Determination of (226)Ra in produced water by liquid scintillation counting

It is proposed a method for the determination of (226)Ra in offshore platform liquid effluent samples (produced water). The method is based on a two-phase liquid scintillation counting system and allows for the direct and simple determination of (226)Ra content. Samples with high barium content may also have high (226)Ra concentration. Therefore, the sample volume is based on the barium concentration and ranges from 10 mL to 100 mL. Our new method was tested using multiple real samples and was compared with the BaSO4 precipitation method. The results based on the LSC were 30% higher than the precipitation method, which is attributed to the self-absorption of alpha particles in the BaSO4 precipitate. The determination of both (226)Ra and (228)Ra in the liquid effluent of offshore oil platforms is mandatory in Brazil. Thus, a second method of accurately assessing (228)Ra content remains necessary.

[Pulmonary adiaspiromycosis: casual finding in a patient who died of yellow fever]

During an outbreak of yellow fever (rural form of the infection) occurred recently in the State of Goiás, Brazil, a patient, with clinical manifestations suggestive of the infection, died in the University Hospital of Brasilia, DF, on the fifth day from admission. Postmortem examination revealed, microscopically, the characteristic alterations of the infection, and discovered in the lungs and hilar lymph nodes round microrganisms identified as adiaconidia of Emmonsia parva var. crescens.

Effect of cholecalciferol treatment on the relaxant responses of spontaneously hypertensive rat arteries to acetylcholine

We studied the effect of oral cholecalciferol treatment on the endothelium-dependent vascular relaxation and hyperpolarization induced by acetylcholine (ACh), which is impaired in spontaneously hypertensive rats (SHR). Adult female SHR and normotensive Wistar-Kyoto rat (WKY) controls received 125 microg of cholecalciferol per kilogram body weight per day for 6 weeks. The responses to ACh of the isolated mesenteric vascular bed and mesenteric artery rings were measured, as well as the smooth muscle cell membrane potential. After cholecalciferol treatment, the systolic blood pressure and basal perfusion pressure of the mesenteric vascular bed of the SHR fell to control levels. The relaxant and hyperpolarizing effects of ACh, which are reduced in SHR, were also brought to control levels after cholecalciferol treatment. These effects of ACh were inhibited by N(omega)-nitro-L-arginine in SHR and by apamin in WKY. After cholecalciferol treatment, SHR hyperpolarizing responses showed the same inhibition pattern as those of WKY. This indicates that, after cholecalciferol treatment, SHR vascular mesenteric preparation responses to ACh are mediated by endothelium-derived hyperpolarizing factor, which induces activation of Ca(2+)-dependent K(+) channels, as in WKY. In untreated SHR, the ACh-mediated response is entirely due to ACh acting via the release of nitric oxide.

Effect of treatment with cholecalciferol on the membrane potential and contractility of aortae from spontaneously hypertensive rats

1. The diet of spontaneously hypertensive rats (SHR) and normotensive Wistar rats (NWR) was supplemented with 12.5 micrograms cholecalciferol per 100 g body weight daily, by gavage, for 4 weeks. 2. The amplitude of the contractile responses of aortic rings from SHR to potassium and adrenaline, which was smaller than in NWR aortae, was increased after treatment with cholecalciferol. No further changes were observed in the responses of NWR and SHR aortae in the presence of 100 nM apamin. 3. The membrane potentials of aortae from SHR, which were higher than those of aortae from NWR, decreased after treatment with cholecalciferol. Further depolarization was observed in aortic rings from NWR, but not in aortic rings from SHR, after their preincubation with 100 nM apamin. 4. It is concluded that cholecalciferol normalizes the membrane potential and contractility of aortae from SHR, probably through an effect on lipid composition and structure of the plasma membrane.

Dual effect of clonidine on mesenteric artery adrenoceptors: agonistic (alpha-2) and antagonistic (alpha-1)

The effect of clonidine on the mesenteric vascular bed and the isolated mesenteric artery was examined in preparations in which tonus was induced by norepinephrine or endothelin. In preparations precontracted by norepinephrine, clonidine caused a relaxation which was not inhibited by the alpha-2 antagonists yohimbine and idazoxan or by the K+ channel blockers apamine, tetraethylammonium and glibenclamide. In preparations precontracted with endothelin, clonidine increased the depolarization and induced a contraction. Both these effects were inhibited by prazosin. In isolated mesenteric arteries, norepinephrine cause a significant depolarization that was inhibited by clonidine or prazosin. On the other hand, clonidine caused a hyperpolarization which was inhibited by idazoxan or yohimbine, but not by prazosin. This hyperpolarization was also abolished by apamine, tetraethylammonium and glibenclamide. It is concluded that clonidine acts on alpha-1 adrenoceptors as a partial agonist, causing relaxation of the mesenteric artery precontracted with norepinephrine or contraction of preparations precontracted with endothelin. Moreover, clonidine can open K+ channels and hyperpolarize the plasma membrane of mesenteric artery by acting on alpha-2 adrenoceptors.

Effect of treatment with vitamin D3 on the responses of the duodenum of spontaneously hypertensive rats to bradykinin and to potassium

1. The diet of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) and Wistar (NWR) rats was supplemented with either 2% calcium lactate in the drinking water or 12.5 micrograms vitamin D3 100 g-1 body weight daily by gavage, for 14 days. 2. The blood pressure of the SHR treated with either calcium or vitamin D decreased to the same levels as that of WKY and NWR. 3. The response to bradykinin of the SHR isolated duodenum, which is predominantly contractile, upon treatment with vitamin D (but not with calcium), became predominantly relaxant, approaching the normal behavior of the WKY and NWR duodenum. 4. The relaxant responses of the SHR and WKY duodenum to potassium were smaller than those of NWR, but treatment with vitamin D increased the response in all three rat strains. 5. It is concluded that, besides sharing the hypotensive effect of calcium, vitamin D treatment of SHR has an effect on the duodenum smooth muscle which might be due to calmodulin-dependent activation of calcium-dependent potassium channels.