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A simple, specific, sensitive, and speedy test for glucose in urine has been described. This enzymatic test based on the activity of glucose oxidase and peroxidase is called Clinistix. Data are presented to show that the test has a high accuracy with both positive and negative specimens.

A simplified analytical procedure for the determination of guanase in serum or plasma at 245 mµ is described. Effects of experimental hepatic injuries in dogs on serum guanase levels and the possible clinical utility of the enzyme serum guanase are also discussed.

A color reaction of protein has been formulated into two simple colorimetric tests for protein in urine; one is a tablet test, consisting of a salicylate buffer and bromphenol blue, and the other is a strip test, consisting of a paper strip impregnated with a citrate buffer and tetrabromphenol blue. The basic principle in both tests is that of "protein error of indicators." Experiments with approximately 5000 urines, taken from both hospital patients and normal subjects, reveal that these tests are simple, rapid, accurate, sensitive, specific, and capable of being used with turbid urines.

Results are presented of a comparative study of several methods for detection of ketone bodies in urine involving nearly 10,000 tests on urines containing no ketones, naturally occurring ketones, and added acetoacetate. Acetest (a tablet nitroprusside test) and Ketostix (a strip nitroprusside test) are more specific and accurate, and have the proper sensitivity in comparison with test tube Rothera nitroprusside modifications or the ferric chloride test. Both the tablet and strip are also satisfactory for detection of ketones and serum or plasma. The tablet test may be used with whole blood for detection of ketonemia.

Galactose absorption studies have been made on normal subjects and on patients with deficiency diseases. In studying the method it was found that the amount of galactose ingested had a marked effect on the level of galactose attained in the blood. Therefore, in such a test the amount of galactose employed should be calculated on the basis of body weight. All of the patients with active pellagra and nontropical sprue showed evidence of impaired absorption. Improvement in absorption accompanied clinical improvement in pellagra but not in sprue. Two of four cases of rosacea keratitis which responded to riboflavin therapy gave indication of decreased absorption which improved when the signs of rosacea keratitis disappeared. Approximately one-half of the patients with pernicious anemia showed impaired absorption. Changes in absorption noted in these patients did not parallel the changes in the red cell counts and the hemoglobin levels. This suggests that a secondary factor is involved in absorptive changes noted in patients with pernicious anemia.

A triple-test strip for the simultaneous estimation of protein, glucose, and pH in urine with one simple dip-and-read operation is described. The three results can be obtained in little more than 10 seconds' time. Each of the three tests is a colorimetric reaction, and each is accompanied by a color chart for standardized results. A total of 12,674 results obtained in blind testing by experienced and inexperienced operators indicates that all three tests give accurate, reliable performance, as compared with other laboratory methods.

A simple dip-and-read strip test for detection of phenylketonuria is described. This test contains ferric and magnesium ions and an acid buffer. It is called PHENISTIX. When the strip is moistened with urine it gives a gray to blue color with samples which contain phenylpyruvic acid, the intensity being proportional to the concentration of this constituent. A color chart provides for standardization of results and reproducible reports. Comparison of the performance of the test with conventional laboratory procedures has been carried out on over 1900 samples as tests on unknowns. The new test is reliable for the recognition of phenylketonuria and has some advantages over conventional laboratory procedures.

A system of enzyme analysis has been developed which permits an accurate estimation of the proteolytic, lipolytic and amylolytic activity of the enzymes of duodenal contents. When this system of analysis is applied to duodenal contents secured after stimulating pancreatic secretion with olive oil, it has been found possible to define the normal range of values with a reasonable degree of accuracy, and give these in terms of the normal taken as 100. Employing this method of recording the enzyme activities to pathological cases, abnormal values stand out very clearly from the normal. Very low values are found in pancreatitis and certain other conditions, while subnormal values are encountered in various gastro-intestinal disorders which may have an effect on the pancreas. In diabetes the enzyme activity may be subnormal, or considerably elevated.

The importance of testing cheese for salt has been well established, but in certain plants practical limitations of present analytical methods may result in fewer analyses than what is considered necessary for uniform control. The utility of Quantab 1 Chloride Titrators for measuring salt in Italian cheese is presented. Quantab titrators provide useful results, within 10% of accepted reference methods, and allow easier multiple routine testing for good salt control, but do not replace more accurate procedures. Quantab titrator analyses of salt in various types of Italian cheese show good agreement with the Volhard method.

