Further experience with computer-assisted diagnosis of diseases of the liver and biliary tree

Computer-assisted classification of disease has largely relied upon testing the diagnostic algorithm in the same population from which it was originally derived, as a means of validation. To evaluate the accuracy of a diagnostic program in which discriminant function analysis is used, we applied it to a separate population, selected by different criteria from those used to define the original case material on which the diagnostic program was based. We selected a group of 315 patients having abnormal values for alkaline phosphatase, bilirubin, or aspartate aminotransferase for further biochemical and immunological investigations. We used a computer program involving discriminant function analysis and classification procedures primed with the results of 10 tests obtained on each of 535 patients in a previous series to allocate those 173 new patients who had diseases of the liver or biliary tree into one of 13 disease groups. The classification was less accurate than was the case in previous cross-validation studies. We developed new discriminants with the new case material, using the same group of tests, and when cross-validation was performed, overall accuracy was greatly improved. These experiences point to the powerful influence of group selection upon computer-assisted diagnostic procedures, and the hazards of applying to one clinical population discriminant functions derived from a different population.

The clinical pharmacology and antiarrhythmic efficacy of acetylprocainamide in patients with arrhythmias

The actions of acetylprocainamide, the major metabolite of procainamide in man, were studied in a placebo-controlled oral-dose-ranging trial in 16 persons with arrhythmias. The occurrences of arrhythmias decreased in 15 patients receiving acetylprocainamide and increased subsequently in 10 of 13 patients given placebo. The frequency of arrhythmias was reduced by more than 75 percent in nine patients. Antiarrhythmic effects were dependent on dose and serum drug concentrations, with levels of 10 to 24 microgram/ml observed in patients with a reduction of more than 70 percent in premature ventricular complexes. The ratio of preejection period to left ventricular ejection time decreased during therapy. Side effects of light-headedness, insomnia, nausea and diarrhea occurred in six patients at serum levels ranging from 11 to 22 microgram/ml. The serum half-life of acetylprocainamide lengthened from 7 to 21 hours as the creatinine clearance decreased from 105 to 35 ml/min. Acetylprocainamide has antiarrhythmic efficacy, but causes side effects in human beings. This compound appears to contribute to the effects of procainamide therapy and may be useful as an antiarrhythmic drug.

Lack of value of serum gamma-glutamyl transferase in the diagnosis of hepatobiliary disease

Serum gamma-glutamyl transferase (GGT, EC. 2.3.2.2. was measured in 173 patients with diseases of the hepatobiliary system (including metastatic cancer) and in 90 patients who were subsequently shown to have primary diseases of other etiology. All patients had been selected because they had abnormal alkaline phosphatase, aspartate aminotransferase or bilirubin on SMA 12/60 screening. Serum GGT was elevated in 97% of patients with primary hepatobiliary disease. The magnitude of the increase in GGT was variable in all groups and was unhelpful in differential diagnosis, even between medical and surgical cases. Moreover, GGT was abnormal in 69 patients who did not have primary hepatobiliary disease (77%), an incidence higher than that for other enzyme tests performed. We conclude that because GGT was more susceptible than other tests to spurious elevation in the absence of hepatobiliary disease and was unhelpful in differential diagnosis, it has little value apart from monitoring alcohol abuse and enzyme induction.

A one-tube micromethod for radioimmunoassay of plasma cortisol

A micro-scale method is presented for measurement of cortisol. Serum or plasma, 2 microliter, is diluted with buffer and the solution heated at 60 degrees C in the presence of high-affinity antibody and [3H] cortisol. Corticosteroid-binding globulin in the serum is denatured, releasing cortisol and making it available to the antibody, which is stable during the incubation. After cooling, ammonium sulfate solution is added, followed by a toluene-based scintillant that does not dissolve in the aqueous phase. The vial is shaken to extract the free cortisol into the scintillant. Antibody bound cortisol remains in the aqueous phase and does not produce any scintillation. The amount of [3H] cortisol that is free at the end of the incubation, and which therefore gives rise to the measured counts, is related to the concentration of cortisol in the original serum, and may be calculated from a standard curve. The assay is sensitive and precise. Ranges are presented for normal and pathologic subjects.

