John A. Lott

Pathophysiology and diagnostic value of urinary trypsin inhibitors.

Abstract Inflammation is an important indicator of tissue injury. In the acute form, there is usually accumulation of fluids and plasma components in the affected tissues. Platelet activation and the appearance in blood of abnormally increased numbers of polymorphonucleocytes, lymphocytes, plasma cells and macrophages usually occur. Infectious disorders such as sepsis, meningitis, respiratory infection, urinary tract infection, viral infection, and bacterial infection usually induce an inflammatory response. Chronic inflammation is often associated with diabetes mellitus, acute myocardial infarction, coronary artery disease, kidney diseases, and certain auto-immune disorders, such as rheumatoid arthritis, organ failures and other disorders with an inflammatory component or etiology. The disorder may occur before inflammation is apparent. Markers of inflammation such as C-reactive protein (CRP) and urinary trypsin inhibitors have changed our appraisal of acute events such as myocardial infarction; the infarct may be a response to acute infection and (or) inflammation. We describe here the pathophysiology of an anti-inflammatory agent termed urinary trypsin inhibitor (uTi). It is an important anti-inflammatory substance that is present in urine, blood and all organs. We also describe the anti-inflammatory agent bikunin, a selective inhibitor of serine proteases. The latter are important in modulating inflammatory events and even shutting them down.

The Enzymology of Skeletal Muscle Disorders

In myopathic disorders, abnormal serum enzyme activities are seen primarily in diseases of skeletal muscle where the condition involves the muscle fibers themselves. In denervation myopathies, serum enzyme activities are usually normal. The most dramatic increases of serum enzymes, particularly creatine kinase, are found in the dystrophic diseases, particularly Duchenne dystrophy. A review is given here of the many causes of abnormal serum enzyme activities where the source of enzymes is believed to be skeletal muscle. These include the dystrophies, various types of trauma, exercise, drug- and poison-induced causes including alcohol, malignant hyperthermia, inflammatory diseases, and miscellaneous causes. Tissue and serum activities are summarized for the commonly performed serum enzymes, i.e., CK, LD, AST, and aldolase. An extensive tabular and current description of the various types of dystrophies is given along with serum CK and pyruvate kinase activities.

Changes in serum enzymes, lactate, and haptoglobin following acute physical stress in international-class athletes

Skeletal muscle is rich in creatine kinase (CK), lactate dehydrogenase (LD), and other enzymes. Many reports describe changes in serum CK and LD following exercise. In our study, 11 male international-class medium-distance runners were followed over a 10-month period prior to the 1984 US Olympic Trials. Cardiorespiratory fitness, evaluated through repetitive treadmill testing, was unchanged in our athletes. Total CK increased significantly during the course of training, and the CK-MB activity was higher than that of sedentary individuals; CK-MB never rose to more than 3% of the total CK. Total LD also rose following acute exercise; however, the proportions of the five isoenzymes were unaltered. There was no change in the LD-1/LD-2 ratio from normal. The origin of the increased serum enzymes was believed to be primarily skeletal muscle. A decrease of serum haptoglobin following acute stress was attributed to intravascular hemolysis and binding of hemoglobin. As expected, serum lactate was dramatically increased immediately postexercise.

Screening School Children for Albuminuria, Proteinuria and Occult Blood with Dipsticks

