Pressurised hot water extraction with on-line particle formation by supercritical fluid technology.

In this work, an on-line process for pressurised hot water extraction (PHWE) of antioxidants from plants as well as drying of the extract in one step by particle formation based on the use of supercritical carbon dioxide (SC-CO(2)) has been developed. This process has been called WEPO®, water extraction and particle formation on-line. With this process, dried extracts from onion with the same composition of quercetin derivatives as non-dried extracts have been obtained as a fine powder with spherical particles from 250 nm to 4 µm in diameter. The major compounds present in the extract were quercetin-3,4'-diglucoside, quercetin-4'-glucoside and quercetin. An auxiliary inert gas (hot N(2)) was used to enhance the drying process. Parameters such as temperature (120 °C), SC-CO(2) and N(2) pressures (80 and 12.5 bar, respectively) and flow rate of SC-CO(2) (10 ml/min), have been settled by trial-and-error in order to achieve a fine and constant spray formation. Water content, size and morphology, antioxidant capacity and quercetin content of the particles were studied to evaluate the efficiency of the WEPO process. Results were compared with the ones from extracts obtained by continuous flow PHWE followed by freeze-drying. Results showed that both processes gave similar results in terms of antioxidant capacity, concentration of quercetin derivatives and water content, while only WEPO was able to produce defined spherical particles smaller than 4 µm.

Actions of enflurane, isoflurane, vecuronium, atracurium, and pancuronium on pulmonary resistance in dogs.

The effects of enflurane, isoflurane, vecuronium, atracurium, and pancuronium on pulmonary resistance and heart rate were studied in 30 vagotomized dogs lying supine and anesthetized with chloralose-urethane. None of the five drugs affected pulmonary resistance when the airway was unstimulated. Enflurane and isoflurane significantly attenuated the increase in pulmonary resistance induced by electrical stimulation of the vagus nerves. This effect was dose-dependent and similar for both anesthetics at equivalent multiples of their minimum alveolar concentration. Atracurium significantly (P less than 0.05) enhanced the increase in pulmonary resistance induced by vagus nerve stimulation; vecuronium had no significant effect. Pancuronium, up to a cumulative dose of 0.14 mg/kg, also significantly (P less than 0.05) enhanced the increase in pulmonary resistance induced by vagus nerve stimulation; but this effect was reversed by further increasing the dose. Pancuronium also attenuated the cardiodecelerator response to vagus nerve stimulation in a dose-dependent fashion. The underlying mechanisms for the attenuation of responses to vagus nerve stimulation by enflurane or isoflurane or for the increase in response with atracurium are unknown. Pancuronium at lower doses increases the response most likely by blocking prejunctional muscarinic receptors (M2) that physiologically inhibit vagally mediated increases in pulmonary resistance.

Ventilation and ventilatory CO2 response in children during halothane anaesthesia after non-opioid (midazolam) and opioid (papaveretum) premedication.

The influence of non-opioid (NO) and opioid (O) premedication on ventilation and ventilatory CO2 response was studied in 18 spontaneously breathing children during halothane anaesthesia. Eight patients in Group NO and 10 in Group O were comparable in age, body weight and type of surgery performed. The sedative effect was evaluated and measurements by pneumotachography and in-line capnography were made immediately after induction of sleep, just before the start of surgery, during surgery and after surgery both before and after 3 min of about 2% CO2 inhalation. Immediately after induction the mean value (+/- s.e. mean) of end-tidal CO2 concentration (ETCO2) was 4.86 +/- 0.21% in Group NO and 5.28 +/- 0.22% in Group O. Before and during surgery, minute ventilation (VE) was higher in Group NO (P less than 0.05) mainly due to higher respiratory rates. ETCO2 was similar in the two groups before, during and after surgery. The ratio of VE to CO2 elimination (VCO2) and of dead space (VD) to tidal volume (VT) was higher in Group NO, but ventilatory response to CO2 inhalation immediately before the postoperative period was similar in both groups. It was concluded that opioid premedication resulted in more efficient ventilation during anaesthesia and surgery, and that CO2 response at the end of surgery was maintained in both groups.

Endocrine response to surgery in children after premedication with midazolam or papaveretum.

The effect of two premedications on the sympatho-adrenal and endocrine stress-response to minor surgery under halothane anaesthesia was investigated in 16 children. One group (n = 9) was premedicated with midazolam, 0.1 mg kg-1, and atropine 0.2-0.4 mg i.m. The other group (n = 7) received papaveretum 0.4 mg kg-1 and hyoscine 0.008 mg kg-1 i.m. Plasma concentrations of catecholamines, ACTH and cortisol were measured during undisturbed anaesthesia, during surgery and 15 min post-operatively. There were no differences in catecholamine concentrations between the groups. Prior to surgery, plasma ACTH was significantly lower (P less than 0.05) in the papaveretum group. During surgery, plasma cortisol and plasma ACTH were significantly lower after papaveretum premedication. Post-operatively there were no differences. End-tidal CO2 concentrations were similar in the two groups. It was concluded that the endocrine stress-response immediately after induction of anaesthesia and during surgery was lower after papaveretum than after midazolam premedication.