A one-tube micromethod for radioimmunoassay of plasma cortisol

A micro-scale method is presented for measurement of cortisol. Serum or plasma, 2 microliter, is diluted with buffer and the solution heated at 60 degrees C in the presence of high-affinity antibody and [3H] cortisol. Corticosteroid-binding globulin in the serum is denatured, releasing cortisol and making it available to the antibody, which is stable during the incubation. After cooling, ammonium sulfate solution is added, followed by a toluene-based scintillant that does not dissolve in the aqueous phase. The vial is shaken to extract the free cortisol into the scintillant. Antibody bound cortisol remains in the aqueous phase and does not produce any scintillation. The amount of [3H] cortisol that is free at the end of the incubation, and which therefore gives rise to the measured counts, is related to the concentration of cortisol in the original serum, and may be calculated from a standard curve. The assay is sensitive and precise. Ranges are presented for normal and pathologic subjects.

Serum enzyme tests in diseases of the liver and biliary tree

Eight serum enzyme tests were performed over a three-year period in 1,147 cases of patients with suspected hepatobiliary disease, of whom 580 had identifiable primary disease of the liver or biliary system. Individually, aminotransferase assays did not provide good discrimination among the various categories of hepatobiliary disease, but when expressed as a ratio a useful degree of discrimination was obtained. Isocitrate dehydrogenase, guanase and glutamate dehydrogenase alone were poor discriminants of the various disease categories studied; combination of the latter enzyme with the aminotransferases in various ratios did not achieve worthwhile improvement. Adenosine deaminase was normal in most patients with extrahepatic obstruction and abnormal in most patients with parenchymal hepatic disease, and is potentially a useful test additional to the aminotransferases in routine diagnosis. 5'-Nucleotidase was more sensitive and specific than alkaline phosphatase in diagnosing hepatobiliary disorders. Abnormalities of all these enzymes were encountered in patients who did not have hepatobiliary disease, most frequently among subjects with cancer, diabetes mellitus, and diseases of the respiratory and cardiovascular systems.

Serum concentrations of 25-hydroxy vitamin D in Europeans and Asians after oral vitamin D3

Serum concentrations of 25-hydroxy vitamin D (25-OHD3) were measured in seven Asians of Indian extraction and eight Europeans before and at intervals after taking 1 mg vitamin D3 by mouth. In all subjects the concentrations rose in the 24 hours after ingestion. There was little change over the next nine days in the concentrations in the Europeans but those in the Asians continued to rise until about day 10. Subsequent rates of fall in 25-OHD3 were similar in the two groups. Our observations suggest that the low serum concentrations of 25-OHD3 found in Asians are not caused by either impaired intestinal absorption of vitamin D or rapid clearance of 25-ODH3 from the plasma.

The sulfophosphovanillin reaction for serum lipids: a reappraisal

New evidence is presented for the mechanism of this reaction, which is used in estimating lipids. The reaction occurs in two stages: (a) Stage 1 evidently involves an oxidation step, forming a specific type of carbonium ion called an alkenyl cation of the general formula R--C+--C==C--R' (previous evidence had indicated that a carbonium ion of general formula R--C+--R' was formed by protonation only.) (b) Stage 2 of the reaction was examined by nuclear magnetic resonance studies and by partition experiments, which have indicated that a vanillin phosphate ester is not formed as previously suggested. Comparative data from other acid-aldehyde reactions indicate that in this reaction 1,1-di(4-hydroxy-3-methoxy phenyl)ethylene ion is formed, a product compatible with the formation of an alkenyl cation at stage 1.

The sulfophosphovanillin reaction for serum lipids: a reappraisal

New evidence is presented for the mechanism of this reaction, which is used in estimating lipids. The reaction occurs in two stages: (a) Stage 1 evidently involves an oxidation step, forming a specific type of carbonium ion called an alkenyl cation of the general formula R--C+--C==C--R' (previous evidence had indicated that a carbonium ion of general formula R--C+--R' was formed by protonation only.) (b) Stage 2 of the reaction was examined by nuclear magnetic resonance studies and by partition experiments, which have indicated that a vanillin phosphate ester is not formed as previously suggested. Comparative data from other acid-aldehyde reactions indicate that in this reaction 1,1-di(4-hydroxy-3-methoxy phenyl)ethylene ion is formed, a product compatible with the formation of an alkenyl cation at stage 1.

Sequential-saturation-type assay for serum 25-hydroxyvitamin D

We describe a method for measuring 25-hydroxyvitamin D in serum. The serum is denatured with ethanol, and the extract purified by chromatography on silicic acid to prevent potential interference from vitamin D and by other substances. 25-Hydoxyvitamin D is assayed by sequential saturation analysis in Tris-HCI buffer, pH 8.6, containing the surfactant Triton X-405 (2 ml/liter) to solubilize the steroid. Diluter, unpurifed normal human serum is used as the binder. The method is sensitive and precise. The dose-response curve is linear. The assay normally gives high count rates (12 000 to 20 000 cpm for the zero standard) and consequently 25-hydroxyvitamin D of low specific activity can be used if necessary. Serum 25-hydroxyvitamin D was determined in normal and osteomalacic subjects.

