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PURPOSE: Sonographic reports are examiner-dependent and may not always be reliable. We investigated concordance between documented findings and diagnostic conclusions--not the objective correctness of both--with the help of a knowledge-based documentation system. MATERIALS AND METHODS: The knowledge-based documentation system SonoConsult (SC) is routinely used in the ultrasound unit of a gastroenterological clinic for more than four years. Physicians documented findings with goal directed questionnaires, and diagnostic conclusions with free text. The consistency of documented findings and diagnoses was checked with the help of SC in a two-step process: 1. the diagnoses inferred by SC based on the documented findings were compared to the diagnoses of the physicians stated as free text. 2. In case of discrepancies, a more thorough comparison was performed manually by the medical authors of this study. For judging the practical relevance of discrepancies, diagnostic codes were pre-classified as a) being presumably of higher and lower relevance for the clinician and b) requiring simple or complex inference rules from the findings. RESULTS: In a first series of 250 consecutive cases with 934 diagnoses (3.7 diagnoses per case), 71.1% showed agreement between diagnoses of the physicians and of SC and were judged as consistent compared to the documented findings. 24.4% of the diagnoses suggested by the documented findings, however, were not mentioned by the physicians (false negative) and 4.5% were mentioned by the physicians but not suggested by the documented findings (false positive). From the 24.4% missing diagnoses, 40% were pre-classified as being of higher relevance for the clinician. In a second series of 161 consecutive cases with 501 diagnoses (3.1 diagnoses per case), 61.1% were judged as consistent compared to the documented findings, 36.1% false negative and 2.8% false positive. In this study, we differentiated the missing diagnoses due to their inferential complexity: From the 152 complex diagnoses, 44% were missing, while from the 349 simple diagnoses, 32.7% were missing. CONCLUSION: As shown for a sonographic department of a clinic of internal medicine, in sonographic reports, one has to be aware of discrepancies between question-set-based documentations of findings and diagnostic conclusions of the examiners. While a detailed documentation of findings is the basis of quality control, consistency checks between documented findings and diagnostic conclusions, which might be done automatically in an electronic patient record, would considerably improve the quality of the reports.

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HepatoConsult is a publicly available knowledge-based second opinion and documentation system aiding in the diagnosis of liver diseases. The positive results of a prospective diagnostic evaluation study encouraged its use in clinical routine, although the available hardware infrastructure was not optimal. The comments of the physicians who used the system confirmed the results of the study and showed that the time for data entering is acceptable and the implicit standardization of terminology and documentation is welcome. Suggestions for improvement included the interface to enter data more easily, the scope to be usable for more patients and the additional capability to generate medical reports from the data.

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BACKGROUND AND OBJECTIVE: HepatoConsult (HC) is a medical expert system, based on the expert system building block D3, designed to aid in the diagnosis of liver and biliary tract disease. It was the aim of this study to evaluate its diagnostic competence in clinical cases prospectively. PATIENTS AND METHODS: The diagnostic accuracy of HC was tested prospectively in 106 consecutive patients with the main diagnosis of liver disease. 57 were ambulant, 49 were in-patients. The data were obtained and stored at defined phases of the diagnosis. The diagnoses put forward by HC were compared with the final clinical diagnosis and, on the basis of the data, checked for plausibility by four experienced physicians. RESULTS: After history taking and physical examination HC put forward the main diagnosis, as established by the doctors in charge, in 60% of patients. After addition of the results of basic laboratory tests and sonography, HC provided the correct diagnosis in 85% and, after inclusion of all the findings, in 93%. In almost all cases HC put forward diagnoses that were, on the basis of the supplied data, considered correct by the four physicians experienced in liver disease. In 56% of cases HC provided more differentiated diagnoses or items in the differential diagnosis than the attending doctors. In the opinion of the four assessors HC had not put forward any seriously wrong diagnoses. CONCLUSION: HC can be useful in solving diagnostic problems and thus in ensuring the quality of medical diagnoses.

