The Impact of a Standardized Pre-visit Laboratory Testing Panel in the Internal Medicine Outpatient Clinic: a Controlled "On-Off" Trial.

BACKGROUND: In several settings, a shorter time to diagnosis has been shown to lead to improved clinical outcomes. The implementation of a rapid laboratory testing allows for a pre-visit testing in the outpatient clinic, meaning that test results are available during the first outpatient visit. OBJECTIVE: To determine whether the pre-visit laboratory testing leads to a shorter time to diagnosis in the general internal medicine outpatient clinic. DESIGN: An "on-off" trial, allocating subjects to one of two treatment arms in consecutive alternating blocks. PARTICIPANTS: All new referrals to the internal medicine outpatient clinic of a university hospital were included, excluding second opinions. A total of 595 patients were eligible; one person declined to participate, leaving data from 594 patients for analysis. INTERVENTION: In the intervention group, patients had a standardized pre-visit laboratory testing before the first visit. MAIN MEASURES: The primary outcome was the time to diagnosis. Secondary outcomes were the correctness of the preliminary diagnosis on the first day, health care utilization, and patient and physician satisfaction. KEY RESULTS: There was no difference in time to diagnosis between the two groups (median 35 days vs 35 days; hazard ratio 1.03 [0.87-1.22]; p = .71). The pre-visit testing group had higher proportions of both correct preliminary diagnoses on day 1 (24% vs 14%; p = .003) and diagnostic workups being completed on day 1 (10% vs 3%; p < .001). The intervention group had more laboratory tests done (50.0 [interquartile range (IQR) 39.0-69.0] vs 43.0 [IQR 31.0-68.5]; p < .001). Otherwise, there were no differences between the groups. CONCLUSIONS: Pre-visit testing did not lead to a shorter overall time to diagnosis. However, a greater proportion of patients had a correct diagnosis on the first day. Further studies should focus on customizing pre-visit laboratory panels, to improve their efficacy. TRIAL REGISTRATION: NL5009.

A computerised decision support system for cardiovascular risk management 'live' in the electronic health record environment: development, validation and implementation-the Utrecht Cardiovascular Cohort Initiative.

PURPOSE: We set out to develop a real-time computerised decision support system (CDSS) embedded in the electronic health record (EHR) with information on risk factors, estimated risk, and guideline-based advice on treatment strategy in order to improve adherence to cardiovascular risk management (CVRM) guidelines with the ultimate aim of improving patient healthcare. METHODS: We defined a project plan including the scope and requirements, infrastructure and interface, data quality and study population, validation and evaluation of the CDSS. RESULTS: In collaboration with clinicians, data scientists, epidemiologists, ICT architects, and user experience and interface designers we developed a CDSS that provides 'live' information on CVRM within the environment of the EHR. The CDSS provides information on cardiovascular risk factors (age, sex, medical and family history, smoking, blood pressure, lipids, kidney function, and glucose intolerance measurements), estimated 10-year cardiovascular risk, guideline-compliant suggestions for both pharmacological and non-pharmacological treatment to optimise risk factors, and an estimate on the change in 10-year risk of cardiovascular disease if treatment goals are adhered to. Our pilot study identified a number of issues that needed to be addressed, such as missing data, rules and regulations, privacy, and patient participation. CONCLUSION: Development of a CDSS is complex and requires a multidisciplinary approach. We identified opportunities and challenges in our project developing a CDSS aimed at improving adherence to CVRM guidelines. The regulatory environment, including guidance on scientific evaluation, legislation, and privacy issues needs to evolve within this emerging field of eHealth.

Development of a nomogram for the estimation of long-term adherence to clozapine therapy using neutrophil fluorescence.