Sequential-saturation-type assay for serum 25-hydroxyvitamin D

We describe a method for measuring 25-hydroxyvitamin D in serum. The serum is denatured with ethanol, and the extract purified by chromatography on silicic acid to prevent potential interference from vitamin D and by other substances. 25-Hydoxyvitamin D is assayed by sequential saturation analysis in Tris-HCI buffer, pH 8.6, containing the surfactant Triton X-405 (2 ml/liter) to solubilize the steroid. Diluter, unpurifed normal human serum is used as the binder. The method is sensitive and precise. The dose-response curve is linear. The assay normally gives high count rates (12 000 to 20 000 cpm for the zero standard) and consequently 25-hydroxyvitamin D of low specific activity can be used if necessary. Serum 25-hydroxyvitamin D was determined in normal and osteomalacic subjects.

Serum-25-hydroxyvitamin-D concentrations in adolescent boys

In March, 1976, vitamin-D status was investigated in 256 thirteen-year-old school boys of Asian, West Indian, andEuropean origin in Birmingham. Serum-25-hydroxyvitamin-D3 (25-OHD3) concentrations in 78% of the 124 Asian boys resembled those found in rickets and osteomalacia. Serum-25-OHD3 concentrations were also low in a few West Indian and European children. Dietary intake of vitamin D and exposure to sunlight were similar in each group. Serum-parathormone concentrations were increased in many children with low serum-25-OHD3. Reinvestigation in October, 1976, of a group of children whose serum-25-OHD, concentration had been less than 8 microng/l in March, 1976, showed pronounced improvement in all, but some still had concentrations which indicated a possible deficiency. It is suggested that the high frequency of vitamin-D deficiency in Asian adolescents would be much reduced if 1 mg of vitamin D3 was given orally each school term during adolescence.

Computed tomography in metrizamide cisternography--importance of coronal and axial views

Computed tomographic scans were performed in 34 patients following lumbar introduction of metrizamide. Imaging of the cranial spaces was obtained with horizontal and inclined (25 degrees) as well as coronal planes. Mass lesions within and encroaching upon the cisternal spaces were demonstrated, and the ventricular system was shown with varying degrees of opacification. Coronal and semicoronal views facilitated the localization of parasellar and incisural mass lesions.

A diagnostic triad for portal cirrhosis

Abnormal serum aminotransferase activities with dominance of aspartate aminotransferase over alanine aminotransferase activity, and elevated serum adenosine deaminase activity and immunoglobulin. A concentration, were commonly encountered among patients with portal cirrhosis. The full triad was present in 31 of 49 cases (63%). As isolated abnormalities, these features were not uncommon in patients with other diseases of the liver and biliary tree, but the full triad was found only in 11 of 163 such cases (6.8%). The presence of this triad in a patient with unexplained hepatomegaly is indicative of portal cirrhosis.

Quality control of serum alkaline phosphatase assays: project report and discussion of some factors affecting the assay

The factors which affect the standardisation and quality control of serum alkaline phosphatase assays are discussed. A quality control project was designed to test the performance of seven Birmingham laboratories in the assay of sera with alkaline phosphatase activities outside the range normally tested by the National Quality Control and Wellcome schemes. The results showed that the precision of individual laboratories was satisfactory. Differences between the results of the laboratories were considerable and could be accounted for by differences in methodology. Auto-Analyzer methods employing phenyl phosphate as substrate would best be standardised by adopting the optimised reaction conditions of Buch and Buch (1939); but the borate buffer of these authors should be replaced by the carbonate-bicarbonate buffer of Moss et al. (1971). To avoid the confusion which may arise in future if alkaline phosphatases are reported in U/l irrespective of the substrate, it is suggested that some substrate--indicative nomenclature may be advisable.

Serum guanase activities after myocardial infarction

Serum guanase, aspartate aminotransferase, alanine aminotransferase, creatine phosphokinase and hydroxybutyrate dehydrogenase activities were measured in 290 blood samples from 96 consecutive patients admitted to a Coronary Care Unit. Elevated serum guanase activities (greater than 2 U/l) were found in 19 patients (20%). The magnitude and frequency of these elevations did not negate the value of guanase as a "liver function test", since all cases with raised guanase also had abnormal serum alanine aminotransferase activities. This fact, together with other information in the literature, indicated that elevated serum guanase activity following myocardial infarction was consequent upon some degree of sub-clinical hepatic necrosis. Caution must be exercised when serum asparate aminotransferase is used as an index of heart muscle necrosis unless guanase or some other "liver specific" enzyme is known to be normal, or unless creatine phosphokinase or hydroxybutyrate dehydrogenase activities are elevated.

