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Biomedical subjects

A P van Zanten

Publications and source records attributed to A P van Zanten.

At least 19 recordsLinked to original sources
PubMed2006

Mast cell mediator tryptase levels after inhalation or intravenous administration of high doses pharmaceutically prepared heroin.

BACKGROUND: Opioids like morphine and heroin induce mast cell degranulation in vitro. The release of mast cell mediators like histamine and tryptase may lead to allergic symptoms. In this study it was investigated whether mast cell mediator release also occurs in vivo in addicted patients who participated in a heroin on medical prescription trial, and were under treatment with large doses of heroin in combination with methadone. METHOD: Plasma levels of tryptase, a specific marker for mast cell degranulation, were measured by immuno-assay at baseline and 60 min after heroin administration. Heroin was administered either by intravenous injection (11 subjects) or by inhalation (nine subjects). Single heroin doses varied from 200 to 450 mg. Besides tryptase, the plasma concentrations of heroin, its metabolite morphine and methadone were measured. RESULTS: After heroin injection, the mean tryptase plasma concentration increased dose dependently by on average 23.1% (95% CI 14.6-31.6%). After heroin inhalation, no tryptase release was observed. Heroin and morphine peak plasma concentrations were 3-5 times greater in heroin injectors than in inhalers. In heroin injectors, tryptase levels were related to morphine peak concentrations, but not to heroin concentrations. Tryptase plasma concentrations were not related to methadone levels. Mild allergic reactions were reported in five cases after intravenous heroin use, but not after inhalation. CONCLUSION: This study revealed that mast cell mediator tryptase concentrations increase after intravenous heroin injection in chronic opioid users, but not after heroin inhalation. This may be explained by the higher Cmax levels of metabolite morphine that were achieved after injection than after inhalation. Although statistical significance was reached, the degree of mast cell degranulation after intravenous injection of heroin was mild, and did not lead to clinically relevant side effects in this group of opioid-tolerant subjects.

Administration, Inhalation↗
PubMed2005

Soluble tissue factor is a candidate marker for progression of microvascular disease in patients with Type 2 diabetes.

OBJECTIVE: To determine the relationship between abnormalities in blood coagulation and prevalent or incident cardiovascular complications in Type 2 diabetes. DESIGN AND METHODS: Prospective cohort study of 128 patients with Type 2 diabetes in whom blood samples were collected at baseline and after 1 year of follow-up. All cardiovascular complications at baseline and follow-up were recorded. Forty-three healthy, age-matched subjects served as a control group. RESULTS: Logistic analysis revealed an independent relationship between soluble tissue factor (TF) and microvascular disease [per pg mL(-1) TF: Exp(B) = 1.008; CI(95%)1.002-1.014], or neurogenic disease [Exp(B) = 1.006; CI(95%)1.001-1.011]. The highest levels of soluble TF were observed in patients with microvascular and neurogenic disease (P < 0.001). Patients with Type 2 diabetes having a soluble TF concentration >300 pg mL(-1) are at a 15-fold higher risk for the presence of microvascular disease and at a 10-fold higher risk for the presence of neurogenic disease compared with the patients with concentrations below 100 pg mL(-1). Soluble TF was correlated with tissue type plasminogen activator, von Willebrand factor antigen, systolic blood pressure and age. Levels of F1' + 2, D-dimer, FVIII activity, t-PA and vWFag were not different among patients with micro-, macro- or neurogenic complications compared with patients without those complications. Forty-eight new micro-, macro- and/or neurogenic complications were diagnosed after 1 year follow-up. With the exception of higher F1 + 2 levels after 1 year all other markers remained unchanged. A trend toward higher soluble TF levels was observed in patients with new microvascular events (P = 0.056). CONCLUSIONS: Soluble TF is associated with existing microvascular and neurogenic complications in patients with Type 2 diabetes and is a candidate marker for progression of microvascular disease.

Adult↗
PubMed2004

Protein C and S and inflammation in sickle cell disease.

