarithmic increase in the velocity of propagation of SD. Substituting Tris for Na+ had no appreciable effect on propagation velocity, suggesting that the propagation of the reaction is not necessarily dependent con Na+. Howeverm choline did not substitute for Na+ because it decreased propagation velocity and, at higher concentration, even blocked the spread of the reaction