Root Uptake and Xylem Translocation of Pesticides from Different Chemical Classes

A pressure-chamber technique was used to study the root uptake and xylem translocation of some fungicides, herbicides and an insecticide from different chemical classes in detopped soybean roots. Physiological parameters such as K⁺ leakage from roots, K⁺ concentrations in the xylem sap, and protein and ATP levels in the root cells were measured so as to evaluate any potential damage of this technique to the root system. HPLC was used to quantify the compounds in the xylem sap. The pressure-chamber technique has proved useful to study the root uptake and translocation of pesticides, does not damage the root system, and allows one to obtain appreciable volumes of xylem sap that can be analysed directly by HPLC, thus avoiding dependence on the availability of radio-labelled compounds. The concentration of each pesticide in the xylem sap showed a steady-state kinetic profile. Non-linear regression analysis was used to calculate the steady-state concentration and the time required to achieve 50% of the steady-state concentration (TSSC₅₀). TSSC₅₀ was well correlated with log K_ow; the more lipophilic the compound the more time was required to reach the steady-state concentration. The efficiency of translocation was assessed by the transpiration stream concentration factor (TSCF) and a non-linear relationship between TSCF and log K_ow was observed. The highest TSCF values were measured for those compounds with log K_ow values around 3, a lipophilicity value similar to that reported earlier in an analogous experiment with detopped soybean plants but slightly higher than that reported in earlier experiments with intact barley plants. Lower TSCF values were obtained with chemicals with log K_ow values below as well as above 3. © 1997 SCI.     

Selective modulation of P-glycoprotein activity by steroidal saponines from Paris polyphylla

Bio-guided fractionation of the roots of Paris polyphylla (Trilliaceae), based on inhibition of P-glycoprotein-mediated daunorubicin efflux in K562/R7 cell line, led to isolation and identification of the three saponins 3-O-Rha(1-->2)[Ara(1-->4)]Glc-pennogenine, gracillin and polyphyllin D, and the two ecdysteroids 20-hydroxyecdysone and pinnatasterone. These compounds were tested for multidrug reversion on P-glycoprotein (ABCB1) with both drug-selected and transfected cell lines, and also on Breast Cancer Resistance Protein (BCRP/ABCG2). By contrast to a weak efficiency on BCRP, the three saponins displayed significant effects as inhibitors of P-glycoprotein-mediated drug efflux.     

Mediterranean diet in relation to body mass index and waist-to-hip ratio

OBJECTIVE: The Mediterranean diet is rich in fat and starch, and hence may be related to overweight. We therefore investigated the relationship between adherence to a Mediterranean diet and body mass index (BMI) and waist-to-hip ratio (WHR). DESIGN AND SETTING: Data were obtained from the control group of a network of case-control studies on cancer conducted in major teaching and general hospitals in four Italian areas between 1991 and 2002. An interviewer-administered validated 78-item food-frequency questionnaire was used to obtain information on the subjects' habitual diet. Information on socio-economic factors, lifestyle habits and anthropometric measures was also collected. A Mediterranean diet score (MDS) was derived on the basis of eight characteristics of the Mediterranean diet. SUBJECTS: Subjects were 6619 patients (3090 men, 3529 women) admitted to hospital for a wide spectrum of acute, non-neoplastic conditions, unrelated to known risk factors for cancer and long-term modifications of diet. RESULTS: In multiple linear regression models adjusted for age, study centre, education, tobacco smoking, occupational physical activity and total energy intake, the MDS was not related to BMI (beta = 0.05 for men and -0.04 for women) or WHR (beta = 0.000 and 0.001, respectively) in both sexes. CONCLUSIONS: Adherence to the major characteristics of the Mediterranean diet is unrelated to BMI and WHR, confirming previous data from Greece and Spain.     

Admissions test for the degree course in veterinary medicine in Italy, 2005

In Italy, access to the degree course in veterinary medicine is regulated each academic year by a government decree that sets the maximum student intake number for each of the 14 existing faculties. Candidates are selected by means of a multiple-choice test on the following subjects: logic and general knowledge, biology, chemistry, physics, and mathematics. Data for the 2005/2006 academic year are presented here. Overall, 4,495 candidates took the test and 1,415 (31.5%) qualified. The questions relating to physics and mathematics were more difficult than those in other subjects (p < 0.001). Logic and general knowledge was the subject in which candidates' knowledge was best. Separate data for each of the 14 Italian faculties are presented, along with the cut-off score for admission. In addition, a "difficulty admission index" has been calculated for each faculty centre.     

Continuous and pulse feedings of urea as a nitrogen source in fed-batch cultivation of Spirulina platensis

Spirulina platensis was autotrophically cultivated by fed-batch addition of urea as a nitrogen source. Continuous and pulse feeding regimes of this nitrogen source (time intervals of 24 h) were compared using a constant mass flow rate. Both series of experiments were carried out at three different temperatures (25, 28 and 31 °C) and total times of urea addition (12, 15 and 18 days), according to a 2² simple factorial design, and the effects of these variables on the nitrogen-to-cell conversion factor and cell productivity were verified by analysis of covariance (ANCOVA). The intermittent addition of urea yielded results similar to those obtained by the continuous feeding, therefore, the former operation mode would be preferable to reduce the production costs of this cyanobacterium in large-scale facilities.