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The humoral immune system of the small intestine of 17 patients with common variable immunodeficiency (CVID) was studied by immunohistology using antibodies specific for IgA1,2, IgM, IgG1-4, the J chain and the secretory component (SC). IgA1,2+, IgG2+ and IgM+ lamina propria B cells were totally lacking in 65% (11/17), 41% (7/17) and 18% (3/17) of CVID patients, respectively. One patient exhibited an isolated IgA1 subclass deficiency. The proportion of plasma cells in conventionally stained histological sections of the same intestinal biopsies showed a close correlation with the numbers of IgA+ and IgM+ cells. Considerable numbers of J chain-synthesizing cells were present in all patients with CVID, indicating the presence of early B cells unable to differentiate into immunoglobulin-producing plasma cells. Most of the patients with intestinal IgA and/or IgM defects strongly expressed the SC in their enterocytes, suggesting an immunoglobulin-independent regulation of the SC. Clinically, only CVID patients with intestinal IgA defects developed intestinal infections with Giardia lamblia, Campylobacter jejuni or Candida albicans. The outcome of in vitro immunoglobulin synthesis assays with peripheral blood lymphocytes did not predict the presence or absence of the respective isotype-producing B cells in the intestinal lamina propria. Thus, immunohistological examinations of intestinal biopsies are required to determine the extent of mucosal immunodeficiency in CVID patients.

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Uptake of 7 beta-NBD-NCT ([N-[7-(4-nitrobenzo-2-oxa-1,3-diazol)]-7 beta-amino-3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oyl)-2'-aminoethanesulfonate) in isolated rat liver hepatocytes occurs by saturable transport without being superimposed by simple diffusion. The dependency of flux rate of uptake on the concentration of 7 beta-NBD-NCT in the presence of Na+ (143 mM) and with Na+ depletion (1 mM) is best described by the assumption of two simple transport systems. Maximal flux rates of uptake Jn and half-saturation constants KT for 7 beta-NBD-NCT are in presence of Na+ for transport system 1 J1(Na+ 143) = 0.15 +/- 0.03 nmol/(min.mg protein) and KT1(Na+ 143) = 3.5 +/- 0.5 microM and for transport system 2 J2(Na+ 143) = 1.0 +/- 0.1 nmol/(min.mg protein) and KT2(Na+ 143) = 190 +/- 25 microM, and in case of Na+ depletion J1(Na+ 1) = 0.1 +/- 0.03 nmol/(min.mg protein), KT1(Na+ 1) = 3.0 +/- 0.5 microM, and J2(Na+ 1) = 0.85 +/- 0.9 nmol/(min.mg protein) and KT2(Na+ 1) = 195 +/- 27 microM. Uptake of 7 beta-NBD-NCT by both transport systems is competitively inhibited by cholyltaurine in the presence of Na+ and with Na+ depletion. Two transport systems are likewise involved in the uptake of cholyltaurine in the presence of Na+ as well as in case of Na+ depletion. Their kinetic parameters are in presence of Na+ J'1(Na+ 143) = 1.55 +/- 0.14 nmol/(min.mg protein) and K'T1(Na+ 143) = 16.1 +/- 3.0 microM, and J'2(Na+ 143) = 0.51 +/- 0.05 nmol/(min.mg protein) and K'T2(Na+ 143) = 38.0 +/- 4.1 microM, and in case of Na+ depletion J'1(Na+ 1) = 0.10 +/- 0.02 nmol/(min.mg protein), K'T1(Na+ 1) = 7.7 +/- 1.2 microM, and J'2(Na+ 1) = 0.40 +/- 0.03 nmol/(min.mg protein) and K'T2(Na+ 1) = 41.0 +/- 4.2 microM. Uptake of cholyltaurine by both transport systems is competitively inhibited by 7 beta-NBD-NCT in the presence of Na+ as well as in case of Na+ depletion. In both cases the inhibition constants are practically identical with the KT values for uptake of 7 beta-NBD-NCT. Photoaffinity labeling of isolated hepatocytes using 7,7-ACT (400 microM) resulted in the irreversible inhibition of uptake of both bile salts to similar extents, confirming the kinetic data that 7 beta-NBD-NCT is a true analogue of cholyltaurine.