An assessment of serum acid and alkaline phosphatase determinations in prostatic cancer with a clinical validation of an acid phosphatase assay utilizing adenosine 3'-monophosphate as substrate

Serum acid phosphatase (AcPase) was measured by a colorimetric method utilizing adenosine 3' -monophosphate as substrate in 389 patients. In about half the cases blood was taken shortly after a rectal examination. The upper reference limit (mean + 2SD) for 116 cases with miscellaneous illness after eliminating outliers was 4.1 International Units per litre (U/I) at 37 degrees C, and no correlation existed between AcPase activity and age in these subjects (r = 0.040). Eight of 18 patients with untreated carcinoma confined within the prostate gland had AcPase activities below 4.1 U/l, and all of 27 cases with extension to pelvic soft tissues or to bone exceeded this value. AcPase activities above 4.1 U/l were found in 6% of cases with benign hypertrophy of the prostate, in 5% of cases with non-prostatic cancer, and in none of 22 cases with other urological illness. Raised serum alkaline phosphatase (APase) activity was found in 60% of patients with untreated prostatic cancer and in only 6% of patients free of prostatic cancer, in most of whom there was a clinical explanation for the elevation. The correlation between the two phosphatase activities was not significant (r = 0.294). While APase activity does not reflect the stage of the disease as closely as AcPase activity, and is not so frequently elevated, it provided useful confirmation of the diagnosis in five patients of the present series whose AcPase levels were normal or only minimally elevated.

Significance of hyperamylasaemia and abdominal pain in diabetic ketoacidosis

An analysis of 35 consecutive episodes of diabetic ketoacidosis confirmed the frequent high levels of serum amylase in this condition. Serum amylase was raised during 21 episodes (60%), and in six instances (17%) the peak level exceeded 1,000 Somogyi units per 100 ml. Hyperamylasaemia was more often found when the initial blood sugar exceeded 500 mg/100 ml, or when the onset of the episode had been relatively acute (less than 48 hours). There was no conclusive evidence in any patient to support a diagnosis of acute pancreatitis and other explanations for the hyperamylasaemia are discussed. Even grossly raised amylase levels were not associated with increased mortality or morbidity.

Routine determination of 5' nucleotidase activity of human serum using the LKB 8600 reaction rate analyser

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Experience of routine live-birth screening for galactosaemia in a British hospital, with emphasis on heterozygote detection

Results are reported of a screening programme for galactosaemia covering a period of 2½ years and 6415 births. The gene frequency for galactosaemia estimated from the data of the screening programme was 0·002. This conflicted with the known live-birth incidence of at least 1: 50,000 during this same period. 2 of the 4 galactosaemic infants concerned died under circumstances that were preventable had they been screened at birth. The need to screen all sick infants for galactosaemia is emphasized, as is the requirement for reliable information on its incidence in Great Britain. The screening test employed (Beutler and Baluda, 1966a) seemed appropriate for this purpose. It was simple to perform and apparently accurate in galactosaemic infants. Its accuracy in detecting heterozygotes is uncertain. This test should be available in all hospitals receiving sick neonates.

Colorimetric determination of serum acid phosphatase activity using adenosine 3'-monophosphate as substrate

The hydrolysis of adenosine 3'-monophosphate by serum acid phosphatase has been coupled to the liberation of ammonia from the adenosine generated through the action of exogenous adenosine deaminase. The ammonia is measured at the end of the incubation by a modification of the phenol-hypochlorite reaction of Berthelot. Optimum conditions for the enzyme reaction have been defined. Inhibition of the Berthelot reaction by the serum used in the assay is small, and may be compensated by a correction factor. Although the value for the control is high in relation to the test over the normal range, this is largely outweighed by the good sensitivity and precision of the method. The substrate is not significantly hydrolysed by erythrocyte acid phosphatase within the limits encountered in haemolysed sera. Experience of the method in routine hospital diagnosis compared favorably with that of a standard method employing disodium phenyl phosphate as substrate. It is suggested that activities greater than 3.1 IU/l should be further investigated and those greater than 3.7 IU/l should be regarded as definitely raised. The stability of human serum AcPase when promptly separated and held at 4 degrees C or - 20 degrees C was confirmed. At room temperature, acidification to pH 6.0 greatly improved stability.