Bacterial pollution of the lagoon of Tunis

The authors present in this paper a study about the bacterian pollution of the lagoon of Tunis based on 120 samples collected in 10 different stations. This study points out that the lagoon is polluted (50.8% of the samples) mostly in autumn and in winter. The pollution is exogenous, chiefly caused by the rain spreading over polluted waters of wastes and of rivers, and also by the action of the winds and of the currents on the sediments hosting microbiological parameters of faecal pollution.     

Bacterial pollution in the coastal waters of the suburbs north and south of Tunis

The inshore waters of Northern and Southern suburbs of Tunis are chiefly polluted aroud urban cities. The pollution increases with temperature, men (touristes and bathers), the actions of wind and currentology.     

Bacterial pollution of the littoral waters of the northern suburbs of Tunis

The authors present in this paper a study of the bacterial pollution of inshore waters of northern suburbs of Tunis, on the basis of 180 sampled collected in 15 different stations, 15 monthly (one for each station). Three districts have been considered: Raouad-Gammarth, La Marsa-Carthage and La Goulette. This last district is mostly submitted to the bacterial pollution, caused by its neighbourhood of the lagoon of Tunis "reserve of pollution" and of the city of Tunis.     

Relationship between temperature and mortality in the city of Tunis: 2005-2007

The influence of thermal stress on health is proved. In the light of the current climate change this relationship should be extensively investigated. This study aims to describe the relationship between temperature and total mortality in the city of Tunis over a period of three years, from 2005 to 2007 using time series analysis. The form of the relation (crude and adjusted) between mortality and temperatures was investigated using Poisson generalized additive models (GAM). Confounders included in the models were pollutant, trend, calendar month, day of the week, the period of Ramadan, and holidays. The adjusted relationship between mortality and temperature was "V" shaped with a steeper slope for low temperatures than for high temperatures. The impact of heat on mortality will be further analyzed to refine our findings and to contribute to the elaboration of guidelines for preventive strategies.     

A serological,parasitological and clinical evaluation of untreated Chagas disease patients and those treated with benznidazole before and thirteen years after intervention

The etiological treatment of Chagas disease is recommended for all patients with acute or recent chronic infection, but controversies remain regarding the benefit of chemotherapy and interpretations of the parasitological cure after etiological treatment. This study compares the laboratory and clinical evaluations of Chagas disease patients who were diagnosed 13 years earlier. Fifty-eight Chagas disease patients (29 treated with benznidazole and 29 untreated) were matched at the time of treatment based on several variables. Conventional serology revealed the absence of seroconversion in all patients. However, lower serological titres were verified in the treated group, primarily among patients who had the indeterminate form of the disease. Haemoculture performed 13 years after the intervention was positive for 6.9% and 27.6% of the treated and untreated patients, respectively. Polymerase chain reaction tests were positive for 44.8% and 13.8% of the treated and untreated patients, respectively. Patients who presented with the indeterminate form of the disease at the beginning of the study exhibited less clinical progression (17.4%) compared with the untreated group (56.5%). Therefore, this global analysis revealed that etiological treatment with benznidazole may benefit patients with respect to the clinical progression of Chagas disease and the prognosis, particularly when administered to patients with the indeterminate form of the disease.     

Bacterial removal of mercury from sewage

Mercury-resistant bacteria, which are able to reduce mercuric ion (Hg(2+)) to metallic mercury (Hg(0)), were examined for their ability to remove mercury from waste-water aerobically. Growth studies in artificial medium indicated that mercury increases the lag phase, but does not effect the growth rate of these bacteria. Further studies demonstrated that growth was minimal during a phase of rapid mercury removal, after which growth resumed. Small but significant amounts of carbohydrates are required for the mercuric ion reduction. Prolonged periods of bacterial growth under nonsterile conditions was accomplished without the loss of the mercuric reducing ability of the culture. A continuous culture of the resistant organism was maintained on raw sewage for two weeks, during which time relatively high concentrations of mercury (70 mg/L) were removed from the sewage at a rate of 2.5 mg/L h and at efficiencies exceeding 98%.     

Bacterial diversity in thermophilic aerobic sewage sludge

Summary Using -amylase as an example, extremely thermophilic Bacilli isolated from heat-treated sewage sludge are shown to be a source for enzymes stable and active at high temperatures. The isolates which are classified as subspecies of Bacillus stearothermophilus differ from each other in protein composition indicating the heterogeneiety of that subspecies. Media are evaluated for good growth and high enzyme productivity. Best media are those composed of three or four different complex components like combinations of peptone, soy grist, and malt extract, -amylase production on simple carbon sources is negligible. From the cultivation supernatants crude -amylase extracts are prepared and their behaviour at high temperatures is described. The optimal temperature of all tested enzymes is 80°C. They are stable at suboptimal temperatures for over 20 h and at 95° C 50% of their activity is lost within 2 h. The activity at 95° C is however preserved for over 3 h in presence of starch. The products of the starch digestion are maltotriose, maltose, and some glucose. The amylases can therefore compete in activity and stability with commercially available -amylases from Bacillus licheniformis.     