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Methotrexate (2.5 mg/day) was used in addition to ursodeoxycholic acid (10-15 mg/kg per day) in 8 female patients with primary biliary cirrhosis. All patients had undergone ursodeoxycholic acid treatment for more than 6 months preceding this study and their serum alkaline phosphatase remained constant at more than 300 U/l for more than 2 months. One patient showed histologic stage I, three stage II, two stage III and two stage IV disease. Within 6 months, fatigue and itching disappeared in all symptomatic patients. Serum alkaline phosphatase activities improved dramatically (621 +/- 299 to 378 +/- 258, mean +/- S.D.) in all but one patient and normalized in four. Serum gamma-glutamyltransferase activities (180 +/- 99 U/l vs. 150 +/- 125 U/l) and immunoglobulin M concentrations (616 +/- 424 vs. 362 +/- 195 mg/dl) also improved. Adverse effects of methotrexate therapy were only regularly observed within the first 2-6 weeks, such as fatigue and transient enhancement of transaminases and serum bile acid concentrations. We conclude that methotrexate may be a highly effective drug for the treatment of primary biliary cirrhosis in patients whose symptoms and/or laboratory liver function tests are not improved enough by ursodeoxycholic acid alone. However, its influence on histology and the natural history of the disease needs to be established.

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The liver has a great reserve capacity for hepatobiliary bile salt transport. This study was performed to elucidate the significance of this capacity in ethinyl estradiol-induced cholestasis by direct visualization of the zonal involvement in taurocholate transport. The acinar distribution of [3H]taurocholate was determined by histoautoradiographical study of cryopreserved liver slices in normal rats and rats treated with ethinyl estradiol for 5 days. Silver grain densities over the different acinar zones were estimated on digitized image analysis. In control animals, histoautoradiographical study performed 4 min after the start of perfusion showed restriction of taurocholate to acinar zone 1. In contrast, in ethinyl estradiol-treated animals, taurocholate was also found in zone 2 and, in smaller concentrations, in zone 3. In control animals, the relative blackenings by silver grains of acinar zones 1, 2 and 3 were 66% +/- 1.2%, 25% +/- 1.6% and 5% +/- 0.6%, respectively. After 5 days of ethinyl estradiol treatment, blackenings were 58% +/- 1.5%, 36% +/- 2.1% and 12% +/- 0.8%, respectively. As early as 15 sec after injection of [3H]taurocholate, the bile canalicular areas of the cell plates and the bile ductules of ethinyl estradiol-treated animals were labeled as intensely as those of control animals. Our results demonstrate ethinyl estradiol-induced recruitment of the acinar zones 2 and 3 for hepatobiliary taurocholate transport. This recruitment may largely compensate for reduction of transport capacity of periportal hepatocytes in early cholestasis.

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In order to visualize bile salt transport, fluorescent bile salt derivatives were synthesized by introduction of the relatively small fluorescent 4-nitrobenzo-2-oxa-1,3-diazol (NBD)-amino group in either the 3-, 7-, or 12-position of the steroid structure, thus providing a complete set of diastereomeric derivatives, 3 alpha-NBD-amino-7 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oic acid, 3 beta-NBD-amino-7 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oic acid, 7 alpha-NBD-amino-3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oic acid, 7 beta-NBD-amino-3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oic acid, 12 alpha-NBD-amino-3 alpha,7 alpha-dihydroxy-5 beta-cholan-24-oic acid, 12 beta-NBD-amino-3 alpha,7 alpha-dihydroxy-5 beta-cholan-24-oic acid, as well as their taurine conjugates. Their optical properties with absorption maxima at about 490 nm and emission maxima at 550 nm make them suitable for fluorescent microscopic studies. Fluorescence of the NBD-derivatives is strongly dependent on polarity of the solvent, on the concentration of the bile salt derivatives, and only slightly on temperature.