AIMS: Previously, we have reported an association between clozapine use and elevated FL3 neutrophil fluorescence, a flow-cytometric parameter for cell viability. Here, we developed and evaluated a pharmacokinetic-pharmacodynamic model relating FL3-fluorescence to clozapine exposure and derived a nomogram for estimation of long-term adherence. METHODS: Data from 27 patients initiating clozapine were analysed using nonlinear mixed effects modelling. A previously described pharmacokinetic model for clozapine was coupled to a FL3 fluorescence model. For this, an effect compartment with clozapine concentrations as input and a first order decay rate as output was linked with an Emax model to FL3-fluorescence. FL3-fluorescence was simulated for clozapine doses of 50, 150 and 400 mg daily (n = 10 000) to establish the nomogram. Finally, true simulated adherence (% of daily doses taken over 100 days) was compared to nomogram-estimated adherence to evaluate the performance of the nomogram. RESULTS: The half-life of FL3-fluorescence was estimated at 228 h (coefficient of variation 35%). Median absolute prediction errors of the nomogram in case of fully random adherence for 50, 150 and 400 mg ranged from -0.193% to -0.525%. The nomogram performed slightly worse in case of nonrandom adherence (median prediction error up to 5.19%), but was still clinically acceptable. Compliance patterns containing longer drug holidays revealed that the nomogram adequately estimates compliance over approximately the last 3 weeks prior to FL3-measurement. CONCLUSION: Our nomogram could provide information regarding long-term adherence based on prescribed clozapine dose and FL3-fluorescence. Future studies should further explore the clinical value of this biomarker and nomogram.

Exploring the value of routinely measured hematology parameters for identification of elderly patients at high risk of death at the Emergency Department.

Of the warning scores in use for recognition of high-risk patients at the Emergency Department (ED), few incorporate laboratory results. Although hematological characteristics have shown prognostic value in small studies, large studies in elderly ED populations are lacking. We studied the association between blood cell and platelet counts and characteristics as well as C-reactive protein (CRP) at ED presentation with mortality in non-multitrauma patients ≥ 65 years. Comparison between survivors and non-survivors showed small, significant differences with AUROCs ranging between 56.6% and 65.2% for 30-day mortality. Combining parameters yielded an evident improvement (AUROC of 70.4%). Efforts should be pursued to study the added value of hematological parameters on top of clinical data when assessing patient risk.

Elevated mean neutrophil volume represents altered neutrophil composition and reflects damage after myocardial infarction.

Myocardial infarction (MI) induces an inflammatory response in which neutrophils fulfill a prominent role. Mean neutrophil volume (MNV) represents the average size of the circulating neutrophil population. Our goal was to determine the effect of MI on MNV and investigate the mechanisms behind MNV elevation. MNV of 84 MI patients was compared with the MNV of 209 stable angina patients and correlated to simultaneously measured CK levels. Fourteen pigs were subjected to temporary coronary balloon occlusion and blood was sampled at multiple time points to measure MNV. Echocardiography was performed followed by ex vivo infarct size assessment after 72 h. MNV was higher in MI patients compared to stable angina patients (602 SD26 AU vs. 580 SD20 AU, p < 0.0001) and correlated with simultaneously measured CK levels (R = 0.357, p < 0.0001). In pigs, MNV was elevated post-MI (451 SD11 AU vs. 469 SD12 AU), p < 0.0001). MNV correlated with infarct size (R = 0.705, p = 0.007) and inversely correlated with left ventricular ejection fraction (R = -0.718, p = 0.009). Cell sorting revealed an increased presence of banded neutrophils after MI, which have a higher MNV compared to mature neutrophils post-MI (495 SD14 AU vs. 478 SD11 AU, p = 0.012). MNV from coronary sinus blood was higher than MNV of neutrophils from simultaneously sampled arterial blood (463 SD7.6 AU vs. 461 SD8.6 AU, p = 0.013) post-MI. The current study shows MNV is elevated and reflects cardiac damage post-MI. MNV increases due to altered neutrophil composition and systemic neutrophil activation. MNV may be an interesting parameter for prognostic assessment in MI and provide new insights into pathological innate immune responses evoked by ischemia-reperfusion.

Genome-wide association study of lymphoblast cell viability after clozapine exposure.