The recent recognition of a specific organic food factor12 necessary for the maintenance of the black fur of black or piebald rats has raised the question as to whether the phenomenon of graying noted by older workers3456 particularly in rats on an exclusive milk diet is due to this cause or is due to a specific mineral deficiency. Jukes and Richardson7 have pointed out that milk is not a good source of filtrate fraction vitamins.The black fur of young piebald rats fed an exclusive diet of either powdered whole milk or of fresh certified milk rapidly and uniformly became gray. Addition of a supplement of 0.25 mg of iron, 0.05 mg of copper and 0.05 mg of manganese cured the grayness if it had developed or prevented any change in the color of the fur of rats which were fed milk with the above mineral supplements from the time of weaning. Attempts to ascertain which of the 3 metals is responsible have not at present yielded entirely conclusive results.Rats developing a nutritional anemia show a marked diminu...

A collaborative study has been made on the use of the QUANTAB Chloride Titrator for monitoring salt concentration in meat, fish, and cheese. Data from 12 collaborators on 6 samples show good agreement of results from all of the collaborators on all of the samples. The QUANTAB method has been adopted as a procedure.

Two procedures, turbidimetric and cylinder plate, are reported for the assay of bacitracin. Two standard curves based on the Food and Drug Administration and the Cooper-Woodman methods are shown for the cylinder plate assay. The mathematical relationship between the antibiotic concentration and the zone of inhibition of bacitracin is discussed.

Publisher Summary This chapter highlights that glucose is important in the metabolism of most cells—animal, plant, and microbe—and a number of enzymes have been identified which catalyze the reactions of glucose. It discusses that enzymatic methods have a number of theoretical advantages, and therefore, it is quite logical that much attention has been devoted to the subject of enzymatic determinations of glucose. In all instances, the theoretical advantages do not necessarily apply in the defined procedures. Early qualitative and quantitative tests in which yeast was employed for either the identification or measurement of glucose might be considered to have an enzymatic basis as the desired actions were accomplished by means of the enzymatic processes in living yeast cells. This chapter describes the history and properties of glucose oxidase. It presents an account of the utilization of glucose oxidase for the measurement of glucose in urine and blood, and for other test situations that may be of interest in clinical chemistry.

The specificity of glucose oxidase for catalyzing the oxidation of β- d -glucose in contrast to α- d -glucose, other hexoses, and pentoses was investigated. The enzyme appears to catalyze the oxidation of the beta form only, and the mutarotation of the alpha form is rate limiting. d -Galactose, d -mannose, and d -xylose are slowly oxidized in the presence of glucose oxidase, but approximately 300 times as much enzyme is required to give a rate of oxidation equal to that for glucose. Galactose and mannose are oxidized directly to the corresponding aldonic acids without a prior conversion to glucose. Thirtyfold purification of the enzyme does not increase the ratio of glucose to galactose oxidation. d -Arabinose, which itself is not oxidized, inhibits glucose oxidase in catalyzing the oxidation of glucose. The clinical implications of these specificity studies are discussed.

The extremely high incidence of salicylate intoxication makes it desirable to have a screening test available. Such a procedure should be simple and rapid enough to be used routinely on all admission and emergency cases since salicylate intoxication may not be suspected. This report describes studies with a stick test used on urine and serum. Test results agree well with quantitative measurements. Specimens tested included urine and serum from dogs and human beings after experimental administration of aspirin as well as samples from cases of salicylate intoxication or high therapeutic salicylate levels. The test strip develops an immediate brownish purple color with as little as 20 mg. per cent free salicylate. Data are presented to show that reliable results are obtained with the test even by inexperienced individuals.

A standardized dip-and-read test for the detection of ketone bodies is described. This simplified nitroprusside test has a reading time of only 15 sec. The test is of value in assessing the severity of human ketosis since it can be used to determine the level of ketone bodies in both urine and serum. Testing urine from small experimental animals and testing cow's milk for early detection of bovine ketosis are easily accomplished with the stick test. The sensitivity and reactivity of the test appear to be the same in all body fluids studied. Data are presented which establish the accuracy, the reliability, and the utility of the stick test as a tool in scientific investigations.