Reduced activity of naturally occurring anticoagulants (NOAC) protein C and protein S may contribute to vaso-occlusion in sickle cell disease (SCD). We studied whether protein C and S are related to clinical vaso-occlusion, hematological markers of disease severity (hemoglobin levels, leukocyte counts, and percentage of fetal hemoglobin), and inflammation in SCD. Protein C activity, protein S (free and total) antigen, endothelial activation markers (soluble vascular cell adhesion molecule-1 [sVCAM-1], von Willebrand antigen [vWF]), and high sensitive C-reactive protein (hsCRP) levels were measured in 30 HbSS and 20 HbSC patients and in race-matched HbAA controls. NOAC levels were reduced in patients, and endothelial activation markers and hsCRP were elevated (except vWF in HbSC patients). Protein C activity and vWF levels were lower in HbSC patients who experienced painful crises compared to HbSC patients who were clinically asymptomatic. No other differences were observed between patients who did and did not experience vaso-occlusive events (painful crises, stroke, acute chest syndromes) or leg ulcers. A significant positive correlation between total protein S with hemoglobin levels and a significant negative correlation between total and free protein S and sVCAM-1 were detected in HbSS patients. Except perhaps for protein C in relation to painful crises in HbSC patients, these markers were not associated with the occurrence of clinical events. The protein S, hemoglobin, and sVCAM-1 associations may suggest decreased endothelial protein S production due to the more severe endothelial perturbation in HbSS patients with lower hemoglobin levels.

Adult↗
PubMed2001

Variation of pH-measurement in platelet concentrates.

To measure pH in platelet concentrates, blood gas analysers with different calibration principles may be used. In this study, variances observed in pH measurements with two types of blood gas analysers were investigated. pH was measured in crystalloid solutions (platelet additive solution (PAS-II), phosphate-buffered solutions) and two types of platelet concentrates (containing 100% plasma, or 65% PAS-II/35% plasma) with two blood gas analysers: either using liquid and gas calibration (AVL 945), or only liquid calibration (AVL OMNI). These measurements were compared with a reference method. Especially for PAS-II, large variation in pH was observed between AVL 945, AVL OMNI and the reference method: 6.91 +/- 0.02, 7.35 +/- 0.02 and 7.188 +/- 0.010, respectively (mean +/- SD; n = 12, P < 0.0001, paired t-test). A significant difference in pH was also found for platelet concentrates in 65% PAS/35% plasma (6.88 +/- 0.09 on AVL 945 and 7.02 +/- 0.09 on AVL OMNI, n = 134, P < 0.0001). Comparison with the reference method revealed minor differences with AVL 945, whereas AVL OMNI gave a mean difference in pH of + 0.17. Platelets in 100% plasma revealed smaller differences (6.93 +/- 0.13 for AVL 945 and 6.99 +/- 0.13 for AVL OMNI, n = 95, P < 0.0001). We conclude that different blood gas analysers can yield different pH values, especially in weak buffered solutions such as platelet concentrates in PAS-II. Validation of blood gas analysers for pH measurement of these solutions is therefore mandatory.

Blood Gas Analysis↗
PubMed2000

The influence of ketoacids on plasma creatinine assays in diabetic ketoacidosis.