Clozapine is an antipsychotic drug with proven efficacy in treatment-resistant schizophrenia but also known to induce potentially lethal agranulocytosis (CIA) in 1% of patients. Genetic factors are likely to play a role in the molecular basis of CIA. We explored an in vitro system to study the genetic susceptibility of CIA. Cell viability was measured in 90 lymphoblast cell lines exposed to a series of increasing concentrations of clozapine for 48 hr. Quantitative trait measures of cell viability as well as area under the survival curve were used in a linear mixed model for genome-wide association analyses. The estimated heritability of clozapine-induced cell viability reduction in these cell lines is h2=0.76. No genome-wide significant association was observed after correction for multiple testing. Two independent loci with nominal evidence of association were observed at 30× clinical clozapine concentration: rs2709505 (P=1.41×10(-8)) in an intron of MDFIC and rs10457252 (P=1.79×10(-8)) located in a gene desert at chromosome 6q21. We identified one locus (rs1293970) near PRG4 that was consistently associated for all separate concentration analyses at P<5×10(-5). PRG4 encodes hemangiopoietin, a growth stimulator for hematopoietic stem cells. No evidence was observed for involvement of the MHC region. Our results demonstrate that clozapine-induced viability reduction in lymphoblast cell lines is a heritable, polygenic trait. Thus, in vitro models of CIA might be a useful tool for future discovery of genetic risk factors, although larger sample sizes will be required to unambiguously identify these loci.

Occurrence and determinants of poor response to short-term pre-operative erythropoietin treatment.

BACKGROUND: This study aimed to explore the occurrence and determinants of poor response to short-term pre-operative erythropoietin treatment and the effect of such poor response on transfusion in total hip arthroplasty patients. METHODS: We studied total hip arthroplasty patients who received erythropoietin before surgery. The primary outcome was the pre-operative increase in haemoglobin (delta haemoglobin) as response to erythropoietin therapy. Additionally, patients were classified in tertiles based on this delta haemoglobin: poor responders (cases), responders and good responders (controls) to erythropoietin. Patient characteristics, comedication and co-morbidity were collected as potential determinants of erythropoietin response. Regression techniques were used to estimate the strength of the associations and to assess the effect of poor response on transfusion requirement. RESULTS: A total of 379 patients receiving erythropoietin were eligible to enter the study. Mean delta haemoglobin was 19.3 g/l (standard deviation 9.4). Factors significantly associated with delta haemoglobin were the use of angiotensin II antagonists [-3.1 g/l; 95% confidence interval (CI) -5.7 to -0.6] and vitamin K antagonists (-6.9 g/l; 95% CI -10.0 to -0.2), together with body mass index (BMI) (-0.3 g/l per unit>; 95% CI -0.5 to -0.2). The additional case-control analysis yielded comparable results. Poor response to erythropoietin was associated with an increased transfusion risk (odds ratio 4.6, 95% CI 2.0-11). CONCLUSION: Use of angiotensin II receptor antagonists and vitamin K antagonists, and having a high BMI were determinants of poor response to short-term pre-operative erythropoietin treatment in total hip arthroplasty patients. Poor responders had a higher risk for perioperative blood transfusion.

Feasibility of point-of-care creatinine testing in community pharmacy to monitor drug therapy in ambulatory elderly patients.