Abstract Beginning in 1974, the Japanese Ministry of Health Welfare directed the screening of schoolchildren for proteinuria. We studied their procedure and methods in 6197 school children and also evaluated a new urine dipstick that measures albumin concentrations down to about 10 mg/l and creatinine down to about 300 mg/l. We used specimens from adult in- and outpatients to test the accuracy of the dipsticks. Based on the quantitative results, we set as cutoffs < 150 mg/l for protein and < 30 mg/l for albumin as the concentrations representing “low risk.” The quantitative values were assumed to be correct, and the dipstick results were judged accordingly, i.e., a dipstick protein of ≥ “150” mg/l or an albumin of | “30” mg/l indicated increased risk of developing or having a genitourinary disorder. The sensitivity/specificity of the protein dipstick was 95.1%/95.5%, and the same for the albumin dipstick was 83.8%/93.8%. The cut-off for the albumin dipsticks probably should be set somewhat lower to reduce the number of false negatives and increase the sensitivity of the dipstick. When we compared the quantitative albumin to the protein dipsticks with the above cut-offs, we found the sensitivity/specificity to be 79.3%/94.4%, i.e., much like the albumin dipstick results. The many reports on the association of albuminuria and risk of renal disease recommend that screening should be done for albumin rather than protein. Based on the data from the school children, we estimate that a dipstick albumin of “30” mg/l is borderline increased risk, and that a protein dipstick of “150” mg/l is the same. If we call the dipstick “10” mg/l albumin, “30” mg/l albumin and the “150” mg/l protein results “low risk,” then we estimate the prevalence of albuminuria in the school children to be about 2.1% and proteinuria to be about 4.3%. Children with these values should have a quantitative test for albumin and protein. We also tested a dipstick for creatinine and found increasing values with increasing age in both genders; the older boys had significantly higher creatinine values than the older girls and younger boys. For the albumin/creatinine ratio, we found 6028 children with a ratio of < 30 mg/g indicating low risk and 159 children with a ratio of ≥30 mg/g indicating increased risk. The ratio may be more useful owing to the likely reduction of the number of false negatives and false positives. Note: 1 mg/l albumin = 8.85 μmol/l .

Assessment of a rapid test on amniotic fluid for estimating fetal lung maturity

We have measured the absorbance of centrifuged amniotic fluids at 650 nm. and found reasonably good correlation between the absorbance and the L/S ratio. In 87 fluids studied, an absorbance of greater than 0.100 predicted correctly an L/S ratio of 2 or more in 98 per cent of the cases. When the absorbance was less than 0.100, 70 per cent of the fluids had an L/S ratio of less than 2.

Precision and Accuracy: Concepts and Assessment by Method Evaluation Testing

Achieving precision and accuracy in routine clinical analyses is a complex task, requiring the identification, estimation, and elimination of sources of analytical error. This review first considers concepts of precision and accuracy, including discussions of the meaning of measurement process, analytical method, state of statistical control, precision, imprecision, accuracy, inaccuracy, systematic error, overall or total error, true value, traceability, and compatability. These concepts provide the basis upon which the performance of analytical methods can be evaluated. The second part of the review considers how precision and accuracy are assessed by the use of method evaluation experiments. The approach emphasizes the development of an evaluation protocol based on the analytical characteristics which represent the performance of the method. This includes discussions of the familiarization period; testing analytic range and linearity; testing precision by a replication experiment; testing accuracy by recovery, interference, and comparison of methods experiments; the selection of a comparative analytical method; the statistical analysis of method comparison data, including the interpretation of that data; the collaborative testing.