Bacterial community composition and function in sewage treatment systems

The application of modern molecular techniques has led to the identification, in situ quantification, and partial ecophysiological characterisation of bacteria responsible for bulking and foaming or for nutrient removal in sewage treatment systems. Unexpectedly, previously unrecognised, yet uncultured bacteria were demonstrated to catalyse nitrogen and phosphorous removal in activated-sludge and biofilm reactors. These findings provide the basis for the development of novel concepts for improving the efficiency and functional stability of waste water treatment systems.     

Bacterial leaching of metals from sewage sludge

Summary Thiobacillus thiooxidans is capable of oxidizing sulfur in digested sludge, while decreasing the pH value from about 5.5 to, say, 1.0 to 1.5. Insoluble metal sulfides can be solubilized through this acidification. Thiobacillus ferrooxidans oxidises pyritic ore in the presence of 6% centrifuged sludge if the pH value is adjusted to about 2.5. When mixing T. thiooxidans and T. ferrooxidans with sludge and 1% sulfur, the former acidifies the sludge and the latter oxidizes metal sulfides; together they solubilize more metal than T. thiooxidans alone. The following metals solubilized from their sulfides have been investigated so far: iron, copper, zinc, nickel, and cadmium. The possibility of recycling metals from sewage sludge with this method is discussed.     

Growth of water hyacinths in treated sewage effluent

Two thousand plants of the water hyacinth,Eichornia crassipes Solms., were introduced on April 11, 1971, into a series of five ponds, each 5000 sq. ft. in area and 2.6 ft. deep. Treated waste water effluent from the Ames sewage treatment plant filled the ponds and was added to pond 1 at 127 gallons per minute. By growth and vegetative reproduction, these plants increased to more than 500,000, and all five ponds were covered completely by July 26. On that date, the extrapolated estimate of total wet weight was 287 U.S. tons/ acre (645 metric tons/hectare; 64500g/m²). The estimate of oven dry weight was 13.2 U.S. tons/acre (29.7 metric tons/hectare; 2970g/m²). Ammonia and nitrate disappeared rapidly from the pond water, and phosphate concentrations were lowered appreciably. Evapotranspiration and seepage accounted for water losses of more than 0.5 inches per day. The potential economic values of this plant and its possible use in tertiary treatment to reduce N and P components in waste waters are discussed briefly.     

Histologic evaluation of L1210 leukemia in treated and untreated mice

Summary BDF₁ mice bearing L1210 leukemia were treated with chemotherapy or in combination with neuraminidase-treated cells and BCG. Histological evaluation was done on these mice at various intervals after therapy in order to determine the rate and extent of metastatic involvement in various tissues and organs. Results were compared to tumor-bearing mice which were not treated. In all animals, tissues were classed as having minimal involvement, moderate involvement or maximal involvement based on a scale of 0 through 4. Results indicated that: (a) mice which were long term survivors did not completely reject their tumor for weeks after treatment with chemotherapy and immunotherapy; (b) complete tumor rejection did not indicate a restoration of normal tissue integrity; and (c) failure of chemotherapy-immunotherapy had no consistent pathology, but was probably due to tumor distribution rather then tumor burden per se.This study was supported, in part, by Contract No. NO1-CB-43864 and Grant No. CA 14460 from the National Cancer InstituteThe Abbreviations used are: BCNU; 1,3-bis-(2-chloroethyl)-1-nitros-ourea; Saline: 0.9% NaCl solution; BCG: Bacillus Calmette-Guerin; C. parvum: Corynebacterium parvum; pfu: plaque-forming units     

克拉玛依市2008年麻疹监测与控制情况分析

分析克拉玛依市麻疹流行状况及预防控制措施,为消除麻疹提供依据。采用描述流行病学分析方法,对2008年克拉玛依市麻疹资料进行分析。结果显示,克拉玛依市2008年麻疹发病率为38.83/10万(138/355381),呈高度散发,较2007年有所上升。发病高峰在3～5月,发病数占全年的83.33%。年龄分布大年龄组高于小年龄组,>20岁年龄组病例占50.00%,<1岁病例占18.84%;流动人口发病占51.11%。应切实提高麻疹常规免疫接种率和做好入托、入学儿童查验预防接种证工作,加强麻疹监测,提高实验室确诊病例的比例。     

Growth of the hydrocarbon-rich microalga Botryococcus braunii in secondarily treated sewage

Summary A hydrocarbon-rich green microalga, Botryococcus braunii, was able to grow well in secondarily treated sewage (STS) from domestic waste-water in a batch system. The growth in STS from domestic waste-water was as good as in the common artificial medium of modified Chu 13 and its hydrocarbon contents were high enough at 53% and 40% compared with 58% in the case of the modified Chu 13 medium. B. braunii utilized nitrate from 7.67 or 4.48 mg/l to a level below detection of < 0.01 mg/l in STS. After this consumption of nitrate, nitrite was consumed, and ammonium was not. Phosphate, even at an extremely low concentration, was also consumed by B. braunii. These results show the possibility of using STS as a medium to grow B. braunii and for removal of nitrogen and phosphorus by algal consumption in STS.Correspondence to: S. Yokoyama