WHAT IS KNOWN AND OBJECTIVE: It is often necessary to adjust drug therapy if renal function is impaired in elderly patients taking drugs for diabetes and/or cardiovascular disease that are cleared by the kidneys. Although clinical guidelines recommend regular monitoring of renal function in these patients, in practice adherence to these recommendations varies from 28% to 75%. To determine whether drug dosing is appropriate, pharmacists need have up-to-date information about patients' renal function. In this study, the feasibility of point-of-care creatinine testing (POCCT) in a community pharmacy was evaluated as part of monitoring the drug therapy of ambulatory elderly patients. METHODS: Elderly patients on maintenance therapy with renally excreted drugs for diabetes or cardiovascular disease were eligible for POCCT. After informed consent was obtained, POCCT was performed by trained personnel. A pharmacist assessed the clinical relevance of electronically generated drug alerts based on the patient's calculated renal function and the Dutch guidelines for adjusting drug dosage in patients with chronic kidney disease. If appropriate, the patient's general practitioner (GP) was consulted and adjustments to treatment were communicated to the patient. The feasibility of POCCT was evaluated by means of questionnaires completed by patients and healthcare professionals (GPs and pharmacists). RESULTS: Of 338 potentially eligible patients, 149 (44%) whose renal function was not known were asked, by letter, to participate in the study. Of these individuals, 46 (31%) gave their informed consent and underwent POCCT. Response rates for completing the patient and professional questionnaires were 87% and 100%, respectively. More than half of the patients who underwent POCCT had mild-to-moderate renal impairment. On the basis of information provided by patients and healthcare professionals, POCCT would appear to be feasible in community pharmacies. WHAT IS NEW AND CONCLUSION: POCCT improves the management of drug therapy by community pharmacists and is feasible in daily practice.

GFR estimation is complicated by a high incidence of non-steady-state serum creatinine concentrations at the emergency department.

BACKGROUND: Acquiring a reliable estimate of glomerular filtration rate (eGFR) at the emergency department (ED) is important for clinical management and for dosing renally excreted drugs. However, renal function formulas such as CKD-EPI can give biased results when serum creatinine (SCr) is not in steady-state because the assumption that urinary creatinine excretion is constant is then invalid. We assessed the extent of this by analysing variability in SCr in patients who visited the ED of a tertiary care centre. METHODS: Data from ED visits at the University Medical Centre Utrecht, the Netherlands between 2012 and 2019 were extracted from the Utrecht Patient Oriented Database. Three measurement time points were defined for each visit: last SCr measurement before visit as baseline (SCr-BL), first measurement during visit (SCr-ED) and a subsequent measurement between 6 and 24 hours during admission (SCr-H1). Non-steady-state SCr was defined as exceeding the Reference Change Value (RCV), with 15% decrease or 18% increase between successive SCr measurements. Exceeding the RCV was deemed as a significant change. RESULTS: Of visits where SCr-BL and SCr-ED were measured (N = 47,540), 28.0% showed significant change in SCr. Of 17,928 visits admitted to the hospital with a SCr-H1 after SCr-ED, 27,7% showed significant change. More than half (55%) of the patients with SCr values available at all three timepoints (11,054) showed at least one significant change in SCr over time. CONCLUSION: One third of ED visits preceded and/or followed by creatinine measurement show non-stable serum creatinine concentration. At the ED automatically calculated eGFR should therefore be interpreted with great caution when assessing kidney function.

Ektacytometry Analysis of Post-splenectomy Red Blood Cell Properties Identifies Cell Membrane Stability Test as a Novel Biomarker of Membrane Health in Hereditary Spherocytosis.

Hereditary spherocytosis (HS) is the most common form of hereditary chronic hemolytic anemia. It is caused by mutations in red blood cell (RBC) membrane and cytoskeletal proteins, which compromise membrane integrity, leading to vesiculation. Eventually, this leads to entrapment of poorly deformable spherocytes in the spleen. Splenectomy is a procedure often performed in HS. The clinical benefit results from removing the primary site of destruction, thereby improving RBC survival. But whether changes in RBC properties contribute to the clinical benefit of splenectomy is unknown. In this study we used ektacytometry to investigate the longitudinal effects of splenectomy on RBC properties in five well-characterized HS patients at four different time points and in a case-control cohort of 26 HS patients. Osmotic gradient ektacytometry showed that splenectomy resulted in improved intracellular viscosity (hydration state) whereas total surface area and surface-to-volume ratio remained essentially unchanged. The cell membrane stability test (CMST), which assesses the in vitro response to shear stress, showed that after splenectomy, HS RBCs had partly regained the ability to shed membrane, a property of healthy RBCs, which was confirmed in the case-control cohort. In particular the CMST holds promise as a novel biomarker in HS that reflects RBC membrane health and may be used to asses treatment response in HS.

Inappropriate laboratory testing in internal medicine inpatients: Prevalence, causes and interventions.