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Interaction of unconjugated and taurine-conjugated NBD-amino-dihydroxy-5 beta-cholan-24-oic acids bearing the fluorophor in the 3 alpha, 3 beta, 7 alpha, 7 beta, 12 alpha, or 12 beta position with albumin results in a small hypsochromic shift of the emission maximum and an increase in quantum yield, suggesting binding by hydrophobic interactions. The different unconjugated fluorescent bile salt derivatives are metabolized by intact rat liver in different ways. The unconjugated 3 beta-NBD-amino derivative is completely transformed to its taurine conjugate and secreted as such, whereas the 3 alpha-NBD-amino derivative is completely transformed to a polar fluorescent compound not identical with its taurine conjugate. The unconjugated 7 alpha- and 7 beta-NBD-amino derivatives are only partially conjugated with taurine and mainly secreted in unmetabolized form. The unconjugated 12 alpha- and 12 beta-NBD-amino derivatives are not at all transformed to their taurine conjugates, but are partially metabolized to unidentified compounds. They are predominantly secreted as the unmetabolized compounds. In contrast to the unconjugated derivatives, all taurine-conjugated fluorescent bile salt derivatives are secreted into bile unmetabolized. With the exception of the 3 alpha-compound, all synthesized taurine-conjugated fluorescent derivatives interfere with the secretion of cholyltaurine. Differential photoaffinity labeling studies using (7,7-azo-3 alpha,12 alpha- dihydroxy-5 beta-cholan-24-oyl)-2'-[2'-3H(N)]aminoethanesulfonate as a photolabile derivative revealed that in liver cells all fluorescent bile salt derivatives interact with the same polypeptides as the physiological bile salts. The hepatobiliary transport of taurine-conjugated NBD-amino bile salt derivatives is, due to hydrophobic interactions, accompanied by an increase in fluorescence intensity which is favorable for the study of biological bile salt transport by fluorescence microscopy.

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The rapid expansion of computer-based systems for problem solving or decision making in medicine, the so-called medical expert systems, emphasize the need for reappraisal of their indication and value. Where specialist knowledge is required, in particular where medical decisions are susceptible to error these systems will probably serve as a valuable support. In the near future computer-based systems should be able to aid the interpretation of findings of technical investigations and the control of treatment, especially where rapid reactions are necessary despite the need of complex analysis of investigated parameters. In the distant future complete support of diagnostic procedures from the history to final diagnosis is possible. It promises to be particularly attractive for the diagnosis of seldom diseases, for difficult differential diagnoses, and in the decision making in the case of expensive, risky or new diagnostic or therapeutic methods. The physician needs to be aware of certain dangers, ranging from misleading information up to abuse. Patient information depends often on subjective reports and error-prone observations. Although basing on problematic knowledge computer-born decisions may have an imperative effect on medical decision making. Also it must be born in mind that medical decisions should always combine the rational with a consideration of human motives.

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The acinar location of tritium-labelled taurocholate taken up from sodium-containing and sodium-free perfusion media in isolated perfused rat liver was made visible by means of histoautoradiography on cryoslices at low, medium and high bile salt concentrations. In antegrade perfusion studies, in the presence of sodium, with taurocholate concentrations of 1 and 20 microM, respectively, the silver grain label was mainly restricted to acinar zones 1. At an 80 microM concentration, zones 2 and 3 were also labelled but with decreasing intensities towards the terminal hepatic venules. At 120 microM taurocholate, all acinar zones were nearly equally labelled. In the absence of sodium, antegrade liver perfusions with 1, 20 and 120 microM taurocholate resulted in an almost homogenous labelling of all acinar zones and retrograde perfusions in a silver grain density slightly decreasing towards the terminal portal venules. The results indicate that hepatocytes of all acinar zones are capable of taking up taurocholate by both a sodium-dependent and a sodium-independent pathway. The contribution of the sodium-independent uptake to the overall uptake of taurocholate increases with increasing zonal recruitment at higher concentrations. The sodium-dependent uptake, however, is always dominant.

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We evaluated fluorescence microscopy combined with digitized image analysis for the investigation of fluorescein transport in the intact rat liver. The images of the surface of isolated rat livers which were perfused directly under a microscope were projected onto a silicone-intensified target camera, stored on a video tape and analyzed with a microcomputer equipped with an image digitizer. It was shown that, after correction of the day-to-day variability of the optical and electronical system, the increase in fluorescence intensity of the liver surface following fluorescein infusion depended linearly on the fluorescein concentration in the perfusion medium up to 1 mM. Since, under the conditions used, biliary secretion and metabolic influences were found to be insignificant the uptake mechanism is probably predominantly simple diffusion.