Clinical utility of a rapid test for uristatin

OBJECTIVES Uristatin is a trypsin inhibitor present in urine that is increased in most patients with bacterial or viral infections and in many with inflammatory disorders. We included the assay of uristatin as part of a screening program carried out by pediatricians on 4207 Japanese schoolchildren to judge the ability of uristatin to identify those with an infection and (or) inflammation of any cause. We used urine dipsticks for the assay of uristatin, creatinine, albumin, blood, leukocyte esterase, and protein. We also performed quantitative assays for uristatin and creatinine. Another aim was to estimate the reference range for uristatin in schoolchildren, ages 5 to 14 yr. METHODS We prepared dipstick pads that were impregnated with a chromogenic substrate for trypsin and measured the uristatin-caused inhibition of trypsin in urine. We measured creatinine so that the ratio of uristatin to creatinine could be calculated to correct for urine concentration. RESULTS We obtained quantitative uristatin and creatinine results for 4207 children. Of these, 177 had an abnormal urine dipstick for albumin or blood or protein or leukocyte esterase or a combination of these. We used data from 3622 children to establish the reference range for the uristatin dipsticks. The 3622 were diagnosed by their pediatricians as free from an infection or inflammation of any cause and with normal urine dipstick tests. We recommend an upper reference limit for uristatin by dipstick of < or = 7.5 mg uristatin/g creatinine. The leftover 408 children ( [4207-3622-177] = 408) fell into two groups: 205 with diagnoses of no infection, possible infection, or possible inflammatory disorders. The remaining 203 children were renal disease follow-up cases. The diagnoses were based on a physical examination, microscopic urinalysis plus urine dipstick tests for albumin, blood, creatinine, protein, leukocyte esterase and a complete blood count. In the 205 children, 46 had an abnormal uristatin dipstick test, 39 had an abnormal uristatin by immunoassay, 41 had an abnormal erythrocyte sedimentation rate (ESR), 27 had an abnormal serum C-reactive protein (CRP), and one had an abnormal urine microscopic exam. For the first 938 children in the study, the agreement was 93% of negative dipstick uristatin results and immunoassays. The agreement of positive uristatin dipsticks with immunoassays was 85%. We assumed that the immunoassay results were correct. In the evaluation of 189 children with fever, 62 also had an abnormal uristatin by dipstick. DISCUSSION A rapid dipstick test for uristatin read on a reflectance photometer gave values that compared well with a quantitative immunoassay method. The uristatin test is sensitive but not specific for any cause of infection or inflammation. Uristatin is easy to determine and appears to be a better indicator than fever, ESR, or CRP for the diagnosis of an infection or inflammation.

The importance of objective data in the diagnosis of pancreatitis

In 78 patients with likely pancreatitis, we used laparotomy, computerized tomography, ultrasonography and other information to make an objective diagnosis of pancreatitis. Laboratory studies included serum amylase, amylase isoenzymes and lipase. We found that both amylase and lipase are highly sensitive tests and P3 amylase by electrophoresis on agarose to be specific; a combination of these tests is recommended to assist in the diagnosis of pancreatitis. The frequent occurrence of an abnormal amylase and lipase in patients without pancreatitis is suggested as the cause of overdiagnosis of this disorder. A markedly increased amylase or lipase was always associated with pancreatic disease.

Inflammatory Diseases of the Pancreas

(1982). Inflammatory Diseases of the Pancreas. CRC Critical Reviews in Clinical Laboratory Sciences: Vol. 17, No. 3, pp. 201-228.

Screening for Proteinuria in Japanese Schoolchildren: a New Approach

Abstract By governmental mandate, Japanese school children are screened annually for proteinuria, hematuria, and glucosuria to identify children with possible renal disorders. We added urine dipstick tests for albumin and creatinine to the Japanese screening protocol, and used their dipstick results for blood, glucose and protein. The sulfosalicylic acid precipitation test was used to confirm “trace” positive protein dipsticks. The Japanese and our screening protocol have in common the same data for glucosuria and proteinuria. Their scheme has an algorithm for repeat testing of children with abnormal results, and further testing and medical evaluation for those showing persistently abnormal values. Out of the 23,121 students, we found seven with likely nephritis, one with confirmed nephritis, one with nephrotic syndrome, 170 with persistent unexplained hematuria, 19 with persistent unexplained proteinuria, 14 cases of urinary tract infection, and 20 cases of likely diabetes mellitus. We conclude that dipstick testing for albumin, protein, creatinine, glucose and occult blood has significant value in a multilevel testing scheme for identifying children with urinary tract abnormalities or diabetes. The assay of albumin increases the sensitivity of the screening, and dividing the albumin by the creatinine concentration reduces the potential errors arising from concentrated or dilute urines.