BACKGROUND: To reduce overutilization of laboratory testing many interventions have been tried, but selecting the most effective intervention for a given setting is challenging. To be sustainable, interventions need to align with healthcare providers' needs and daily practices. This study aimed to assess the extent of overutilization and the perspectives of healthcare providers, which may be used to guide the choice of intervention. METHODS: The extent of inappropriate laboratory testing in internal medicine inpatients was evaluated using a database. Surveys and focus groups were used to investigate healthcare providers' perceptions on its causes and solutions. RESULTS: On average, patients had 5.7 laboratory orders done during the first week of admission, whereas guidelines advise performing laboratory testing no more than twice per week. Repeat testing of normal test results occurred in up to 85% of patients. The frequency of laboratory testing was underestimated by survey responders, even though the majority of responders (78%) thought that laboratory tests are ordered too frequently. Residents were considered to be most responsible for laboratory test ordering.The primary causes of overutilization discussed were personal factors, such as a lack of awareness and knowledge, as well as feelings of insecurity. Regarding possible solutions, residents generally recommended educational interventions, whereas specialists tended to favour technical solutions such as lockouts. CONCLUSION: Inappropriate laboratory testing is common in internal medicine. The most important causes are a lack of awareness and knowledge, especially in residents. The intervention most favoured by residents is education, suggesting educational interventions may be most applicable.

Digital microscopy as a screening tool for the diagnosis of hereditary hemolytic anemia.

INTRODUCTION: Evaluation of red blood cell (RBC) morphology is an important first step in the differential diagnosis of hereditary hemolytic anemia. It is, however, labor intensive, expensive, and prone to subjectivity. To improve and standardize the analysis of RBC morphology as a screening tool in the diagnosis of hereditary hemolytic anemia, we studied its automated analysis by digital microscopy (DM). METHODS: Blood from 90 patients with hereditary hemolytic anemia and 32 normal control subjects was analyzed by the CellaVision DM96 Digital Microscope. RESULTS: All hemolytic RBC abnormalities could be distinguished by the presence of at least one aberrant red cell type. In particular, the percentage of microcytes was highly sensitive and specific (AUCROC  = 0.97) for RBC membrane disorders, and a cut-off of 5.7% microcytes was calculated to be optimal to distinguish patients from healthy controls. Subgroup analysis of patients with RBC membrane disorders revealed additional distinct differences according to the underlying gene defect. A number of cell types were significantly elevated in sickle cell anemia patients, such as polychromatic cells, macrocytes, and poikilocytes. The increase in helmet cells (AUCROC  = 0.96) and hypochromic cells (AUCROC  = 0.91) was specific for ß-thalassemia, whereas patients with pyruvate kinase deficiency showed a significant increased polychromatic cells, macrocytes, and ovalocytes. Patients with hereditary xerocytosis showed significantly higher numbers of polychromatic cells, macrocytes, and target cells. CONCLUSION: DM holds a promise as a useful screening tool in the diagnosis of hereditary hemolytic anemia by detecting and quantifying distinct morphological changes in RBCs in patients with various forms of hereditary hemolytic anemia.

[A flow chart for the laboratory diagnosis of anaemia as requested by general practice]. / Het stroomschema voor de laboratoriumdiagnostiek van anemie, zoals die wordt aangevraagd vanuit de huisartsenpraktijk.

Anaemia is a common problem in primary care. It can be a symptom of an underlying disease such as a malignancy, and should therefore not be ignored. The diagnosis of anaemia is laboratory-based and is defined as a haemoglobin concentration below the lower reference value. The reference values are currently under debate; some authors argue that the WHO lower reference values are incorrect and should be replaced by higher values. Algorithms for requesting laboratory tests can be applied as a guide to the classification and diagnosis ofanaemia. The Dutch College of General Practitioners has issued such a flow chart which is based on Wintrobe's classification and in which the red cell volume is a central value i.e. the 'mean corpuscular volume' (MCV). An alternative flow chart has been proposed which starts with the determination of the ferritin concentration. However, neither of these algorithms is always practical. They often do not lead to a diagnosis, and combined diagnoses may not be accounted for. In general practice, the initial diagnosis of anaemia could be based on a reliable haemoglobin measurement which would establish if anaemia is or is not present. Consequently, a simple laboratory diagnosis algorithm could be applied to frequently occurring causes of anaemia, such as iron deficiency. Should the cause be a rarer one, then a specialist should be consulted.