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[3H]glutamate, [3H]alpha-ketoglutarate or [3H]aspartate was injected in physiological concentrations into antegrade (from portal to hepatic vein) or retrograde (from hepatic to portal vein) perfused rat liver, and the tissue distribution of radioactivity was studied by histoautoradiography. Independent of the direction of perfusion, radioactivity was accumulated in a small perivenous liver parenchymal cell population, which surrounded the terminal hepatic venules as a layer of about two to five cells thick. In contrast, accumulation of radioactivity in periportal hepatocytes was low and sometimes not detectable. This distribution pattern roughly resembled that described for the immunohistochemical distribution of glutamine synthetase in liver. The present histoautoradiographic findings demonstrate a predominant uptake of vascular glutamate, aspartate and ketoglutarate into a small perivenous cell population. They confirm previous label incorporation studies in the metabolically intact liver, demonstrating an almost exclusive uptake of vascular glutamate and alpha-ketoglutarate into perivenous glutamine synthetase containing hepatocytes. In addition, evidence is presented suggesting that perivenous uptake of alpha-ketoglutarate may be one determinant for hepatic glutamine synthesis, at least under the experimental conditions used here.

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The humoral immune system of the intestinal mucosa of patients with common variable immuno deficiency (CVID) syndrome was studied immunohistologically using antibodies against immunoglobulin (Ig) A1-2, M and G1-4, against the J chain and the secretory component. In 9/13 CVID-patients IgA-positive cells were totally absent whereas a total IgM-defect was found only in 3/14 patients. Considerable numbers of J chain-positive cells were present in all CVID-patients irrespective of the extent of the Ig-defect indicating the presence of early B-cells unable to differentiate and to produce Ig. There was a strong expression of the secretory component in the cytoplasm and at the surface of enterocytes even in those CVID-patients who were totally defective in IgA- and IgM-positive cells.

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Based on 1099 endoscopic retrograde cholangiopancreatograms (ERCP), 659 examinations conducted in 1973-1980 prior to the introduction of computed tomography (CT) and 440 performed in 1988-1989, the impact of sonography and CT on ERCP is studied. The availability of CT did not cause any significant change in the frequency of and indications for ERCP. The rate of successful ERCP examinations increased from 73.6% to 92%. Complications occurred in 2.3%, and the mortality rate was 0.4% and was similar in both periods. ERCP was the third imaging procedure, being applied after sonography and CT, in most patients. The diagnostic value of ERCP in pancreatic disease is compared with that of sonography and CT in 116 patients with histologically or clinically proven diagnosis. The sensitivity is 79% for ERCP and 78% for CT. Indeterminate findings were recorded in 11% of the ERCP and 8% of the CT examinations; these rates can be decreased by complementary use of both imaging modalities.

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In clinical practice the acquired or de novo resistance of tumors to antitumor chemotherapy remains a big problem. However, in the past few years some progress has been made in understanding the two principal mechanisms: metabolic alterations leading to a reduced cytostatic or cytotoxic effect of drugs, and reduced accumulation of drugs within the tumor cells [15, 34, 35]. The second phenomenon is usually attributed to the ability of tumor cells to accelerate the efflux of various xenobiotics. This phenomenon is considered primarily responsible for the development of multidrug resistance (MDR). However, loss or impairment of drug uptake by the tumor cells may also contribute to resistance to antitumor drugs. This paper focuses on recent findings with hepatoma cells, which support this view.

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New endoscopic and radiological techniques, together with pharmacological developments, prompted by high-surgical risk patients or those developing bile duct stones after prior cholecystectomy--but also by the wish to have less invasive alternatives available, have led to a variety of non-operative therapeutic modalities in gallstone diseases. Both endoscopic and radiological procedures are employed to remove stones from the biliary tract and gallbladder. Extracorporeal lithotripsy and chemical litholysis are being increasingly employed to treat gallbladder stones. Laparoscopic cholecystectomy is a new operative possibility. These different approaches, sometimes used in combination, are associated with different preconditions for success. Indications and results must be measured against the gold standard of cholecystectomy.

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