OBJECTIVE: Analysis of the interference of ketoacids on various routine plasma creatinine assays during a clinical episode of diabetic ketoacidosis (DKA). DESIGN: Observational study. Blood samples were drawn before, during and after standard in-hospital treatment. Plasma creatinine was measured with two dissimilar enzymatic assays (creatininase PAP + and creatinine iminohydrolase Serapak), a kinetic alkaline picrate method (Jaffé) and a high-performance liquid chromatography (HPLC) procedure. Acetoacetate and beta-hydroxybutyrate were analysed by enzymatic methods. SETTING: Department of Medicine, University Hospital. SUBJECTS: Nine patients who experienced 10 episodes of DKA. MAIN OUTCOME MEASURES: Agreement of the routine plasma creatinine assays with HPLC and analysis of possible interferents. RESULTS: At presentation, the Jaffé assay gave falsely high values of plasma creatinine (median 99 micromol L(-1)), in contrast to the PAP+ (median 60.5 micromol L(-1)) and HPLC assays (median 67.5 micromol L(-1)). This positive error decreased during treatment. This was due to a decrease in acetoacetate, as the positive error by the Jaffé method correlated with the acetoacetate concentration (r = 0.79, P < 0.0001). In the multiple regression analysis, beta-hydroxybutyrate caused no additional interference by the Jaffé assay, confirmed by in vitro experiments. Analysis of agreement showed that the difference between PAP+ and HPLC creatinine was -4.6 +/- 3.0 micromol L(-1) (mean +/- SD), and 2.0 +/- 5.3 micromol L(-1) between Serapak and HPLC. This was statistically significant, but clinically negligible. CONCLUSION: Acetoacetate caused severe interference of the alkaline picrate (Jaffé) assay, which might influence therapeutic decisions at the start of diabetic ketoacidosis. Enzymatic assays lack this interference.

Adult↗
PubMed1999

Glomerular filtration rate estimation from plasma creatinine after inhibition of tubular secretion: relevance of the creatinine assay.

BACKGROUND: Estimation of glomerular filtration rate (GFR) from plasma creatinine concentration after inhibition of tubular creatinine secretion with cimetidine provides a good assessment in patients with various nephropathies and with non-insulin-dependent diabetes mellitus (NIDDM). The aim of this study was to compare cimetidine-aided GFR estimations using various creatinine assays. METHODS: In 30 outpatients with NIDDM GFR was measured as the urinary clearance of continuously infused [125I]iothalamate. Plasma creatinine concentration was analysed after oral cimetidine with an alkaline picrate (AP) method, with an enzymatic (PAP) assay and with HPLC. GFR estimations were calculated with the Cockcroft Gault formula (CG). RESULTS: AP creatinine concentrations were significantly higher than PAP or HPLC values. GFR estimations by AP (CG(AP) 66 +/- 19 ml/min/1.73 m2, mean SD) were significantly lower than GFR (89 +/- 30), whereas CG(PAP) (85 +/- 30) and CG(HPLC) (84 +/- 34 ml/min/1.73 m2) were not. Bland and Altman analysis showed a difference between CG(AP) and GFR of -22.4 +/- 17.7 ml/min/1.73 m2; this difference becomes larger when the GFR increases. The difference between CG and GFR was only -3.8 +/- 14.8 ml/min/1.73 m2 for PAP and -4.4 +/- 17.5 ml/min/1.73 m2 for HPLC, without any systematic difference. CONCLUSION: A good assessment of the GFR from plasma creatinine after cimetidine administration is possible when creatinine is measured with an enzymatic assay or with the less convenient HPLC method. The more widespread and cheaper alkaline picrate assay is not suitable for GFR-estimation.

Adult↗
PubMed1999

Preparation of leukodepleted platelet concentrates from pooled buffy coats: prestorage filtration with Autostop BC.