Ovarian cancers express and process progastrin.

Gastrin synthesis in ovarian tumors has been described in a few isolated cases associated with the Zollinger-Ellison syndrome. Consequently, ovarian gastrin synthesis has been considered exceptional. In order to evaluate whether expression of gastrin in ovarian tumors indeed is rare, we examined the expression and processing of progastrin in 16 malignant and 5 benign ovarian tumors and 4 normal postmenopausal ovaria. Using a library of sequence specific radioimmunoassays, cleavage by processing-like enzymes, and gel chromatography, we found that one-half of the malignant tumors expressed significant concentrations of amidated gastrins [6.7 +/- 2.7 (SEM) pmol/g; range, 1.4-20.0 pmol/g, n = 7]. The concentrations of glycine-extended gastrins and progastrins were low (0.25 +/- 0.03 and 1.4 +/- 0.4 pmol/g, respectively) but higher than in controls and benign tumors. Chromatography showed that the majority of the bioactive gastrins was unsulfated gastrin-17. The other half of the malignant tumors expressed glycine-extended gastrins and progastrins (0.2 +/- 0.03 and 0.6 +/- 0.1 pmol/g; n = 9), but the amidation of the peptides was impaired (0.1 +/- 0.03 pmol/g). Low concentrations of glycine-extended gastrins and progastrins were detected in the normal ovarian tissues (0.2 +/- 0.05 pmol/g tissue and 0.2 +/- 0.06 pmol/g, respectively, n = 4) and in the benign tumors (0.1 +/- 0.02 pmol/g and 0.5 +/- 0.03 pmol/g; n = 5). Amidated gastrins were undetectable, except in low amounts in a single benign tumor (0.2 pmol/g tissue). The results show that postmenopausal ovaria and neoplastic ovarian tissues express the gastrin gene at peptide level. The synthesis and processing of progastrin increase considerably in malignant tumors.

Co-transcription of the gastrin and cholecystokinin genes with selective translation of gastrin mRNA in a human gastric carcinoma cell line.

So far, no cells have been found to synthesize both of the homologous hormones, cholecystokinin and gastrin. Northern analysis and reverse transcription PCR showed, that the human gastric carcinoma cell line (AGS) expresses both a gastrin mRNA of 0.7 kb and a cholecystokinin transcript of 0.8 kb. A library of sequence-specific radioimmunoassays, cleavage with processing-like enzymes and chromatography subsequently revealed that the gastrin mRNA was translated into progastrin that was constitutively secreted into the medium (45 +/- 3 pmol/l). Neither procholecystokinin nor any of its processing products were detectable in cells and media. The results suggest that differentiation into gastrin- or cholecystokinin-producing cells may be regulated at the translational level. The gastric cell line, AGS, provides a model for studies of translational regulation of cell differentiation.

A distal Sp1-element is necessary for maximal activity of the human gastrin gene promoter.

Studies of transgenic mice have shown that transcriptional control of the gastrin gene exhibits significant species differences. Transfection of the human gastrin promoter in murine cells have depicted proximal Sp1, E-box and CACC elements as the major determinants of transcription. We have examined cis-regulatory elements of the human promoter on a human gastrin expressing cell line and find that a distal -135 to -142 Sp1 element is necessary for maximal activity. Alignment of the mouse and human promoters shows that the proximal human Sp1 and CACC elements are not conserved, whereas the E-box element is retained. The distal Sp1 element is present in mouse but exhibits a C to T transition in the core that is likely to reduce binding affinity of Sp1. We conclude that gastrin gene transcription is regulated by distinct elements in man and rodents.

