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Pathogens and pesticides are likely to co-occur in honeybee hives, but much remains to be investigated regarding their potential interactions. Here, we first investigated the metabolisation kinetics of thiamethoxam in chronically fed honeybees. We show that thiamethoxam, at a dose of 0.25ng/bee/day, is quickly and effectively metabolised into clothianidin, throughout a 20day exposure period. Using a similar chronic exposure to pesticide, we then studied, in a separate experiment, the impact of thiamethoxam and Chronic bee paralysis virus (CBPV) co-exposure in honeybees. The honeybees were exposed to the virus by contact, mimicking the natural transmission route in the hive. We demonstrate that a high dose of thiamethoxam (5.0ng/bee/day) can cause a synergistic increase in mortality in co-exposed honeybees after 8 to 10days of exposure, with no increase in viral loads. At a lower dose (2.5ng/bee/day), there was no synergistic increase of mortality, but viral loads were significantly higher in naturally dead honeybees, compared with sacrificed honeybees exposed to the same conditions. These results show that the interactions between pathogens and pesticides in honeybees can be complex: increasing pesticide doses may not necessarily be linked to a rise in viral loads, suggesting that honeybee tolerance to the viral infection might change with pesticide exposure.

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ICL670 is a representative of a new class of orally active tridentate selective iron chelators. Two molecules of ICL670 are required to form a complete hexacoordinate chelate Fe-[ICL670]2 with one ferric iron. A simple and rapid HPLC-UV method for the separate determination of ICL670 and Fe-[ICL670]2 in the plasma of iron-overloaded patients is described. Plasma samples were prepared as rapidly as possible, the tubes being kept at 4 degrees C. Plasma proteins were precipitated with methanol. The supernatant was diluted with water and placed on the refrigerated sample rack of an autosampler before injection. The chromatographic separations were achieved on an Alltima C18 column using 0.05 M Na2HPO4 and 0.01 M tetrabutylammonium hydrogen sulfate-acetonitrile-methanol (41:9:50, v/v/v) as mobile phase. The analytes were detected at 295 nm. Calibration and quality control samples were prepared in normal human plasma. The mean accuracy (n=6) over the entire investigated concentration range 0.25-20 microg/ml ranged from 91 to 109% with a coefficient of variation (C.V.) from 4 to 8% for ICL670, and from 95 to 105% with a C.V. from 2 to 20% for the iron complex. The dissociation of the complex during analysis was shown to be marginal. The iron removal from plasma of iron-overloaded patients by free ICL670 during analysis was low. The in vitro iron transfer from the iron pools of iron-overloaded plasma onto ICL670 was shown to be a slow process.

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We evaluated blood pressure profile in a population of 380 untreated hypertensives (210 males, 170 females, stage 1 and 2 JNC 1993) observed consecutively. A 24-hour ambulatory blood pressure monitoring was performed using and A&D TM 2420 model 6 device programmed to measure systolic and diastolic blood pressure every 15 min from 7 am to 10 pm (daytime) and every 30 min from 10 pm to 7 am (night-time). Statistical analysis was carried out by dividing the patients into four groups on the basis of age: Group I, from 26 to 35 years (26 males, 14 females); Group II, from 36 to 45 years (48 males, 39 females); Group III, from 46 to 55 years (85 males, 72 females); Group IV, from 56 to 65 years (51 males, 45 females). Systolic blood pressure was higher in older male hypertensives (56 to 65 years) who also had a persistent systolic blood pressure elevation during night-time (non-dippers); diastolic blood pressure was significantly higher in male hypertensives aged 36 to 55 years.

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The simultaneous determination of CGP 50 068, S(-)-enantiomer (I), its (-)-carboxylic acid metabolite CGP 55 461 (II) and the related (+)-enantiomer CGP 54 228 (III) by stereospecific high-performance liquid chromatography, in human plasma, is described. The three compounds and racemic acebutolol, used as internal standard, were isolated from plasma by liquid-solid extraction on disposable C18 columns. The resolution and determination of I and the two carboxylic acid enantiomers were achieved by direct chromatography using a Chiral-AGP column refrigerated at 5 degrees C. The mobile phase was tetrabutylammonium iodide in a pH 7 phosphate buffer solution used at a constant flow-rate of 0.5 ml/min. The UV detection wavelength was set at 270 nm. The reproducibility and accuracy of the method were found to be suitable over the concentration range 0.56-28.0 mumol/l for II and III and 2.0-26.7 mumol/l for I.

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A fully automated analytical system based on liquid-solid extraction combined with column liquid chromatography is described for the determination of diclofenac in plasma. After addition of pH 5 buffer and the internal standard solution to the plasma sample, both sample preparation via a C18 disposable extraction column and injection were performed by a Gilson ASPEC system. Diclofenac and the internal standard were separated on a reversed-phase column, using methanol-pH 7.2 phosphate buffer (56:44, v/v) as mobile phase at a flow-rate of 0.4 ml/min. The reproducibility and accuracy of the method were acceptable over the concentration range 31-3140 nmol/l in plasma.

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Thirty-two pregnant hypertensive patients were treated with oxprenolol administered in combination with dihydralazine as Trasipressol tablets. Before delivery, oxprenolol was demonstrable in the maternal plasma and the amniotic fluid. The free fraction of oxprenolol in the maternal serum (15% +/- 7.8; mean +/- s.d.; n = 25) was similar to that in normal serum. At the end of delivery, oxprenolol was found in both the maternal and umbilical plasma in most cases. Measurable, but low oxprenolol concentrations were present in the newborn plasma. After delivery, oxprenolol was demonstrable in the maternal plasma and breast milk. An infant weighing 3 kg and consuming 500 ml of breast milk per day would receive a maximum dose 60 times less than the normal daily dose for a hypertensive adult (4 mg/kg).

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A method for the determination of unconjugated phentolamine at concentrations down to 5 ng/ml in human plasma, and of free and total (free plus conjugated) phentolamine down to 25 ng/ml in urine is described. After addition of 2-[N-(p-chlorophenyl)-N-(m-hydroxyphenyl)-aminomethyl]-2-imidazoline as internal standard, both compounds are extracted into benzene-ethyl acetate (1:1, v/v) at pH 10, transferred into an acidic aqueous solution and back-extracted at pH 10 into benzene-ethyl acetate. They are then derivatized with N-heptafluorobutyrylimidazole. The derivatives are determined by gas chromatography using a 63Ni electron-capture detector. In urine, total (free plus conjugated) phentolamine is determined after enzymatic hydrolysis. The technique was applied for the study of the plasma concentrations and urinary elimination after oral administration to man.

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