BACKGROUND AND OBJECTIVES: Our requirements for leukocyte-depleted platelet concentrates (LD-PC) for an adult patient are: platelets >240x10(9), leukocytes <5x10(6), volume of 150-400 ml; and at the end of storage a pH between 6.8 and 7.4 and presence of the swirling effect. Our aim was to develop a standardized, semiautomated method for the production of LD-PC, by pooling of buffy coats (BC), and prestorage leukoreduction by filtration. MATERIALS AND METHODS: Whole blood was collected in Top and Bottom systems, and separated automatically with the Compomattrade mark G3 equipment into a red cell concentrate, a plasma and a BC. Subsequently, a pool of 5 BC was made, and 200 g plasma from one of the donors was added. Then, after soft spin centrifugation, the platelet rich plasma was leukocyte depleted by filtration using the Autostoptrade markBC filter, and stored in a 1,000 ml polyolefin platelet storage bag. RESULTS: BC (n = 60) had a volume of 51+/-2 ml (mean +/- SD) with a hematocrit of 0.44+/-0.03 l/l and contained 80+/-5% of the platelets and 74+/-12% of the leukocytes of the whole blood. Routinely prepared LD-PC (n = 15,037) contained a median of 341x10(9) platelets (range 49-599x10(9)), with only 104/15,037 (0.7%) containing fewer than 240x10(9) platelets; the median volume was 263 ml (range 134-373 ml). In 118/917 (13%) LD-PC leukocytes were observed in the Nageotte hemocytometer, but only twice exceeding 1x10(6) leukocytes per unit, and none exceeding 5x10(6) (median <0. 6x10(6); range <0.6-1.41x10(6)). Storage experiments of the LD-PC (n = 12) revealed adequate oxygenation and maintenance of pH and swirling effect up to 9 days. CONCLUSIONS: This method warrants with 99% confidence that LD-PC contain more than 240x10(9) platelets; with 97.5% confidence that 100% of the LD-PC contain <5x10(6) leukocytes, and with 95% confidence that more than 99% of the LD-PC contain fewer than 1x10(6) leukocytes; these LD-PC can be stored satisfactorily for up to 9 days.

Automation↗
PubMed1991

Cerebrospinal fluid tumour markers in patients treated for meningeal malignancy.

The results of cerebrospinal fluid (CSF) biochemical markers were compared with conventional CSF cytology in patients treated for leptomeningeal metastases from extra cranial malignancies. For lumbar CSF, before treatment, no statistically significant difference of the probabilities of being positive was found between CSF cytology and a classification by linear discriminant analysis, based on patient's age, of beta-glucuronidase and beta 2-microglobulin. During treatment, classification by linear discriminant analysis was found more often positive than cytology. Possible mechanisms for this difference are discussed. For ventricular CSF a correlation was found between CSF cytology and beta-glucuronidase for solid tumours, and between CSF cytology and beta 2-microglobulin for haematological malignancies. Reference values for ventricular protein, CEA beta-glucuronidase and beta 2-microglobulin were obtained for cytological negative samples.

Adult↗
PubMed1991

Interferences in current methods for measurements of creatinine.

We measured the interference of carbonyl compounds, drugs, and other substances in human serum on the determination of creatinine by the two-point, fixed-time kinetic modification of the Jaffé reaction as well as by four enzymatic methods. We added known concentrations of the interfering substances to a solution of creatinine in water. For bilirubin, we used both pooled normal sera with added bilirubin and icteric patient sera. The magnitude of interferences varies widely from method to method. Carbonyl compounds, dopamine, cephalosporines, and bilirubin interfere with the Jaffé reaction. Bilirubin, creatine, dopamine, ascorbic acid, and sarcosine interfere with the enzymatic methods. We conclude that the elimination of interferences in the determination of creatinine has still not been achieved.

Blood Chemical Analysis↗
PubMed1989

Serial lumbar and ventricular cerebrospinal fluid biochemical marker measurements in patients with leptomeningeal metastases from solid and hematological tumors.

This study presents results of investigations of lumbar and ventricular cerebrospinal fluid (CSF) biochemical markers (Beta-glucuronidase (B-gluc), Beta-2-microglobulin (B2-m), and carcinoembrionic antigen (CEA] in 28 patients with five different tumor types with leptomeningeal metastasis diagnosed by CSF cytology and/or autopsy. All received methotrexate and radiotherapy at some stage. Decadron or other symptomatic treatments were not used. Measurements of the concentrations of B-gluc, B2-m and CEA were evaluated with the aim of correlating the results of these measurements to site of disease, of monitoring response and early relapse of leptomeningeal disease, and of establishing the duration of survival. In almost all our patients the results of ventricular CSF B-gluc, B2-m and CEA measurements were lower than those obtained from lumbar CSF. The markers did not correlate with site of disease or CSF cytology. A clear relationship was found between pretreatment lumbar CSF B2-m and CEA levels, response to therapy and survival. The markers are also useful for monitoring response. The findings of this study indicate that B2-m and CEA levels have a prognostic value with regard to response to therapy and time of survival.