Acute intraduodenal bile salt depletion leads to strong gallbladder contraction, altered antroduodenal motility and high plasma motilin levels in humans.

Cholecystokinin is the main hormone involved in postprandial gallbladder contraction. There is also considerable gallbladder contraction in the fasting state, associated with phase III of the gastrointestinal migrating motor complex and release of the hormone motilin. It has been proposed that intraduodenal bile salts exert a negative-feedback control on postprandial cholecystokinin release and resulting gallbladder contraction. We wanted to elucidate whether a similar control mechanism on gallbladder contraction exists in the fasting state. We therefore performed gallbladder ultrasonography and 24-h antroduodenal motility registrations and determined plasma cholecystokinin and motilin levels in six healthy subjects before and after acute (4 g) and chronic (8 days; 8 g day(-1)) oral cholestyramine. Acute cholestyramine strongly decreased gallbladder volumes and increased motilin without changed cholecystokinin levels. There was a negative relationship between gallbladder volumes and plasma motilin levels. Although there was a persistent fasting pattern of antroduodenal motility, its cycle length was increased (P < 0.03) with markedly longer phase II (P < 0. 005). Fasting gallbladder volumes 24 h later were still strongly decreased but gradually increased to pretreatment levels. Before and after 8 days cholestyramine, interdigestive and postprandial gallbladder emptying, intestinal migrating motor complex and hormone levels did not differ. We conclude that acute (but not chronic) intraduodenal bile salt depletion with cholestyramine affects gallbladder and antroduodenal motility, possibly partly related to motilin release.

Gastrin, cholecystokinin and their precursors in acoustic neuromas.

Using sequence-specific radioimmunoassays the occurrence of 4 neuropeptides (cholecystokinin (CCK), gastrin, somatostatin, substance P and some of their precursors) was examined in 19 human acoustic nerve tumors and corresponding normal tissue. The normal acoustic nerve tissue obtained by autopsy contained traces of CCK, somatostatin, and substance P (less than or equal to 0.5 pmol/g), but neither proCCK, gastrin nor progastrin. In contrast 8 tumors expressed proCCK (range 0.2-4.5 pmol/g), 3 tumors gastrin (0.1-7.3 pmol/g) and 14 tumors progastrin (0.6-2.2 pmol/g). Traces of somatostatin were present in two and substance P in one tumor. The results show that acoustic neuromas often express the homologous CCK and gastrin genes, but process their propeptides poorly to transmitter-active peptides. The tumor synthesis of gastrin/progastrin contrasts to the rare, sporadic expression of the gastrin gene in normal nerve tissue.

Radioimmunoassay for sequence 38-54 of human progastrin: increased diagnostic specificity of gastrin-cell diseases.

Antisera were raised against fragment 38-54 of human progastrin. All of eight immunized rabbits responded, but only one (No. 2145) produced high-titer (3.2 x 10(4)) and high-avidity (Keff degrees = 1.2 x 10(12) l/mol) antibodies. A radioimmunoassay based on antiserum 2145 and monoiodinated gastrin-34 was specific for the N-terminal sequence of human gastrin-34. It measured concentrations of 9.7 +/- 1, 18.4 +/- 2 pmol/l (mean +/- SEM) and 1.553 (0.7-476) nmol/l (median (range], respectively, in sera from normal subjects (n = 20), patients with duodenal ulcer (n = 19), and Zollinger-Ellison patients (n = 8). Conventionally measured concentrations of carboxyamidated gastrins in the same sera were 21.4 +/- 1, 23.8 +/- 3 pmol/l (mean +/- SEM) and 0.833 (0.4-214) nmol/l (median (range)), respectively. The results show that radioimmunoassays specific for the N-terminus of human gastrin-34 discriminate between healthy subjects and patients with duodenal ulcer. The improved diagnostic specificity is due to co-measurement of unprocessed and partly processed progastrins that occur in plasma of patients with duodenal ulcer disease and gastrinomas. We suggest that conventional gastrin assays are supplemented with assays specific for the N-terminus of gastrin-34 in studies of duodenal ulcer disease.