An improved method for the automated determination of urine calcium.
The problems of accurately determining urine calcium are described. The basic technique described is little changed from that originally used by Clark and Collip but the pitfalls encountered when applying this to automated procedures are demonstrated and a means of overcoming them proposed.
The accuracy of commercial calibration sera and assayed control sera.
Commercial calibration sera and assayed control sera have been extensively studied in parallel runs. An attempt has been made to assess the accuracy of the stated values of these sera, using mehtods that in two major quality control schemes have been shown to be reliably accurate. The Technicon product has proven to be generally the most reliable of the calibration sera. Many discrepancies were found in the assayed control sera values, particularly for calcium, phosphate and bilirubin, and our results indicate that the products of some manufacturers need to be improved.
The Elements of Qualitative Chemical Analysis with Special Consideration of the Application of the Laws of Equilibrium and of the Modern Theories of Solution
chyme, however, is soon neutralized by the alkaline bile and pancreatic juices, and then the free acid in the stomach produces again an inhibition of the sphincter tonus and another quantity of chyme is driven out. This hypothesis has been tested by Cannon in numerous ways. He has shown, for example, that anything which delays the appearance of free acid delays the onset of the discharge from the stomach; that hastening the appearance of free acid hastens the time of discharge; and by means of a fistula, he was able to observe that the appearance of free acid closely precedes the first gastric discharge into the duodenum. In addition, Cannon showed that free acid causes opening of the pylorus in the excised stomach of a cat, thus proving that the control of the pylorus is independent of the central nervous system and resides probably in the local nerve plexus. Free acid, therefore, above the gastric sphincter causes it to relax, and this explains why carbohydrates leave the stomach much earlier than proteids, for both these foodclasses stimulate the secretion of gastric juice, as Pavlov has shown, but the proteids unite with the acid as it is produced, forming acid albumen; there is thus no free acid available for a considerable period of time, and, as shown above, free acid is necessary to cause a relaxation of the pylorus. There is no such difficulty with carbohydrates; as soon as the free acid appears the pylorus relaxes, and the crackers, potato-mush, or whatever carbohydrate was fed, is at once transferred to the gut by the peristaltic waves of the stomach. The evidence that free acid below the sphincter, in the duodenum, causes closure of the pylorus, is just as conclusive, for various investigators had shown that acid in the duodenum slows the output of chyme from the stomach, and this must be due to an effect on the pylorus, for Cannon demonstrated that gastric peristalsis was not stopped during this condition. Another support was furnished by the observation of Pavlov that acid solutions leave the stomach much more slowly in dogs with a pancreatic fistula than in normal animals. This is easily explained by the 895