Adult↗
PubMed1988

Tumour markers in the cerebrospinal fluid of patients with central nervous system metastases from extracranial malignancies.

We have assessed the diagnostic value of the determination of cerebrospinal fluid lactate dehydrogenase, carcinoembryonic antigen, beta 2-microglobulin, beta-glucuronidase and total protein, using linear discriminant analysis, in detecting central nervous system metastases from extracranial malignancies. We conclude that, using these tests, it is impossible to differentiate between control individuals and patients with brain or epidural metastases. Leptomeningeal dissemination from either solid tumours or non-Hodgkin lymphoma could be differentiated from control individuals and patients with brain or epidural metastases. In this differentiation it is essential that bacterial, fungal or tuberculous meningitis be excluded from the differential diagnosis by other diagnostic procedures. The combination of beta-glucuronidase and beta 2-microglobulin provides almost the same diagnostic information as the combination of all parameters.

Age Factors↗
PubMed1988

Routine investigations of the CSF with special reference to meningeal malignancy and infectious meningitis.

Usefulness of cell count and concentrations of glucose and total protein in CSF are analysed with regard to the diagnosis of leptomeningeal metastasis from solid and hematological malignancy. A group of patients with pleiocytosis in CSF of non-neoplastic origin served as a reference group. It is concluded that these routine tests have limited value for the determination of the viral, bacterial or neoplastic etiology of meningeal disorders. The most important value of these tests appears to be the discriminating capacity of the finding of an increased number of polymorphonuclear leucocytes, regularly found in patients with acute bacterial meningitis.

Adolescent↗
PubMed1987

Diagnosis of leptomeningeal metastasis.

Forty-one cases of leptomeningeal metastases from solid and hematological tumours were studied clinically and pathologically. Neurological symptoms and signs, cerebrospinal fluid characteristics and radiographic appearance were reviewed. The role of the biochemical markers, computer tomography scans of the brain and myelography in the diagnosis of patients with leptomeningeal metastasis were determined. The subject of the study was an investigation of the value of various diagnostic procedures to increase the accuracy of the diagnosis leptomeningeal metastasis.

Adult↗
PubMed1987

Serial lumbar and ventricle cerebrospinal fluid lactate dehydrogenase activities in patients with leptomeningeal metastases from solid and haematological tumours.

Lactate dehydrogenase (LDH) activities were measured in cerebrospinal fluid in 350 patients with various neurological diseases to establish the sensitivity and specificity of the CSF LDH as a marker for the diagnosis of leptomeningeal metastases. Slight elevations of CSF LDH were observed in nonmalignant diseases, while marked elevations were observed in a considerable number of patients with bacterial meningitis. A sensitivity of 79% and a specificity of 83% were calculated. In the 34 patients with leptomeningeal metastases from solid and haematological tumours, the LDH in lumbar and ventricular CSF were measured simultaneously. The lumbar CSF LDH concentration in patients with leptomeningeal metastases was about five times greater than that in the ventricular CSF. No relationship was found between the CSF LDH and histology of the primary tumour. A good correlation was demonstrated between the lumbar CSF LDH and the effected area of the neuraxis. Serial determinations of CSF LDH showed a relationship between level changes and responses to therapy or progression. The findings of this study indicate that measurement of LDH in CSF can be used as an adjunctive diagnostic test for leptomeningeal metastases and in monitoring the efficacy of treatment.

Adolescent↗
PubMed1987

Direct kinetic method for the determination of phosphate.

Serum phosphate can be measured accurately, precisely and economically using an initial rate spectrophotometric procedure. This procedure measures the formation of the unreduced phosphomolybdate heteropolyacid complex at 334 nm. The concentration of polyvinylpyrrolidone Mr = 40,000 has been optimised to allow the determination of serum inorganic phosphate on a discrete analyser, the Eppendorf Epos. Possible interference due to hyperlipaemia, high bilirubin or high protein content of the serum samples is discussed.

Humans↗